drivers/mmc/core/pwrseq_emmc.c

   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
  24 struct 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
  32 static 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
  42 static 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
  55 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  56         .reset = mmc_pwrseq_emmc_reset,
  57 };
  58
  59 static 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
  93 static 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
 103 static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
 104         { .compatible = "mmc-pwrseq-emmc",},
 105         {/* sentinel */},
 106 };
 107
 108 MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
 109
 110 static 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
 119 module_platform_driver(mmc_pwrseq_emmc_driver);
 120 MODULE_LICENSE("GPL v2");