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
19 struct 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
27 static 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
mctrl_gpio_flags_is_dir_out(unsigned int idx)40 static 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 */
mctrl_gpio_set(struct mctrl_gpios * gpios,unsigned int mctrl)52 void 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 }
71 EXPORT_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 */
mctrl_gpio_to_gpiod(struct mctrl_gpios * gpios,enum mctrl_gpio_idx gidx)79 struct 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 }
87 EXPORT_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 */
mctrl_gpio_get(struct mctrl_gpios * gpios,unsigned int * mctrl)97 unsigned 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 }
115 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
116
117 unsigned int
mctrl_gpio_get_outputs(struct mctrl_gpios * gpios,unsigned int * mctrl)118 mctrl_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 }
136 EXPORT_SYMBOL_GPL(mctrl_gpio_get_outputs);
137
mctrl_gpio_init_noauto(struct device * dev,unsigned int idx)138 struct 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 }
174 EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
175
176 #define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
mctrl_gpio_irq_handle(int irq,void * context)177 static 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 spin_lock_irqsave(&port->lock, 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 spin_unlock_irqrestore(&port->lock, 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 call mctrl_gpio_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 */
mctrl_gpio_init(struct uart_port * port,unsigned int idx)224 struct 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 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(ret);
263 }
264 }
265
266 return gpios;
267 }
268 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
269
270 /**
271 * mctrl_gpio_free - explicitly free uart gpios
272 * @dev: uart port's device
273 * @gpios: gpios structure to be freed
274 *
275 * This will free the requested gpios in mctrl_gpio_init(). As `devm_*`
276 * functions are used, there's generally no need to call this function.
277 */
mctrl_gpio_free(struct device * dev,struct mctrl_gpios * gpios)278 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
279 {
280 enum mctrl_gpio_idx i;
281
282 if (gpios == NULL)
283 return;
284
285 for (i = 0; i < UART_GPIO_MAX; i++) {
286 if (gpios->irq[i])
287 devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);
288
289 if (gpios->gpio[i])
290 devm_gpiod_put(dev, gpios->gpio[i]);
291 }
292 devm_kfree(dev, gpios);
293 }
294 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
295
296 /**
297 * mctrl_gpio_enable_ms - enable irqs and handling of changes to the ms lines
298 * @gpios: gpios to enable
299 */
mctrl_gpio_enable_ms(struct mctrl_gpios * gpios)300 void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
301 {
302 enum mctrl_gpio_idx i;
303
304 if (gpios == NULL)
305 return;
306
307 /* .enable_ms may be called multiple times */
308 if (gpios->mctrl_on)
309 return;
310
311 gpios->mctrl_on = true;
312
313 /* get initial status of modem lines GPIOs */
314 mctrl_gpio_get(gpios, &gpios->mctrl_prev);
315
316 for (i = 0; i < UART_GPIO_MAX; ++i) {
317 if (!gpios->irq[i])
318 continue;
319
320 enable_irq(gpios->irq[i]);
321 }
322 }
323 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
324
325 /**
326 * mctrl_gpio_disable_ms - disable irqs and handling of changes to the ms lines
327 * @gpios: gpios to disable
328 */
mctrl_gpio_disable_ms(struct mctrl_gpios * gpios)329 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
330 {
331 enum mctrl_gpio_idx i;
332
333 if (gpios == NULL)
334 return;
335
336 if (!gpios->mctrl_on)
337 return;
338
339 gpios->mctrl_on = false;
340
341 for (i = 0; i < UART_GPIO_MAX; ++i) {
342 if (!gpios->irq[i])
343 continue;
344
345 disable_irq(gpios->irq[i]);
346 }
347 }
348 EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
349
mctrl_gpio_enable_irq_wake(struct mctrl_gpios * gpios)350 void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
351 {
352 enum mctrl_gpio_idx i;
353
354 if (!gpios)
355 return;
356
357 if (!gpios->mctrl_on)
358 return;
359
360 for (i = 0; i < UART_GPIO_MAX; ++i) {
361 if (!gpios->irq[i])
362 continue;
363
364 enable_irq_wake(gpios->irq[i]);
365 }
366 }
367 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_irq_wake);
368
mctrl_gpio_disable_irq_wake(struct mctrl_gpios * gpios)369 void mctrl_gpio_disable_irq_wake(struct mctrl_gpios *gpios)
370 {
371 enum mctrl_gpio_idx i;
372
373 if (!gpios)
374 return;
375
376 if (!gpios->mctrl_on)
377 return;
378
379 for (i = 0; i < UART_GPIO_MAX; ++i) {
380 if (!gpios->irq[i])
381 continue;
382
383 disable_irq_wake(gpios->irq[i]);
384 }
385 }
386 EXPORT_SYMBOL_GPL(mctrl_gpio_disable_irq_wake);
387
388 MODULE_LICENSE("GPL");
389