drivers/mmc/core/slot-gpio.c

/*
 * Generic GPIO card-detect helper
 *
 * Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/mmc/host.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/module.h>
#include <linux/slab.h>

struct mmc_gpio {
	int cd_gpio;
	char cd_label[0];
};

static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
{
	/* Schedule a card detection after a debounce timeout */
	mmc_detect_change(dev_id, msecs_to_jiffies(100));
	return IRQ_HANDLED;
}

static int mmc_gpio_alloc(struct mmc_host *host)
{
	size_t len = strlen(dev_name(host->parent)) + 4;
	struct mmc_gpio *ctx;

	mutex_lock(&host->slot.lock);

	ctx = host->slot.handler_priv;
	if (!ctx) {
		/*
		 * devm_kzalloc() can be called after device_initialize(), even
		 * before device_add(), i.e., between mmc_alloc_host() and
		 * mmc_add_host()
		 */
		ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + len,
				   GFP_KERNEL);
		if (ctx) {
			snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
			ctx->cd_gpio = -EINVAL;
			host->slot.handler_priv = ctx;
		}
	}

	mutex_unlock(&host->slot.lock);

	return ctx ? 0 : -ENOMEM;
}

int mmc_gpio_get_cd(struct mmc_host *host)
{
	struct mmc_gpio *ctx = host->slot.handler_priv;

	if (!ctx || !gpio_is_valid(ctx->cd_gpio))
		return -ENOSYS;

	return !gpio_get_value_cansleep(ctx->cd_gpio) ^
		!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
}
EXPORT_SYMBOL(mmc_gpio_get_cd);

int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
{
	struct mmc_gpio *ctx;
	int irq = gpio_to_irq(gpio);
	int ret;

	ret = mmc_gpio_alloc(host);
	if (ret < 0)
		return ret;

	ctx = host->slot.handler_priv;

	ret = gpio_request_one(gpio, GPIOF_DIR_IN, ctx->cd_label);
	if (ret < 0)
		/*
		 * don't bother freeing memory. It might still get used by other
		 * slot functions, in any case it will be freed, when the device
		 * is destroyed.
		 */
		return ret;

	/*
	 * Even if gpio_to_irq() returns a valid IRQ number, the platform might
	 * still prefer to poll, e.g., because that IRQ number is already used
	 * by another unit and cannot be shared.
	 */
	if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
		irq = -EINVAL;

	if (irq >= 0) {
		ret = request_threaded_irq(irq, NULL, mmc_gpio_cd_irqt,
			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
			ctx->cd_label, host);
		if (ret < 0)
			irq = ret;
	}

	host->slot.cd_irq = irq;

	if (irq < 0)
		host->caps |= MMC_CAP_NEEDS_POLL;

	ctx->cd_gpio = gpio;

	return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_cd);

void mmc_gpio_free_cd(struct mmc_host *host)
{
	struct mmc_gpio *ctx = host->slot.handler_priv;
	int gpio;

	if (!ctx || !gpio_is_valid(ctx->cd_gpio))
		return;

	if (host->slot.cd_irq >= 0) {
		free_irq(host->slot.cd_irq, host);
		host->slot.cd_irq = -EINVAL;
	}

	gpio = ctx->cd_gpio;
	ctx->cd_gpio = -EINVAL;

	gpio_free(gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_cd);