1	// SPDX-License-Identifier: GPL-2.0+
2	/*
3	* Driver core for serial ports
4	*
5	* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6	*
7	* Copyright 1999 ARM Limited
8	* Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
9	*/
10	#include <linux/module.h>
11	#include <linux/tty.h>
12	#include <linux/tty_flip.h>
13	#include <linux/slab.h>
14	#include <linux/sched/signal.h>
15	#include <linux/init.h>
16	#include <linux/console.h>
17	#include <linux/gpio/consumer.h>
18	#include <linux/kernel.h>
19	#include <linux/of.h>
20	#include <linux/pm_runtime.h>
21	#include <linux/proc_fs.h>
22	#include <linux/seq_file.h>
23	#include <linux/device.h>
24	#include <linux/serial.h> /* for serial_state and serial_icounter_struct */
25	#include <linux/serial_core.h>
26	#include <linux/sysrq.h>
27	#include <linux/delay.h>
28	#include <linux/mutex.h>
29	#include <linux/math64.h>
30	#include <linux/security.h>
31
32	#include <linux/irq.h>
33	#include <linux/uaccess.h>
34
35	#include "serial_base.h"
36
37	/*
38	* This is used to lock changes in serial line configuration.
39	*/
40	static DEFINE_MUTEX(port_mutex);
41
42	/*
43	* lockdep: port->lock is initialized in two places, but we
44	* want only one lock-class:
45	*/
46	static struct lock_class_key port_lock_key;
47
48	#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
49
50	/*
51	* Max time with active RTS before/after data is sent.
52	*/
53	#define RS485_MAX_RTS_DELAY 100 /* msecs */
54
55	static void uart_change_pm(struct uart_state *state,
56	enum uart_pm_state pm_state);
57
58	static void uart_port_shutdown(struct tty_port *port);
59
60	static int uart_dcd_enabled(struct uart_port *uport)
61	{
62	return !!(uport->status & UPSTAT_DCD_ENABLE);
63	}
64
65	static inline struct uart_port *uart_port_ref(struct uart_state *state)
66	{
67	if (atomic_add_unless(v: &state->refcount, a: 1, u: 0))
68	return state->uart_port;
69	return NULL;
70	}
71
72	static inline void uart_port_deref(struct uart_port *uport)
73	{
74	if (atomic_dec_and_test(v: &uport->state->refcount))
75	wake_up(&uport->state->remove_wait);
76	}
77
78	static inline struct uart_port *uart_port_ref_lock(struct uart_state *state, unsigned long *flags)
79	{
80	struct uart_port *uport = uart_port_ref(state);
81
82	if (uport)
83	uart_port_lock_irqsave(up: uport, flags);
84
85	return uport;
86	}
87
88	static inline void uart_port_unlock_deref(struct uart_port *uport, unsigned long flags)
89	{
90	if (uport) {
91	uart_port_unlock_irqrestore(up: uport, flags);
92	uart_port_deref(uport);
93	}
94	}
95
96	static inline struct uart_port *uart_port_check(struct uart_state *state)
97	{
98	lockdep_assert_held(&state->port.mutex);
99	return state->uart_port;
100	}
101
102	/**
103	* uart_write_wakeup - schedule write processing
104	* @port: port to be processed
105	*
106	* This routine is used by the interrupt handler to schedule processing in the
107	* software interrupt portion of the driver. A driver is expected to call this
108	* function when the number of characters in the transmit buffer have dropped
109	* below a threshold.
110	*
111	* Locking: @port->lock should be held
112	*/
113	void uart_write_wakeup(struct uart_port *port)
114	{
115	struct uart_state *state = port->state;
116	/*
117	* This means you called this function _after_ the port was
118	* closed. No cookie for you.
119	*/
120	BUG_ON(!state);
121	tty_port_tty_wakeup(port: &state->port);
122	}
123	EXPORT_SYMBOL(uart_write_wakeup);
124
125	static void uart_stop(struct tty_struct *tty)
126	{
127	struct uart_state *state = tty->driver_data;
128	struct uart_port *port;
129	unsigned long flags;
130
131	port = uart_port_ref_lock(state, flags: &flags);
132	if (port)
133	port->ops->stop_tx(port);
134	uart_port_unlock_deref(uport: port, flags);
135	}
136
137	static void __uart_start(struct uart_state *state)
138	{
139	struct uart_port *port = state->uart_port;
140	struct serial_port_device *port_dev;
141	int err;
142
143	if (!port || port->flags & UPF_DEAD || uart_tx_stopped(port))
144	return;
145
146	port_dev = port->port_dev;
147
148	/* Increment the runtime PM usage count for the active check below */
149	err = pm_runtime_get(dev: &port_dev->dev);
150	if (err < 0 && err != -EINPROGRESS) {
151	pm_runtime_put_noidle(dev: &port_dev->dev);
152	return;
153	}
154
155	/*
156	* Start TX if enabled, and kick runtime PM. If the device is not
157	* enabled, serial_port_runtime_resume() calls start_tx() again
158	* after enabling the device.
159	*/
160	if (!pm_runtime_enabled(dev: port->dev) || pm_runtime_active(dev: &port_dev->dev))
161	port->ops->start_tx(port);
162	pm_runtime_mark_last_busy(dev: &port_dev->dev);
163	pm_runtime_put_autosuspend(dev: &port_dev->dev);
164	}
165
166	static void uart_start(struct tty_struct *tty)
167	{
168	struct uart_state *state = tty->driver_data;
169	struct uart_port *port;
170	unsigned long flags;
171
172	port = uart_port_ref_lock(state, flags: &flags);
173	__uart_start(state);
174	uart_port_unlock_deref(uport: port, flags);
175	}
176
177	static void
178	uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
179	{
180	unsigned int old;
181
182	guard(uart_port_lock_irqsave)(l: port);
183	old = port->mctrl;
184	port->mctrl = (old & ~clear) | set;
185	if (old != port->mctrl && !(port->rs485.flags & SER_RS485_ENABLED))
186	port->ops->set_mctrl(port, port->mctrl);
187	}
188
189	#define uart_set_mctrl(port, set) uart_update_mctrl(port, set, 0)
190	#define uart_clear_mctrl(port, clear) uart_update_mctrl(port, 0, clear)
191
192	static void uart_port_dtr_rts(struct uart_port *uport, bool active)
193	{
194	if (active)
195	uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
196	else
197	uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
198	}
199
200	/* Caller holds port mutex */
201	static void uart_change_line_settings(struct tty_struct *tty, struct uart_state *state,
202	const struct ktermios *old_termios)
203	{
204	struct uart_port *uport = uart_port_check(state);
205	struct ktermios *termios;
206	bool old_hw_stopped;
207
208	/*
209	* If we have no tty, termios, or the port does not exist,
210	* then we can't set the parameters for this port.
211	*/
212	if (!tty || uport->type == PORT_UNKNOWN)
213	return;
214
215	termios = &tty->termios;
216	uport->ops->set_termios(uport, termios, old_termios);
217
218	/*
219	* Set modem status enables based on termios cflag
220	*/
221	guard(uart_port_lock_irq)(T: uport);
222	if (termios->c_cflag & CRTSCTS)
223	uport->status |= UPSTAT_CTS_ENABLE;
224	else
225	uport->status &= ~UPSTAT_CTS_ENABLE;
226
227	if (termios->c_cflag & CLOCAL)
228	uport->status &= ~UPSTAT_DCD_ENABLE;
229	else
230	uport->status |= UPSTAT_DCD_ENABLE;
231
232	/* reset sw-assisted CTS flow control based on (possibly) new mode */
233	old_hw_stopped = uport->hw_stopped;
234	uport->hw_stopped = uart_softcts_mode(uport) &&
235	!(uport->ops->get_mctrl(uport) & TIOCM_CTS);
236	if (uport->hw_stopped != old_hw_stopped) {
237	if (!old_hw_stopped)
238	uport->ops->stop_tx(uport);
239	else
240	__uart_start(state);
241	}
242	}
243
244	static int uart_alloc_xmit_buf(struct tty_port *port)
245	{
246	struct uart_state *state = container_of(port, struct uart_state, port);
247	struct uart_port *uport;
248	unsigned long flags;
249	unsigned long page;
250
251	/*
252	* Initialise and allocate the transmit and temporary
253	* buffer.
254	*/
255	page = get_zeroed_page(GFP_KERNEL);
256	if (!page)
257	return -ENOMEM;
258
259	uport = uart_port_ref_lock(state, flags: &flags);
260	if (!state->port.xmit_buf) {
261	state->port.xmit_buf = (unsigned char *)page;
262	kfifo_init(&state->port.xmit_fifo, state->port.xmit_buf,
263	PAGE_SIZE);
264	uart_port_unlock_deref(uport, flags);
265	} else {
266	uart_port_unlock_deref(uport, flags);
267	/*
268	* Do not free() the page under the port lock, see
269	* uart_free_xmit_buf().
270	*/
271	free_page(page);
272	}
273
274	return 0;
275	}
276
277	static void uart_free_xmit_buf(struct tty_port *port)
278	{
279	struct uart_state *state = container_of(port, struct uart_state, port);
280	struct uart_port *uport;
281	unsigned long flags;
282	char *xmit_buf;
283
284	/*
285	* Do not free() the transmit buffer page under the port lock since
286	* this can create various circular locking scenarios. For instance,
287	* console driver may need to allocate/free a debug object, which
288	* can end up in printk() recursion.
289	*/
290	uport = uart_port_ref_lock(state, flags: &flags);
291	xmit_buf = port->xmit_buf;
292	port->xmit_buf = NULL;
293	INIT_KFIFO(port->xmit_fifo);
294	uart_port_unlock_deref(uport, flags);
295
296	free_page((unsigned long)xmit_buf);
297	}
298
299	/*
300	* Startup the port. This will be called once per open. All calls
301	* will be serialised by the per-port mutex.
302	*/
303	static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
304	bool init_hw)
305	{
306	struct uart_port *uport = uart_port_check(state);
307	int retval;
308
309	if (uport->type == PORT_UNKNOWN)
310	return 1;
311
312	/*
313	* Make sure the device is in D0 state.
314	*/
315	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
316
317	retval = uart_alloc_xmit_buf(port: &state->port);
318	if (retval)
319	return retval;
320
321	retval = uport->ops->startup(uport);
322	if (retval == 0) {
323	if (uart_console(uport) && uport->cons->cflag) {
324	tty->termios.c_cflag = uport->cons->cflag;
325	tty->termios.c_ispeed = uport->cons->ispeed;
326	tty->termios.c_ospeed = uport->cons->ospeed;
327	uport->cons->cflag = 0;
328	uport->cons->ispeed = 0;
329	uport->cons->ospeed = 0;
330	}
331	/*
332	* Initialise the hardware port settings.
333	*/
334	uart_change_line_settings(tty, state, NULL);
335
336	/*
337	* Setup the RTS and DTR signals once the
338	* port is open and ready to respond.
339	*/
340	if (init_hw && C_BAUD(tty))
341	uart_port_dtr_rts(uport, active: true);
342	}
343
344	/*
345	* This is to allow setserial on this port. People may want to set
346	* port/irq/type and then reconfigure the port properly if it failed
347	* now.
348	*/
349	if (retval && capable(CAP_SYS_ADMIN))
350	return 1;
351
352	return retval;
353	}
354
355	static int uart_startup(struct tty_struct *tty, struct uart_state *state,
356	bool init_hw)
357	{
358	struct tty_port *port = &state->port;
359	struct uart_port *uport;
360	int retval;
361
362	if (tty_port_initialized(port))
363	goto out_base_port_startup;
364
365	retval = uart_port_startup(tty, state, init_hw);
366	if (retval) {
367	set_bit(nr: TTY_IO_ERROR, addr: &tty->flags);
368	return retval;
369	}
370
371	out_base_port_startup:
372	uport = uart_port_check(state);
373	if (!uport)
374	return -EIO;
375
376	serial_base_port_startup(port: uport);
377
378	return 0;
379	}
380
381	/*
382	* This routine will shutdown a serial port; interrupts are disabled, and
383	* DTR is dropped if the hangup on close termio flag is on. Calls to
384	* uart_shutdown are serialised by the per-port semaphore.
385	*
386	* uport == NULL if uart_port has already been removed
387	*/
388	static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
389	{
390	struct uart_port *uport = uart_port_check(state);
391	struct tty_port *port = &state->port;
392
393	/*
394	* Set the TTY IO error marker
395	*/
396	if (tty)
397	set_bit(nr: TTY_IO_ERROR, addr: &tty->flags);
398
399	if (uport)
400	serial_base_port_shutdown(port: uport);
401
402	if (tty_port_initialized(port)) {
403	tty_port_set_initialized(port, val: false);
404
405	/*
406	* Turn off DTR and RTS early.
407	*/
408	if (uport) {
409	if (uart_console(uport) && tty) {
410	uport->cons->cflag = tty->termios.c_cflag;
411	uport->cons->ispeed = tty->termios.c_ispeed;
412	uport->cons->ospeed = tty->termios.c_ospeed;
413	}
414
415	if (!tty || C_HUPCL(tty))
416	uart_port_dtr_rts(uport, active: false);
417	}
418
419	uart_port_shutdown(port);
420	}
421
422	/*
423	* It's possible for shutdown to be called after suspend if we get
424	* a DCD drop (hangup) at just the right time. Clear suspended bit so
425	* we don't try to resume a port that has been shutdown.
426	*/
427	tty_port_set_suspended(port, val: false);
428
429	uart_free_xmit_buf(port);
430	}
431
432	/**
433	* uart_update_timeout - update per-port frame timing information
434	* @port: uart_port structure describing the port
435	* @cflag: termios cflag value
436	* @baud: speed of the port
437	*
438	* Set the @port frame timing information from which the FIFO timeout value is
439	* derived. The @cflag value should reflect the actual hardware settings as
440	* number of bits, parity, stop bits and baud rate is taken into account here.
441	*
442	* Locking: caller is expected to take @port->lock
443	*/
444	void
445	uart_update_timeout(struct uart_port *port, unsigned int cflag,
446	unsigned int baud)
447	{
448	u64 temp = tty_get_frame_size(cflag);
449
450	temp *= NSEC_PER_SEC;
451	port->frame_time = (unsigned int)DIV64_U64_ROUND_UP(temp, baud);
452	}
453	EXPORT_SYMBOL(uart_update_timeout);
454
455	/**
456	* uart_get_baud_rate - return baud rate for a particular port
457	* @port: uart_port structure describing the port in question.
458	* @termios: desired termios settings
459	* @old: old termios (or %NULL)
460	* @min: minimum acceptable baud rate
461	* @max: maximum acceptable baud rate
462	*
463	* Decode the termios structure into a numeric baud rate, taking account of the
464	* magic 38400 baud rate (with spd_* flags), and mapping the %B0 rate to 9600
465	* baud.
466	*
467	* If the new baud rate is invalid, try the @old termios setting. If it's still
468	* invalid, we try 9600 baud. If that is also invalid 0 is returned.
469	*
470	* The @termios structure is updated to reflect the baud rate we're actually
471	* going to be using. Don't do this for the case where B0 is requested ("hang
472	* up").
473	*
474	* Locking: caller dependent
475	*/
476	unsigned int
477	uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
478	const struct ktermios *old, unsigned int min, unsigned int max)
479	{
480	unsigned int try;
481	unsigned int baud;
482	unsigned int altbaud;
483	int hung_up = 0;
484	upf_t flags = port->flags & UPF_SPD_MASK;
485
486	switch (flags) {
487	case UPF_SPD_HI:
488	altbaud = 57600;
489	break;
490	case UPF_SPD_VHI:
491	altbaud = 115200;
492	break;
493	case UPF_SPD_SHI:
494	altbaud = 230400;
495	break;
496	case UPF_SPD_WARP:
497	altbaud = 460800;
498	break;
499	default:
500	altbaud = 38400;
501	break;
502	}
503
504	for (try = 0; try < 2; try++) {
505	baud = tty_termios_baud_rate(termios);
506
507	/*
508	* The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
509	* Die! Die! Die!
510	*/
511	if (try == 0 && baud == 38400)
512	baud = altbaud;
513
514	/*
515	* Special case: B0 rate.
516	*/
517	if (baud == 0) {
518	hung_up = 1;
519	baud = 9600;
520	}
521
522	if (baud >= min && baud <= max)
523	return baud;
524
525	/*
526	* Oops, the quotient was zero. Try again with
527	* the old baud rate if possible.
528	*/
529	termios->c_cflag &= ~CBAUD;
530	if (old) {
531	baud = tty_termios_baud_rate(termios: old);
532	if (!hung_up)
533	tty_termios_encode_baud_rate(termios,
534	ibaud: baud, obaud: baud);
535	old = NULL;
536	continue;
537	}
538
539	/*
540	* As a last resort, if the range cannot be met then clip to
541	* the nearest chip supported rate.
542	*/
543	if (!hung_up) {
544	if (baud <= min)
545	tty_termios_encode_baud_rate(termios,
546	ibaud: min + 1, obaud: min + 1);
547	else
548	tty_termios_encode_baud_rate(termios,
549	ibaud: max - 1, obaud: max - 1);
550	}
551	}
552	return 0;
553	}
554	EXPORT_SYMBOL(uart_get_baud_rate);
555
556	/**
557	* uart_get_divisor - return uart clock divisor
558	* @port: uart_port structure describing the port
559	* @baud: desired baud rate
560	*
561	* Calculate the divisor (baud_base / baud) for the specified @baud,
562	* appropriately rounded.
563	*
564	* If 38400 baud and custom divisor is selected, return the custom divisor
565	* instead.
566	*
567	* Locking: caller dependent
568	*/
569	unsigned int
570	uart_get_divisor(struct uart_port *port, unsigned int baud)
571	{
572	unsigned int quot;
573
574	/*
575	* Old custom speed handling.
576	*/
577	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
578	quot = port->custom_divisor;
579	else
580	quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);
581
582	return quot;
583	}
584	EXPORT_SYMBOL(uart_get_divisor);
585
586	static int uart_put_char(struct tty_struct *tty, u8 c)
587	{
588	struct uart_state *state = tty->driver_data;
589	struct uart_port *port;
590	unsigned long flags;
591	int ret = 0;
592
593	port = uart_port_ref_lock(state, flags: &flags);
594	if (!state->port.xmit_buf) {
595	uart_port_unlock_deref(uport: port, flags);
596	return 0;
597	}
598
599	if (port)
600	ret = kfifo_put(&state->port.xmit_fifo, c);
601	uart_port_unlock_deref(uport: port, flags);
602	return ret;
603	}
604
605	static void uart_flush_chars(struct tty_struct *tty)
606	{
607	uart_start(tty);
608	}
609
610	static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count)
611	{
612	struct uart_state *state = tty->driver_data;
613	struct uart_port *port;
614	unsigned long flags;
615	int ret = 0;
616
617	/*
618	* This means you called this function _after_ the port was
619	* closed. No cookie for you.
620	*/
621	if (WARN_ON(!state))
622	return -EL3HLT;
623
624	port = uart_port_ref_lock(state, flags: &flags);
625	if (!state->port.xmit_buf) {
626	uart_port_unlock_deref(uport: port, flags);
627	return 0;
628	}
629
630	if (port)
631	ret = kfifo_in(&state->port.xmit_fifo, buf, count);
632
633	__uart_start(state);
634	uart_port_unlock_deref(uport: port, flags);
635	return ret;
636	}
637
638	static unsigned int uart_write_room(struct tty_struct *tty)
639	{
640	struct uart_state *state = tty->driver_data;
641	struct uart_port *port;
642	unsigned long flags;
643	unsigned int ret;
644
645	port = uart_port_ref_lock(state, flags: &flags);
646	ret = kfifo_avail(&state->port.xmit_fifo);
647	uart_port_unlock_deref(uport: port, flags);
648	return ret;
649	}
650
651	static unsigned int uart_chars_in_buffer(struct tty_struct *tty)
652	{
653	struct uart_state *state = tty->driver_data;
654	struct uart_port *port;
655	unsigned long flags;
656	unsigned int ret;
657
658	port = uart_port_ref_lock(state, flags: &flags);
659	ret = kfifo_len(&state->port.xmit_fifo);
660	uart_port_unlock_deref(uport: port, flags);
661	return ret;
662	}
663
664	static void uart_flush_buffer(struct tty_struct *tty)
665	{
666	struct uart_state *state = tty->driver_data;
667	struct uart_port *port;
668	unsigned long flags;
669
670	/*
671	* This means you called this function _after_ the port was
672	* closed. No cookie for you.
673	*/
674	if (WARN_ON(!state))
675	return;
676
677	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
678
679	port = uart_port_ref_lock(state, flags: &flags);
680	if (!port)
681	return;
682	kfifo_reset(&state->port.xmit_fifo);
683	if (port->ops->flush_buffer)
684	port->ops->flush_buffer(port);
685	uart_port_unlock_deref(uport: port, flags);
686	tty_port_tty_wakeup(port: &state->port);
687	}
688
689	/*
690	* This function performs low-level write of high-priority XON/XOFF
691	* character and accounting for it.
692	*
693	* Requires uart_port to implement .serial_out().
694	*/
695	void uart_xchar_out(struct uart_port *uport, int offset)
696	{
697	serial_port_out(up: uport, offset, value: uport->x_char);
698	uport->icount.tx++;
699	uport->x_char = 0;
700	}
701	EXPORT_SYMBOL_GPL(uart_xchar_out);
702
703	/*
704	* This function is used to send a high-priority XON/XOFF character to
705	* the device
706	*/
707	static void uart_send_xchar(struct tty_struct *tty, u8 ch)
708	{
709	struct uart_state *state = tty->driver_data;
710	struct uart_port *port;
711
712	port = uart_port_ref(state);
713	if (!port)
714	return;
715
716	if (port->ops->send_xchar)
717	port->ops->send_xchar(port, ch);
718	else {
719	guard(uart_port_lock_irqsave)(l: port);
720	port->x_char = ch;
721	if (ch)
722	port->ops->start_tx(port);
723	}
724	uart_port_deref(uport: port);
725	}
726
727	static void uart_throttle(struct tty_struct *tty)
728	{
729	struct uart_state *state = tty->driver_data;
730	upstat_t mask = UPSTAT_SYNC_FIFO;
731	struct uart_port *port;
732
733	port = uart_port_ref(state);
734	if (!port)
735	return;
736
737	if (I_IXOFF(tty))
738	mask |= UPSTAT_AUTOXOFF;
739	if (C_CRTSCTS(tty))
740	mask |= UPSTAT_AUTORTS;
741
742	if (port->status & mask) {
743	port->ops->throttle(port);
744	mask &= ~port->status;
745	}
746
747	if (mask & UPSTAT_AUTORTS)
748	uart_clear_mctrl(port, TIOCM_RTS);
749
750	if (mask & UPSTAT_AUTOXOFF)
751	uart_send_xchar(tty, STOP_CHAR(tty));
752
753	uart_port_deref(uport: port);
754	}
755
756	static void uart_unthrottle(struct tty_struct *tty)
757	{
758	struct uart_state *state = tty->driver_data;
759	upstat_t mask = UPSTAT_SYNC_FIFO;
760	struct uart_port *port;
761
762	port = uart_port_ref(state);
763	if (!port)
764	return;
765
766	if (I_IXOFF(tty))
767	mask |= UPSTAT_AUTOXOFF;
768	if (C_CRTSCTS(tty))
769	mask |= UPSTAT_AUTORTS;
770
771	if (port->status & mask) {
772	port->ops->unthrottle(port);
773	mask &= ~port->status;
774	}
775
776	if (mask & UPSTAT_AUTORTS)
777	uart_set_mctrl(port, TIOCM_RTS);
778
779	if (mask & UPSTAT_AUTOXOFF)
780	uart_send_xchar(tty, START_CHAR(tty));
781
782	uart_port_deref(uport: port);
783	}
784
785	static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
786	{
787	struct uart_state *state = container_of(port, struct uart_state, port);
788	struct uart_port *uport;
789
790	/* Initialize structure in case we error out later to prevent any stack info leakage. */
791	*retinfo = (struct serial_struct){};
792
793	/*
794	* Ensure the state we copy is consistent and no hardware changes
795	* occur as we go
796	*/
797	guard(mutex)(T: &port->mutex);
798	uport = uart_port_check(state);
799	if (!uport)
800	return -ENODEV;
801
802	retinfo->type = uport->type;
803	retinfo->line = uport->line;
804	retinfo->port = uport->iobase;
805	if (HIGH_BITS_OFFSET)
806	retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
807	retinfo->irq = uport->irq;
808	retinfo->flags = (__force int)uport->flags;
809	retinfo->xmit_fifo_size = uport->fifosize;
810	retinfo->baud_base = uport->uartclk / 16;
811	retinfo->close_delay = jiffies_to_msecs(j: port->close_delay) / 10;
812	retinfo->closing_wait = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
813	ASYNC_CLOSING_WAIT_NONE :
814	jiffies_to_msecs(j: port->closing_wait) / 10;
815	retinfo->custom_divisor = uport->custom_divisor;
816	retinfo->hub6 = uport->hub6;
817	retinfo->io_type = uport->iotype;
818	retinfo->iomem_reg_shift = uport->regshift;
819	retinfo->iomem_base = (void *)(unsigned long)uport->mapbase;
820
821	return 0;
822	}
823
824	static int uart_get_info_user(struct tty_struct *tty,
825	struct serial_struct *ss)
826	{
827	struct uart_state *state = tty->driver_data;
828	struct tty_port *port = &state->port;
829
830	return uart_get_info(port, retinfo: ss) < 0 ? -EIO : 0;
831	}
832
833	static int uart_change_port(struct uart_port *uport,
834	const struct serial_struct *new_info,
835	unsigned long new_port)
836	{
837	unsigned long old_iobase, old_mapbase;
838	unsigned int old_type, old_iotype, old_hub6, old_shift;
839	int retval;
840
841	old_iobase = uport->iobase;
842	old_mapbase = uport->mapbase;
843	old_type = uport->type;
844	old_hub6 = uport->hub6;
845	old_iotype = uport->iotype;
846	old_shift = uport->regshift;
847
848	if (old_type != PORT_UNKNOWN && uport->ops->release_port)
849	uport->ops->release_port(uport);
850
851	uport->iobase = new_port;
852	uport->type = new_info->type;
853	uport->hub6 = new_info->hub6;
854	uport->iotype = new_info->io_type;
855	uport->regshift = new_info->iomem_reg_shift;
856	uport->mapbase = (unsigned long)new_info->iomem_base;
857
858	if (uport->type == PORT_UNKNOWN || !uport->ops->request_port)
859	return 0;
860
861	retval = uport->ops->request_port(uport);
862	if (retval == 0)
863	return 0; /* succeeded => done */
864
865	/*
866	* If we fail to request resources for the new port, try to restore the
867	* old settings.
868	*/
869	uport->iobase = old_iobase;
870	uport->type = old_type;
871	uport->hub6 = old_hub6;
872	uport->iotype = old_iotype;
873	uport->regshift = old_shift;
874	uport->mapbase = old_mapbase;
875
876	if (old_type == PORT_UNKNOWN)
877	return retval;
878
879	retval = uport->ops->request_port(uport);
880	/* If we failed to restore the old settings, we fail like this. */
881	if (retval)
882	uport->type = PORT_UNKNOWN;
883
884	/* We failed anyway. */
885	return -EBUSY;
886	}
887
888	static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
889	struct uart_state *state,
890	struct serial_struct *new_info)
891	{
892	struct uart_port *uport = uart_port_check(state);
893	unsigned long new_port;
894	unsigned int old_custom_divisor, close_delay, closing_wait;
895	bool change_irq, change_port;
896	upf_t old_flags, new_flags;
897	int retval;
898
899	if (!uport)
900	return -EIO;
901
902	new_port = new_info->port;
903	if (HIGH_BITS_OFFSET)
904	new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
905
906	new_info->irq = irq_canonicalize(irq: new_info->irq);
907	close_delay = msecs_to_jiffies(m: new_info->close_delay * 10);
908	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
909	ASYNC_CLOSING_WAIT_NONE :
910	msecs_to_jiffies(m: new_info->closing_wait * 10);
911
912
913	change_irq = !(uport->flags & UPF_FIXED_PORT)
914	&& new_info->irq != uport->irq;
915
916	/*
917	* Since changing the 'type' of the port changes its resource
918	* allocations, we should treat type changes the same as
919	* IO port changes.
920	*/
921	change_port = !(uport->flags & UPF_FIXED_PORT)
922	&& (new_port != uport->iobase ||
923	(unsigned long)new_info->iomem_base != uport->mapbase ||
924	new_info->hub6 != uport->hub6 ||
925	new_info->io_type != uport->iotype ||
926	new_info->iomem_reg_shift != uport->regshift ||
927	new_info->type != uport->type);
928
929	old_flags = uport->flags;
930	new_flags = (__force upf_t)new_info->flags;
931	old_custom_divisor = uport->custom_divisor;
932
933	if (!(uport->flags & UPF_FIXED_PORT)) {
934	unsigned int uartclk = new_info->baud_base * 16;
935	/* check needs to be done here before other settings made */
936	if (uartclk == 0)
937	return -EINVAL;
938	}
939	if (!capable(CAP_SYS_ADMIN)) {
940	if (change_irq || change_port ||
941	(new_info->baud_base != uport->uartclk / 16) ||
942	(close_delay != port->close_delay) ||
943	(closing_wait != port->closing_wait) ||
944	(new_info->xmit_fifo_size &&
945	new_info->xmit_fifo_size != uport->fifosize) ||
946	(((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
947	return -EPERM;
948	uport->flags = ((uport->flags & ~UPF_USR_MASK) |
949	(new_flags & UPF_USR_MASK));
950	uport->custom_divisor = new_info->custom_divisor;
951	goto check_and_exit;
952	}
953
954	if (change_irq || change_port) {
955	retval = security_locked_down(what: LOCKDOWN_TIOCSSERIAL);
956	if (retval)
957	return retval;
958	}
959
960	/* Ask the low level driver to verify the settings. */
961	if (uport->ops->verify_port) {
962	retval = uport->ops->verify_port(uport, new_info);
963	if (retval)
964	return retval;
965	}
966
967	if ((new_info->irq >= irq_get_nr_irqs()) || (new_info->irq < 0) ||
968	(new_info->baud_base < 9600))
969	return -EINVAL;
970
971	if (change_port || change_irq) {
972	/* Make sure that we are the sole user of this port. */
973	if (tty_port_users(port) > 1)
974	return -EBUSY;
975
976	/*
977	* We need to shutdown the serial port at the old
978	* port/type/irq combination.
979	*/
980	uart_shutdown(tty, state);
981	}
982
983	if (change_port) {
984	retval = uart_change_port(uport, new_info, new_port);
985	if (retval)
986	return retval;
987	}
988
989	if (change_irq)
990	uport->irq = new_info->irq;
991	if (!(uport->flags & UPF_FIXED_PORT))
992	uport->uartclk = new_info->baud_base * 16;
993	uport->flags = (uport->flags & ~UPF_CHANGE_MASK) |
994	(new_flags & UPF_CHANGE_MASK);
995	uport->custom_divisor = new_info->custom_divisor;
996	port->close_delay = close_delay;
997	port->closing_wait = closing_wait;
998	if (new_info->xmit_fifo_size)
999	uport->fifosize = new_info->xmit_fifo_size;
1000
1001	check_and_exit:
1002	if (uport->type == PORT_UNKNOWN)
1003	return 0;
1004
1005	if (tty_port_initialized(port)) {
1006	if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
1007	old_custom_divisor != uport->custom_divisor) {
1008	/*
1009	* If they're setting up a custom divisor or speed,
1010	* instead of clearing it, then bitch about it.
1011	*/
1012	if (uport->flags & UPF_SPD_MASK) {
1013	dev_notice_ratelimited(uport->dev,
1014	"%s sets custom speed on %s. This is deprecated.\n",
1015	current->comm,
1016	tty_name(port->tty));
1017	}
1018	uart_change_line_settings(tty, state, NULL);
1019	}
1020
1021	return 0;
1022	}
1023
1024	retval = uart_startup(tty, state, init_hw: true);
1025	if (retval < 0)
1026	return retval;
1027	if (retval == 0)
1028	tty_port_set_initialized(port, val: true);
1029
1030	return 0;
1031	}
1032
1033	static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
1034	{
1035	struct uart_state *state = tty->driver_data;
1036	struct tty_port *port = &state->port;
1037
1038	guard(rwsem_write)(T: &tty->termios_rwsem);
1039	/*
1040	* This semaphore protects port->count. It is also
1041	* very useful to prevent opens. Also, take the
1042	* port configuration semaphore to make sure that a
1043	* module insertion/removal doesn't change anything
1044	* under us.
1045	*/
1046	guard(mutex)(T: &port->mutex);
1047	return uart_set_info(tty, port, state, new_info: ss);
1048	}
1049
1050	/**
1051	* uart_get_lsr_info - get line status register info
1052	* @tty: tty associated with the UART
1053	* @state: UART being queried
1054	* @value: returned modem value
1055	*/
1056	static int uart_get_lsr_info(struct tty_struct *tty,
1057	struct uart_state *state, unsigned int __user *value)
1058	{
1059	struct uart_port *uport = uart_port_check(state);
1060	unsigned int result;
1061
1062	result = uport->ops->tx_empty(uport);
1063
1064	/*
1065	* If we're about to load something into the transmit
1066	* register, we'll pretend the transmitter isn't empty to
1067	* avoid a race condition (depending on when the transmit
1068	* interrupt happens).
1069	*/
1070	if (uport->x_char ||
1071	(!kfifo_is_empty(&state->port.xmit_fifo) &&
1072	!uart_tx_stopped(port: uport)))
1073	result &= ~TIOCSER_TEMT;
1074
1075	return put_user(result, value);
1076	}
1077
1078	static int uart_tiocmget(struct tty_struct *tty)
1079	{
1080	struct uart_state *state = tty->driver_data;
1081	struct tty_port *port = &state->port;
1082	struct uart_port *uport;
1083
1084	guard(mutex)(T: &port->mutex);
1085
1086	uport = uart_port_check(state);
1087	if (!uport || tty_io_error(tty))
1088	return -EIO;
1089
1090	guard(uart_port_lock_irq)(T: uport);
1091
1092	return uport->mctrl | uport->ops->get_mctrl(uport);
1093	}
1094
1095	static int
1096	uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
1097	{
1098	struct uart_state *state = tty->driver_data;
1099	struct tty_port *port = &state->port;
1100	struct uart_port *uport;
1101
1102	guard(mutex)(T: &port->mutex);
1103
1104	uport = uart_port_check(state);
1105	if (!uport || tty_io_error(tty))
1106	return -EIO;
1107
1108	uart_update_mctrl(port: uport, set, clear);
1109
1110	return 0;
1111	}
1112
1113	static int uart_break_ctl(struct tty_struct *tty, int break_state)
1114	{
1115	struct uart_state *state = tty->driver_data;
1116	struct tty_port *port = &state->port;
1117	struct uart_port *uport;
1118
1119	guard(mutex)(T: &port->mutex);
1120
1121	uport = uart_port_check(state);
1122	if (!uport)
1123	return -EIO;
1124
1125	if (uport->type != PORT_UNKNOWN && uport->ops->break_ctl)
1126	uport->ops->break_ctl(uport, break_state);
1127
1128	return 0;
1129	}
1130
1131	static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state)
1132	{
1133	struct tty_port *port = &state->port;
1134	struct uart_port *uport;
1135	int flags, ret;
1136
1137	if (!capable(CAP_SYS_ADMIN))
1138	return -EPERM;
1139
1140	/*
1141	* Take the per-port semaphore. This prevents count from
1142	* changing, and hence any extra opens of the port while
1143	* we're auto-configuring.
1144	*/
1145	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &port->mutex) {
1146	uport = uart_port_check(state);
1147	if (!uport)
1148	return -EIO;
1149
1150	if (tty_port_users(port) != 1)
1151	return -EBUSY;
1152
1153	uart_shutdown(tty, state);
1154
1155	/*
1156	* If we already have a port type configured,
1157	* we must release its resources.
1158	*/
1159	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
1160	uport->ops->release_port(uport);
1161
1162	flags = UART_CONFIG_TYPE;
1163	if (uport->flags & UPF_AUTO_IRQ)
1164	flags |= UART_CONFIG_IRQ;
1165
1166	/*
1167	* This will claim the ports resources if
1168	* a port is found.
1169	*/
1170	uport->ops->config_port(uport, flags);
1171
1172	ret = uart_startup(tty, state, init_hw: true);
1173	if (ret < 0)
1174	return ret;
1175	if (ret > 0)
1176	return 0;
1177
1178	tty_port_set_initialized(port, val: true);
1179	}
1180
1181	return 0;
1182	}
1183
1184	static void uart_enable_ms(struct uart_port *uport)
1185	{
1186	/*
1187	* Force modem status interrupts on
1188	*/
1189	if (uport->ops->enable_ms)
1190	uport->ops->enable_ms(uport);
1191	}
1192
1193	/*
1194	* Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
1195	* - mask passed in arg for lines of interest
1196	* (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
1197	* Caller should use TIOCGICOUNT to see which one it was
1198	*
1199	* FIXME: This wants extracting into a common all driver implementation
1200	* of TIOCMWAIT using tty_port.
1201	*/
1202	static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
1203	{
1204	struct uart_port *uport;
1205	struct tty_port *port = &state->port;
1206	DECLARE_WAITQUEUE(wait, current);
1207	struct uart_icount cprev, cnow;
1208	int ret;
1209
1210	/*
1211	* note the counters on entry
1212	*/
1213	uport = uart_port_ref(state);
1214	if (!uport)
1215	return -EIO;
1216	scoped_guard(uart_port_lock_irq, uport) {
1217	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
1218	uart_enable_ms(uport);
1219	}
1220
1221	add_wait_queue(wq_head: &port->delta_msr_wait, wq_entry: &wait);
1222	for (;;) {
1223	scoped_guard(uart_port_lock_irq, uport)
1224	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1225
1226	set_current_state(TASK_INTERRUPTIBLE);
1227
1228	if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
1229	((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
1230	((arg & TIOCM_CD) && (cnow.dcd != cprev.dcd)) ||
1231	((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
1232	ret = 0;
1233	break;
1234	}
1235
1236	schedule();
1237
1238	/* see if a signal did it */
1239	if (signal_pending(current)) {
1240	ret = -ERESTARTSYS;
1241	break;
1242	}
1243
1244	cprev = cnow;
1245	}
1246	__set_current_state(TASK_RUNNING);
1247	remove_wait_queue(wq_head: &port->delta_msr_wait, wq_entry: &wait);
1248	uart_port_deref(uport);
1249
1250	return ret;
1251	}
1252
1253	/*
1254	* Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
1255	* Return: write counters to the user passed counter struct
1256	* NB: both 1->0 and 0->1 transitions are counted except for
1257	* RI where only 0->1 is counted.
1258	*/
1259	static int uart_get_icount(struct tty_struct *tty,
1260	struct serial_icounter_struct *icount)
1261	{
1262	struct uart_state *state = tty->driver_data;
1263	struct uart_icount cnow;
1264	struct uart_port *uport;
1265	unsigned long flags;
1266
1267	uport = uart_port_ref_lock(state, flags: &flags);
1268	if (!uport)
1269	return -EIO;
1270	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1271	uart_port_unlock_deref(uport, flags);
1272
1273	icount->cts = cnow.cts;
1274	icount->dsr = cnow.dsr;
1275	icount->rng = cnow.rng;
1276	icount->dcd = cnow.dcd;
1277	icount->rx = cnow.rx;
1278	icount->tx = cnow.tx;
1279	icount->frame = cnow.frame;
1280	icount->overrun = cnow.overrun;
1281	icount->parity = cnow.parity;
1282	icount->brk = cnow.brk;
1283	icount->buf_overrun = cnow.buf_overrun;
1284
1285	return 0;
1286	}
1287
1288	#define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
1289	SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
1290	SER_RS485_TERMINATE_BUS)
1291
1292	static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
1293	{
1294	u32 flags = rs485->flags;
1295
1296	/* Don't return -EINVAL for unsupported legacy flags */
1297	flags &= ~SER_RS485_LEGACY_FLAGS;
1298
1299	/*
1300	* For any bit outside of the legacy ones that is not supported by
1301	* the driver, return -EINVAL.
1302	*/
1303	if (flags & ~port->rs485_supported.flags)
1304	return -EINVAL;
1305
1306	/* Asking for address w/o addressing mode? */
1307	if (!(rs485->flags & SER_RS485_ADDRB) &&
1308	(rs485->flags & (SER_RS485_ADDR_RECV|SER_RS485_ADDR_DEST)))
1309	return -EINVAL;
1310
1311	/* Address given but not enabled? */
1312	if (!(rs485->flags & SER_RS485_ADDR_RECV) && rs485->addr_recv)
1313	return -EINVAL;
1314	if (!(rs485->flags & SER_RS485_ADDR_DEST) && rs485->addr_dest)
1315	return -EINVAL;
1316
1317	return 0;
1318	}
1319
1320	static void uart_sanitize_serial_rs485_delays(struct uart_port *port,
1321	struct serial_rs485 *rs485)
1322	{
1323	if (!port->rs485_supported.delay_rts_before_send) {
1324	if (rs485->delay_rts_before_send) {
1325	dev_warn_ratelimited(port->dev,
1326	"%s (%u): RTS delay before sending not supported\n",
1327	port->name, port->line);
1328	}
1329	rs485->delay_rts_before_send = 0;
1330	} else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
1331	rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY;
1332	dev_warn_ratelimited(port->dev,
1333	"%s (%u): RTS delay before sending clamped to %u ms\n",
1334	port->name, port->line, rs485->delay_rts_before_send);
1335	}
1336
1337	if (!port->rs485_supported.delay_rts_after_send) {
1338	if (rs485->delay_rts_after_send) {
1339	dev_warn_ratelimited(port->dev,
1340	"%s (%u): RTS delay after sending not supported\n",
1341	port->name, port->line);
1342	}
1343	rs485->delay_rts_after_send = 0;
1344	} else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
1345	rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY;
1346	dev_warn_ratelimited(port->dev,
1347	"%s (%u): RTS delay after sending clamped to %u ms\n",
1348	port->name, port->line, rs485->delay_rts_after_send);
1349	}
1350	}
1351
1352	static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
1353	{
1354	u32 supported_flags = port->rs485_supported.flags;
1355
1356	if (!(rs485->flags & SER_RS485_ENABLED)) {
1357	memset(rs485, 0, sizeof(*rs485));
1358	return;
1359	}
1360
1361	/* Clear other RS485 flags but SER_RS485_TERMINATE_BUS and return if enabling RS422 */
1362	if (rs485->flags & SER_RS485_MODE_RS422) {
1363	rs485->flags &= (SER_RS485_ENABLED | SER_RS485_MODE_RS422 | SER_RS485_TERMINATE_BUS);
1364	return;
1365	}
1366
1367	rs485->flags &= supported_flags;
1368
1369	/* Pick sane settings if the user hasn't */
1370	if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
1371	!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
1372	if (supported_flags & SER_RS485_RTS_ON_SEND) {
1373	rs485->flags |= SER_RS485_RTS_ON_SEND;
1374	rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
1375
1376	dev_warn_ratelimited(port->dev,
1377	"%s (%u): invalid RTS setting, using RTS_ON_SEND instead\n",
1378	port->name, port->line);
1379	} else {
1380	rs485->flags |= SER_RS485_RTS_AFTER_SEND;
1381	rs485->flags &= ~SER_RS485_RTS_ON_SEND;
1382
1383	dev_warn_ratelimited(port->dev,
1384	"%s (%u): invalid RTS setting, using RTS_AFTER_SEND instead\n",
1385	port->name, port->line);
1386	}
1387	}
1388
1389	uart_sanitize_serial_rs485_delays(port, rs485);
1390
1391	/* Return clean padding area to userspace */
1392	memset(rs485->padding0, 0, sizeof(rs485->padding0));
1393	memset(rs485->padding1, 0, sizeof(rs485->padding1));
1394	}
1395
1396	static void uart_set_rs485_termination(struct uart_port *port,
1397	const struct serial_rs485 *rs485)
1398	{
1399	if (!(rs485->flags & SER_RS485_ENABLED))
1400	return;
1401
1402	gpiod_set_value_cansleep(desc: port->rs485_term_gpio,
1403	value: !!(rs485->flags & SER_RS485_TERMINATE_BUS));
1404	}
1405
1406	static void uart_set_rs485_rx_during_tx(struct uart_port *port,
1407	const struct serial_rs485 *rs485)
1408	{
1409	if (!(rs485->flags & SER_RS485_ENABLED))
1410	return;
1411
1412	gpiod_set_value_cansleep(desc: port->rs485_rx_during_tx_gpio,
1413	value: !!(rs485->flags & SER_RS485_RX_DURING_TX));
1414	}
1415
1416	static int uart_rs485_config(struct uart_port *port)
1417	{
1418	struct serial_rs485 *rs485 = &port->rs485;
1419	int ret;
1420
1421	if (!(rs485->flags & SER_RS485_ENABLED))
1422	return 0;
1423
1424	uart_sanitize_serial_rs485(port, rs485);
1425	uart_set_rs485_termination(port, rs485);
1426	uart_set_rs485_rx_during_tx(port, rs485);
1427
1428	scoped_guard(uart_port_lock_irqsave, port)
1429	ret = port->rs485_config(port, NULL, rs485);
1430	if (ret) {
1431	memset(rs485, 0, sizeof(*rs485));
1432	/* unset GPIOs */
1433	gpiod_set_value_cansleep(desc: port->rs485_term_gpio, value: 0);
1434	gpiod_set_value_cansleep(desc: port->rs485_rx_during_tx_gpio, value: 0);
1435	}
1436
1437	return ret;
1438	}
1439
1440	static int uart_get_rs485_config(struct uart_port *port,
1441	struct serial_rs485 __user *rs485)
1442	{
1443	struct serial_rs485 aux;
1444
1445	scoped_guard(uart_port_lock_irqsave, port)
1446	aux = port->rs485;
1447
1448	if (copy_to_user(to: rs485, from: &aux, n: sizeof(aux)))
1449	return -EFAULT;
1450
1451	return 0;
1452	}
1453
1454	static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
1455	struct serial_rs485 __user *rs485_user)
1456	{
1457	struct serial_rs485 rs485;
1458	int ret;
1459
1460	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
1461	return -ENOTTY;
1462
1463	if (copy_from_user(to: &rs485, from: rs485_user, n: sizeof(*rs485_user)))
1464	return -EFAULT;
1465
1466	ret = uart_check_rs485_flags(port, rs485: &rs485);
1467	if (ret)
1468	return ret;
1469	uart_sanitize_serial_rs485(port, rs485: &rs485);
1470	uart_set_rs485_termination(port, rs485: &rs485);
1471	uart_set_rs485_rx_during_tx(port, rs485: &rs485);
1472
1473	scoped_guard(uart_port_lock_irqsave, port) {
1474	ret = port->rs485_config(port, &tty->termios, &rs485);
1475	if (!ret) {
1476	port->rs485 = rs485;
1477
1478	/* Reset RTS and other mctrl lines when disabling RS485 */
1479	if (!(rs485.flags & SER_RS485_ENABLED))
1480	port->ops->set_mctrl(port, port->mctrl);
1481	}
1482	}
1483	if (ret) {
1484	/* restore old GPIO settings */
1485	gpiod_set_value_cansleep(desc: port->rs485_term_gpio,
1486	value: !!(port->rs485.flags & SER_RS485_TERMINATE_BUS));
1487	gpiod_set_value_cansleep(desc: port->rs485_rx_during_tx_gpio,
1488	value: !!(port->rs485.flags & SER_RS485_RX_DURING_TX));
1489	return ret;
1490	}
1491
1492	if (copy_to_user(to: rs485_user, from: &port->rs485, n: sizeof(port->rs485)))
1493	return -EFAULT;
1494
1495	return 0;
1496	}
1497
1498	static int uart_get_iso7816_config(struct uart_port *port,
1499	struct serial_iso7816 __user *iso7816)
1500	{
1501	struct serial_iso7816 aux;
1502
1503	if (!port->iso7816_config)
1504	return -ENOTTY;
1505
1506	scoped_guard(uart_port_lock_irqsave, port)
1507	aux = port->iso7816;
1508
1509	if (copy_to_user(to: iso7816, from: &aux, n: sizeof(aux)))
1510	return -EFAULT;
1511
1512	return 0;
1513	}
1514
1515	static int uart_set_iso7816_config(struct uart_port *port,
1516	struct serial_iso7816 __user *iso7816_user)
1517	{
1518	struct serial_iso7816 iso7816;
1519	int i;
1520
1521	if (!port->iso7816_config)
1522	return -ENOTTY;
1523
1524	if (copy_from_user(to: &iso7816, from: iso7816_user, n: sizeof(*iso7816_user)))
1525	return -EFAULT;
1526
1527	/*
1528	* There are 5 words reserved for future use. Check that userspace
1529	* doesn't put stuff in there to prevent breakages in the future.
1530	*/
1531	for (i = 0; i < ARRAY_SIZE(iso7816.reserved); i++)
1532	if (iso7816.reserved[i])
1533	return -EINVAL;
1534
1535	scoped_guard(uart_port_lock_irqsave, port) {
1536	int ret = port->iso7816_config(port, &iso7816);
1537	if (ret)
1538	return ret;
1539	}
1540
1541	if (copy_to_user(to: iso7816_user, from: &port->iso7816, n: sizeof(port->iso7816)))
1542	return -EFAULT;
1543
1544	return 0;
1545	}
1546
1547	/*
1548	* Called via sys_ioctl. We can use spin_lock_irq() here.
1549	*/
1550	static int
1551	uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
1552	{
1553	struct uart_state *state = tty->driver_data;
1554	struct tty_port *port = &state->port;
1555	struct uart_port *uport;
1556	void __user *uarg = (void __user *)arg;
1557	int ret = -ENOIOCTLCMD;
1558
1559	/* This ioctl doesn't rely on the hardware to be present. */
1560	if (cmd == TIOCSERCONFIG) {
1561	guard(rwsem_write)(T: &tty->termios_rwsem);
1562	return uart_do_autoconfig(tty, state);
1563	}
1564
1565	if (tty_io_error(tty))
1566	return -EIO;
1567
1568	/* This should only be used when the hardware is present. */
1569	if (cmd == TIOCMIWAIT)
1570	return uart_wait_modem_status(state, arg);
1571
1572	/* rs485_config requires more locking than others */
1573	if (cmd == TIOCSRS485)
1574	down_write(sem: &tty->termios_rwsem);
1575
1576	scoped_guard(mutex, &port->mutex) {
1577	uport = uart_port_check(state);
1578
1579	if (!uport || tty_io_error(tty)) {
1580	ret = -EIO;
1581	break;
1582	}
1583
1584	/*
1585	* All these rely on hardware being present and need to be
1586	* protected against the tty being hung up.
1587	*/
1588
1589	switch (cmd) {
1590	case TIOCSERGETLSR: /* Get line status register */
1591	ret = uart_get_lsr_info(tty, state, value: uarg);
1592	break;
1593
1594	case TIOCGRS485:
1595	ret = uart_get_rs485_config(port: uport, rs485: uarg);
1596	break;
1597
1598	case TIOCSRS485:
1599	ret = uart_set_rs485_config(tty, port: uport, rs485_user: uarg);
1600	break;
1601
1602	case TIOCSISO7816:
1603	ret = uart_set_iso7816_config(port: state->uart_port, iso7816_user: uarg);
1604	break;
1605
1606	case TIOCGISO7816:
1607	ret = uart_get_iso7816_config(port: state->uart_port, iso7816: uarg);
1608	break;
1609	default:
1610	if (uport->ops->ioctl)
1611	ret = uport->ops->ioctl(uport, cmd, arg);
1612	break;
1613	}
1614	}
1615
1616	if (cmd == TIOCSRS485)
1617	up_write(sem: &tty->termios_rwsem);
1618
1619	return ret;
1620	}
1621
1622	static void uart_set_ldisc(struct tty_struct *tty)
1623	{
1624	struct uart_state *state = tty->driver_data;
1625	struct uart_port *uport;
1626	struct tty_port *port = &state->port;
1627
1628	if (!tty_port_initialized(port))
1629	return;
1630
1631	guard(mutex)(T: &state->port.mutex);
1632	uport = uart_port_check(state);
1633	if (uport && uport->ops->set_ldisc)
1634	uport->ops->set_ldisc(uport, &tty->termios);
1635	}
1636
1637	static void uart_set_termios(struct tty_struct *tty,
1638	const struct ktermios *old_termios)
1639	{
1640	struct uart_state *state = tty->driver_data;
1641	struct uart_port *uport;
1642	unsigned int cflag = tty->termios.c_cflag;
1643	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
1644	bool sw_changed = false;
1645
1646	guard(mutex)(T: &state->port.mutex);
1647
1648	uport = uart_port_check(state);
1649	if (!uport)
1650	return;
1651
1652	/*
1653	* Drivers doing software flow control also need to know
1654	* about changes to these input settings.
1655	*/
1656	if (uport->flags & UPF_SOFT_FLOW) {
1657	iflag_mask |= IXANY|IXON|IXOFF;
1658	sw_changed =
1659	tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
1660	tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
1661	}
1662
1663	/*
1664	* These are the bits that are used to setup various
1665	* flags in the low level driver. We can ignore the Bfoo
1666	* bits in c_cflag; c_[io]speed will always be set
1667	* appropriately by set_termios() in tty_ioctl.c
1668	*/
1669	if ((cflag ^ old_termios->c_cflag) == 0 &&
1670	tty->termios.c_ospeed == old_termios->c_ospeed &&
1671	tty->termios.c_ispeed == old_termios->c_ispeed &&
1672	((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
1673	!sw_changed)
1674	return;
1675
1676	uart_change_line_settings(tty, state, old_termios);
1677	/* reload cflag from termios; port driver may have overridden flags */
1678	cflag = tty->termios.c_cflag;
1679
1680	/* Handle transition to B0 status */
1681	if (((old_termios->c_cflag & CBAUD) != B0) && ((cflag & CBAUD) == B0))
1682	uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
1683	/* Handle transition away from B0 status */
1684	else if (((old_termios->c_cflag & CBAUD) == B0) && ((cflag & CBAUD) != B0)) {
1685	unsigned int mask = TIOCM_DTR;
1686
1687	if (!(cflag & CRTSCTS) || !tty_throttled(tty))
1688	mask |= TIOCM_RTS;
1689	uart_set_mctrl(uport, mask);
1690	}
1691	}
1692
1693	/*
1694	* Calls to uart_close() are serialised via the tty_lock in
1695	* drivers/tty/tty_io.c:tty_release()
1696	* drivers/tty/tty_io.c:do_tty_hangup()
1697	*/
1698	static void uart_close(struct tty_struct *tty, struct file *filp)
1699	{
1700	struct uart_state *state = tty->driver_data;
1701
1702	if (!state) {
1703	struct uart_driver *drv = tty->driver->driver_state;
1704	struct tty_port *port;
1705
1706	state = drv->state + tty->index;
1707	port = &state->port;
1708	guard(spinlock_irq)(l: &port->lock);
1709	--port->count;
1710	return;
1711	}
1712
1713	pr_debug("uart_close(%d) called\n", tty->index);
1714
1715	tty_port_close(port: tty->port, tty, filp);
1716	}
1717
1718	static void uart_tty_port_shutdown(struct tty_port *port)
1719	{
1720	struct uart_state *state = container_of(port, struct uart_state, port);
1721	struct uart_port *uport = uart_port_check(state);
1722
1723	/*
1724	* At this point, we stop accepting input. To do this, we
1725	* disable the receive line status interrupts.
1726	*/
1727	if (WARN(!uport, "detached port still initialized!\n"))
1728	return;
1729
1730	scoped_guard(uart_port_lock_irq, uport)
1731	uport->ops->stop_rx(uport);
1732
1733	serial_base_port_shutdown(port: uport);
1734	uart_port_shutdown(port);
1735
1736	/*
1737	* It's possible for shutdown to be called after suspend if we get
1738	* a DCD drop (hangup) at just the right time. Clear suspended bit so
1739	* we don't try to resume a port that has been shutdown.
1740	*/
1741	tty_port_set_suspended(port, val: false);
1742
1743	uart_free_xmit_buf(port);
1744
1745	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
1746	}
1747
1748	static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1749	{
1750	struct uart_state *state = tty->driver_data;
1751	struct uart_port *port;
1752	unsigned long char_time, expire, fifo_timeout;
1753
1754	port = uart_port_ref(state);
1755	if (!port)
1756	return;
1757
1758	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
1759	uart_port_deref(uport: port);
1760	return;
1761	}
1762
1763	/*
1764	* Set the check interval to be 1/5 of the estimated time to
1765	* send a single character, and make it at least 1. The check
1766	* interval should also be less than the timeout.
1767	*
1768	* Note: we have to use pretty tight timings here to satisfy
1769	* the NIST-PCTS.
1770	*/
1771	char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);
1772
1773	if (timeout && timeout < char_time)
1774	char_time = timeout;
1775
1776	if (!uart_cts_enabled(uport: port)) {
1777	/*
1778	* If the transmitter hasn't cleared in twice the approximate
1779	* amount of time to send the entire FIFO, it probably won't
1780	* ever clear. This assumes the UART isn't doing flow
1781	* control, which is currently the case. Hence, if it ever
1782	* takes longer than FIFO timeout, this is probably due to a
1783	* UART bug of some kind. So, we clamp the timeout parameter at
1784	* 2 * FIFO timeout.
1785	*/
1786	fifo_timeout = uart_fifo_timeout(port);
1787	if (timeout == 0 || timeout > 2 * fifo_timeout)
1788	timeout = 2 * fifo_timeout;
1789	}
1790
1791	expire = jiffies + timeout;
1792
1793	pr_debug("uart_wait_until_sent(%u), jiffies=%lu, expire=%lu...\n",
1794	port->line, jiffies, expire);
1795
1796	/*
1797	* Check whether the transmitter is empty every 'char_time'.
1798	* 'timeout' / 'expire' give us the maximum amount of time
1799	* we wait.
1800	*/
1801	while (!port->ops->tx_empty(port)) {
1802	msleep_interruptible(msecs: jiffies_to_msecs(j: char_time));
1803	if (signal_pending(current))
1804	break;
1805	if (timeout && time_after(jiffies, expire))
1806	break;
1807	}
1808	uart_port_deref(uport: port);
1809	}
1810
1811	/*
1812	* Calls to uart_hangup() are serialised by the tty_lock in
1813	* drivers/tty/tty_io.c:do_tty_hangup()
1814	* This runs from a workqueue and can sleep for a _short_ time only.
1815	*/
1816	static void uart_hangup(struct tty_struct *tty)
1817	{
1818	struct uart_state *state = tty->driver_data;
1819	struct tty_port *port = &state->port;
1820	struct uart_port *uport;
1821
1822	pr_debug("uart_hangup(%d)\n", tty->index);
1823
1824	guard(mutex)(T: &port->mutex);
1825	uport = uart_port_check(state);
1826	WARN(!uport, "hangup of detached port!\n");
1827
1828	if (tty_port_active(port)) {
1829	uart_flush_buffer(tty);
1830	uart_shutdown(tty, state);
1831	scoped_guard(spinlock_irqsave, &port->lock)
1832	port->count = 0;
1833	tty_port_set_active(port, val: false);
1834	tty_port_tty_set(port, NULL);
1835	if (uport && !uart_console(uport))
1836	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
1837	wake_up_interruptible(&port->open_wait);
1838	wake_up_interruptible(&port->delta_msr_wait);
1839	}
1840	}
1841
1842	/* uport == NULL if uart_port has already been removed */
1843	static void uart_port_shutdown(struct tty_port *port)
1844	{
1845	struct uart_state *state = container_of(port, struct uart_state, port);
1846	struct uart_port *uport = uart_port_check(state);
1847
1848	/*
1849	* clear delta_msr_wait queue to avoid mem leaks: we may free
1850	* the irq here so the queue might never be woken up. Note
1851	* that we won't end up waiting on delta_msr_wait again since
1852	* any outstanding file descriptors should be pointing at
1853	* hung_up_tty_fops now.
1854	*/
1855	wake_up_interruptible(&port->delta_msr_wait);
1856
1857	if (uport) {
1858	/* Free the IRQ and disable the port. */
1859	uport->ops->shutdown(uport);
1860
1861	/* Ensure that the IRQ handler isn't running on another CPU. */
1862	synchronize_irq(irq: uport->irq);
1863	}
1864	}
1865
1866	static bool uart_carrier_raised(struct tty_port *port)
1867	{
1868	struct uart_state *state = container_of(port, struct uart_state, port);
1869	struct uart_port *uport;
1870	unsigned long flags;
1871	int mctrl;
1872
1873	uport = uart_port_ref_lock(state, flags: &flags);
1874	/*
1875	* Should never observe uport == NULL since checks for hangup should
1876	* abort the tty_port_block_til_ready() loop before checking for carrier
1877	* raised -- but report carrier raised if it does anyway so open will
1878	* continue and not sleep
1879	*/
1880	if (WARN_ON(!uport))
1881	return true;
1882	uart_enable_ms(uport);
1883	mctrl = uport->ops->get_mctrl(uport);
1884	uart_port_unlock_deref(uport, flags);
1885
1886	return mctrl & TIOCM_CAR;
1887	}
1888
1889	static void uart_dtr_rts(struct tty_port *port, bool active)
1890	{
1891	struct uart_state *state = container_of(port, struct uart_state, port);
1892	struct uart_port *uport;
1893
1894	uport = uart_port_ref(state);
1895	if (!uport)
1896	return;
1897	uart_port_dtr_rts(uport, active);
1898	uart_port_deref(uport);
1899	}
1900
1901	static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
1902	{
1903	struct uart_driver *drv = driver->driver_state;
1904	struct uart_state *state = drv->state + tty->index;
1905
1906	tty->driver_data = state;
1907
1908	return tty_standard_install(driver, tty);
1909	}
1910
1911	/*
1912	* Calls to uart_open are serialised by the tty_lock in
1913	* drivers/tty/tty_io.c:tty_open()
1914	* Note that if this fails, then uart_close() _will_ be called.
1915	*
1916	* In time, we want to scrap the "opening nonpresent ports"
1917	* behaviour and implement an alternative way for setserial
1918	* to set base addresses/ports/types. This will allow us to
1919	* get rid of a certain amount of extra tests.
1920	*/
1921	static int uart_open(struct tty_struct *tty, struct file *filp)
1922	{
1923	struct uart_state *state = tty->driver_data;
1924	int retval;
1925
1926	retval = tty_port_open(port: &state->port, tty, filp);
1927	if (retval > 0)
1928	retval = 0;
1929
1930	return retval;
1931	}
1932
1933	static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
1934	{
1935	struct uart_state *state = container_of(port, struct uart_state, port);
1936	struct uart_port *uport;
1937	int ret;
1938
1939	uport = uart_port_check(state);
1940	if (!uport || uport->flags & UPF_DEAD)
1941	return -ENXIO;
1942
1943	/*
1944	* Start up the serial port.
1945	*/
1946	ret = uart_startup(tty, state, init_hw: false);
1947	if (ret > 0)
1948	tty_port_set_active(port, val: true);
1949
1950	return ret;
1951	}
1952
1953	static const char *uart_type(struct uart_port *port)
1954	{
1955	const char *str = NULL;
1956
1957	if (port->ops->type)
1958	str = port->ops->type(port);
1959
1960	if (!str)
1961	str = "unknown";
1962
1963	return str;
1964	}
1965
1966	#ifdef CONFIG_PROC_FS
1967
1968	static void uart_line_info(struct seq_file *m, struct uart_state *state)
1969	{
1970	struct tty_port *port = &state->port;
1971	enum uart_pm_state pm_state;
1972	struct uart_port *uport;
1973	char stat_buf[32];
1974	unsigned int status;
1975	int mmio;
1976
1977	guard(mutex)(T: &port->mutex);
1978
1979	uport = uart_port_check(state);
1980	if (!uport)
1981	return;
1982
1983	mmio = uport->iotype >= UPIO_MEM;
1984	seq_printf(m, fmt: "%u: uart:%s %s%08llX irq:%u",
1985	uport->line, uart_type(port: uport),
1986	mmio ? "mmio:0x" : "port:",
1987	mmio ? (unsigned long long)uport->mapbase
1988	: (unsigned long long)uport->iobase,
1989	uport->irq);
1990
1991	if (uport->type == PORT_UNKNOWN) {
1992	seq_putc(m, c: '\n');
1993	return;
1994	}
1995
1996	if (capable(CAP_SYS_ADMIN)) {
1997	pm_state = state->pm_state;
1998	if (pm_state != UART_PM_STATE_ON)
1999	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2000	scoped_guard(uart_port_lock_irq, uport)
2001	status = uport->ops->get_mctrl(uport);
2002	if (pm_state != UART_PM_STATE_ON)
2003	uart_change_pm(state, pm_state);
2004
2005	seq_printf(m, fmt: " tx:%u rx:%u",
2006	uport->icount.tx, uport->icount.rx);
2007	if (uport->icount.frame)
2008	seq_printf(m, fmt: " fe:%u", uport->icount.frame);
2009	if (uport->icount.parity)
2010	seq_printf(m, fmt: " pe:%u", uport->icount.parity);
2011	if (uport->icount.brk)
2012	seq_printf(m, fmt: " brk:%u", uport->icount.brk);
2013	if (uport->icount.overrun)
2014	seq_printf(m, fmt: " oe:%u", uport->icount.overrun);
2015	if (uport->icount.buf_overrun)
2016	seq_printf(m, fmt: " bo:%u", uport->icount.buf_overrun);
2017
2018	#define INFOBIT(bit, str) \
2019	if (uport->mctrl & (bit)) \
2020	strncat(stat_buf, (str), sizeof(stat_buf) - \
2021	strlen(stat_buf) - 2)
2022	#define STATBIT(bit, str) \
2023	if (status & (bit)) \
2024	strncat(stat_buf, (str), sizeof(stat_buf) - \
2025	strlen(stat_buf) - 2)
2026
2027	stat_buf[0] = '\0';
2028	stat_buf[1] = '\0';
2029	INFOBIT(TIOCM_RTS, "|RTS");
2030	STATBIT(TIOCM_CTS, "|CTS");
2031	INFOBIT(TIOCM_DTR, "|DTR");
2032	STATBIT(TIOCM_DSR, "|DSR");
2033	STATBIT(TIOCM_CAR, "|CD");
2034	STATBIT(TIOCM_RNG, "|RI");
2035	if (stat_buf[0])
2036	stat_buf[0] = ' ';
2037
2038	seq_puts(m, s: stat_buf);
2039	}
2040	seq_putc(m, c: '\n');
2041	#undef STATBIT
2042	#undef INFOBIT
2043	}
2044
2045	static int uart_proc_show(struct seq_file *m, void *v)
2046	{
2047	struct tty_driver *ttydrv = m->private;
2048	struct uart_driver *drv = ttydrv->driver_state;
2049	int i;
2050
2051	seq_printf(m, fmt: "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
2052	for (i = 0; i < drv->nr; i++)
2053	uart_line_info(m, state: drv->state + i);
2054	return 0;
2055	}
2056	#endif
2057
2058	static void uart_port_spin_lock_init(struct uart_port *port)
2059	{
2060	spin_lock_init(&port->lock);
2061	lockdep_set_class(&port->lock, &port_lock_key);
2062	}
2063
2064	#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
2065	/**
2066	* uart_console_write - write a console message to a serial port
2067	* @port: the port to write the message
2068	* @s: array of characters
2069	* @count: number of characters in string to write
2070	* @putchar: function to write character to port
2071	*/
2072	void uart_console_write(struct uart_port *port, const char *s,
2073	unsigned int count,
2074	void (*putchar)(struct uart_port *, unsigned char))
2075	{
2076	unsigned int i;
2077
2078	for (i = 0; i < count; i++, s++) {
2079	if (*s == '\n')
2080	putchar(port, '\r');
2081	putchar(port, *s);
2082	}
2083	}
2084	EXPORT_SYMBOL_GPL(uart_console_write);
2085
2086	/**
2087	* uart_parse_earlycon - Parse earlycon options
2088	* @p: ptr to 2nd field (ie., just beyond '<name>,')
2089	* @iotype: ptr for decoded iotype (out)
2090	* @addr: ptr for decoded mapbase/iobase (out)
2091	* @options: ptr for <options> field; %NULL if not present (out)
2092	*
2093	* Decodes earlycon kernel command line parameters of the form:
2094	* * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2095	* * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
2096	*
2097	* The optional form:
2098	* * earlycon=<name>,0x<addr>,<options>
2099	* * console=<name>,0x<addr>,<options>
2100	*
2101	* is also accepted; the returned @iotype will be %UPIO_MEM.
2102	*
2103	* Returns: 0 on success or -%EINVAL on failure
2104	*/
2105	int uart_parse_earlycon(char *p, enum uart_iotype *iotype,
2106	resource_size_t *addr, char **options)
2107	{
2108	if (strncmp(p, "mmio,", 5) == 0) {
2109	*iotype = UPIO_MEM;
2110	p += 5;
2111	} else if (strncmp(p, "mmio16,", 7) == 0) {
2112	*iotype = UPIO_MEM16;
2113	p += 7;
2114	} else if (strncmp(p, "mmio32,", 7) == 0) {
2115	*iotype = UPIO_MEM32;
2116	p += 7;
2117	} else if (strncmp(p, "mmio32be,", 9) == 0) {
2118	*iotype = UPIO_MEM32BE;
2119	p += 9;
2120	} else if (strncmp(p, "mmio32native,", 13) == 0) {
2121	*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
2122	UPIO_MEM32BE : UPIO_MEM32;
2123	p += 13;
2124	} else if (strncmp(p, "io,", 3) == 0) {
2125	*iotype = UPIO_PORT;
2126	p += 3;
2127	} else if (strncmp(p, "0x", 2) == 0) {
2128	*iotype = UPIO_MEM;
2129	} else {
2130	return -EINVAL;
2131	}
2132
2133	/*
2134	* Before you replace it with kstrtoull(), think about options separator
2135	* (',') it will not tolerate
2136	*/
2137	*addr = simple_strtoull(p, NULL, 0);
2138	p = strchr(p, ',');
2139	if (p)
2140	p++;
2141
2142	*options = p;
2143	return 0;
2144	}
2145	EXPORT_SYMBOL_GPL(uart_parse_earlycon);
2146
2147	/**
2148	* uart_parse_options - Parse serial port baud/parity/bits/flow control.
2149	* @options: pointer to option string
2150	* @baud: pointer to an 'int' variable for the baud rate.
2151	* @parity: pointer to an 'int' variable for the parity.
2152	* @bits: pointer to an 'int' variable for the number of data bits.
2153	* @flow: pointer to an 'int' variable for the flow control character.
2154	*
2155	* uart_parse_options() decodes a string containing the serial console
2156	* options. The format of the string is <baud><parity><bits><flow>,
2157	* eg: 115200n8r
2158	*/
2159	void
2160	uart_parse_options(const char *options, int *baud, int *parity,
2161	int *bits, int *flow)
2162	{
2163	const char *s = options;
2164
2165	*baud = simple_strtoul(s, NULL, 10);
2166	while (*s >= '0' && *s <= '9')
2167	s++;
2168	if (*s)
2169	*parity = *s++;
2170	if (*s)
2171	*bits = *s++ - '0';
2172	if (*s)
2173	*flow = *s;
2174	}
2175	EXPORT_SYMBOL_GPL(uart_parse_options);
2176
2177	/**
2178	* uart_set_options - setup the serial console parameters
2179	* @port: pointer to the serial ports uart_port structure
2180	* @co: console pointer
2181	* @baud: baud rate
2182	* @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
2183	* @bits: number of data bits
2184	* @flow: flow control character - 'r' (rts)
2185	*
2186	* Locking: Caller must hold console_list_lock in order to serialize
2187	* early initialization of the serial-console lock.
2188	*/
2189	int
2190	uart_set_options(struct uart_port *port, struct console *co,
2191	int baud, int parity, int bits, int flow)
2192	{
2193	struct ktermios termios;
2194	static struct ktermios dummy;
2195
2196	/*
2197	* Ensure that the serial-console lock is initialised early.
2198	*
2199	* Note that the console-registered check is needed because
2200	* kgdboc can call uart_set_options() for an already registered
2201	* console via tty_find_polling_driver() and uart_poll_init().
2202	*/
2203	if (!uart_console_registered_locked(port) && !port->console_reinit)
2204	uart_port_spin_lock_init(port);
2205
2206	memset(&termios, 0, sizeof(struct ktermios));
2207
2208	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
2209	tty_termios_encode_baud_rate(termios: &termios, ibaud: baud, obaud: baud);
2210
2211	if (bits == 7)
2212	termios.c_cflag |= CS7;
2213	else
2214	termios.c_cflag |= CS8;
2215
2216	switch (parity) {
2217	case 'o': case 'O':
2218	termios.c_cflag |= PARODD;
2219	fallthrough;
2220	case 'e': case 'E':
2221	termios.c_cflag |= PARENB;
2222	break;
2223	}
2224
2225	if (flow == 'r')
2226	termios.c_cflag |= CRTSCTS;
2227
2228	/*
2229	* some uarts on other side don't support no flow control.
2230	* So we set * DTR in host uart to make them happy
2231	*/
2232	port->mctrl |= TIOCM_DTR;
2233
2234	port->ops->set_termios(port, &termios, &dummy);
2235	/*
2236	* Allow the setting of the UART parameters with a NULL console
2237	* too:
2238	*/
2239	if (co) {
2240	co->cflag = termios.c_cflag;
2241	co->ispeed = termios.c_ispeed;
2242	co->ospeed = termios.c_ospeed;
2243	}
2244
2245	return 0;
2246	}
2247	EXPORT_SYMBOL_GPL(uart_set_options);
2248	#endif /* CONFIG_SERIAL_CORE_CONSOLE */
2249
2250	/**
2251	* uart_change_pm - set power state of the port
2252	*
2253	* @state: port descriptor
2254	* @pm_state: new state
2255	*
2256	* Locking: port->mutex has to be held
2257	*/
2258	static void uart_change_pm(struct uart_state *state,
2259	enum uart_pm_state pm_state)
2260	{
2261	struct uart_port *port = uart_port_check(state);
2262
2263	if (state->pm_state != pm_state) {
2264	if (port && port->ops->pm)
2265	port->ops->pm(port, pm_state, state->pm_state);
2266	state->pm_state = pm_state;
2267	}
2268	}
2269
2270	struct uart_match {
2271	struct uart_port *port;
2272	struct uart_driver *driver;
2273	};
2274
2275	static int serial_match_port(struct device *dev, const void *data)
2276	{
2277	const struct uart_match *match = data;
2278	struct tty_driver *tty_drv = match->driver->tty_driver;
2279	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2280	match->port->line;
2281
2282	return dev->devt == devt; /* Actually, only one tty per port */
2283	}
2284
2285	int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
2286	{
2287	struct uart_state *state = drv->state + uport->line;
2288	struct tty_port *port = &state->port;
2289	struct device *tty_dev;
2290	struct uart_match match = {uport, drv};
2291
2292	guard(mutex)(T: &port->mutex);
2293
2294	tty_dev = device_find_child(parent: &uport->port_dev->dev, data: &match, match: serial_match_port);
2295	if (tty_dev && device_may_wakeup(dev: tty_dev)) {
2296	enable_irq_wake(irq: uport->irq);
2297	put_device(dev: tty_dev);
2298	return 0;
2299	}
2300	put_device(dev: tty_dev);
2301
2302	/*
2303	* Nothing to do if the console is not suspending
2304	* except stop_rx to prevent any asynchronous data
2305	* over RX line. However ensure that we will be
2306	* able to Re-start_rx later.
2307	*/
2308	if (!console_suspend_enabled && uart_console(uport)) {
2309	if (uport->ops->start_rx) {
2310	guard(uart_port_lock_irq)(T: uport);
2311	uport->ops->stop_rx(uport);
2312	}
2313	device_set_awake_path(dev: uport->dev);
2314	return 0;
2315	}
2316
2317	uport->suspended = 1;
2318
2319	if (tty_port_initialized(port)) {
2320	const struct uart_ops *ops = uport->ops;
2321	int tries;
2322	unsigned int mctrl;
2323
2324	tty_port_set_suspended(port, val: true);
2325	tty_port_set_initialized(port, val: false);
2326
2327	scoped_guard(uart_port_lock_irq, uport) {
2328	ops->stop_tx(uport);
2329	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2330	ops->set_mctrl(uport, 0);
2331	/* save mctrl so it can be restored on resume */
2332	mctrl = uport->mctrl;
2333	uport->mctrl = 0;
2334	ops->stop_rx(uport);
2335	}
2336
2337	/*
2338	* Wait for the transmitter to empty.
2339	*/
2340	for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
2341	msleep(msecs: 10);
2342	if (!tries)
2343	dev_err(uport->dev, "%s: Unable to drain transmitter\n",
2344	uport->name);
2345
2346	ops->shutdown(uport);
2347	uport->mctrl = mctrl;
2348	}
2349
2350	/*
2351	* Suspend the console device before suspending the port.
2352	*/
2353	if (uart_console(uport))
2354	console_suspend(uport->cons);
2355
2356	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
2357
2358	return 0;
2359	}
2360	EXPORT_SYMBOL(uart_suspend_port);
2361
2362	int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
2363	{
2364	struct uart_state *state = drv->state + uport->line;
2365	struct tty_port *port = &state->port;
2366	struct device *tty_dev;
2367	struct uart_match match = {uport, drv};
2368	struct ktermios termios;
2369
2370	guard(mutex)(T: &port->mutex);
2371
2372	tty_dev = device_find_child(parent: &uport->port_dev->dev, data: &match, match: serial_match_port);
2373	if (!uport->suspended && device_may_wakeup(dev: tty_dev)) {
2374	if (irqd_is_wakeup_set(d: irq_get_irq_data(irq: (uport->irq))))
2375	disable_irq_wake(irq: uport->irq);
2376	put_device(dev: tty_dev);
2377	return 0;
2378	}
2379	put_device(dev: tty_dev);
2380	uport->suspended = 0;
2381
2382	/*
2383	* Re-enable the console device after suspending.
2384	*/
2385	if (uart_console(uport)) {
2386	/*
2387	* First try to use the console cflag setting.
2388	*/
2389	memset(&termios, 0, sizeof(struct ktermios));
2390	termios.c_cflag = uport->cons->cflag;
2391	termios.c_ispeed = uport->cons->ispeed;
2392	termios.c_ospeed = uport->cons->ospeed;
2393
2394	/*
2395	* If that's unset, use the tty termios setting.
2396	*/
2397	if (port->tty && termios.c_cflag == 0)
2398	termios = port->tty->termios;
2399
2400	if (console_suspend_enabled)
2401	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2402	uport->ops->set_termios(uport, &termios, NULL);
2403	if (!console_suspend_enabled && uport->ops->start_rx) {
2404	guard(uart_port_lock_irq)(T: uport);
2405	uport->ops->start_rx(uport);
2406	}
2407	if (console_suspend_enabled)
2408	console_resume(uport->cons);
2409	}
2410
2411	if (tty_port_suspended(port)) {
2412	const struct uart_ops *ops = uport->ops;
2413	int ret;
2414
2415	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2416	scoped_guard(uart_port_lock_irq, uport)
2417	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2418	ops->set_mctrl(uport, 0);
2419	if (console_suspend_enabled || !uart_console(uport)) {
2420	/* Protected by port mutex for now */
2421	struct tty_struct *tty = port->tty;
2422
2423	ret = ops->startup(uport);
2424	if (ret == 0) {
2425	if (tty)
2426	uart_change_line_settings(tty, state, NULL);
2427	uart_rs485_config(port: uport);
2428	scoped_guard(uart_port_lock_irq, uport) {
2429	if (!(uport->rs485.flags & SER_RS485_ENABLED))
2430	ops->set_mctrl(uport, uport->mctrl);
2431	ops->start_tx(uport);
2432	}
2433	tty_port_set_initialized(port, val: true);
2434	} else {
2435	/*
2436	* Failed to resume - maybe hardware went away?
2437	* Clear the "initialized" flag so we won't try
2438	* to call the low level drivers shutdown method.
2439	*/
2440	uart_shutdown(tty, state);
2441	}
2442	}
2443
2444	tty_port_set_suspended(port, val: false);
2445	}
2446
2447	return 0;
2448	}
2449	EXPORT_SYMBOL(uart_resume_port);
2450
2451	static inline void
2452	uart_report_port(struct uart_driver *drv, struct uart_port *port)
2453	{
2454	char address[64];
2455
2456	switch (port->iotype) {
2457	case UPIO_PORT:
2458	snprintf(buf: address, size: sizeof(address), fmt: "I/O 0x%lx", port->iobase);
2459	break;
2460	case UPIO_HUB6:
2461	snprintf(buf: address, size: sizeof(address),
2462	fmt: "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
2463	break;
2464	case UPIO_MEM:
2465	case UPIO_MEM16:
2466	case UPIO_MEM32:
2467	case UPIO_MEM32BE:
2468	case UPIO_AU:
2469	case UPIO_TSI:
2470	snprintf(buf: address, size: sizeof(address),
2471	fmt: "MMIO 0x%llx", (unsigned long long)port->mapbase);
2472	break;
2473	default:
2474	strscpy(address, "*unknown*", sizeof(address));
2475	break;
2476	}
2477
2478	pr_info("%s%s%s at %s (irq = %u, base_baud = %u) is a %s\n",
2479	port->dev ? dev_name(port->dev) : "",
2480	port->dev ? ": " : "",
2481	port->name,
2482	address, port->irq, port->uartclk / 16, uart_type(port));
2483
2484	/* The magic multiplier feature is a bit obscure, so report it too. */
2485	if (port->flags & UPF_MAGIC_MULTIPLIER)
2486	pr_info("%s%s%s extra baud rates supported: %u, %u",
2487	port->dev ? dev_name(port->dev) : "",
2488	port->dev ? ": " : "",
2489	port->name,
2490	port->uartclk / 8, port->uartclk / 4);
2491	}
2492
2493	static void
2494	uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2495	struct uart_port *port)
2496	{
2497	unsigned int flags;
2498
2499	/*
2500	* If there isn't a port here, don't do anything further.
2501	*/
2502	if (!port->iobase && !port->mapbase && !port->membase)
2503	return;
2504
2505	/*
2506	* Now do the auto configuration stuff. Note that config_port
2507	* is expected to claim the resources and map the port for us.
2508	*/
2509	flags = 0;
2510	if (port->flags & UPF_AUTO_IRQ)
2511	flags |= UART_CONFIG_IRQ;
2512	if (port->flags & UPF_BOOT_AUTOCONF) {
2513	if (!(port->flags & UPF_FIXED_TYPE)) {
2514	port->type = PORT_UNKNOWN;
2515	flags |= UART_CONFIG_TYPE;
2516	}
2517	/* Synchronize with possible boot console. */
2518	if (uart_console(port))
2519	console_lock();
2520	port->ops->config_port(port, flags);
2521	if (uart_console(port))
2522	console_unlock();
2523	}
2524
2525	if (port->type != PORT_UNKNOWN) {
2526	uart_report_port(drv, port);
2527
2528	/* Synchronize with possible boot console. */
2529	if (uart_console(port))
2530	console_lock();
2531
2532	/* Power up port for set_mctrl() */
2533	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2534
2535	/*
2536	* Ensure that the modem control lines are de-activated.
2537	* keep the DTR setting that is set in uart_set_options()
2538	* We probably don't need a spinlock around this, but
2539	*/
2540	scoped_guard(uart_port_lock_irqsave, port) {
2541	port->mctrl &= TIOCM_DTR;
2542	if (!(port->rs485.flags & SER_RS485_ENABLED))
2543	port->ops->set_mctrl(port, port->mctrl);
2544	}
2545
2546	uart_rs485_config(port);
2547
2548	if (uart_console(port))
2549	console_unlock();
2550
2551	/*
2552	* If this driver supports console, and it hasn't been
2553	* successfully registered yet, try to re-register it.
2554	* It may be that the port was not available.
2555	*/
2556	if (port->cons && !console_is_registered(con: port->cons))
2557	register_console(port->cons);
2558
2559	/*
2560	* Power down all ports by default, except the
2561	* console if we have one.
2562	*/
2563	if (!uart_console(port))
2564	uart_change_pm(state, pm_state: UART_PM_STATE_OFF);
2565	}
2566	}
2567
2568	#ifdef CONFIG_CONSOLE_POLL
2569
2570	static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2571	{
2572	struct uart_driver *drv = driver->driver_state;
2573	struct uart_state *state = drv->state + line;
2574	enum uart_pm_state pm_state;
2575	struct tty_port *tport;
2576	struct uart_port *port;
2577	int baud = 9600;
2578	int bits = 8;
2579	int parity = 'n';
2580	int flow = 'n';
2581	int ret = 0;
2582
2583	tport = &state->port;
2584
2585	guard(mutex)(T: &tport->mutex);
2586
2587	port = uart_port_check(state);
2588	if (!port || port->type == PORT_UNKNOWN ||
2589	!(port->ops->poll_get_char && port->ops->poll_put_char))
2590	return -1;
2591
2592	pm_state = state->pm_state;
2593	uart_change_pm(state, pm_state: UART_PM_STATE_ON);
2594
2595	if (port->ops->poll_init) {
2596	/*
2597	* We don't set initialized as we only initialized the hw,
2598	* e.g. state->xmit is still uninitialized.
2599	*/
2600	if (!tty_port_initialized(port: tport))
2601	ret = port->ops->poll_init(port);
2602	}
2603
2604	if (!ret && options) {
2605	uart_parse_options(options, &baud, &parity, &bits, &flow);
2606	console_list_lock();
2607	ret = uart_set_options(port, NULL, baud, parity, bits, flow);
2608	console_list_unlock();
2609	}
2610
2611	if (ret)
2612	uart_change_pm(state, pm_state);
2613
2614	return ret;
2615	}
2616
2617	static int uart_poll_get_char(struct tty_driver *driver, int line)
2618	{
2619	struct uart_driver *drv = driver->driver_state;
2620	struct uart_state *state = drv->state + line;
2621	struct uart_port *port;
2622	int ret = -1;
2623
2624	port = uart_port_ref(state);
2625	if (port) {
2626	ret = port->ops->poll_get_char(port);
2627	uart_port_deref(uport: port);
2628	}
2629
2630	return ret;
2631	}
2632
2633	static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2634	{
2635	struct uart_driver *drv = driver->driver_state;
2636	struct uart_state *state = drv->state + line;
2637	struct uart_port *port;
2638
2639	port = uart_port_ref(state);
2640	if (!port)
2641	return;
2642
2643	if (ch == '\n')
2644	port->ops->poll_put_char(port, '\r');
2645	port->ops->poll_put_char(port, ch);
2646	uart_port_deref(uport: port);
2647	}
2648	#endif
2649
2650	static const struct tty_operations uart_ops = {
2651	.install = uart_install,
2652	.open = uart_open,
2653	.close = uart_close,
2654	.write = uart_write,
2655	.put_char = uart_put_char,
2656	.flush_chars = uart_flush_chars,
2657	.write_room = uart_write_room,
2658	.chars_in_buffer= uart_chars_in_buffer,
2659	.flush_buffer = uart_flush_buffer,
2660	.ioctl = uart_ioctl,
2661	.throttle = uart_throttle,
2662	.unthrottle = uart_unthrottle,
2663	.send_xchar = uart_send_xchar,
2664	.set_termios = uart_set_termios,
2665	.set_ldisc = uart_set_ldisc,
2666	.stop = uart_stop,
2667	.start = uart_start,
2668	.hangup = uart_hangup,
2669	.break_ctl = uart_break_ctl,
2670	.wait_until_sent= uart_wait_until_sent,
2671	#ifdef CONFIG_PROC_FS
2672	.proc_show = uart_proc_show,
2673	#endif
2674	.tiocmget = uart_tiocmget,
2675	.tiocmset = uart_tiocmset,
2676	.set_serial = uart_set_info_user,
2677	.get_serial = uart_get_info_user,
2678	.get_icount = uart_get_icount,
2679	#ifdef CONFIG_CONSOLE_POLL
2680	.poll_init = uart_poll_init,
2681	.poll_get_char = uart_poll_get_char,
2682	.poll_put_char = uart_poll_put_char,
2683	#endif
2684	};
2685
2686	static const struct tty_port_operations uart_port_ops = {
2687	.carrier_raised = uart_carrier_raised,
2688	.dtr_rts = uart_dtr_rts,
2689	.activate = uart_port_activate,
2690	.shutdown = uart_tty_port_shutdown,
2691	};
2692
2693	/**
2694	* uart_register_driver - register a driver with the uart core layer
2695	* @drv: low level driver structure
2696	*
2697	* Register a uart driver with the core driver. We in turn register with the
2698	* tty layer, and initialise the core driver per-port state.
2699	*
2700	* We have a proc file in /proc/tty/driver which is named after the normal
2701	* driver.
2702	*
2703	* @drv->port should be %NULL, and the per-port structures should be registered
2704	* using uart_add_one_port() after this call has succeeded.
2705	*
2706	* Locking: none, Interrupts: enabled
2707	*/
2708	int uart_register_driver(struct uart_driver *drv)
2709	{
2710	struct tty_driver *normal;
2711	int i, retval = -ENOMEM;
2712
2713	BUG_ON(drv->state);
2714
2715	/*
2716	* Maybe we should be using a slab cache for this, especially if
2717	* we have a large number of ports to handle.
2718	*/
2719	drv->state = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
2720	if (!drv->state)
2721	goto out;
2722
2723	normal = tty_alloc_driver(drv->nr, TTY_DRIVER_REAL_RAW |
2724	TTY_DRIVER_DYNAMIC_DEV);
2725	if (IS_ERR(ptr: normal)) {
2726	retval = PTR_ERR(ptr: normal);
2727	goto out_kfree;
2728	}
2729
2730	drv->tty_driver = normal;
2731
2732	normal->driver_name = drv->driver_name;
2733	normal->name = drv->dev_name;
2734	normal->major = drv->major;
2735	normal->minor_start = drv->minor;
2736	normal->type = TTY_DRIVER_TYPE_SERIAL;
2737	normal->subtype = SERIAL_TYPE_NORMAL;
2738	normal->init_termios = tty_std_termios;
2739	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2740	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2741	normal->driver_state = drv;
2742	tty_set_operations(driver: normal, op: &uart_ops);
2743
2744	/*
2745	* Initialise the UART state(s).
2746	*/
2747	for (i = 0; i < drv->nr; i++) {
2748	struct uart_state *state = drv->state + i;
2749	struct tty_port *port = &state->port;
2750
2751	tty_port_init(port);
2752	port->ops = &uart_port_ops;
2753	}
2754
2755	retval = tty_register_driver(driver: normal);
2756	if (retval >= 0)
2757	return retval;
2758
2759	for (i = 0; i < drv->nr; i++)
2760	tty_port_destroy(port: &drv->state[i].port);
2761	tty_driver_kref_put(driver: normal);
2762	out_kfree:
2763	kfree(objp: drv->state);
2764	out:
2765	return retval;
2766	}
2767	EXPORT_SYMBOL(uart_register_driver);
2768
2769	/**
2770	* uart_unregister_driver - remove a driver from the uart core layer
2771	* @drv: low level driver structure
2772	*
2773	* Remove all references to a driver from the core driver. The low level
2774	* driver must have removed all its ports via the uart_remove_one_port() if it
2775	* registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
2776	*
2777	* Locking: none, Interrupts: enabled
2778	*/
2779	void uart_unregister_driver(struct uart_driver *drv)
2780	{
2781	struct tty_driver *p = drv->tty_driver;
2782	unsigned int i;
2783
2784	tty_unregister_driver(driver: p);
2785	tty_driver_kref_put(driver: p);
2786	for (i = 0; i < drv->nr; i++)
2787	tty_port_destroy(port: &drv->state[i].port);
2788	kfree(objp: drv->state);
2789	drv->state = NULL;
2790	drv->tty_driver = NULL;
2791	}
2792	EXPORT_SYMBOL(uart_unregister_driver);
2793
2794	struct tty_driver *uart_console_device(struct console *co, int *index)
2795	{
2796	struct uart_driver *p = co->data;
2797	*index = co->index;
2798	return p->tty_driver;
2799	}
2800	EXPORT_SYMBOL_GPL(uart_console_device);
2801
2802	static ssize_t uartclk_show(struct device *dev,
2803	struct device_attribute *attr, char *buf)
2804	{
2805	struct serial_struct tmp;
2806	struct tty_port *port = dev_get_drvdata(dev);
2807
2808	uart_get_info(port, retinfo: &tmp);
2809	return sprintf(buf, fmt: "%d\n", tmp.baud_base * 16);
2810	}
2811
2812	static ssize_t type_show(struct device *dev,
2813	struct device_attribute *attr, char *buf)
2814	{
2815	struct serial_struct tmp;
2816	struct tty_port *port = dev_get_drvdata(dev);
2817
2818	uart_get_info(port, retinfo: &tmp);
2819	return sprintf(buf, fmt: "%d\n", tmp.type);
2820	}
2821
2822	static ssize_t line_show(struct device *dev,
2823	struct device_attribute *attr, char *buf)
2824	{
2825	struct serial_struct tmp;
2826	struct tty_port *port = dev_get_drvdata(dev);
2827
2828	uart_get_info(port, retinfo: &tmp);
2829	return sprintf(buf, fmt: "%d\n", tmp.line);
2830	}
2831
2832	static ssize_t port_show(struct device *dev,
2833	struct device_attribute *attr, char *buf)
2834	{
2835	struct serial_struct tmp;
2836	struct tty_port *port = dev_get_drvdata(dev);
2837	unsigned long ioaddr;
2838
2839	uart_get_info(port, retinfo: &tmp);
2840	ioaddr = tmp.port;
2841	if (HIGH_BITS_OFFSET)
2842	ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
2843	return sprintf(buf, fmt: "0x%lX\n", ioaddr);
2844	}
2845
2846	static ssize_t irq_show(struct device *dev,
2847	struct device_attribute *attr, char *buf)
2848	{
2849	struct serial_struct tmp;
2850	struct tty_port *port = dev_get_drvdata(dev);
2851
2852	uart_get_info(port, retinfo: &tmp);
2853	return sprintf(buf, fmt: "%d\n", tmp.irq);
2854	}
2855
2856	static ssize_t flags_show(struct device *dev,
2857	struct device_attribute *attr, char *buf)
2858	{
2859	struct serial_struct tmp;
2860	struct tty_port *port = dev_get_drvdata(dev);
2861
2862	uart_get_info(port, retinfo: &tmp);
2863	return sprintf(buf, fmt: "0x%X\n", tmp.flags);
2864	}
2865
2866	static ssize_t xmit_fifo_size_show(struct device *dev,
2867	struct device_attribute *attr, char *buf)
2868	{
2869	struct serial_struct tmp;
2870	struct tty_port *port = dev_get_drvdata(dev);
2871
2872	uart_get_info(port, retinfo: &tmp);
2873	return sprintf(buf, fmt: "%d\n", tmp.xmit_fifo_size);
2874	}
2875
2876	static ssize_t close_delay_show(struct device *dev,
2877	struct device_attribute *attr, char *buf)
2878	{
2879	struct serial_struct tmp;
2880	struct tty_port *port = dev_get_drvdata(dev);
2881
2882	uart_get_info(port, retinfo: &tmp);
2883	return sprintf(buf, fmt: "%u\n", tmp.close_delay);
2884	}
2885
2886	static ssize_t closing_wait_show(struct device *dev,
2887	struct device_attribute *attr, char *buf)
2888	{
2889	struct serial_struct tmp;
2890	struct tty_port *port = dev_get_drvdata(dev);
2891
2892	uart_get_info(port, retinfo: &tmp);
2893	return sprintf(buf, fmt: "%u\n", tmp.closing_wait);
2894	}
2895
2896	static ssize_t custom_divisor_show(struct device *dev,
2897	struct device_attribute *attr, char *buf)
2898	{
2899	struct serial_struct tmp;
2900	struct tty_port *port = dev_get_drvdata(dev);
2901
2902	uart_get_info(port, retinfo: &tmp);
2903	return sprintf(buf, fmt: "%d\n", tmp.custom_divisor);
2904	}
2905
2906	static ssize_t io_type_show(struct device *dev,
2907	struct device_attribute *attr, char *buf)
2908	{
2909	struct serial_struct tmp;
2910	struct tty_port *port = dev_get_drvdata(dev);
2911
2912	uart_get_info(port, retinfo: &tmp);
2913	return sprintf(buf, fmt: "%u\n", tmp.io_type);
2914	}
2915
2916	static ssize_t iomem_base_show(struct device *dev,
2917	struct device_attribute *attr, char *buf)
2918	{
2919	struct serial_struct tmp;
2920	struct tty_port *port = dev_get_drvdata(dev);
2921
2922	uart_get_info(port, retinfo: &tmp);
2923	return sprintf(buf, fmt: "0x%lX\n", (unsigned long)tmp.iomem_base);
2924	}
2925
2926	static ssize_t iomem_reg_shift_show(struct device *dev,
2927	struct device_attribute *attr, char *buf)
2928	{
2929	struct serial_struct tmp;
2930	struct tty_port *port = dev_get_drvdata(dev);
2931
2932	uart_get_info(port, retinfo: &tmp);
2933	return sprintf(buf, fmt: "%u\n", tmp.iomem_reg_shift);
2934	}
2935
2936	static ssize_t console_show(struct device *dev,
2937	struct device_attribute *attr, char *buf)
2938	{
2939	struct tty_port *port = dev_get_drvdata(dev);
2940	struct uart_state *state = container_of(port, struct uart_state, port);
2941	struct uart_port *uport;
2942	bool console = false;
2943
2944	scoped_guard(mutex, &port->mutex) {
2945	uport = uart_port_check(state);
2946	if (uport)
2947	console = uart_console_registered(port: uport);
2948	}
2949
2950	return sprintf(buf, fmt: "%c\n", console ? 'Y' : 'N');
2951	}
2952
2953	static ssize_t console_store(struct device *dev,
2954	struct device_attribute *attr, const char *buf, size_t count)
2955	{
2956	struct tty_port *port = dev_get_drvdata(dev);
2957	struct uart_state *state = container_of(port, struct uart_state, port);
2958	struct uart_port *uport;
2959	bool oldconsole, newconsole;
2960	int ret;
2961
2962	ret = kstrtobool(s: buf, res: &newconsole);
2963	if (ret)
2964	return ret;
2965
2966	guard(mutex)(T: &port->mutex);
2967	uport = uart_port_check(state);
2968	if (!uport)
2969	return -ENXIO;
2970
2971	oldconsole = uart_console_registered(port: uport);
2972	if (oldconsole && !newconsole) {
2973	ret = unregister_console(uport->cons);
2974	if (ret < 0)
2975	return ret;
2976	} else if (!oldconsole && newconsole) {
2977	if (!uart_console(uport))
2978	return -ENOENT;
2979
2980	uport->console_reinit = 1;
2981	register_console(uport->cons);
2982	}
2983
2984	return count;
2985	}
2986
2987	static DEVICE_ATTR_RO(uartclk);
2988	static DEVICE_ATTR_RO(type);
2989	static DEVICE_ATTR_RO(line);
2990	static DEVICE_ATTR_RO(port);
2991	static DEVICE_ATTR_RO(irq);
2992	static DEVICE_ATTR_RO(flags);
2993	static DEVICE_ATTR_RO(xmit_fifo_size);
2994	static DEVICE_ATTR_RO(close_delay);
2995	static DEVICE_ATTR_RO(closing_wait);
2996	static DEVICE_ATTR_RO(custom_divisor);
2997	static DEVICE_ATTR_RO(io_type);
2998	static DEVICE_ATTR_RO(iomem_base);
2999	static DEVICE_ATTR_RO(iomem_reg_shift);
3000	static DEVICE_ATTR_RW(console);
3001
3002	static struct attribute *tty_dev_attrs[] = {
3003	&dev_attr_uartclk.attr,
3004	&dev_attr_type.attr,
3005	&dev_attr_line.attr,
3006	&dev_attr_port.attr,
3007	&dev_attr_irq.attr,
3008	&dev_attr_flags.attr,
3009	&dev_attr_xmit_fifo_size.attr,
3010	&dev_attr_close_delay.attr,
3011	&dev_attr_closing_wait.attr,
3012	&dev_attr_custom_divisor.attr,
3013	&dev_attr_io_type.attr,
3014	&dev_attr_iomem_base.attr,
3015	&dev_attr_iomem_reg_shift.attr,
3016	&dev_attr_console.attr,
3017	NULL
3018	};
3019
3020	static const struct attribute_group tty_dev_attr_group = {
3021	.attrs = tty_dev_attrs,
3022	};
3023
3024	/**
3025	* serial_core_add_one_port - attach a driver-defined port structure
3026	* @drv: pointer to the uart low level driver structure for this port
3027	* @uport: uart port structure to use for this port.
3028	*
3029	* Context: task context, might sleep
3030	*
3031	* This allows the driver @drv to register its own uart_port structure with the
3032	* core driver. The main purpose is to allow the low level uart drivers to
3033	* expand uart_port, rather than having yet more levels of structures.
3034	* Caller must hold port_mutex.
3035	*/
3036	static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *uport)
3037	{
3038	struct uart_state *state;
3039	struct tty_port *port;
3040	struct device *tty_dev;
3041	int num_groups;
3042
3043	if (uport->line >= drv->nr)
3044	return -EINVAL;
3045
3046	state = drv->state + uport->line;
3047	port = &state->port;
3048
3049	guard(mutex)(T: &port->mutex);
3050	if (state->uart_port)
3051	return -EINVAL;
3052
3053	/* Link the port to the driver state table and vice versa */
3054	atomic_set(v: &state->refcount, i: 1);
3055	init_waitqueue_head(&state->remove_wait);
3056	state->uart_port = uport;
3057	uport->state = state;
3058
3059	/*
3060	* If this port is in use as a console then the spinlock is already
3061	* initialised.
3062	*/
3063	if (!uart_console_registered(port: uport))
3064	uart_port_spin_lock_init(port: uport);
3065
3066	state->pm_state = UART_PM_STATE_UNDEFINED;
3067	uart_port_set_cons(up: uport, con: drv->cons);
3068	uport->minor = drv->tty_driver->minor_start + uport->line;
3069	uport->name = kasprintf(GFP_KERNEL, fmt: "%s%u", drv->dev_name,
3070	drv->tty_driver->name_base + uport->line);
3071	if (!uport->name)
3072	return -ENOMEM;
3073
3074	if (uport->cons && uport->dev)
3075	of_console_check(dn: uport->dev->of_node, name: uport->cons->name, index: uport->line);
3076
3077	/*
3078	* TTY port has to be linked with the driver before register_console()
3079	* in uart_configure_port(), because user-space could open the console
3080	* immediately after.
3081	*/
3082	tty_port_link_device(port, driver: drv->tty_driver, index: uport->line);
3083	uart_configure_port(drv, state, port: uport);
3084
3085	port->console = uart_console(uport);
3086
3087	num_groups = 2;
3088	if (uport->attr_group)
3089	num_groups++;
3090
3091	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
3092	GFP_KERNEL);
3093	if (!uport->tty_groups)
3094	return -ENOMEM;
3095
3096	uport->tty_groups[0] = &tty_dev_attr_group;
3097	if (uport->attr_group)
3098	uport->tty_groups[1] = uport->attr_group;
3099
3100	/* Ensure serdev drivers can call serdev_device_open() right away */
3101	uport->flags &= ~UPF_DEAD;
3102
3103	/*
3104	* Register the port whether it's detected or not. This allows
3105	* setserial to be used to alter this port's parameters.
3106	*/
3107	tty_dev = tty_port_register_device_attr_serdev(port, driver: drv->tty_driver,
3108	index: uport->line, host: uport->dev, parent: &uport->port_dev->dev, drvdata: port,
3109	attr_grp: uport->tty_groups);
3110	if (!IS_ERR(ptr: tty_dev)) {
3111	device_set_wakeup_capable(dev: tty_dev, capable: 1);
3112	} else {
3113	uport->flags |= UPF_DEAD;
3114	dev_err(uport->dev, "Cannot register tty device on line %u\n",
3115	uport->line);
3116	}
3117
3118	return 0;
3119	}
3120
3121	/**
3122	* serial_core_remove_one_port - detach a driver defined port structure
3123	* @drv: pointer to the uart low level driver structure for this port
3124	* @uport: uart port structure for this port
3125	*
3126	* Context: task context, might sleep
3127	*
3128	* This unhooks (and hangs up) the specified port structure from the core
3129	* driver. No further calls will be made to the low-level code for this port.
3130	* Caller must hold port_mutex.
3131	*/
3132	static void serial_core_remove_one_port(struct uart_driver *drv,
3133	struct uart_port *uport)
3134	{
3135	struct uart_state *state = drv->state + uport->line;
3136	struct tty_port *port = &state->port;
3137	struct uart_port *uart_port;
3138
3139	scoped_guard(mutex, &port->mutex) {
3140	uart_port = uart_port_check(state);
3141	if (uart_port != uport)
3142	dev_alert(uport->dev, "Removing wrong port: %p != %p\n", uart_port, uport);
3143
3144	if (!uart_port)
3145	return;
3146	}
3147
3148	/*
3149	* Remove the devices from the tty layer
3150	*/
3151	tty_port_unregister_device(port, driver: drv->tty_driver, index: uport->line);
3152
3153	tty_port_tty_vhangup(port);
3154
3155	/*
3156	* If the port is used as a console, unregister it
3157	*/
3158	if (uart_console(uport))
3159	unregister_console(uport->cons);
3160
3161	/*
3162	* Free the port IO and memory resources, if any.
3163	*/
3164	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
3165	uport->ops->release_port(uport);
3166	kfree(objp: uport->tty_groups);
3167	kfree(objp: uport->name);
3168
3169	/*
3170	* Indicate that there isn't a port here anymore.
3171	*/
3172	uport->type = PORT_UNKNOWN;
3173	uport->port_dev = NULL;
3174
3175	guard(mutex)(T: &port->mutex);
3176	WARN_ON(atomic_dec_return(&state->refcount) < 0);
3177	wait_event(state->remove_wait, !atomic_read(&state->refcount));
3178	state->uart_port = NULL;
3179	}
3180
3181	/**
3182	* uart_match_port - are the two ports equivalent?
3183	* @port1: first port
3184	* @port2: second port
3185	*
3186	* This utility function can be used to determine whether two uart_port
3187	* structures describe the same port.
3188	*/
3189	bool uart_match_port(const struct uart_port *port1,
3190	const struct uart_port *port2)
3191	{
3192	if (port1->iotype != port2->iotype)
3193	return false;
3194
3195	switch (port1->iotype) {
3196	case UPIO_PORT:
3197	return port1->iobase == port2->iobase;
3198	case UPIO_HUB6:
3199	return port1->iobase == port2->iobase &&
3200	port1->hub6 == port2->hub6;
3201	case UPIO_MEM:
3202	case UPIO_MEM16:
3203	case UPIO_MEM32:
3204	case UPIO_MEM32BE:
3205	case UPIO_AU:
3206	case UPIO_TSI:
3207	return port1->mapbase == port2->mapbase;
3208	default:
3209	return false;
3210	}
3211	}
3212	EXPORT_SYMBOL(uart_match_port);
3213
3214	static struct serial_ctrl_device *
3215	serial_core_get_ctrl_dev(struct serial_port_device *port_dev)
3216	{
3217	struct device *dev = &port_dev->dev;
3218
3219	return to_serial_base_ctrl_device(dev->parent);
3220	}
3221
3222	/*
3223	* Find a registered serial core controller device if one exists. Returns
3224	* the first device matching the ctrl_id. Caller must hold port_mutex.
3225	*/
3226	static struct serial_ctrl_device *serial_core_ctrl_find(struct uart_driver *drv,
3227	struct device *phys_dev,
3228	int ctrl_id)
3229	{
3230	struct uart_state *state;
3231	int i;
3232
3233	lockdep_assert_held(&port_mutex);
3234
3235	for (i = 0; i < drv->nr; i++) {
3236	state = drv->state + i;
3237	if (!state->uart_port || !state->uart_port->port_dev)
3238	continue;
3239
3240	if (state->uart_port->dev == phys_dev &&
3241	state->uart_port->ctrl_id == ctrl_id)
3242	return serial_core_get_ctrl_dev(port_dev: state->uart_port->port_dev);
3243	}
3244
3245	return NULL;
3246	}
3247
3248	static struct serial_ctrl_device *serial_core_ctrl_device_add(struct uart_port *port)
3249	{
3250	return serial_base_ctrl_add(port, parent: port->dev);
3251	}
3252
3253	static int serial_core_port_device_add(struct serial_ctrl_device *ctrl_dev,
3254	struct uart_port *port)
3255	{
3256	struct serial_port_device *port_dev;
3257
3258	port_dev = serial_base_port_add(port, parent: ctrl_dev);
3259	if (IS_ERR(ptr: port_dev))
3260	return PTR_ERR(ptr: port_dev);
3261
3262	port->port_dev = port_dev;
3263
3264	return 0;
3265	}
3266
3267	/*
3268	* Initialize a serial core port device, and a controller device if needed.
3269	*/
3270	int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
3271	{
3272	struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
3273	int ret;
3274
3275	guard(mutex)(T: &port_mutex);
3276
3277	/*
3278	* Prevent serial_port_runtime_resume() from trying to use the port
3279	* until serial_core_add_one_port() has completed
3280	*/
3281	port->flags |= UPF_DEAD;
3282
3283	/* Inititalize a serial core controller device if needed */
3284	ctrl_dev = serial_core_ctrl_find(drv, phys_dev: port->dev, ctrl_id: port->ctrl_id);
3285	if (!ctrl_dev) {
3286	new_ctrl_dev = serial_core_ctrl_device_add(port);
3287	if (IS_ERR(ptr: new_ctrl_dev))
3288	return PTR_ERR(ptr: new_ctrl_dev);
3289	ctrl_dev = new_ctrl_dev;
3290	}
3291
3292	/*
3293	* Initialize a serial core port device. Tag the port dead to prevent
3294	* serial_port_runtime_resume() trying to do anything until port has
3295	* been registered. It gets cleared by serial_core_add_one_port().
3296	*/
3297	ret = serial_core_port_device_add(ctrl_dev, port);
3298	if (ret)
3299	goto err_unregister_ctrl_dev;
3300
3301	ret = serial_base_match_and_update_preferred_console(drv, port);
3302	if (ret)
3303	goto err_unregister_port_dev;
3304
3305	ret = serial_core_add_one_port(drv, uport: port);
3306	if (ret)
3307	goto err_unregister_port_dev;
3308
3309	return 0;
3310
3311	err_unregister_port_dev:
3312	serial_base_port_device_remove(port_dev: port->port_dev);
3313
3314	err_unregister_ctrl_dev:
3315	serial_base_ctrl_device_remove(ctrl_dev: new_ctrl_dev);
3316
3317	return ret;
3318	}
3319
3320	/*
3321	* Removes a serial core port device, and the related serial core controller
3322	* device if the last instance.
3323	*/
3324	void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port)
3325	{
3326	struct device *phys_dev = port->dev;
3327	struct serial_port_device *port_dev = port->port_dev;
3328	struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
3329	int ctrl_id = port->ctrl_id;
3330
3331	guard(mutex)(T: &port_mutex);
3332
3333	port->flags |= UPF_DEAD;
3334
3335	serial_core_remove_one_port(drv, uport: port);
3336
3337	/* Note that struct uart_port *port is no longer valid at this point */
3338	serial_base_port_device_remove(port_dev);
3339
3340	/* Drop the serial core controller device if no ports are using it */
3341	if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
3342	serial_base_ctrl_device_remove(ctrl_dev);
3343	}
3344
3345	/**
3346	* uart_handle_dcd_change - handle a change of carrier detect state
3347	* @uport: uart_port structure for the open port
3348	* @active: new carrier detect status
3349	*
3350	* Caller must hold uport->lock.
3351	*/
3352	void uart_handle_dcd_change(struct uart_port *uport, bool active)
3353	{
3354	struct tty_port *port = &uport->state->port;
3355	struct tty_struct *tty = port->tty;
3356	struct tty_ldisc *ld;
3357
3358	lockdep_assert_held_once(&uport->lock);
3359
3360	if (tty) {
3361	ld = tty_ldisc_ref(tty);
3362	if (ld) {
3363	if (ld->ops->dcd_change)
3364	ld->ops->dcd_change(tty, active);
3365	tty_ldisc_deref(ld);
3366	}
3367	}
3368
3369	uport->icount.dcd++;
3370
3371	if (uart_dcd_enabled(uport)) {
3372	if (active)
3373	wake_up_interruptible(&port->open_wait);
3374	else if (tty)
3375	tty_hangup(tty);
3376	}
3377	}
3378	EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
3379
3380	/**
3381	* uart_handle_cts_change - handle a change of clear-to-send state
3382	* @uport: uart_port structure for the open port
3383	* @active: new clear-to-send status
3384	*
3385	* Caller must hold uport->lock.
3386	*/
3387	void uart_handle_cts_change(struct uart_port *uport, bool active)
3388	{
3389	lockdep_assert_held_once(&uport->lock);
3390
3391	uport->icount.cts++;
3392
3393	if (uart_softcts_mode(uport)) {
3394	if (uport->hw_stopped) {
3395	if (active) {
3396	uport->hw_stopped = false;
3397	uport->ops->start_tx(uport);
3398	uart_write_wakeup(uport);
3399	}
3400	} else {
3401	if (!active) {
3402	uport->hw_stopped = true;
3403	uport->ops->stop_tx(uport);
3404	}
3405	}
3406
3407	}
3408	}
3409	EXPORT_SYMBOL_GPL(uart_handle_cts_change);
3410
3411	/**
3412	* uart_insert_char - push a char to the uart layer
3413	*
3414	* User is responsible to call tty_flip_buffer_push when they are done with
3415	* insertion.
3416	*
3417	* @port: corresponding port
3418	* @status: state of the serial port RX buffer (LSR for 8250)
3419	* @overrun: mask of overrun bits in @status
3420	* @ch: character to push
3421	* @flag: flag for the character (see TTY_NORMAL and friends)
3422	*/
3423	void uart_insert_char(struct uart_port *port, unsigned int status,
3424	unsigned int overrun, u8 ch, u8 flag)
3425	{
3426	struct tty_port *tport = &port->state->port;
3427
3428	if ((status & port->ignore_status_mask & ~overrun) == 0)
3429	if (tty_insert_flip_char(port: tport, ch, flag) == 0)
3430	++port->icount.buf_overrun;
3431
3432	/*
3433	* Overrun is special. Since it's reported immediately,
3434	* it doesn't affect the current character.
3435	*/
3436	if (status & ~port->ignore_status_mask & overrun)
3437	if (tty_insert_flip_char(port: tport, ch: 0, TTY_OVERRUN) == 0)
3438	++port->icount.buf_overrun;
3439	}
3440	EXPORT_SYMBOL_GPL(uart_insert_char);
3441
3442	#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
3443	static const u8 sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
3444
3445	static void uart_sysrq_on(struct work_struct *w)
3446	{
3447	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3448
3449	sysrq_toggle_support(enable_mask: 1);
3450	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
3451	sysrq_toggle_seq_len, sysrq_toggle_seq);
3452	}
3453	static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
3454
3455	/**
3456	* uart_try_toggle_sysrq - Enables SysRq from serial line
3457	* @port: uart_port structure where char(s) after BREAK met
3458	* @ch: new character in the sequence after received BREAK
3459	*
3460	* Enables magic SysRq when the required sequence is met on port
3461	* (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
3462	*
3463	* Returns: %false if @ch is out of enabling sequence and should be
3464	* handled some other way, %true if @ch was consumed.
3465	*/
3466	bool uart_try_toggle_sysrq(struct uart_port *port, u8 ch)
3467	{
3468	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3469
3470	if (!sysrq_toggle_seq_len)
3471	return false;
3472
3473	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
3474	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
3475	port->sysrq_seq = 0;
3476	return false;
3477	}
3478
3479	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
3480	port->sysrq = jiffies + SYSRQ_TIMEOUT;
3481	return true;
3482	}
3483
3484	schedule_work(work: &sysrq_enable_work);
3485
3486	port->sysrq = 0;
3487	return true;
3488	}
3489	EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
3490	#endif
3491
3492	/**
3493	* uart_get_rs485_mode() - retrieve rs485 properties for given uart
3494	* @port: uart device's target port
3495	*
3496	* This function implements the device tree binding described in
3497	* Documentation/devicetree/bindings/serial/rs485.txt.
3498	*/
3499	int uart_get_rs485_mode(struct uart_port *port)
3500	{
3501	struct serial_rs485 *rs485conf = &port->rs485;
3502	struct device *dev = port->dev;
3503	enum gpiod_flags dflags;
3504	struct gpio_desc *desc;
3505	u32 rs485_delay[2];
3506	int ret;
3507
3508	if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
3509	return 0;
3510
3511	/*
3512	* Retrieve properties only if a firmware node exists. If no firmware
3513	* node exists, then don't touch rs485 config and keep initial rs485
3514	* properties set by driver.
3515	*/
3516	if (!dev_fwnode(dev))
3517	return 0;
3518
3519	ret = device_property_read_u32_array(dev, propname: "rs485-rts-delay",
3520	val: rs485_delay, nval: 2);
3521	if (!ret) {
3522	rs485conf->delay_rts_before_send = rs485_delay[0];
3523	rs485conf->delay_rts_after_send = rs485_delay[1];
3524	} else {
3525	rs485conf->delay_rts_before_send = 0;
3526	rs485conf->delay_rts_after_send = 0;
3527	}
3528
3529	uart_sanitize_serial_rs485_delays(port, rs485: rs485conf);
3530
3531	/*
3532	* Clear full-duplex and enabled flags, set RTS polarity to active high
3533	* to get to a defined state with the following properties:
3534	*/
3535	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
3536	SER_RS485_TERMINATE_BUS |
3537	SER_RS485_RTS_AFTER_SEND);
3538	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
3539
3540	if (device_property_read_bool(dev, propname: "rs485-rx-during-tx"))
3541	rs485conf->flags |= SER_RS485_RX_DURING_TX;
3542
3543	if (device_property_read_bool(dev, propname: "linux,rs485-enabled-at-boot-time"))
3544	rs485conf->flags |= SER_RS485_ENABLED;
3545
3546	if (device_property_read_bool(dev, propname: "rs485-rts-active-low")) {
3547	rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
3548	rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
3549	}
3550
3551	/*
3552	* Disabling termination by default is the safe choice: Else if many
3553	* bus participants enable it, no communication is possible at all.
3554	* Works fine for short cables and users may enable for longer cables.
3555	*/
3556	desc = devm_gpiod_get_optional(dev, con_id: "rs485-term", flags: GPIOD_OUT_LOW);
3557	if (IS_ERR(ptr: desc))
3558	return dev_err_probe(dev, err: PTR_ERR(ptr: desc), fmt: "Cannot get rs485-term-gpios\n");
3559	port->rs485_term_gpio = desc;
3560	if (port->rs485_term_gpio)
3561	port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;
3562
3563	dflags = (rs485conf->flags & SER_RS485_RX_DURING_TX) ?
3564	GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
3565	desc = devm_gpiod_get_optional(dev, con_id: "rs485-rx-during-tx", flags: dflags);
3566	if (IS_ERR(ptr: desc))
3567	return dev_err_probe(dev, err: PTR_ERR(ptr: desc), fmt: "Cannot get rs485-rx-during-tx-gpios\n");
3568	port->rs485_rx_during_tx_gpio = desc;
3569	if (port->rs485_rx_during_tx_gpio)
3570	port->rs485_supported.flags |= SER_RS485_RX_DURING_TX;
3571
3572	return 0;
3573	}
3574	EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
3575
3576	/* Compile-time assertions for serial_rs485 layout */
3577	static_assert(offsetof(struct serial_rs485, padding) ==
3578	(offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
3579	static_assert(offsetof(struct serial_rs485, padding1) ==
3580	offsetof(struct serial_rs485, padding[1]));
3581	static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
3582	sizeof(struct serial_rs485));
3583
3584	MODULE_DESCRIPTION("Serial driver core");
3585	MODULE_LICENSE("GPL");
3586