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                         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
  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);