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
 25struct 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
 33static 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
 41static 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
 48static 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
 58static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
 59	.reset = mmc_pwrseq_emmc_reset,
 60};
 61
 62static 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
 92static 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
102static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
103	{ .compatible = "mmc-pwrseq-emmc",},
104	{/* sentinel */},
105};
106
107MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
108
109static 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
118module_platform_driver(mmc_pwrseq_emmc_driver);
119MODULE_LICENSE("GPL v2");