LXR linux/drivers/mmc/core/pwrseq

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2015, Samsung Electronics Co., Ltd.
   4 *
   5 * Author: Marek Szyprowski <m.szyprowski@samsung.com>
   6 *
   7 * Simple eMMC hardware reset provider
   8 */
   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 from
  75                 * emergency_reboot(), priority 255 is the highest priority
  76                 * 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 int 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        return 0;
 101}
 102
 103static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
 104        { .compatible = "mmc-pwrseq-emmc",},
 105        {/* sentinel */},
 106};
 107
 108MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
 109
 110static struct platform_driver mmc_pwrseq_emmc_driver = {
 111        .probe = mmc_pwrseq_emmc_probe,
 112        .remove = mmc_pwrseq_emmc_remove,
 113        .driver = {
 114                .name = "pwrseq_emmc",
 115                .of_match_table = mmc_pwrseq_emmc_of_match,
 116        },
 117};
 118
 119module_platform_driver(mmc_pwrseq_emmc_driver);
 120MODULE_LICENSE("GPL v2");
 121