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
25 struct 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
__mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc * pwrseq)33 static 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
mmc_pwrseq_emmc_reset(struct mmc_host * host)41 static 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
mmc_pwrseq_emmc_reset_nb(struct notifier_block * this,unsigned long mode,void * cmd)48 static 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
58 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
59 .reset = mmc_pwrseq_emmc_reset,
60 };
61
mmc_pwrseq_emmc_probe(struct platform_device * pdev)62 static 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
mmc_pwrseq_emmc_remove(struct platform_device * pdev)92 static 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
102 static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
103 { .compatible = "mmc-pwrseq-emmc",},
104 {/* sentinel */},
105 };
106
107 MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
108
109 static 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
118 module_platform_driver(mmc_pwrseq_emmc_driver);
119 MODULE_LICENSE("GPL v2");
120
