tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 .post_power_on = 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");