drivers/mmc/core/pwrseq_emmc.c

   1 /*
   2  * Copyright (C) 2015, Samsung Electronics Co., Ltd.
   3  *
   4  * Author: Marek Szyprowski <m.szyprowski@samsung.com>
   5  *
   6  * License terms: GNU General Public License (GPL) version 2
   7  *
   8  * Simple eMMC hardware reset provider
   9  */
  10 #include <linux/delay.h>
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/device.h>
  17 #include <linux/err.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/reboot.h>
  20
  21 #include <linux/mmc/host.h>
  22
  23 #include "pwrseq.h"
  24
  25 struct mmc_pwrseq_emmc {
  26         struct mmc_pwrseq pwrseq;
  27         struct notifier_block reset_nb;
  28         struct gpio_desc *reset_gpio;
  29 };
  30
  31 #define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
  32
  33 static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq)
  34 {
  35         gpiod_set_value(pwrseq->reset_gpio, 1);
  36         udelay(1);
  37         gpiod_set_value(pwrseq->reset_gpio, 0);
  38         udelay(200);
  39 }
  40
  41 static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
  42 {
  43         struct mmc_pwrseq_emmc *pwrseq =  to_pwrseq_emmc(host->pwrseq);
  44
  45         __mmc_pwrseq_emmc_reset(pwrseq);
  46 }
  47
  48 static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
  49                                     unsigned long mode, void *cmd)
  50 {
  51         struct mmc_pwrseq_emmc *pwrseq = container_of(this,
  52                                         struct mmc_pwrseq_emmc, reset_nb);
  53
  54         __mmc_pwrseq_emmc_reset(pwrseq);
  55         return NOTIFY_DONE;
  56 }
  57
  58 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  59         .reset = mmc_pwrseq_emmc_reset,
  60 };
  61
  62 static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
  63 {
  64         struct mmc_pwrseq_emmc *pwrseq;
  65         struct device *dev = &pdev->dev;
  66
  67         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
  68         if (!pwrseq)
  69                 return -ENOMEM;
  70
  71         pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
  72         if (IS_ERR(pwrseq->reset_gpio))
  73                 return PTR_ERR(pwrseq->reset_gpio);
  74
  75         /*
  76          * register reset handler to ensure emmc reset also from
  77          * emergency_reboot(), priority 255 is the highest priority
  78          * so it will be executed before any system reboot handler.
  79          */
  80         pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
  81         pwrseq->reset_nb.priority = 255;
  82         register_restart_handler(&pwrseq->reset_nb);
  83
  84         pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
  85         pwrseq->pwrseq.dev = dev;
  86         pwrseq->pwrseq.owner = THIS_MODULE;
  87         platform_set_drvdata(pdev, pwrseq);
  88
  89         return mmc_pwrseq_register(&pwrseq->pwrseq);
  90 }
  91
  92 static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
  93 {
  94         struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
  95
  96         unregister_restart_handler(&pwrseq->reset_nb);
  97         mmc_pwrseq_unregister(&pwrseq->pwrseq);
  98
  99         return 0;
 100 }
 101
 102 static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
 103         { .compatible = "mmc-pwrseq-emmc",},
 104         {/* sentinel */},
 105 };
 106
 107 MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
 108
 109 static struct platform_driver mmc_pwrseq_emmc_driver = {
 110         .probe = mmc_pwrseq_emmc_probe,
 111         .remove = mmc_pwrseq_emmc_remove,
 112         .driver = {
 113                 .name = "pwrseq_emmc",
 114                 .of_match_table = mmc_pwrseq_emmc_of_match,
 115         },
 116 };
 117
 118 module_platform_driver(mmc_pwrseq_emmc_driver);
 119 MODULE_LICENSE("GPL v2");