1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Helpers for controlling modem lines via GPIO
4 *
5 * Copyright (C) 2014 Paratronic S.A.
6 */
7
8#include <linux/err.h>
9#include <linux/device.h>
10#include <linux/irq.h>
11#include <linux/gpio/consumer.h>
12#include <linux/termios.h>
13#include <linux/serial_core.h>
14#include <linux/module.h>
15#include <linux/property.h>
16
17#include "serial_mctrl_gpio.h"
18
19struct mctrl_gpios {
20 struct uart_port *port;
21 struct gpio_desc *gpio[UART_GPIO_MAX];
22 int irq[UART_GPIO_MAX];
23 unsigned int mctrl_prev;
24 bool mctrl_on;
25};
26
27static const struct {
28 const char *name;
29 unsigned int mctrl;
30 enum gpiod_flags flags;
31} mctrl_gpios_desc[UART_GPIO_MAX] = {
32 { "cts", TIOCM_CTS, GPIOD_IN, },
33 { "dsr", TIOCM_DSR, GPIOD_IN, },
34 { "dcd", TIOCM_CD, GPIOD_IN, },
35 { "rng", TIOCM_RNG, GPIOD_IN, },
36 { "rts", TIOCM_RTS, GPIOD_OUT_LOW, },
37 { "dtr", TIOCM_DTR, GPIOD_OUT_LOW, },
38};
39
40static bool mctrl_gpio_flags_is_dir_out(unsigned int idx)
41{
42 return mctrl_gpios_desc[idx].flags & GPIOD_FLAGS_BIT_DIR_OUT;
43}
44
45/**
46 * mctrl_gpio_set - set gpios according to mctrl state
47 * @gpios: gpios to set
48 * @mctrl: state to set
49 *
50 * Set the gpios according to the mctrl state.
51 */
52void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
53{
54 enum mctrl_gpio_idx i;
55 struct gpio_desc *desc_array[UART_GPIO_MAX];
56 DECLARE_BITMAP(values, UART_GPIO_MAX);
57 unsigned int count = 0;
58
59 if (gpios == NULL)
60 return;
61
62 for (i = 0; i < UART_GPIO_MAX; i++)
63 if (gpios->gpio[i] && mctrl_gpio_flags_is_dir_out(idx: i)) {
64 desc_array[count] = gpios->gpio[i];
65 __assign_bit(count, values,
66 mctrl & mctrl_gpios_desc[i].mctrl);
67 count++;
68 }
69 gpiod_set_array_value(array_size: count, desc_array, NULL, value_bitmap: values);
70}
71EXPORT_SYMBOL_GPL(mctrl_gpio_set);
72
73/**
74 * mctrl_gpio_to_gpiod - obtain gpio_desc of modem line index
75 * @gpios: gpios to look into
76 * @gidx: index of the modem line
77 * Returns: the gpio_desc structure associated to the modem line index
78 */
79struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
80 enum mctrl_gpio_idx gidx)
81{
82 if (gpios == NULL)
83 return NULL;
84
85 return gpios->gpio[gidx];
86}
87EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
88
89/**
90 * mctrl_gpio_get - update mctrl with the gpios values.
91 * @gpios: gpios to get the info from
92 * @mctrl: mctrl to set
93 * Returns: modified mctrl (the same value as in @mctrl)
94 *
95 * Update mctrl with the gpios values.
96 */
97unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
98{
99 enum mctrl_gpio_idx i;
100
101 if (gpios == NULL)
102 return *mctrl;
103
104 for (i = 0; i < UART_GPIO_MAX; i++) {
105 if (gpios->gpio[i] && !mctrl_gpio_flags_is_dir_out(idx: i)) {
106 if (gpiod_get_value(desc: gpios->gpio[i]))
107 *mctrl |= mctrl_gpios_desc[i].mctrl;
108 else
109 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
110 }
111 }
112
113 return *mctrl;
114}
115EXPORT_SYMBOL_GPL(mctrl_gpio_get);
116
117unsigned int
118mctrl_gpio_get_outputs(struct mctrl_gpios *gpios, unsigned int *mctrl)
119{
120 enum mctrl_gpio_idx i;
121
122 if (gpios == NULL)
123 return *mctrl;
124
125 for (i = 0; i < UART_GPIO_MAX; i++) {
126 if (gpios->gpio[i] && mctrl_gpio_flags_is_dir_out(idx: i)) {
127 if (gpiod_get_value(desc: gpios->gpio[i]))
128 *mctrl |= mctrl_gpios_desc[i].mctrl;
129 else
130 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
131 }
132 }
133
134 return *mctrl;
135}
136EXPORT_SYMBOL_GPL(mctrl_gpio_get_outputs);
137
138struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
139{
140 struct mctrl_gpios *gpios;
141 enum mctrl_gpio_idx i;
142
143 gpios = devm_kzalloc(dev, size: sizeof(*gpios), GFP_KERNEL);
144 if (!gpios)
145 return ERR_PTR(error: -ENOMEM);
146
147 for (i = 0; i < UART_GPIO_MAX; i++) {
148 char *gpio_str;
149 bool present;
150
151 /* Check if GPIO property exists and continue if not */
152 gpio_str = kasprintf(GFP_KERNEL, fmt: "%s-gpios",
153 mctrl_gpios_desc[i].name);
154 if (!gpio_str)
155 continue;
156
157 present = device_property_present(dev, propname: gpio_str);
158 kfree(objp: gpio_str);
159 if (!present)
160 continue;
161
162 gpios->gpio[i] =
163 devm_gpiod_get_index_optional(dev,
164 con_id: mctrl_gpios_desc[i].name,
165 index: idx,
166 flags: mctrl_gpios_desc[i].flags);
167
168 if (IS_ERR(ptr: gpios->gpio[i]))
169 return ERR_CAST(ptr: gpios->gpio[i]);
170 }
171
172 return gpios;
173}
174EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
175
176#define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
177static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
178{
179 struct mctrl_gpios *gpios = context;
180 struct uart_port *port = gpios->port;
181 u32 mctrl = gpios->mctrl_prev;
182 u32 mctrl_diff;
183 unsigned long flags;
184
185 mctrl_gpio_get(gpios, &mctrl);
186
187 uart_port_lock_irqsave(up: port, flags: &flags);
188
189 mctrl_diff = mctrl ^ gpios->mctrl_prev;
190 gpios->mctrl_prev = mctrl;
191
192 if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {
193 if ((mctrl_diff & mctrl) & TIOCM_RI)
194 port->icount.rng++;
195
196 if ((mctrl_diff & mctrl) & TIOCM_DSR)
197 port->icount.dsr++;
198
199 if (mctrl_diff & TIOCM_CD)
200 uart_handle_dcd_change(uport: port, active: mctrl & TIOCM_CD);
201
202 if (mctrl_diff & TIOCM_CTS)
203 uart_handle_cts_change(uport: port, active: mctrl & TIOCM_CTS);
204
205 wake_up_interruptible(&port->state->port.delta_msr_wait);
206 }
207
208 uart_port_unlock_irqrestore(up: port, flags);
209
210 return IRQ_HANDLED;
211}
212
213/**
214 * mctrl_gpio_init - initialize uart gpios
215 * @port: port to initialize gpios for
216 * @idx: index of the gpio in the @port's device
217 *
218 * This will get the {cts,rts,...}-gpios from device tree if they are present
219 * and request them, set direction etc, and return an allocated structure.
220 * `devm_*` functions are used, so there's no need to explicitly free.
221 * As this sets up the irq handling, make sure to not handle changes to the
222 * gpio input lines in your driver, too.
223 */
224struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
225{
226 struct mctrl_gpios *gpios;
227 enum mctrl_gpio_idx i;
228
229 gpios = mctrl_gpio_init_noauto(port->dev, idx);
230 if (IS_ERR(ptr: gpios))
231 return gpios;
232
233 gpios->port = port;
234
235 for (i = 0; i < UART_GPIO_MAX; ++i) {
236 int ret;
237
238 if (!gpios->gpio[i] || mctrl_gpio_flags_is_dir_out(idx: i))
239 continue;
240
241 ret = gpiod_to_irq(desc: gpios->gpio[i]);
242 if (ret < 0) {
243 dev_err(port->dev,
244 "failed to find corresponding irq for %s (idx=%d, err=%d)\n",
245 mctrl_gpios_desc[i].name, idx, ret);
246 return ERR_PTR(error: ret);
247 }
248 gpios->irq[i] = ret;
249
250 /* irqs should only be enabled in .enable_ms */
251 irq_set_status_flags(irq: gpios->irq[i], set: IRQ_NOAUTOEN);
252
253 ret = devm_request_irq(dev: port->dev, irq: gpios->irq[i],
254 handler: mctrl_gpio_irq_handle,
255 irqflags: IRQ_TYPE_EDGE_BOTH, devname: dev_name(dev: port->dev),
256 dev_id: gpios);
257 if (ret) {
258 /* alternatively implement polling */
259 dev_err(port->dev,
260 "failed to request irq for %s (idx=%d, err=%d)\n",
261 mctrl_gpios_desc[i].name, idx, ret);
262 return ERR_PTR(error: ret);
263 }
264 }
265
266 return gpios;
267}
268EXPORT_SYMBOL_GPL(mctrl_gpio_init);
269
270/**
271 * mctrl_gpio_enable_ms - enable irqs and handling of changes to the ms lines
272 * @gpios: gpios to enable
273 */
274void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
275{
276 enum mctrl_gpio_idx i;
277
278 if (gpios == NULL)
279 return;
280
281 /* .enable_ms may be called multiple times */
282 if (gpios->mctrl_on)
283 return;
284
285 gpios->mctrl_on = true;
286
287 /* get initial status of modem lines GPIOs */
288 mctrl_gpio_get(gpios, &gpios->mctrl_prev);
289
290 for (i = 0; i < UART_GPIO_MAX; ++i) {
291 if (!gpios->irq[i])
292 continue;
293
294 enable_irq(irq: gpios->irq[i]);
295 }
296}
297EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
298
299static void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios, bool sync)
300{
301 enum mctrl_gpio_idx i;
302
303 if (gpios == NULL)
304 return;
305
306 if (!gpios->mctrl_on)
307 return;
308
309 gpios->mctrl_on = false;
310
311 for (i = 0; i < UART_GPIO_MAX; ++i) {
312 if (!gpios->irq[i])
313 continue;
314
315 if (sync)
316 disable_irq(irq: gpios->irq[i]);
317 else
318 disable_irq_nosync(irq: gpios->irq[i]);
319 }
320}
321
322/**
323 * mctrl_gpio_disable_ms_sync - disable irqs and handling of changes to the ms
324 * lines, and wait for any pending IRQ to be processed
325 * @gpios: gpios to disable
326 */
327void mctrl_gpio_disable_ms_sync(struct mctrl_gpios *gpios)
328{
329 mctrl_gpio_disable_ms(gpios, sync: true);
330}
331EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_sync);
332
333/**
334 * mctrl_gpio_disable_ms_no_sync - disable irqs and handling of changes to the
335 * ms lines, and return immediately
336 * @gpios: gpios to disable
337 */
338void mctrl_gpio_disable_ms_no_sync(struct mctrl_gpios *gpios)
339{
340 mctrl_gpio_disable_ms(gpios, sync: false);
341}
342EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_no_sync);
343
344void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
345{
346 enum mctrl_gpio_idx i;
347
348 if (!gpios)
349 return;
350
351 if (!gpios->mctrl_on)
352 return;
353
354 for (i = 0; i < UART_GPIO_MAX; ++i) {
355 if (!gpios->irq[i])
356 continue;
357
358 enable_irq_wake(irq: gpios->irq[i]);
359 }
360}
361EXPORT_SYMBOL_GPL(mctrl_gpio_enable_irq_wake);
362
363void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios)
364{
365 enum mctrl_gpio_idx i;
366
367 if (!gpios)
368 return;
369
370 if (!gpios->mctrl_on)
371 return;
372
373 for (i = 0; i < UART_GPIO_MAX; ++i) {
374 if (!gpios->irq[i])
375 continue;
376
377 disable_irq_wake(irq: gpios->irq[i]);
378 }
379}
380EXPORT_SYMBOL_GPL(mctrl_gpio_disable_irq_wake);
381
382MODULE_DESCRIPTION("Helpers for controlling modem lines via GPIO");
383MODULE_LICENSE("GPL");
384

source code of linux/drivers/tty/serial/serial_mctrl_gpio.c