LXR linux/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
  20struct mmc_cd_gpio {
  21        unsigned int gpio;
  22        char label[0];
  23};
  24
  25static 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
  32int 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
  64eirqreq:
  65        gpio_free(gpio);
  66egpioreq:
  67        kfree(cd);
  68        return ret;
  69}
  70EXPORT_SYMBOL(mmc_cd_gpio_request);
  71
  72void mmc_cd_gpio_free(struct mmc_host *host)
  73{
  74        struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
  75
  76        free_irq(host->hotplug.irq, host);
  77        gpio_free(cd->gpio);
  78        kfree(cd);
  79}
  80EXPORT_SYMBOL(mmc_cd_gpio_free);
  81