1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2014 Linaro Ltd.
4 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
5 *
6 * PCC (Platform Communication Channel) is defined in the ACPI 5.0+
7 * specification. It is a mailbox like mechanism to allow clients
8 * such as CPPC (Collaborative Processor Performance Control), RAS
9 * (Reliability, Availability and Serviceability) and MPST (Memory
10 * Node Power State Table) to talk to the platform (e.g. BMC) through
11 * shared memory regions as defined in the PCC table entries. The PCC
12 * specification supports a Doorbell mechanism for the PCC clients
13 * to notify the platform about new data. This Doorbell information
14 * is also specified in each PCC table entry.
15 *
16 * Typical high level flow of operation is:
17 *
18 * PCC Reads:
19 * * Client tries to acquire a channel lock.
20 * * After it is acquired it writes READ cmd in communication region cmd
21 * address.
22 * * Client issues mbox_send_message() which rings the PCC doorbell
23 * for its PCC channel.
24 * * If command completes, then client has control over channel and
25 * it can proceed with its reads.
26 * * Client releases lock.
27 *
28 * PCC Writes:
29 * * Client tries to acquire channel lock.
30 * * Client writes to its communication region after it acquires a
31 * channel lock.
32 * * Client writes WRITE cmd in communication region cmd address.
33 * * Client issues mbox_send_message() which rings the PCC doorbell
34 * for its PCC channel.
35 * * If command completes, then writes have succeeded and it can release
36 * the channel lock.
37 *
38 * There is a Nominal latency defined for each channel which indicates
39 * how long to wait until a command completes. If command is not complete
40 * the client needs to retry or assume failure.
41 *
42 * For more details about PCC, please see the ACPI specification from
43 * http://www.uefi.org/ACPIv5.1 Section 14.
44 *
45 * This file implements PCC as a Mailbox controller and allows for PCC
46 * clients to be implemented as its Mailbox Client Channels.
47 */
48
49#include <linux/acpi.h>
50#include <linux/delay.h>
51#include <linux/io.h>
52#include <linux/init.h>
53#include <linux/interrupt.h>
54#include <linux/list.h>
55#include <linux/log2.h>
56#include <linux/platform_device.h>
57#include <linux/mailbox_controller.h>
58#include <linux/mailbox_client.h>
59#include <linux/io-64-nonatomic-lo-hi.h>
60#include <acpi/pcc.h>
61
62#include "mailbox.h"
63
64#define MBOX_IRQ_NAME "pcc-mbox"
65
66/**
67 * struct pcc_chan_reg - PCC register bundle
68 *
69 * @vaddr: cached virtual address for this register
70 * @gas: pointer to the generic address structure for this register
71 * @preserve_mask: bitmask to preserve when writing to this register
72 * @set_mask: bitmask to set when writing to this register
73 * @status_mask: bitmask to determine and/or update the status for this register
74 */
75struct pcc_chan_reg {
76 void __iomem *vaddr;
77 struct acpi_generic_address *gas;
78 u64 preserve_mask;
79 u64 set_mask;
80 u64 status_mask;
81};
82
83/**
84 * struct pcc_chan_info - PCC channel specific information
85 *
86 * @chan: PCC channel information with Shared Memory Region info
87 * @db: PCC register bundle for the doorbell register
88 * @plat_irq_ack: PCC register bundle for the platform interrupt acknowledge
89 * register
90 * @cmd_complete: PCC register bundle for the command complete check register
91 * @cmd_update: PCC register bundle for the command complete update register
92 * @error: PCC register bundle for the error status register
93 * @plat_irq: platform interrupt
94 * @type: PCC subspace type
95 * @plat_irq_flags: platform interrupt flags
96 * @chan_in_use: this flag is used just to check if the interrupt needs
97 * handling when it is shared. Since only one transfer can occur
98 * at a time and mailbox takes care of locking, this flag can be
99 * accessed without a lock. Note: the type only support the
100 * communication from OSPM to Platform, like type3, use it, and
101 * other types completely ignore it.
102 */
103struct pcc_chan_info {
104 struct pcc_mbox_chan chan;
105 struct pcc_chan_reg db;
106 struct pcc_chan_reg plat_irq_ack;
107 struct pcc_chan_reg cmd_complete;
108 struct pcc_chan_reg cmd_update;
109 struct pcc_chan_reg error;
110 int plat_irq;
111 u8 type;
112 unsigned int plat_irq_flags;
113 bool chan_in_use;
114};
115
116#define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
117static struct pcc_chan_info *chan_info;
118static int pcc_chan_count;
119
120/*
121 * PCC can be used with perf critical drivers such as CPPC
122 * So it makes sense to locally cache the virtual address and
123 * use it to read/write to PCC registers such as doorbell register
124 *
125 * The below read_register and write_registers are used to read and
126 * write from perf critical registers such as PCC doorbell register
127 */
128static void read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
129{
130 switch (bit_width) {
131 case 8:
132 *val = readb(addr: vaddr);
133 break;
134 case 16:
135 *val = readw(addr: vaddr);
136 break;
137 case 32:
138 *val = readl(addr: vaddr);
139 break;
140 case 64:
141 *val = readq(addr: vaddr);
142 break;
143 }
144}
145
146static void write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
147{
148 switch (bit_width) {
149 case 8:
150 writeb(val, addr: vaddr);
151 break;
152 case 16:
153 writew(val, addr: vaddr);
154 break;
155 case 32:
156 writel(val, addr: vaddr);
157 break;
158 case 64:
159 writeq(val, addr: vaddr);
160 break;
161 }
162}
163
164static int pcc_chan_reg_read(struct pcc_chan_reg *reg, u64 *val)
165{
166 int ret = 0;
167
168 if (!reg->gas) {
169 *val = 0;
170 return 0;
171 }
172
173 if (reg->vaddr)
174 read_register(vaddr: reg->vaddr, val, bit_width: reg->gas->bit_width);
175 else
176 ret = acpi_read(value: val, reg: reg->gas);
177
178 return ret;
179}
180
181static int pcc_chan_reg_write(struct pcc_chan_reg *reg, u64 val)
182{
183 int ret = 0;
184
185 if (!reg->gas)
186 return 0;
187
188 if (reg->vaddr)
189 write_register(vaddr: reg->vaddr, val, bit_width: reg->gas->bit_width);
190 else
191 ret = acpi_write(value: val, reg: reg->gas);
192
193 return ret;
194}
195
196static int pcc_chan_reg_read_modify_write(struct pcc_chan_reg *reg)
197{
198 int ret = 0;
199 u64 val;
200
201 ret = pcc_chan_reg_read(reg, val: &val);
202 if (ret)
203 return ret;
204
205 val &= reg->preserve_mask;
206 val |= reg->set_mask;
207
208 return pcc_chan_reg_write(reg, val);
209}
210
211/**
212 * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
213 * @interrupt: GSI number.
214 * @flags: interrupt flags
215 *
216 * Returns: a valid linux IRQ number on success
217 * 0 or -EINVAL on failure
218 */
219static int pcc_map_interrupt(u32 interrupt, u32 flags)
220{
221 int trigger, polarity;
222
223 if (!interrupt)
224 return 0;
225
226 trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
227 : ACPI_LEVEL_SENSITIVE;
228
229 polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
230 : ACPI_ACTIVE_HIGH;
231
232 return acpi_register_gsi(NULL, gsi: interrupt, triggering: trigger, polarity);
233}
234
235static bool pcc_chan_plat_irq_can_be_shared(struct pcc_chan_info *pchan)
236{
237 return (pchan->plat_irq_flags & ACPI_PCCT_INTERRUPT_MODE) ==
238 ACPI_LEVEL_SENSITIVE;
239}
240
241static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
242{
243 u64 val;
244 int ret;
245
246 if (!pchan->cmd_complete.gas)
247 return true;
248
249 ret = pcc_chan_reg_read(reg: &pchan->cmd_complete, val: &val);
250 if (ret)
251 return false;
252
253 /*
254 * Judge if the channel respond the interrupt based on the value of
255 * command complete.
256 */
257 val &= pchan->cmd_complete.status_mask;
258
259 /*
260 * If this is PCC slave subspace channel, and the command complete
261 * bit 0 indicates that Platform is sending a notification and OSPM
262 * needs to respond this interrupt to process this command.
263 */
264 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
265 return !val;
266
267 return !!val;
268}
269
270static int pcc_mbox_error_check_and_clear(struct pcc_chan_info *pchan)
271{
272 u64 val;
273 int ret;
274
275 ret = pcc_chan_reg_read(reg: &pchan->error, val: &val);
276 if (ret)
277 return ret;
278
279 if (val & pchan->error.status_mask) {
280 val &= pchan->error.preserve_mask;
281 pcc_chan_reg_write(reg: &pchan->error, val);
282 return -EIO;
283 }
284
285 return 0;
286}
287
288static void pcc_chan_acknowledge(struct pcc_chan_info *pchan)
289{
290 struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_hdr;
291
292 if (pchan->type != ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
293 return;
294
295 pcc_chan_reg_read_modify_write(reg: &pchan->cmd_update);
296
297 pcc_hdr = pchan->chan.shmem;
298
299 /*
300 * The PCC slave subspace channel needs to set the command
301 * complete bit after processing message. If the PCC_ACK_FLAG
302 * is set, it should also ring the doorbell.
303 */
304 if (ioread32(&pcc_hdr->flags) & PCC_CMD_COMPLETION_NOTIFY)
305 pcc_chan_reg_read_modify_write(reg: &pchan->db);
306}
307
308static void *write_response(struct pcc_chan_info *pchan)
309{
310 struct pcc_header pcc_header;
311 void *buffer;
312 int data_len;
313
314 memcpy_fromio(&pcc_header, pchan->chan.shmem,
315 sizeof(pcc_header));
316 data_len = pcc_header.length - sizeof(u32) + sizeof(struct pcc_header);
317
318 buffer = pchan->chan.rx_alloc(pchan->chan.mchan->cl, data_len);
319 if (buffer != NULL)
320 memcpy_fromio(buffer, pchan->chan.shmem, data_len);
321 return buffer;
322}
323
324/**
325 * pcc_mbox_irq - PCC mailbox interrupt handler
326 * @irq: interrupt number
327 * @p: data/cookie passed from the caller to identify the channel
328 *
329 * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
330 */
331static irqreturn_t pcc_mbox_irq(int irq, void *p)
332{
333 struct pcc_chan_info *pchan;
334 struct mbox_chan *chan = p;
335 struct pcc_header *pcc_header = chan->active_req;
336 void *handle = NULL;
337
338 pchan = chan->con_priv;
339
340 if (pcc_chan_reg_read_modify_write(reg: &pchan->plat_irq_ack))
341 return IRQ_NONE;
342
343 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE &&
344 !pchan->chan_in_use)
345 return IRQ_NONE;
346
347 if (!pcc_mbox_cmd_complete_check(pchan))
348 return IRQ_NONE;
349
350 if (pcc_mbox_error_check_and_clear(pchan))
351 return IRQ_NONE;
352
353 /*
354 * Clear this flag after updating interrupt ack register and just
355 * before mbox_chan_received_data() which might call pcc_send_data()
356 * where the flag is set again to start new transfer. This is
357 * required to avoid any possible race in updatation of this flag.
358 */
359 pchan->chan_in_use = false;
360
361 if (pchan->chan.rx_alloc)
362 handle = write_response(pchan);
363
364 if (chan->active_req) {
365 pcc_header = chan->active_req;
366 if (pcc_header->flags & PCC_CMD_COMPLETION_NOTIFY)
367 mbox_chan_txdone(chan, r: 0);
368 }
369
370 mbox_chan_received_data(chan, data: handle);
371
372 pcc_chan_acknowledge(pchan);
373
374 return IRQ_HANDLED;
375}
376
377/**
378 * pcc_mbox_request_channel - PCC clients call this function to
379 * request a pointer to their PCC subspace, from which they
380 * can get the details of communicating with the remote.
381 * @cl: Pointer to Mailbox client, so we know where to bind the
382 * Channel.
383 * @subspace_id: The PCC Subspace index as parsed in the PCC client
384 * ACPI package. This is used to lookup the array of PCC
385 * subspaces as parsed by the PCC Mailbox controller.
386 *
387 * Return: Pointer to the PCC Mailbox Channel if successful or ERR_PTR.
388 */
389struct pcc_mbox_chan *
390pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
391{
392 struct pcc_mbox_chan *pcc_mchan;
393 struct pcc_chan_info *pchan;
394 struct mbox_chan *chan;
395 int rc;
396
397 if (subspace_id < 0 || subspace_id >= pcc_chan_count)
398 return ERR_PTR(error: -ENOENT);
399
400 pchan = chan_info + subspace_id;
401 chan = pchan->chan.mchan;
402 if (IS_ERR(ptr: chan) || chan->cl) {
403 pr_err("Channel not found for idx: %d\n", subspace_id);
404 return ERR_PTR(error: -EBUSY);
405 }
406
407 rc = mbox_bind_client(chan, cl);
408 if (rc)
409 return ERR_PTR(error: rc);
410
411 pcc_mchan = &pchan->chan;
412 pcc_mchan->shmem = acpi_os_ioremap(pcc_mchan->shmem_base_addr,
413 pcc_mchan->shmem_size);
414 if (!pcc_mchan->shmem)
415 goto err;
416
417 pcc_mchan->manage_writes = false;
418
419 /* This indicates that the channel is ready to accept messages.
420 * This needs to happen after the channel has registered
421 * its callback. There is no access point to do that in
422 * the mailbox API. That implies that the mailbox client must
423 * have set the allocate callback function prior to
424 * sending any messages.
425 */
426 if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
427 pcc_chan_reg_read_modify_write(reg: &pchan->cmd_update);
428
429 return pcc_mchan;
430
431err:
432 mbox_free_channel(chan);
433 return ERR_PTR(error: -ENXIO);
434}
435EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
436
437/**
438 * pcc_mbox_free_channel - Clients call this to free their Channel.
439 *
440 * @pchan: Pointer to the PCC mailbox channel as returned by
441 * pcc_mbox_request_channel()
442 */
443void pcc_mbox_free_channel(struct pcc_mbox_chan *pchan)
444{
445 struct mbox_chan *chan = pchan->mchan;
446 struct pcc_chan_info *pchan_info;
447 struct pcc_mbox_chan *pcc_mbox_chan;
448
449 if (!chan || !chan->cl)
450 return;
451 pchan_info = chan->con_priv;
452 pcc_mbox_chan = &pchan_info->chan;
453 if (pcc_mbox_chan->shmem) {
454 iounmap(addr: pcc_mbox_chan->shmem);
455 pcc_mbox_chan->shmem = NULL;
456 }
457
458 mbox_free_channel(chan);
459}
460EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
461
462static int pcc_write_to_buffer(struct mbox_chan *chan, void *data)
463{
464 struct pcc_chan_info *pchan = chan->con_priv;
465 struct pcc_mbox_chan *pcc_mbox_chan = &pchan->chan;
466 struct pcc_header *pcc_header = data;
467
468 if (!pchan->chan.manage_writes)
469 return 0;
470
471 /* The PCC header length includes the command field
472 * but not the other values from the header.
473 */
474 int len = pcc_header->length - sizeof(u32) + sizeof(struct pcc_header);
475 u64 val;
476
477 pcc_chan_reg_read(reg: &pchan->cmd_complete, val: &val);
478 if (!val) {
479 pr_info("%s pchan->cmd_complete not set", __func__);
480 return -1;
481 }
482 memcpy_toio(pcc_mbox_chan->shmem, data, len);
483 return 0;
484}
485
486
487/**
488 * pcc_send_data - Called from Mailbox Controller code. If
489 * pchan->chan.rx_alloc is set, then the command complete
490 * flag is checked and the data is written to the shared
491 * buffer io memory.
492 *
493 * If pchan->chan.rx_alloc is not set, then it is used
494 * here only to ring the channel doorbell. The PCC client
495 * specific read/write is done in the client driver in
496 * order to maintain atomicity over PCC channel once
497 * OS has control over it. See above for flow of operations.
498 * @chan: Pointer to Mailbox channel over which to send data.
499 * @data: Client specific data written over channel. Used here
500 * only for debug after PCC transaction completes.
501 *
502 * Return: Err if something failed else 0 for success.
503 */
504static int pcc_send_data(struct mbox_chan *chan, void *data)
505{
506 int ret;
507 struct pcc_chan_info *pchan = chan->con_priv;
508
509 ret = pcc_write_to_buffer(chan, data);
510 if (ret)
511 return ret;
512
513 ret = pcc_chan_reg_read_modify_write(reg: &pchan->cmd_update);
514 if (ret)
515 return ret;
516
517 ret = pcc_chan_reg_read_modify_write(reg: &pchan->db);
518
519 if (!ret && pchan->plat_irq > 0)
520 pchan->chan_in_use = true;
521
522 return ret;
523}
524
525
526static bool pcc_last_tx_done(struct mbox_chan *chan)
527{
528 struct pcc_chan_info *pchan = chan->con_priv;
529 u64 val;
530
531 pcc_chan_reg_read(reg: &pchan->cmd_complete, val: &val);
532 if (!val)
533 return false;
534 else
535 return true;
536}
537
538
539
540/**
541 * pcc_startup - Called from Mailbox Controller code. Used here
542 * to request the interrupt.
543 * @chan: Pointer to Mailbox channel to startup.
544 *
545 * Return: Err if something failed else 0 for success.
546 */
547static int pcc_startup(struct mbox_chan *chan)
548{
549 struct pcc_chan_info *pchan = chan->con_priv;
550 unsigned long irqflags;
551 int rc;
552
553 if (pchan->plat_irq > 0) {
554 irqflags = pcc_chan_plat_irq_can_be_shared(pchan) ?
555 IRQF_SHARED | IRQF_ONESHOT : 0;
556 rc = devm_request_irq(dev: chan->mbox->dev, irq: pchan->plat_irq, handler: pcc_mbox_irq,
557 irqflags, MBOX_IRQ_NAME, dev_id: chan);
558 if (unlikely(rc)) {
559 dev_err(chan->mbox->dev, "failed to register PCC interrupt %d\n",
560 pchan->plat_irq);
561 return rc;
562 }
563 }
564
565 return 0;
566}
567
568/**
569 * pcc_shutdown - Called from Mailbox Controller code. Used here
570 * to free the interrupt.
571 * @chan: Pointer to Mailbox channel to shutdown.
572 */
573static void pcc_shutdown(struct mbox_chan *chan)
574{
575 struct pcc_chan_info *pchan = chan->con_priv;
576
577 if (pchan->plat_irq > 0)
578 devm_free_irq(dev: chan->mbox->dev, irq: pchan->plat_irq, dev_id: chan);
579}
580
581static const struct mbox_chan_ops pcc_chan_ops = {
582 .send_data = pcc_send_data,
583 .startup = pcc_startup,
584 .shutdown = pcc_shutdown,
585 .last_tx_done = pcc_last_tx_done,
586};
587
588/**
589 * parse_pcc_subspace - Count PCC subspaces defined
590 * @header: Pointer to the ACPI subtable header under the PCCT.
591 * @end: End of subtable entry.
592 *
593 * Return: If we find a PCC subspace entry of a valid type, return 0.
594 * Otherwise, return -EINVAL.
595 *
596 * This gets called for each entry in the PCC table.
597 */
598static int parse_pcc_subspace(union acpi_subtable_headers *header,
599 const unsigned long end)
600{
601 struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
602
603 if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
604 return 0;
605
606 return -EINVAL;
607}
608
609static int
610pcc_chan_reg_init(struct pcc_chan_reg *reg, struct acpi_generic_address *gas,
611 u64 preserve_mask, u64 set_mask, u64 status_mask, char *name)
612{
613 if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
614 if (!(gas->bit_width >= 8 && gas->bit_width <= 64 &&
615 is_power_of_2(n: gas->bit_width))) {
616 pr_err("Error: Cannot access register of %u bit width",
617 gas->bit_width);
618 return -EFAULT;
619 }
620
621 reg->vaddr = acpi_os_ioremap(gas->address, gas->bit_width / 8);
622 if (!reg->vaddr) {
623 pr_err("Failed to ioremap PCC %s register\n", name);
624 return -ENOMEM;
625 }
626 }
627 reg->gas = gas;
628 reg->preserve_mask = preserve_mask;
629 reg->set_mask = set_mask;
630 reg->status_mask = status_mask;
631 return 0;
632}
633
634/**
635 * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
636 *
637 * @pchan: Pointer to the PCC channel info structure.
638 * @pcct_entry: Pointer to the ACPI subtable header.
639 *
640 * Return: 0 for Success, else errno.
641 *
642 * There should be one entry per PCC channel. This gets called for each
643 * entry in the PCC table. This uses PCCY Type1 structure for all applicable
644 * types(Type 1-4) to fetch irq
645 */
646static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
647 struct acpi_subtable_header *pcct_entry)
648{
649 int ret = 0;
650 struct acpi_pcct_hw_reduced *pcct_ss;
651
652 if (pcct_entry->type < ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
653 pcct_entry->type > ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
654 return 0;
655
656 pcct_ss = (struct acpi_pcct_hw_reduced *)pcct_entry;
657 pchan->plat_irq = pcc_map_interrupt(interrupt: pcct_ss->platform_interrupt,
658 flags: (u32)pcct_ss->flags);
659 if (pchan->plat_irq <= 0) {
660 pr_err("PCC GSI %d not registered\n",
661 pcct_ss->platform_interrupt);
662 return -EINVAL;
663 }
664 pchan->plat_irq_flags = pcct_ss->flags;
665
666 if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
667 struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
668
669 ret = pcc_chan_reg_init(reg: &pchan->plat_irq_ack,
670 gas: &pcct2_ss->platform_ack_register,
671 preserve_mask: pcct2_ss->ack_preserve_mask,
672 set_mask: pcct2_ss->ack_write_mask, status_mask: 0,
673 name: "PLAT IRQ ACK");
674
675 } else if (pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE ||
676 pcct_ss->header.type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE) {
677 struct acpi_pcct_ext_pcc_master *pcct_ext = (void *)pcct_ss;
678
679 ret = pcc_chan_reg_init(reg: &pchan->plat_irq_ack,
680 gas: &pcct_ext->platform_ack_register,
681 preserve_mask: pcct_ext->ack_preserve_mask,
682 set_mask: pcct_ext->ack_set_mask, status_mask: 0,
683 name: "PLAT IRQ ACK");
684 }
685
686 if (pcc_chan_plat_irq_can_be_shared(pchan) &&
687 !pchan->plat_irq_ack.gas) {
688 pr_err("PCC subspace has level IRQ with no ACK register\n");
689 return -EINVAL;
690 }
691
692 return ret;
693}
694
695/**
696 * pcc_parse_subspace_db_reg - Parse the PCC doorbell register
697 *
698 * @pchan: Pointer to the PCC channel info structure.
699 * @pcct_entry: Pointer to the ACPI subtable header.
700 *
701 * Return: 0 for Success, else errno.
702 */
703static int pcc_parse_subspace_db_reg(struct pcc_chan_info *pchan,
704 struct acpi_subtable_header *pcct_entry)
705{
706 int ret = 0;
707
708 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
709 struct acpi_pcct_subspace *pcct_ss;
710
711 pcct_ss = (struct acpi_pcct_subspace *)pcct_entry;
712
713 ret = pcc_chan_reg_init(reg: &pchan->db,
714 gas: &pcct_ss->doorbell_register,
715 preserve_mask: pcct_ss->preserve_mask,
716 set_mask: pcct_ss->write_mask, status_mask: 0, name: "Doorbell");
717
718 } else {
719 struct acpi_pcct_ext_pcc_master *pcct_ext;
720
721 pcct_ext = (struct acpi_pcct_ext_pcc_master *)pcct_entry;
722
723 ret = pcc_chan_reg_init(reg: &pchan->db,
724 gas: &pcct_ext->doorbell_register,
725 preserve_mask: pcct_ext->preserve_mask,
726 set_mask: pcct_ext->write_mask, status_mask: 0, name: "Doorbell");
727 if (ret)
728 return ret;
729
730 ret = pcc_chan_reg_init(reg: &pchan->cmd_complete,
731 gas: &pcct_ext->cmd_complete_register,
732 preserve_mask: 0, set_mask: 0, status_mask: pcct_ext->cmd_complete_mask,
733 name: "Command Complete Check");
734 if (ret)
735 return ret;
736
737 ret = pcc_chan_reg_init(reg: &pchan->cmd_update,
738 gas: &pcct_ext->cmd_update_register,
739 preserve_mask: pcct_ext->cmd_update_preserve_mask,
740 set_mask: pcct_ext->cmd_update_set_mask, status_mask: 0,
741 name: "Command Complete Update");
742 if (ret)
743 return ret;
744
745 ret = pcc_chan_reg_init(reg: &pchan->error,
746 gas: &pcct_ext->error_status_register,
747 preserve_mask: ~pcct_ext->error_status_mask, set_mask: 0,
748 status_mask: pcct_ext->error_status_mask,
749 name: "Error Status");
750 }
751 return ret;
752}
753
754/**
755 * pcc_parse_subspace_shmem - Parse the PCC Shared Memory Region information
756 *
757 * @pchan: Pointer to the PCC channel info structure.
758 * @pcct_entry: Pointer to the ACPI subtable header.
759 *
760 */
761static void pcc_parse_subspace_shmem(struct pcc_chan_info *pchan,
762 struct acpi_subtable_header *pcct_entry)
763{
764 if (pcct_entry->type <= ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
765 struct acpi_pcct_subspace *pcct_ss =
766 (struct acpi_pcct_subspace *)pcct_entry;
767
768 pchan->chan.shmem_base_addr = pcct_ss->base_address;
769 pchan->chan.shmem_size = pcct_ss->length;
770 pchan->chan.latency = pcct_ss->latency;
771 pchan->chan.max_access_rate = pcct_ss->max_access_rate;
772 pchan->chan.min_turnaround_time = pcct_ss->min_turnaround_time;
773 } else {
774 struct acpi_pcct_ext_pcc_master *pcct_ext =
775 (struct acpi_pcct_ext_pcc_master *)pcct_entry;
776
777 pchan->chan.shmem_base_addr = pcct_ext->base_address;
778 pchan->chan.shmem_size = pcct_ext->length;
779 pchan->chan.latency = pcct_ext->latency;
780 pchan->chan.max_access_rate = pcct_ext->max_access_rate;
781 pchan->chan.min_turnaround_time = pcct_ext->min_turnaround_time;
782 }
783}
784
785/**
786 * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
787 *
788 * Return: 0 for Success, else errno.
789 */
790static int __init acpi_pcc_probe(void)
791{
792 int count, i, rc = 0;
793 acpi_status status;
794 struct acpi_table_header *pcct_tbl;
795 struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
796
797 status = acpi_get_table(ACPI_SIG_PCCT, instance: 0, out_table: &pcct_tbl);
798 if (ACPI_FAILURE(status) || !pcct_tbl)
799 return -ENODEV;
800
801 /* Set up the subtable handlers */
802 for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
803 i < ACPI_PCCT_TYPE_RESERVED; i++) {
804 proc[i].id = i;
805 proc[i].count = 0;
806 proc[i].handler = parse_pcc_subspace;
807 }
808
809 count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
810 table_size: sizeof(struct acpi_table_pcct), proc,
811 proc_num: ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
812 if (count <= 0 || count > MAX_PCC_SUBSPACES) {
813 if (count < 0)
814 pr_warn("Error parsing PCC subspaces from PCCT\n");
815 else
816 pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
817
818 rc = -EINVAL;
819 } else {
820 pcc_chan_count = count;
821 }
822
823 acpi_put_table(table: pcct_tbl);
824
825 return rc;
826}
827
828/**
829 * pcc_mbox_probe - Called when we find a match for the
830 * PCCT platform device. This is purely used to represent
831 * the PCCT as a virtual device for registering with the
832 * generic Mailbox framework.
833 *
834 * @pdev: Pointer to platform device returned when a match
835 * is found.
836 *
837 * Return: 0 for Success, else errno.
838 */
839static int pcc_mbox_probe(struct platform_device *pdev)
840{
841 struct device *dev = &pdev->dev;
842 struct mbox_controller *pcc_mbox_ctrl;
843 struct mbox_chan *pcc_mbox_channels;
844 struct acpi_table_header *pcct_tbl;
845 struct acpi_subtable_header *pcct_entry;
846 struct acpi_table_pcct *acpi_pcct_tbl;
847 acpi_status status = AE_OK;
848 int i, rc, count = pcc_chan_count;
849
850 /* Search for PCCT */
851 status = acpi_get_table(ACPI_SIG_PCCT, instance: 0, out_table: &pcct_tbl);
852
853 if (ACPI_FAILURE(status) || !pcct_tbl)
854 return -ENODEV;
855
856 pcc_mbox_channels = devm_kcalloc(dev, n: count, size: sizeof(*pcc_mbox_channels),
857 GFP_KERNEL);
858 if (!pcc_mbox_channels) {
859 rc = -ENOMEM;
860 goto err;
861 }
862
863 chan_info = devm_kcalloc(dev, n: count, size: sizeof(*chan_info), GFP_KERNEL);
864 if (!chan_info) {
865 rc = -ENOMEM;
866 goto err;
867 }
868
869 pcc_mbox_ctrl = devm_kzalloc(dev, size: sizeof(*pcc_mbox_ctrl), GFP_KERNEL);
870 if (!pcc_mbox_ctrl) {
871 rc = -ENOMEM;
872 goto err;
873 }
874
875 /* Point to the first PCC subspace entry */
876 pcct_entry = (struct acpi_subtable_header *) (
877 (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
878
879 acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
880 if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
881 pcc_mbox_ctrl->txdone_irq = true;
882
883 for (i = 0; i < count; i++) {
884 struct pcc_chan_info *pchan = chan_info + i;
885
886 pcc_mbox_channels[i].con_priv = pchan;
887 pchan->chan.mchan = &pcc_mbox_channels[i];
888
889 if (pcct_entry->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE &&
890 !pcc_mbox_ctrl->txdone_irq) {
891 pr_err("Platform Interrupt flag must be set to 1");
892 rc = -EINVAL;
893 goto err;
894 }
895
896 if (pcc_mbox_ctrl->txdone_irq) {
897 rc = pcc_parse_subspace_irq(pchan, pcct_entry);
898 if (rc < 0)
899 goto err;
900 }
901 rc = pcc_parse_subspace_db_reg(pchan, pcct_entry);
902 if (rc < 0)
903 goto err;
904
905 pcc_parse_subspace_shmem(pchan, pcct_entry);
906
907 pchan->type = pcct_entry->type;
908 pcct_entry = (struct acpi_subtable_header *)
909 ((unsigned long) pcct_entry + pcct_entry->length);
910 }
911
912 pcc_mbox_ctrl->num_chans = count;
913
914 pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl->num_chans);
915
916 pcc_mbox_ctrl->chans = pcc_mbox_channels;
917 pcc_mbox_ctrl->ops = &pcc_chan_ops;
918 pcc_mbox_ctrl->dev = dev;
919
920 pr_info("Registering PCC driver as Mailbox controller\n");
921 rc = mbox_controller_register(mbox: pcc_mbox_ctrl);
922 if (rc)
923 pr_err("Err registering PCC as Mailbox controller: %d\n", rc);
924 else
925 return 0;
926err:
927 acpi_put_table(table: pcct_tbl);
928 return rc;
929}
930
931static struct platform_driver pcc_mbox_driver = {
932 .probe = pcc_mbox_probe,
933 .driver = {
934 .name = "PCCT",
935 },
936};
937
938static int __init pcc_init(void)
939{
940 int ret;
941 struct platform_device *pcc_pdev;
942
943 if (acpi_disabled)
944 return -ENODEV;
945
946 /* Check if PCC support is available. */
947 ret = acpi_pcc_probe();
948
949 if (ret) {
950 pr_debug("ACPI PCC probe failed.\n");
951 return -ENODEV;
952 }
953
954 pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
955 pcc_mbox_probe, NULL, 0, NULL, 0);
956
957 if (IS_ERR(ptr: pcc_pdev)) {
958 pr_debug("Err creating PCC platform bundle\n");
959 pcc_chan_count = 0;
960 return PTR_ERR(ptr: pcc_pdev);
961 }
962
963 return 0;
964}
965
966/*
967 * Make PCC init postcore so that users of this mailbox
968 * such as the ACPI Processor driver have it available
969 * at their init.
970 */
971postcore_initcall(pcc_init);
972

source code of linux/drivers/mailbox/pcc.c