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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2015, Samsung Electronics Co., Ltd.4 *5 * Author: Marek Szyprowski <m.szyprowski@samsung.com>6 *7 * Simple eMMC hardware reset provider8 */9#include <linux/delay.h>10#include <linux/kernel.h>11#include <linux/init.h>12#include <linux/platform_device.h>13#include <linux/module.h>14#include <linux/slab.h>15#include <linux/device.h>16#include <linux/err.h>17#include <linux/gpio/consumer.h>18#include <linux/reboot.h>19 20#include <linux/mmc/host.h>21 22#include "pwrseq.h"23 24struct mmc_pwrseq_emmc {25 struct mmc_pwrseq pwrseq;26 struct notifier_block reset_nb;27 struct gpio_desc *reset_gpio;28};29 30#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)31 32static void mmc_pwrseq_emmc_reset(struct mmc_host *host)33{34 struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);35 36 gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);37 udelay(1);38 gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);39 udelay(200);40}41 42static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,43 unsigned long mode, void *cmd)44{45 struct mmc_pwrseq_emmc *pwrseq = container_of(this,46 struct mmc_pwrseq_emmc, reset_nb);47 gpiod_set_value(pwrseq->reset_gpio, 1);48 udelay(1);49 gpiod_set_value(pwrseq->reset_gpio, 0);50 udelay(200);51 52 return NOTIFY_DONE;53}54 55static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {56 .reset = mmc_pwrseq_emmc_reset,57};58 59static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)60{61 struct mmc_pwrseq_emmc *pwrseq;62 struct device *dev = &pdev->dev;63 64 pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);65 if (!pwrseq)66 return -ENOMEM;67 68 pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);69 if (IS_ERR(pwrseq->reset_gpio))70 return PTR_ERR(pwrseq->reset_gpio);71 72 if (!gpiod_cansleep(pwrseq->reset_gpio)) {73 /*74 * register reset handler to ensure emmc reset also from75 * emergency_reboot(), priority 255 is the highest priority76 * so it will be executed before any system reboot handler.77 */78 pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;79 pwrseq->reset_nb.priority = 255;80 register_restart_handler(&pwrseq->reset_nb);81 } else {82 dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");83 }84 85 pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;86 pwrseq->pwrseq.dev = dev;87 pwrseq->pwrseq.owner = THIS_MODULE;88 platform_set_drvdata(pdev, pwrseq);89 90 return mmc_pwrseq_register(&pwrseq->pwrseq);91}92 93static void mmc_pwrseq_emmc_remove(struct platform_device *pdev)94{95 struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);96 97 unregister_restart_handler(&pwrseq->reset_nb);98 mmc_pwrseq_unregister(&pwrseq->pwrseq);99}100 101static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {102 { .compatible = "mmc-pwrseq-emmc",},103 {/* sentinel */},104};105 106MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);107 108static struct platform_driver mmc_pwrseq_emmc_driver = {109 .probe = mmc_pwrseq_emmc_probe,110 .remove_new = mmc_pwrseq_emmc_remove,111 .driver = {112 .name = "pwrseq_emmc",113 .of_match_table = mmc_pwrseq_emmc_of_match,114 },115};116 117module_platform_driver(mmc_pwrseq_emmc_driver);118MODULE_DESCRIPTION("Hardware reset support for eMMC");119MODULE_LICENSE("GPL v2");120