pwrseq_emmc.c
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/*
* Copyright (C) 2015, Samsung Electronics Co., Ltd.
*
* Author: Marek Szyprowski <m.szyprowski@samsung.com>
*
* License terms: GNU General Public License (GPL) version 2
*
* Simple eMMC hardware reset provider
*/
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/reboot.h>
#include <linux/mmc/host.h>
#include "pwrseq.h"
struct mmc_pwrseq_emmc {
struct mmc_pwrseq pwrseq;
struct notifier_block reset_nb;
struct gpio_desc *reset_gpio;
};
static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq)
{
gpiod_set_value(pwrseq->reset_gpio, 1);
udelay(1);
gpiod_set_value(pwrseq->reset_gpio, 0);
udelay(200);
}
static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
{
struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq,
struct mmc_pwrseq_emmc, pwrseq);
__mmc_pwrseq_emmc_reset(pwrseq);
}
static void mmc_pwrseq_emmc_free(struct mmc_host *host)
{
struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq,
struct mmc_pwrseq_emmc, pwrseq);
unregister_restart_handler(&pwrseq->reset_nb);
gpiod_put(pwrseq->reset_gpio);
kfree(pwrseq);
}
static struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
.post_power_on = mmc_pwrseq_emmc_reset,
.free = mmc_pwrseq_emmc_free,
};
static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
unsigned long mode, void *cmd)
{
struct mmc_pwrseq_emmc *pwrseq = container_of(this,
struct mmc_pwrseq_emmc, reset_nb);
__mmc_pwrseq_emmc_reset(pwrseq);
return NOTIFY_DONE;
}
struct mmc_pwrseq *mmc_pwrseq_emmc_alloc(struct mmc_host *host,
struct device *dev)
{
struct mmc_pwrseq_emmc *pwrseq;
int ret = 0;
pwrseq = kzalloc(sizeof(struct mmc_pwrseq_emmc), GFP_KERNEL);
if (!pwrseq)
return ERR_PTR(-ENOMEM);
pwrseq->reset_gpio = gpiod_get(dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(pwrseq->reset_gpio)) {
ret = PTR_ERR(pwrseq->reset_gpio);
goto free;
}
/*
* register reset handler to ensure emmc reset also from
* emergency_reboot(), priority 255 is the highest priority
* so it will be executed before any system reboot handler.
*/
pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
pwrseq->reset_nb.priority = 255;
register_restart_handler(&pwrseq->reset_nb);
pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
return &pwrseq->pwrseq;
free:
kfree(pwrseq);
return ERR_PTR(ret);
}