drivers/mmc/core/cd-gpio.c

   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/cd-gpio.h>
  16 #include <linux/mmc/host.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19
  20 struct mmc_cd_gpio {
  21         unsigned int gpio;
  22         char label[0];
  23 };
  24
  25 static irqreturn_t mmc_cd_gpio_irqt(int irq, void *dev_id)
  26 {
  27         /* Schedule a card detection after a debounce timeout */
  28         mmc_detect_change(dev_id, msecs_to_jiffies(100));
  29         return IRQ_HANDLED;
  30 }
  31
  32 int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio)
  33 {
  34         size_t len = strlen(dev_name(host->parent)) + 4;
  35         struct mmc_cd_gpio *cd;
  36         int irq = gpio_to_irq(gpio);
  37         int ret;
  38
  39         if (irq < 0)
  40                 return irq;
  41
  42         cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
  43         if (!cd)
  44                 return -ENOMEM;
  45
  46         snprintf(cd->label, len, "%s cd", dev_name(host->parent));
  47
  48         ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
  49         if (ret < 0)
  50                 goto egpioreq;
  51
  52         ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
  53                                    IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
  54                                    cd->label, host);
  55         if (ret < 0)
  56                 goto eirqreq;
  57
  58         cd->gpio = gpio;
  59         host->hotplug.irq = irq;
  60         host->hotplug.handler_priv = cd;
  61
  62         return 0;
  63
  64 eirqreq:
  65         gpio_free(gpio);
  66 egpioreq:
  67         kfree(cd);
  68         return ret;
  69 }
  70 EXPORT_SYMBOL(mmc_cd_gpio_request);
  71
  72 void mmc_cd_gpio_free(struct mmc_host *host)
  73 {
  74         struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
  75
  76         if (!cd)
  77                 return;
  78
  79         free_irq(host->hotplug.irq, host);
  80         gpio_free(cd->gpio);
  81         kfree(cd);
  82 }
  83 EXPORT_SYMBOL(mmc_cd_gpio_free);