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(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}
101