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_host *host)
34{
35 struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
36
37 gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
38 udelay(1);
39 gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
40 udelay(200);
41}
42
43static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
44 unsigned long mode, void *cmd)
45{
46 struct mmc_pwrseq_emmc *pwrseq = container_of(this,
47 struct mmc_pwrseq_emmc, reset_nb);
48 gpiod_set_value(pwrseq->reset_gpio, 1);
49 udelay(1);
50 gpiod_set_value(pwrseq->reset_gpio, 0);
51 udelay(200);
52
53 return NOTIFY_DONE;
54}
55
56static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
57 .reset = mmc_pwrseq_emmc_reset,
58};
59
60static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
61{
62 struct mmc_pwrseq_emmc *pwrseq;
63 struct device *dev = &pdev->dev;
64
65 pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
66 if (!pwrseq)
67 return -ENOMEM;
68
69 pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
70 if (IS_ERR(pwrseq->reset_gpio))
71 return PTR_ERR(pwrseq->reset_gpio);
72
73 if (!gpiod_cansleep(pwrseq->reset_gpio)) {
74 /*
75 * register reset handler to ensure emmc reset also from
76 * emergency_reboot(), priority 255 is the highest priority
77 * so it will be executed before any system reboot handler.
78 */
79 pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
80 pwrseq->reset_nb.priority = 255;
81 register_restart_handler(&pwrseq->reset_nb);
82 } else {
83 dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
84 }
85
86 pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
87 pwrseq->pwrseq.dev = dev;
88 pwrseq->pwrseq.owner = THIS_MODULE;
89 platform_set_drvdata(pdev, pwrseq);
90
91 return mmc_pwrseq_register(&pwrseq->pwrseq);
92}
93
94static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
95{
96 struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
97
98 unregister_restart_handler(&pwrseq->reset_nb);
99 mmc_pwrseq_unregister(&pwrseq->pwrseq);
100
101 return 0;
102}
103
104static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
105 { .compatible = "mmc-pwrseq-emmc",},
106 {/* sentinel */},
107};
108
109MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
110
111static struct platform_driver mmc_pwrseq_emmc_driver = {
112 .probe = mmc_pwrseq_emmc_probe,
113 .remove = mmc_pwrseq_emmc_remove,
114 .driver = {
115 .name = "pwrseq_emmc",
116 .of_match_table = mmc_pwrseq_emmc_of_match,
117 },
118};
119
120module_platform_driver(mmc_pwrseq_emmc_driver);
121MODULE_LICENSE("GPL v2");