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 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
 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(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;
 97free:
 98	kfree(pwrseq);
 99	return ERR_PTR(ret);
100}