slot-gpio.c revision c8bdfea7c3e60c99ce7cc3459d8acfa0ce8854e3 
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/interrupt.h>
14#include <linux/jiffies.h>
15#include <linux/mmc/host.h>
16#include <linux/mmc/slot-gpio.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19
20struct mmc_gpio {
21	int ro_gpio;
22	int cd_gpio;
23	char *ro_label;
24	char cd_label[0];
25};
26
27static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
28{
29	/* Schedule a card detection after a debounce timeout */
30	struct mmc_host *host = dev_id;
31
32	if (host->ops->card_event)
33		host->ops->card_event(host);
34
35	mmc_detect_change(host, msecs_to_jiffies(200));
36
37	return IRQ_HANDLED;
38}
39
40static int mmc_gpio_alloc(struct mmc_host *host)
41{
42	size_t len = strlen(dev_name(host->parent)) + 4;
43	struct mmc_gpio *ctx;
44
45	mutex_lock(&host->slot.lock);
46
47	ctx = host->slot.handler_priv;
48	if (!ctx) {
49		/*
50		 * devm_kzalloc() can be called after device_initialize(), even
51		 * before device_add(), i.e., between mmc_alloc_host() and
52		 * mmc_add_host()
53		 */
54		ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + 2 * len,
55				   GFP_KERNEL);
56		if (ctx) {
57			ctx->ro_label = ctx->cd_label + len;
58			snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
59			snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
60			ctx->cd_gpio = -EINVAL;
61			ctx->ro_gpio = -EINVAL;
62			host->slot.handler_priv = ctx;
63		}
64	}
65
66	mutex_unlock(&host->slot.lock);
67
68	return ctx ? 0 : -ENOMEM;
69}
70
71int mmc_gpio_get_ro(struct mmc_host *host)
72{
73	struct mmc_gpio *ctx = host->slot.handler_priv;
74
75	if (!ctx || !gpio_is_valid(ctx->ro_gpio))
76		return -ENOSYS;
77
78	return !gpio_get_value_cansleep(ctx->ro_gpio) ^
79		!!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
80}
81EXPORT_SYMBOL(mmc_gpio_get_ro);
82
83int mmc_gpio_get_cd(struct mmc_host *host)
84{
85	struct mmc_gpio *ctx = host->slot.handler_priv;
86
87	if (!ctx || !gpio_is_valid(ctx->cd_gpio))
88		return -ENOSYS;
89
90	return !gpio_get_value_cansleep(ctx->cd_gpio) ^
91		!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
92}
93EXPORT_SYMBOL(mmc_gpio_get_cd);
94
95/**
96 * mmc_gpio_request_ro - request a gpio for write-protection
97 * @host: mmc host
98 * @gpio: gpio number requested
99 *
100 * As devm_* managed functions are used in mmc_gpio_request_ro(), client
101 * drivers do not need to explicitly call mmc_gpio_free_ro() for freeing up,
102 * if the requesting and freeing are only needed at probing and unbinding time
103 * for once.  However, if client drivers do something special like runtime
104 * switching for write-protection, they are responsible for calling
105 * mmc_gpio_request_ro() and mmc_gpio_free_ro() as a pair on their own.
106 *
107 * Returns zero on success, else an error.
108 */
109int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
110{
111	struct mmc_gpio *ctx;
112	int ret;
113
114	if (!gpio_is_valid(gpio))
115		return -EINVAL;
116
117	ret = mmc_gpio_alloc(host);
118	if (ret < 0)
119		return ret;
120
121	ctx = host->slot.handler_priv;
122
123	ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
124				    ctx->ro_label);
125	if (ret < 0)
126		return ret;
127
128	ctx->ro_gpio = gpio;
129
130	return 0;
131}
132EXPORT_SYMBOL(mmc_gpio_request_ro);
133
134/**
135 * mmc_gpio_request_cd - request a gpio for card-detection
136 * @host: mmc host
137 * @gpio: gpio number requested
138 *
139 * As devm_* managed functions are used in mmc_gpio_request_cd(), client
140 * drivers do not need to explicitly call mmc_gpio_free_cd() for freeing up,
141 * if the requesting and freeing are only needed at probing and unbinding time
142 * for once.  However, if client drivers do something special like runtime
143 * switching for card-detection, they are responsible for calling
144 * mmc_gpio_request_cd() and mmc_gpio_free_cd() as a pair on their own.
145 *
146 * Returns zero on success, else an error.
147 */
148int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
149{
150	struct mmc_gpio *ctx;
151	int irq = gpio_to_irq(gpio);
152	int ret;
153
154	ret = mmc_gpio_alloc(host);
155	if (ret < 0)
156		return ret;
157
158	ctx = host->slot.handler_priv;
159
160	ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
161				    ctx->cd_label);
162	if (ret < 0)
163		/*
164		 * don't bother freeing memory. It might still get used by other
165		 * slot functions, in any case it will be freed, when the device
166		 * is destroyed.
167		 */
168		return ret;
169
170	/*
171	 * Even if gpio_to_irq() returns a valid IRQ number, the platform might
172	 * still prefer to poll, e.g., because that IRQ number is already used
173	 * by another unit and cannot be shared.
174	 */
175	if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
176		irq = -EINVAL;
177
178	if (irq >= 0) {
179		ret = devm_request_threaded_irq(&host->class_dev, irq,
180			NULL, mmc_gpio_cd_irqt,
181			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
182			ctx->cd_label, host);
183		if (ret < 0)
184			irq = ret;
185	}
186
187	host->slot.cd_irq = irq;
188
189	if (irq < 0)
190		host->caps |= MMC_CAP_NEEDS_POLL;
191
192	ctx->cd_gpio = gpio;
193
194	return 0;
195}
196EXPORT_SYMBOL(mmc_gpio_request_cd);
197
198/**
199 * mmc_gpio_free_ro - free the write-protection gpio
200 * @host: mmc host
201 *
202 * It's provided only for cases that client drivers need to manually free
203 * up the write-protection gpio requested by mmc_gpio_request_ro().
204 */
205void mmc_gpio_free_ro(struct mmc_host *host)
206{
207	struct mmc_gpio *ctx = host->slot.handler_priv;
208	int gpio;
209
210	if (!ctx || !gpio_is_valid(ctx->ro_gpio))
211		return;
212
213	gpio = ctx->ro_gpio;
214	ctx->ro_gpio = -EINVAL;
215
216	devm_gpio_free(&host->class_dev, gpio);
217}
218EXPORT_SYMBOL(mmc_gpio_free_ro);
219
220/**
221 * mmc_gpio_free_cd - free the card-detection gpio
222 * @host: mmc host
223 *
224 * It's provided only for cases that client drivers need to manually free
225 * up the card-detection gpio requested by mmc_gpio_request_cd().
226 */
227void mmc_gpio_free_cd(struct mmc_host *host)
228{
229	struct mmc_gpio *ctx = host->slot.handler_priv;
230	int gpio;
231
232	if (!ctx || !gpio_is_valid(ctx->cd_gpio))
233		return;
234
235	if (host->slot.cd_irq >= 0) {
236		devm_free_irq(&host->class_dev, host->slot.cd_irq, host);
237		host->slot.cd_irq = -EINVAL;
238	}
239
240	gpio = ctx->cd_gpio;
241	ctx->cd_gpio = -EINVAL;
242
243	devm_gpio_free(&host->class_dev, gpio);
244}
245EXPORT_SYMBOL(mmc_gpio_free_cd);
246