xref: /openbmc/linux/drivers/mmc/core/slot-gpio.c (revision d2999e1b)
1 /*
2  * Generic GPIO card-detect helper
3  *
4  * Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/err.h>
12 #include <linux/gpio.h>
13 #include <linux/gpio/consumer.h>
14 #include <linux/interrupt.h>
15 #include <linux/jiffies.h>
16 #include <linux/mmc/host.h>
17 #include <linux/mmc/slot-gpio.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 
21 struct mmc_gpio {
22 	struct gpio_desc *ro_gpio;
23 	struct gpio_desc *cd_gpio;
24 	bool override_ro_active_level;
25 	bool override_cd_active_level;
26 	char *ro_label;
27 	char cd_label[0];
28 };
29 
30 static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
31 {
32 	/* Schedule a card detection after a debounce timeout */
33 	struct mmc_host *host = dev_id;
34 
35 	host->trigger_card_event = true;
36 	mmc_detect_change(host, msecs_to_jiffies(200));
37 
38 	return IRQ_HANDLED;
39 }
40 
41 static int mmc_gpio_alloc(struct mmc_host *host)
42 {
43 	size_t len = strlen(dev_name(host->parent)) + 4;
44 	struct mmc_gpio *ctx;
45 
46 	mutex_lock(&host->slot.lock);
47 
48 	ctx = host->slot.handler_priv;
49 	if (!ctx) {
50 		/*
51 		 * devm_kzalloc() can be called after device_initialize(), even
52 		 * before device_add(), i.e., between mmc_alloc_host() and
53 		 * mmc_add_host()
54 		 */
55 		ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + 2 * len,
56 				   GFP_KERNEL);
57 		if (ctx) {
58 			ctx->ro_label = ctx->cd_label + len;
59 			snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
60 			snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
61 			host->slot.handler_priv = ctx;
62 		}
63 	}
64 
65 	mutex_unlock(&host->slot.lock);
66 
67 	return ctx ? 0 : -ENOMEM;
68 }
69 
70 int mmc_gpio_get_ro(struct mmc_host *host)
71 {
72 	struct mmc_gpio *ctx = host->slot.handler_priv;
73 
74 	if (!ctx || !ctx->ro_gpio)
75 		return -ENOSYS;
76 
77 	if (ctx->override_ro_active_level)
78 		return !gpiod_get_raw_value_cansleep(ctx->ro_gpio) ^
79 			!!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
80 
81 	return gpiod_get_value_cansleep(ctx->ro_gpio);
82 }
83 EXPORT_SYMBOL(mmc_gpio_get_ro);
84 
85 int mmc_gpio_get_cd(struct mmc_host *host)
86 {
87 	struct mmc_gpio *ctx = host->slot.handler_priv;
88 
89 	if (!ctx || !ctx->cd_gpio)
90 		return -ENOSYS;
91 
92 	if (ctx->override_cd_active_level)
93 		return !gpiod_get_raw_value_cansleep(ctx->cd_gpio) ^
94 			!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
95 
96 	return gpiod_get_value_cansleep(ctx->cd_gpio);
97 }
98 EXPORT_SYMBOL(mmc_gpio_get_cd);
99 
100 /**
101  * mmc_gpio_request_ro - request a gpio for write-protection
102  * @host: mmc host
103  * @gpio: gpio number requested
104  *
105  * As devm_* managed functions are used in mmc_gpio_request_ro(), client
106  * drivers do not need to explicitly call mmc_gpio_free_ro() for freeing up,
107  * if the requesting and freeing are only needed at probing and unbinding time
108  * for once.  However, if client drivers do something special like runtime
109  * switching for write-protection, they are responsible for calling
110  * mmc_gpio_request_ro() and mmc_gpio_free_ro() as a pair on their own.
111  *
112  * Returns zero on success, else an error.
113  */
114 int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
115 {
116 	struct mmc_gpio *ctx;
117 	int ret;
118 
119 	if (!gpio_is_valid(gpio))
120 		return -EINVAL;
121 
122 	ret = mmc_gpio_alloc(host);
123 	if (ret < 0)
124 		return ret;
125 
126 	ctx = host->slot.handler_priv;
127 
128 	ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
129 				    ctx->ro_label);
130 	if (ret < 0)
131 		return ret;
132 
133 	ctx->override_ro_active_level = true;
134 	ctx->ro_gpio = gpio_to_desc(gpio);
135 
136 	return 0;
137 }
138 EXPORT_SYMBOL(mmc_gpio_request_ro);
139 
140 void mmc_gpiod_request_cd_irq(struct mmc_host *host)
141 {
142 	struct mmc_gpio *ctx = host->slot.handler_priv;
143 	int ret, irq;
144 
145 	if (host->slot.cd_irq >= 0 || !ctx || !ctx->cd_gpio)
146 		return;
147 
148 	irq = gpiod_to_irq(ctx->cd_gpio);
149 
150 	/*
151 	 * Even if gpiod_to_irq() returns a valid IRQ number, the platform might
152 	 * still prefer to poll, e.g., because that IRQ number is already used
153 	 * by another unit and cannot be shared.
154 	 */
155 	if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
156 		irq = -EINVAL;
157 
158 	if (irq >= 0) {
159 		ret = devm_request_threaded_irq(&host->class_dev, irq,
160 			NULL, mmc_gpio_cd_irqt,
161 			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
162 			ctx->cd_label, host);
163 		if (ret < 0)
164 			irq = ret;
165 	}
166 
167 	host->slot.cd_irq = irq;
168 
169 	if (irq < 0)
170 		host->caps |= MMC_CAP_NEEDS_POLL;
171 }
172 EXPORT_SYMBOL(mmc_gpiod_request_cd_irq);
173 
174 /**
175  * mmc_gpio_request_cd - request a gpio for card-detection
176  * @host: mmc host
177  * @gpio: gpio number requested
178  * @debounce: debounce time in microseconds
179  *
180  * As devm_* managed functions are used in mmc_gpio_request_cd(), client
181  * drivers do not need to explicitly call mmc_gpio_free_cd() for freeing up,
182  * if the requesting and freeing are only needed at probing and unbinding time
183  * for once.  However, if client drivers do something special like runtime
184  * switching for card-detection, they are responsible for calling
185  * mmc_gpio_request_cd() and mmc_gpio_free_cd() as a pair on their own.
186  *
187  * If GPIO debouncing is desired, set the debounce parameter to a non-zero
188  * value. The caller is responsible for ensuring that the GPIO driver associated
189  * with the GPIO supports debouncing, otherwise an error will be returned.
190  *
191  * Returns zero on success, else an error.
192  */
193 int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
194 			unsigned int debounce)
195 {
196 	struct mmc_gpio *ctx;
197 	int ret;
198 
199 	ret = mmc_gpio_alloc(host);
200 	if (ret < 0)
201 		return ret;
202 
203 	ctx = host->slot.handler_priv;
204 
205 	ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
206 				    ctx->cd_label);
207 	if (ret < 0)
208 		/*
209 		 * don't bother freeing memory. It might still get used by other
210 		 * slot functions, in any case it will be freed, when the device
211 		 * is destroyed.
212 		 */
213 		return ret;
214 
215 	if (debounce) {
216 		ret = gpio_set_debounce(gpio, debounce);
217 		if (ret < 0)
218 			return ret;
219 	}
220 
221 	ctx->override_cd_active_level = true;
222 	ctx->cd_gpio = gpio_to_desc(gpio);
223 
224 	mmc_gpiod_request_cd_irq(host);
225 
226 	return 0;
227 }
228 EXPORT_SYMBOL(mmc_gpio_request_cd);
229 
230 /**
231  * mmc_gpio_free_ro - free the write-protection gpio
232  * @host: mmc host
233  *
234  * It's provided only for cases that client drivers need to manually free
235  * up the write-protection gpio requested by mmc_gpio_request_ro().
236  */
237 void mmc_gpio_free_ro(struct mmc_host *host)
238 {
239 	struct mmc_gpio *ctx = host->slot.handler_priv;
240 	int gpio;
241 
242 	if (!ctx || !ctx->ro_gpio)
243 		return;
244 
245 	gpio = desc_to_gpio(ctx->ro_gpio);
246 	ctx->ro_gpio = NULL;
247 
248 	devm_gpio_free(&host->class_dev, gpio);
249 }
250 EXPORT_SYMBOL(mmc_gpio_free_ro);
251 
252 /**
253  * mmc_gpio_free_cd - free the card-detection gpio
254  * @host: mmc host
255  *
256  * It's provided only for cases that client drivers need to manually free
257  * up the card-detection gpio requested by mmc_gpio_request_cd().
258  */
259 void mmc_gpio_free_cd(struct mmc_host *host)
260 {
261 	struct mmc_gpio *ctx = host->slot.handler_priv;
262 	int gpio;
263 
264 	if (!ctx || !ctx->cd_gpio)
265 		return;
266 
267 	if (host->slot.cd_irq >= 0) {
268 		devm_free_irq(&host->class_dev, host->slot.cd_irq, host);
269 		host->slot.cd_irq = -EINVAL;
270 	}
271 
272 	gpio = desc_to_gpio(ctx->cd_gpio);
273 	ctx->cd_gpio = NULL;
274 
275 	devm_gpio_free(&host->class_dev, gpio);
276 }
277 EXPORT_SYMBOL(mmc_gpio_free_cd);
278 
279 /**
280  * mmc_gpiod_request_cd - request a gpio descriptor for card-detection
281  * @host: mmc host
282  * @con_id: function within the GPIO consumer
283  * @idx: index of the GPIO to obtain in the consumer
284  * @override_active_level: ignore %GPIO_ACTIVE_LOW flag
285  * @debounce: debounce time in microseconds
286  *
287  * Use this function in place of mmc_gpio_request_cd() to use the GPIO
288  * descriptor API.  Note that it is paired with mmc_gpiod_free_cd() not
289  * mmc_gpio_free_cd().  Note also that it must be called prior to mmc_add_host()
290  * otherwise the caller must also call mmc_gpiod_request_cd_irq().
291  *
292  * Returns zero on success, else an error.
293  */
294 int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
295 			 unsigned int idx, bool override_active_level,
296 			 unsigned int debounce)
297 {
298 	struct mmc_gpio *ctx;
299 	struct gpio_desc *desc;
300 	int ret;
301 
302 	ret = mmc_gpio_alloc(host);
303 	if (ret < 0)
304 		return ret;
305 
306 	ctx = host->slot.handler_priv;
307 
308 	if (!con_id)
309 		con_id = ctx->cd_label;
310 
311 	desc = devm_gpiod_get_index(host->parent, con_id, idx);
312 	if (IS_ERR(desc))
313 		return PTR_ERR(desc);
314 
315 	ret = gpiod_direction_input(desc);
316 	if (ret < 0)
317 		return ret;
318 
319 	if (debounce) {
320 		ret = gpiod_set_debounce(desc, debounce);
321 		if (ret < 0)
322 			return ret;
323 	}
324 
325 	ctx->override_cd_active_level = override_active_level;
326 	ctx->cd_gpio = desc;
327 
328 	return 0;
329 }
330 EXPORT_SYMBOL(mmc_gpiod_request_cd);
331 
332 /**
333  * mmc_gpiod_free_cd - free the card-detection gpio descriptor
334  * @host: mmc host
335  *
336  * It's provided only for cases that client drivers need to manually free
337  * up the card-detection gpio requested by mmc_gpiod_request_cd().
338  */
339 void mmc_gpiod_free_cd(struct mmc_host *host)
340 {
341 	struct mmc_gpio *ctx = host->slot.handler_priv;
342 
343 	if (!ctx || !ctx->cd_gpio)
344 		return;
345 
346 	if (host->slot.cd_irq >= 0) {
347 		devm_free_irq(&host->class_dev, host->slot.cd_irq, host);
348 		host->slot.cd_irq = -EINVAL;
349 	}
350 
351 	devm_gpiod_put(&host->class_dev, ctx->cd_gpio);
352 
353 	ctx->cd_gpio = NULL;
354 }
355 EXPORT_SYMBOL(mmc_gpiod_free_cd);
356