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/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
  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
  31 int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio)
  32 {
  33         size_t len = strlen(dev_name(host->parent)) + 4;
  34         struct mmc_cd_gpio *cd;
  35         int irq = gpio_to_irq(gpio);
  36         int ret;
  37
  38         if (irq < 0)
  39                 return irq;
  40
  41         cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
  42         if (!cd)
  43                 return -ENOMEM;
  44
  45         snprintf(cd->label, len, "%s cd", dev_name(host->parent));
  46
  47         ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
  48         if (ret < 0)
  49                 goto egpioreq;
  50
  51         ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
  52                                    IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
  53                                    cd->label, host);
  54         if (ret < 0)
  55                 goto eirqreq;
  56
  57         cd->gpio = gpio;
  58         host->hotplug.irq = irq;
  59         host->hotplug.handler_priv = cd;
  60
  61         return 0;
  62
  63 eirqreq:
  64         gpio_free(gpio);
  65 egpioreq:
  66         kfree(cd);
  67         return ret;
  68 }
  69 EXPORT_SYMBOL(mmc_cd_gpio_request);
  70
  71 void mmc_cd_gpio_free(struct mmc_host *host)
  72 {
  73         struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
  74
  75         free_irq(host->hotplug.irq, host);
  76         gpio_free(cd->gpio);
  77         kfree(cd);
  78 }
  79 EXPORT_SYMBOL(mmc_cd_gpio_free);