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_host *host)
  34 {
  35         struct mmc_pwrseq_emmc *pwrseq =  to_pwrseq_emmc(host->pwrseq);
  36
  37         gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
  38         udelay(1);
  39         gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
  40         udelay(200);
  41 }
  42
  43 static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
  44                                     unsigned long mode, void *cmd)
  45 {
  46         struct mmc_pwrseq_emmc *pwrseq = container_of(this,
  47                                         struct mmc_pwrseq_emmc, reset_nb);
  48         gpiod_set_value(pwrseq->reset_gpio, 1);
  49         udelay(1);
  50         gpiod_set_value(pwrseq->reset_gpio, 0);
  51         udelay(200);
  52
  53         return NOTIFY_DONE;
  54 }
  55
  56 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  57         .post_power_on = mmc_pwrseq_emmc_reset,
  58 };
  59
  60 static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
  61 {
  62         struct mmc_pwrseq_emmc *pwrseq;
  63         struct device *dev = &pdev->dev;
  64
  65         pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
  66         if (!pwrseq)
  67                 return -ENOMEM;
  68
  69         pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
  70         if (IS_ERR(pwrseq->reset_gpio))
  71                 return PTR_ERR(pwrseq->reset_gpio);
  72
  73         if (!gpiod_cansleep(pwrseq->reset_gpio)) {
  74                 /*
  75                  * register reset handler to ensure emmc reset also from
  76                  * emergency_reboot(), priority 255 is the highest priority
  77                  * so it will be executed before any system reboot handler.
  78                  */
  79                 pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
  80                 pwrseq->reset_nb.priority = 255;
  81                 register_restart_handler(&pwrseq->reset_nb);
  82         } else {
  83                 dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
  84         }
  85
  86         pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
  87         pwrseq->pwrseq.dev = dev;
  88         pwrseq->pwrseq.owner = THIS_MODULE;
  89         platform_set_drvdata(pdev, pwrseq);
  90
  91         return mmc_pwrseq_register(&pwrseq->pwrseq);
  92 }
  93
  94 static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
  95 {
  96         struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
  97
  98         unregister_restart_handler(&pwrseq->reset_nb);
  99         mmc_pwrseq_unregister(&pwrseq->pwrseq);
 100
 101         return 0;
 102 }
 103
 104 static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
 105         { .compatible = "mmc-pwrseq-emmc",},
 106         {/* sentinel */},
 107 };
 108
 109 MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
 110
 111 static struct platform_driver mmc_pwrseq_emmc_driver = {
 112         .probe = mmc_pwrseq_emmc_probe,
 113         .remove = mmc_pwrseq_emmc_remove,
 114         .driver = {
 115                 .name = "pwrseq_emmc",
 116                 .of_match_table = mmc_pwrseq_emmc_of_match,
 117         },
 118 };
 119
 120 module_platform_driver(mmc_pwrseq_emmc_driver);
 121 MODULE_LICENSE("GPL v2");