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119 lines · 3.1 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2015, Samsung Electronics Co., Ltd.
4 *
5 * Author: Marek Szyprowski <[email protected]>
6 *
7 * Simple eMMC hardware reset provider
8 */
9#include <linux/delay.h>
10#include <linux/kernel.h>
11#include <linux/init.h>
12#include <linux/platform_device.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/device.h>
16#include <linux/err.h>
17#include <linux/gpio/consumer.h>
18#include <linux/reboot.h>
19
20#include <linux/mmc/host.h>
21
22#include "pwrseq.h"
23
24struct mmc_pwrseq_emmc {
25 struct mmc_pwrseq pwrseq;
26 struct notifier_block reset_nb;
27 struct gpio_desc *reset_gpio;
28};
29
30#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
31
32static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
33{
34 struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
35
36 gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
37 udelay(1);
38 gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
39 udelay(200);
40}
41
42static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
43 unsigned long mode, void *cmd)
44{
45 struct mmc_pwrseq_emmc *pwrseq = container_of(this,
46 struct mmc_pwrseq_emmc, reset_nb);
47 gpiod_set_value(pwrseq->reset_gpio, 1);
48 udelay(1);
49 gpiod_set_value(pwrseq->reset_gpio, 0);
50 udelay(200);
51
52 return NOTIFY_DONE;
53}
54
55static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
56 .reset = mmc_pwrseq_emmc_reset,
57};
58
59static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
60{
61 struct mmc_pwrseq_emmc *pwrseq;
62 struct device *dev = &pdev->dev;
63
64 pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
65 if (!pwrseq)
66 return -ENOMEM;
67
68 pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
69 if (IS_ERR(pwrseq->reset_gpio))
70 return PTR_ERR(pwrseq->reset_gpio);
71
72 if (!gpiod_cansleep(pwrseq->reset_gpio)) {
73 /*
74 * register reset handler to ensure emmc reset also from
75 * emergency_reboot(), priority 255 is the highest priority
76 * so it will be executed before any system reboot handler.
77 */
78 pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
79 pwrseq->reset_nb.priority = 255;
80 register_restart_handler(&pwrseq->reset_nb);
81 } else {
82 dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
83 }
84
85 pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
86 pwrseq->pwrseq.dev = dev;
87 pwrseq->pwrseq.owner = THIS_MODULE;
88 platform_set_drvdata(pdev, pwrseq);
89
90 return mmc_pwrseq_register(&pwrseq->pwrseq);
91}
92
93static void mmc_pwrseq_emmc_remove(struct platform_device *pdev)
94{
95 struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
96
97 unregister_restart_handler(&pwrseq->reset_nb);
98 mmc_pwrseq_unregister(&pwrseq->pwrseq);
99}
100
101static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
102 { .compatible = "mmc-pwrseq-emmc",},
103 {/* sentinel */},
104};
105
106MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
107
108static struct platform_driver mmc_pwrseq_emmc_driver = {
109 .probe = mmc_pwrseq_emmc_probe,
110 .remove = mmc_pwrseq_emmc_remove,
111 .driver = {
112 .name = "pwrseq_emmc",
113 .of_match_table = mmc_pwrseq_emmc_of_match,
114 },
115};
116
117module_platform_driver(mmc_pwrseq_emmc_driver);
118MODULE_DESCRIPTION("Hardware reset support for eMMC");
119MODULE_LICENSE("GPL v2");