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 
18 struct 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 
32 static 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 
40 static struct reset_syscfg *st_restart_syscfg;
41 
42 static 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 
60 static struct notifier_block st_restart_nb = {
61 	.notifier_call = st_restart,
62 	.priority = 192,
63 };
64 
65 static const struct of_device_id st_reset_of_match[] = {
66 	{
67 		.compatible = "st,stih407-restart",
68 		.data = (void *)&stih407_reset,
69 	},
70 	{}
71 };
72 
73 static 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 
95 static 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 
103 static int __init st_reset_init(void)
104 {
105 	return platform_driver_register(&st_reset_driver);
106 }
107 
108 device_initcall(st_reset_init);
109 
110 MODULE_AUTHOR("Christophe Kerello <christophe.kerello@st.com>");
111 MODULE_DESCRIPTION("STMicroelectronics Power off Restart driver");
112 MODULE_LICENSE("GPL v2");
113