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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2015, Samsung Electronics Co., Ltd.
*
* Author: Marek Szyprowski <m.szyprowski@samsung.com>
*
* Simple eMMC hardware reset provider
*/
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/module.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;
};
#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
{
struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
udelay(1);
gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
udelay(200);
}
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);
gpiod_set_value(pwrseq->reset_gpio, 1);
udelay(1);
gpiod_set_value(pwrseq->reset_gpio, 0);
udelay(200);
return NOTIFY_DONE;
}
static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
.reset = mmc_pwrseq_emmc_reset,
};
static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
{
struct mmc_pwrseq_emmc *pwrseq;
struct device *dev = &pdev->dev;
pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
if (!pwrseq)
return -ENOMEM;
pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(pwrseq->reset_gpio))
return PTR_ERR(pwrseq->reset_gpio);
if (!gpiod_cansleep(pwrseq->reset_gpio)) {
/*
* 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);
} else {
dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
}
pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
pwrseq->pwrseq.dev = dev;
pwrseq->pwrseq.owner = THIS_MODULE;
platform_set_drvdata(pdev, pwrseq);
return mmc_pwrseq_register(&pwrseq->pwrseq);
}
static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
{
struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
unregister_restart_handler(&pwrseq->reset_nb);
mmc_pwrseq_unregister(&pwrseq->pwrseq);
return 0;
}
static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
{ .compatible = "mmc-pwrseq-emmc",},
{/* sentinel */},
};
MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
static struct platform_driver mmc_pwrseq_emmc_driver = {
.probe = mmc_pwrseq_emmc_probe,
.remove = mmc_pwrseq_emmc_remove,
.driver = {
.name = "pwrseq_emmc",
.of_match_table = mmc_pwrseq_emmc_of_match,
},
};
module_platform_driver(mmc_pwrseq_emmc_driver);
MODULE_LICENSE("GPL v2");
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