slot-gpio.c

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/*
 * Generic GPIO card-detect helper
 *
 * Copyright (C) 2011, Guennadi Liakhovetski <[email protected]>
 *
 * 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 */
    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) + 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);

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 = gpio_request_one(gpio, GPIOF_DIR_IN, ctx->ro_label);
    if (ret < 0)
        return ret;

    ctx->ro_gpio = gpio;

    return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_ro);

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_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;

    gpio_free(gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_ro);

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);