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/module.h>
17 #include <linux/slab.h>
18
19 struct mmc_cd_gpio {
20 unsigned int gpio;
21 char label[0];
22 };
23
mmc_cd_gpio_irqt(int irq,void * dev_id)24 static irqreturn_t mmc_cd_gpio_irqt(int irq, void *dev_id)
25 {
26 /* Schedule a card detection after a debounce timeout */
27 mmc_detect_change(dev_id, msecs_to_jiffies(100));
28 return IRQ_HANDLED;
29 }
30
mmc_cd_gpio_request(struct mmc_host * host,unsigned int gpio,unsigned int irq,unsigned long flags)31 int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
32 unsigned int irq, unsigned long flags)
33 {
34 size_t len = strlen(dev_name(host->parent)) + 4;
35 struct mmc_cd_gpio *cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
36 int ret;
37
38 if (!cd)
39 return -ENOMEM;
40
41 snprintf(cd->label, len, "%s cd", dev_name(host->parent));
42
43 ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
44 if (ret < 0)
45 goto egpioreq;
46
47 ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
48 flags, cd->label, host);
49 if (ret < 0)
50 goto eirqreq;
51
52 cd->gpio = gpio;
53 host->hotplug.irq = irq;
54 host->hotplug.handler_priv = cd;
55
56 return 0;
57
58 eirqreq:
59 gpio_free(gpio);
60 egpioreq:
61 kfree(cd);
62 return ret;
63 }
64 EXPORT_SYMBOL(mmc_cd_gpio_request);
65
mmc_cd_gpio_free(struct mmc_host * host)66 void mmc_cd_gpio_free(struct mmc_host *host)
67 {
68 struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
69
70 free_irq(host->hotplug.irq, host);
71 gpio_free(cd->gpio);
72 kfree(cd);
73 }
74 EXPORT_SYMBOL(mmc_cd_gpio_free);
75