// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2015, Samsung Electronics Co., Ltd.
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*
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* Author: Marek Szyprowski <m.szyprowski@samsung.com>
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*
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* Simple eMMC hardware reset provider
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*/
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/reboot.h>
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#include <linux/mmc/host.h>
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#include "pwrseq.h"
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struct mmc_pwrseq_emmc {
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struct mmc_pwrseq pwrseq;
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struct notifier_block reset_nb;
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struct gpio_desc *reset_gpio;
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};
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#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
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static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
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{
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struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
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gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
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udelay(1);
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gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
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udelay(200);
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}
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static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
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unsigned long mode, void *cmd)
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{
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struct mmc_pwrseq_emmc *pwrseq = container_of(this,
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struct mmc_pwrseq_emmc, reset_nb);
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gpiod_set_value(pwrseq->reset_gpio, 1);
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udelay(1);
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gpiod_set_value(pwrseq->reset_gpio, 0);
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udelay(200);
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return NOTIFY_DONE;
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}
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static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
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.reset = mmc_pwrseq_emmc_reset,
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};
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static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
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{
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struct mmc_pwrseq_emmc *pwrseq;
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struct device *dev = &pdev->dev;
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pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
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if (!pwrseq)
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return -ENOMEM;
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pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
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if (IS_ERR(pwrseq->reset_gpio))
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return PTR_ERR(pwrseq->reset_gpio);
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if (!gpiod_cansleep(pwrseq->reset_gpio)) {
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/*
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* register reset handler to ensure emmc reset also from
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* emergency_reboot(), priority 255 is the highest priority
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* so it will be executed before any system reboot handler.
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*/
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pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
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pwrseq->reset_nb.priority = 255;
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register_restart_handler(&pwrseq->reset_nb);
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} else {
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dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
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}
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pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
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pwrseq->pwrseq.dev = dev;
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pwrseq->pwrseq.owner = THIS_MODULE;
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platform_set_drvdata(pdev, pwrseq);
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return mmc_pwrseq_register(&pwrseq->pwrseq);
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}
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static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
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{
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struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
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unregister_restart_handler(&pwrseq->reset_nb);
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mmc_pwrseq_unregister(&pwrseq->pwrseq);
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return 0;
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}
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static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
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{ .compatible = "mmc-pwrseq-emmc",},
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{/* sentinel */},
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};
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MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
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static struct platform_driver mmc_pwrseq_emmc_driver = {
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.probe = mmc_pwrseq_emmc_probe,
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.remove = mmc_pwrseq_emmc_remove,
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.driver = {
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.name = "pwrseq_emmc",
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.of_match_table = mmc_pwrseq_emmc_of_match,
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},
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};
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module_platform_driver(mmc_pwrseq_emmc_driver);
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MODULE_LICENSE("GPL v2");
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