1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2014 STMicroelectronics
4 *
5 * Power off Restart driver, used in STMicroelectronics devices.
6 *
7 * Author: Christophe Kerello <christophe.kerello@st.com>
8 */
9
10#include <linux/module.h>
11#include <linux/of.h>
12#include <linux/of_device.h>
13#include <linux/platform_device.h>
14#include <linux/mfd/syscon.h>
15#include <linux/reboot.h>
16#include <linux/regmap.h>
17
18struct reset_syscfg {
19	struct regmap *regmap;
20	/* syscfg used for reset */
21	unsigned int offset_rst;
22	unsigned int mask_rst;
23	/* syscfg used for unmask the reset */
24	unsigned int offset_rst_msk;
25	unsigned int mask_rst_msk;
26};
27
28/* STiH407 */
29#define STIH407_SYSCFG_4000	0x0
30#define STIH407_SYSCFG_4008	0x20
31
32static struct reset_syscfg stih407_reset = {
33	.offset_rst = STIH407_SYSCFG_4000,
34	.mask_rst = BIT(0),
35	.offset_rst_msk = STIH407_SYSCFG_4008,
36	.mask_rst_msk = BIT(0)
37};
38
39
40static struct reset_syscfg *st_restart_syscfg;
41
42static int st_restart(struct notifier_block *this, unsigned long mode,
43		      void *cmd)
44{
45	/* reset syscfg updated */
46	regmap_update_bits(st_restart_syscfg->regmap,
47			   st_restart_syscfg->offset_rst,
48			   st_restart_syscfg->mask_rst,
49			   0);
50
51	/* unmask the reset */
52	regmap_update_bits(st_restart_syscfg->regmap,
53			   st_restart_syscfg->offset_rst_msk,
54			   st_restart_syscfg->mask_rst_msk,
55			   0);
56
57	return NOTIFY_DONE;
58}
59
60static struct notifier_block st_restart_nb = {
61	.notifier_call = st_restart,
62	.priority = 192,
63};
64
65static const struct of_device_id st_reset_of_match[] = {
66	{
67		.compatible = "st,stih407-restart",
68		.data = (void *)&stih407_reset,
69	},
70	{}
71};
72
73static int st_reset_probe(struct platform_device *pdev)
74{
75	struct device_node *np = pdev->dev.of_node;
76	const struct of_device_id *match;
77	struct device *dev = &pdev->dev;
78
79	match = of_match_device(st_reset_of_match, dev);
80	if (!match)
81		return -ENODEV;
82
83	st_restart_syscfg = (struct reset_syscfg *)match->data;
84
85	st_restart_syscfg->regmap =
86		syscon_regmap_lookup_by_phandle(np, "st,syscfg");
87	if (IS_ERR(st_restart_syscfg->regmap)) {
88		dev_err(dev, "No syscfg phandle specified\n");
89		return PTR_ERR(st_restart_syscfg->regmap);
90	}
91
92	return register_restart_handler(&st_restart_nb);
93}
94
95static struct platform_driver st_reset_driver = {
96	.probe = st_reset_probe,
97	.driver = {
98		.name = "st_reset",
99		.of_match_table = st_reset_of_match,
100	},
101};
102
103static int __init st_reset_init(void)
104{
105	return platform_driver_register(&st_reset_driver);
106}
107
108device_initcall(st_reset_init);
109
110MODULE_AUTHOR("Christophe Kerello <christophe.kerello@st.com>");
111MODULE_DESCRIPTION("STMicroelectronics Power off Restart driver");
112MODULE_LICENSE("GPL v2");
113