projects/linux·blob master · refs

380 lines · 8.6 KiB

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(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(count, desc_array, NULL, 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(i)) {
106 if (gpiod_get_value(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(i)) {
127 if (gpiod_get_value(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, sizeof(*gpios), GFP_KERNEL);
144 if (!gpios)
145 return ERR_PTR(-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, "%s-gpios",
153 mctrl_gpios_desc[i].name);
154 if (!gpio_str)
155 continue;
156
157 present = device_property_present(dev, gpio_str);
158 kfree(gpio_str);
159 if (!present)
160 continue;
161
162 gpios->gpio[i] =
163 devm_gpiod_get_index_optional(dev,
164 mctrl_gpios_desc[i].name,
165 idx,
166 mctrl_gpios_desc[i].flags);
167
168 if (IS_ERR(gpios->gpio[i]))
169 return ERR_CAST(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(port, &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(port, mctrl & TIOCM_CD);
201
202 if (mctrl_diff & TIOCM_CTS)
203 uart_handle_cts_change(port, mctrl & TIOCM_CTS);
204
205 wake_up_interruptible(&port->state->port.delta_msr_wait);
206 }
207
208 uart_port_unlock_irqrestore(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(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(i))
239 continue;
240
241 ret = gpiod_to_irq(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(ret);
247 }
248 gpios->irq[i] = ret;
249
250 /* irqs should only be enabled in .enable_ms */
251 irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);
252
253 ret = devm_request_irq(port->dev, gpios->irq[i],
254 mctrl_gpio_irq_handle,
255 IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),
256 gpios);
257 if (ret) {
258 /* alternatively implement polling */
259 return ERR_PTR(ret);
260 }
261 }
262
263 return gpios;
264}
265EXPORT_SYMBOL_GPL(mctrl_gpio_init);
266
267/**
268 * mctrl_gpio_enable_ms - enable irqs and handling of changes to the ms lines
269 * @gpios: gpios to enable
270 */
271void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
272{
273 enum mctrl_gpio_idx i;
274
275 if (gpios == NULL)
276 return;
277
278 /* .enable_ms may be called multiple times */
279 if (gpios->mctrl_on)
280 return;
281
282 gpios->mctrl_on = true;
283
284 /* get initial status of modem lines GPIOs */
285 mctrl_gpio_get(gpios, &gpios->mctrl_prev);
286
287 for (i = 0; i < UART_GPIO_MAX; ++i) {
288 if (!gpios->irq[i])
289 continue;
290
291 enable_irq(gpios->irq[i]);
292 }
293}
294EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
295
296static void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios, bool sync)
297{
298 enum mctrl_gpio_idx i;
299
300 if (gpios == NULL)
301 return;
302
303 if (!gpios->mctrl_on)
304 return;
305
306 gpios->mctrl_on = false;
307
308 for (i = 0; i < UART_GPIO_MAX; ++i) {
309 if (!gpios->irq[i])
310 continue;
311
312 if (sync)
313 disable_irq(gpios->irq[i]);
314 else
315 disable_irq_nosync(gpios->irq[i]);
316 }
317}
318
319/**
320 * mctrl_gpio_disable_ms_sync - disable irqs and handling of changes to the ms
321 * lines, and wait for any pending IRQ to be processed
322 * @gpios: gpios to disable
323 */
324void mctrl_gpio_disable_ms_sync(struct mctrl_gpios *gpios)
325{
326 mctrl_gpio_disable_ms(gpios, true);
327}
328EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_sync);
329
330/**
331 * mctrl_gpio_disable_ms_no_sync - disable irqs and handling of changes to the
332 * ms lines, and return immediately
333 * @gpios: gpios to disable
334 */
335void mctrl_gpio_disable_ms_no_sync(struct mctrl_gpios *gpios)
336{
337 mctrl_gpio_disable_ms(gpios, false);
338}
339EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_no_sync);
340
341void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
342{
343 enum mctrl_gpio_idx i;
344
345 if (!gpios)
346 return;
347
348 if (!gpios->mctrl_on)
349 return;
350
351 for (i = 0; i < UART_GPIO_MAX; ++i) {
352 if (!gpios->irq[i])
353 continue;
354
355 enable_irq_wake(gpios->irq[i]);
356 }
357}
358EXPORT_SYMBOL_GPL(mctrl_gpio_enable_irq_wake);
359
360void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios)
361{
362 enum mctrl_gpio_idx i;
363
364 if (!gpios)
365 return;
366
367 if (!gpios->mctrl_on)
368 return;
369
370 for (i = 0; i < UART_GPIO_MAX; ++i) {
371 if (!gpios->irq[i])
372 continue;
373
374 disable_irq_wake(gpios->irq[i]);
375 }
376}
377EXPORT_SYMBOL_GPL(mctrl_gpio_disable_irq_wake);
378
379MODULE_DESCRIPTION("Helpers for controlling modem lines via GPIO");
380MODULE_LICENSE("GPL");