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/slab.h>
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/gpio/consumer.h>
  16 #include <linux/reboot.h>
  17
  18 #include <linux/mmc/host.h>
  19
  20 #include "pwrseq.h"
  21
  22 struct mmc_pwrseq_emmc {
  23         struct mmc_pwrseq pwrseq;
  24         struct notifier_block reset_nb;
  25         struct gpio_desc *reset_gpio;
  26 };
  27
  28 static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq)
  29 {
  30         gpiod_set_value(pwrseq->reset_gpio, 1);
  31         udelay(1);
  32         gpiod_set_value(pwrseq->reset_gpio, 0);
  33         udelay(200);
  34 }
  35
  36 static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
  37 {
  38         struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq,
  39                                         struct mmc_pwrseq_emmc, pwrseq);
  40
  41         __mmc_pwrseq_emmc_reset(pwrseq);
  42 }
  43
  44 static void mmc_pwrseq_emmc_free(struct mmc_host *host)
  45 {
  46         struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq,
  47                                         struct mmc_pwrseq_emmc, pwrseq);
  48
  49         unregister_restart_handler(&pwrseq->reset_nb);
  50         gpiod_put(pwrseq->reset_gpio);
  51         kfree(pwrseq);
  52 }
  53
  54 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  55         .post_power_on = mmc_pwrseq_emmc_reset,
  56         .free = mmc_pwrseq_emmc_free,
  57 };
  58
  59 static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
  60                                     unsigned long mode, void *cmd)
  61 {
  62         struct mmc_pwrseq_emmc *pwrseq = container_of(this,
  63                                         struct mmc_pwrseq_emmc, reset_nb);
  64
  65         __mmc_pwrseq_emmc_reset(pwrseq);
  66         return NOTIFY_DONE;
  67 }
  68
  69 struct mmc_pwrseq *mmc_pwrseq_emmc_alloc(struct mmc_host *host,
  70                                          struct device *dev)
  71 {
  72         struct mmc_pwrseq_emmc *pwrseq;
  73         int ret = 0;
  74
  75         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_emmc), GFP_KERNEL);
  76         if (!pwrseq)
  77                 return ERR_PTR(-ENOMEM);
  78
  79         pwrseq->reset_gpio = gpiod_get(dev, "reset", GPIOD_OUT_LOW);
  80         if (IS_ERR(pwrseq->reset_gpio)) {
  81                 ret = PTR_ERR(pwrseq->reset_gpio);
  82                 goto free;
  83         }
  84
  85         /*
  86          * register reset handler to ensure emmc reset also from
  87          * emergency_reboot(), priority 255 is the highest priority
  88          * so it will be executed before any system reboot handler.
  89          */
  90         pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
  91         pwrseq->reset_nb.priority = 255;
  92         register_restart_handler(&pwrseq->reset_nb);
  93
  94         pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
  95
  96         return &pwrseq->pwrseq;
  97 free:
  98         kfree(pwrseq);
  99         return ERR_PTR(ret);
 100 }