/*
 * 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/gpio/consumer.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 {
	struct gpio_desc *ro_gpio;
	struct gpio_desc *cd_gpio;
	bool override_ro_active_level;
	bool override_cd_active_level;
	char *ro_label;
	char cd_label[0];
};

static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
{
	/* Schedule a card detection after a debounce timeout */
	struct mmc_host *host = dev_id;

	host->trigger_card_event = true;
	mmc_detect_change(host, msecs_to_jiffies(200));

	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) + 2 * len,
				   GFP_KERNEL);
		if (ctx) {
			ctx->ro_label = ctx->cd_label + len;
			snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
			snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
			host->slot.handler_priv = ctx;
		}
	}

	mutex_unlock(&host->slot.lock);

	return ctx ? 0 : -ENOMEM;
}

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

	if (!ctx || !ctx->ro_gpio)
		return -ENOSYS;

	if (ctx->override_ro_active_level)
		return !gpiod_get_raw_value_cansleep(ctx->ro_gpio) ^
			!!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);

	return gpiod_get_value_cansleep(ctx->ro_gpio);
}
EXPORT_SYMBOL(mmc_gpio_get_ro);

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

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

	if (ctx->override_cd_active_level)
		return !gpiod_get_raw_value_cansleep(ctx->cd_gpio) ^
			!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);

	return gpiod_get_value_cansleep(ctx->cd_gpio);
}
EXPORT_SYMBOL(mmc_gpio_get_cd);

/**
 * mmc_gpio_request_ro - request a gpio for write-protection
 * @host: mmc host
 * @gpio: gpio number requested
 *
 * As devm_* managed functions are used in mmc_gpio_request_ro(), client
 * drivers do not need to explicitly call mmc_gpio_free_ro() for freeing up,
 * if the requesting and freeing are only needed at probing and unbinding time
 * for once.  However, if client drivers do something special like runtime
 * switching for write-protection, they are responsible for calling
 * mmc_gpio_request_ro() and mmc_gpio_free_ro() as a pair on their own.
 *
 * Returns zero on success, else an error.
 */
int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
{
	struct mmc_gpio *ctx;
	int ret;

	if (!gpio_is_valid(gpio))
		return -EINVAL;

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

	ctx = host->slot.handler_priv;

	ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
				    ctx->ro_label);
	if (ret < 0)
		return ret;

	ctx->override_ro_active_level = true;
	ctx->ro_gpio = gpio_to_desc(gpio);

	return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_ro);

void mmc_gpiod_request_cd_irq(struct mmc_host *host)
{
	struct mmc_gpio *ctx = host->slot.handler_priv;
	int ret, irq;

	if (host->slot.cd_irq >= 0 || !ctx || !ctx->cd_gpio)
		return;

	irq = gpiod_to_irq(ctx->cd_gpio);

	/*
	 * Even if gpiod_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 = devm_request_threaded_irq(&host->class_dev, 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;
}
EXPORT_SYMBOL(mmc_gpiod_request_cd_irq);

/**
 * mmc_gpio_request_cd - request a gpio for card-detection
 * @host: mmc host
 * @gpio: gpio number requested
 * @debounce: debounce time in microseconds
 *
 * As devm_* managed functions are used in mmc_gpio_request_cd(), client
 * drivers do not need to explicitly call mmc_gpio_free_cd() for freeing up,
 * if the requesting and freeing are only needed at probing and unbinding time
 * for once.  However, if client drivers do something special like runtime
 * switching for card-detection, they are responsible for calling
 * mmc_gpio_request_cd() and mmc_gpio_free_cd() as a pair on their own.
 *
 * If GPIO debouncing is desired, set the debounce parameter to a non-zero
 * value. The caller is responsible for ensuring that the GPIO driver associated
 * with the GPIO supports debouncing, otherwise an error will be returned.
 *
 * Returns zero on success, else an error.
 */
int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
			unsigned int debounce)
{
	struct mmc_gpio *ctx;
	int ret;

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

	ctx = host->slot.handler_priv;

	ret = devm_gpio_request_one(&host->class_dev, 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;

	if (debounce) {
		ret = gpio_set_debounce(gpio, debounce);
		if (ret < 0)
			return ret;
	}

	ctx->override_cd_active_level = true;
	ctx->cd_gpio = gpio_to_desc(gpio);

	mmc_gpiod_request_cd_irq(host);

	return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_cd);

/**
 * mmc_gpio_free_ro - free the write-protection gpio
 * @host: mmc host
 *
 * It's provided only for cases that client drivers need to manually free
 * up the write-protection gpio requested by mmc_gpio_request_ro().
 */
void mmc_gpio_free_ro(struct mmc_host *host)
{
	struct mmc_gpio *ctx = host->slot.handler_priv;
	int gpio;

	if (!ctx || !ctx->ro_gpio)
		return;

	gpio = desc_to_gpio(ctx->ro_gpio);
	ctx->ro_gpio = NULL;

	devm_gpio_free(&host->class_dev, gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_ro);

/**
 * mmc_gpio_free_cd - free the card-detection gpio
 * @host: mmc host
 *
 * It's provided only for cases that client drivers need to manually free
 * up the card-detection gpio requested by 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 || !ctx->cd_gpio)
		return;

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

	gpio = desc_to_gpio(ctx->cd_gpio);
	ctx->cd_gpio = NULL;

	devm_gpio_free(&host->class_dev, gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_cd);

/**
 * mmc_gpiod_request_cd - request a gpio descriptor for card-detection
 * @host: mmc host
 * @con_id: function within the GPIO consumer
 * @idx: index of the GPIO to obtain in the consumer
 * @override_active_level: ignore %GPIO_ACTIVE_LOW flag
 * @debounce: debounce time in microseconds
 *
 * Use this function in place of mmc_gpio_request_cd() to use the GPIO
 * descriptor API.  Note that it is paired with mmc_gpiod_free_cd() not
 * mmc_gpio_free_cd().  Note also that it must be called prior to mmc_add_host()
 * otherwise the caller must also call mmc_gpiod_request_cd_irq().
 *
 * Returns zero on success, else an error.
 */
int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
			 unsigned int idx, bool override_active_level,
			 unsigned int debounce)
{
	struct mmc_gpio *ctx;
	struct gpio_desc *desc;
	int ret;

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

	ctx = host->slot.handler_priv;

	if (!con_id)
		con_id = ctx->cd_label;

	desc = devm_gpiod_get_index(host->parent, con_id, idx);
	if (IS_ERR(desc))
		return PTR_ERR(desc);

	ret = gpiod_direction_input(desc);
	if (ret < 0)
		return ret;

	if (debounce) {
		ret = gpiod_set_debounce(desc, debounce);
		if (ret < 0)
			return ret;
	}

	ctx->override_cd_active_level = override_active_level;
	ctx->cd_gpio = desc;

	return 0;
}
EXPORT_SYMBOL(mmc_gpiod_request_cd);

/**
 * mmc_gpiod_free_cd - free the card-detection gpio descriptor
 * @host: mmc host
 *
 * It's provided only for cases that client drivers need to manually free
 * up the card-detection gpio requested by mmc_gpiod_request_cd().
 */
void mmc_gpiod_free_cd(struct mmc_host *host)
{
	struct mmc_gpio *ctx = host->slot.handler_priv;

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

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

	devm_gpiod_put(&host->class_dev, ctx->cd_gpio);

	ctx->cd_gpio = NULL;
}
EXPORT_SYMBOL(mmc_gpiod_free_cd);