/*
 * 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 ro_gpio;
        int cd_gpio;
        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;

        if (host->ops->card_event)
                host->ops->card_event(host);

        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));
                        ctx->cd_gpio = -EINVAL;
                        ctx->ro_gpio = -EINVAL;
                        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 || !gpio_is_valid(ctx->ro_gpio))
                return -ENOSYS;

        return !gpio_get_value_cansleep(ctx->ro_gpio) ^
                !!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
}
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 || !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);

/**
 * 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->ro_gpio = gpio;

        return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_ro);

/**
 * 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 irq = gpio_to_irq(gpio);
        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;
        }

        /*
         * 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 = 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;

        ctx->cd_gpio = gpio;

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

        gpio = ctx->ro_gpio;
        ctx->ro_gpio = -EINVAL;

        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 || !gpio_is_valid(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 = ctx->cd_gpio;
        ctx->cd_gpio = -EINVAL;

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