LXR linux/drivers/mmc/core/pwrseq

   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
  22struct mmc_pwrseq_emmc {
  23        struct mmc_pwrseq pwrseq;
  24        struct notifier_block reset_nb;
  25        struct gpio_desc *reset_gpio;
  26};
  27
  28static 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
  36static 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
  44static 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
  54static struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  55        .post_power_on = mmc_pwrseq_emmc_reset,
  56        .free = mmc_pwrseq_emmc_free,
  57};
  58
  59static 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
  69struct 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_index(dev, "reset", 0, 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 129 schedules it just before
  88         * system reboot
  89         */
  90        pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
  91        pwrseq->reset_nb.priority = 129;
  92        register_restart_handler(&pwrseq->reset_nb);
  93
  94        pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
  95
  96        return &pwrseq->pwrseq;
  97free:
  98        kfree(pwrseq);
  99        return ERR_PTR(ret);
 100}
 101