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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic Syscon Reboot Driver
4 *
5 * Copyright (c) 2013, Applied Micro Circuits Corporation
6 * Author: Feng Kan <[email protected]>
7 */
8#include <linux/delay.h>
9#include <linux/io.h>
10#include <linux/notifier.h>
11#include <linux/mfd/syscon.h>
12#include <linux/of.h>
13#include <linux/platform_device.h>
14#include <linux/reboot.h>
15#include <linux/regmap.h>
16
17struct reboot_mode_bits {
18 u32 offset;
19 u32 mask;
20 u32 value;
21 bool valid;
22};
23
24struct reboot_data {
25 struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1];
26 struct reboot_mode_bits catchall;
27};
28
29struct syscon_reboot_context {
30 struct regmap *map;
31
32 const struct reboot_data *rd; /* from of match data, if any */
33 struct reboot_mode_bits catchall; /* from DT */
34
35 struct notifier_block restart_handler;
36};
37
38static int syscon_restart_handle(struct notifier_block *this,
39 unsigned long mode, void *cmd)
40{
41 struct syscon_reboot_context *ctx =
42 container_of(this, struct syscon_reboot_context,
43 restart_handler);
44 const struct reboot_mode_bits *mode_bits;
45
46 if (ctx->rd) {
47 if (mode < ARRAY_SIZE(ctx->rd->mode_bits) &&
48 ctx->rd->mode_bits[mode].valid)
49 mode_bits = &ctx->rd->mode_bits[mode];
50 else
51 mode_bits = &ctx->rd->catchall;
52 } else {
53 mode_bits = &ctx->catchall;
54 }
55
56 /* Issue the reboot */
57 regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask,
58 mode_bits->value);
59
60 mdelay(1000);
61
62 pr_emerg("Unable to restart system\n");
63 return NOTIFY_DONE;
64}
65
66static int syscon_reboot_probe(struct platform_device *pdev)
67{
68 struct syscon_reboot_context *ctx;
69 struct device *dev = &pdev->dev;
70 u32 priority;
71 int err;
72
73 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
74 if (!ctx)
75 return -ENOMEM;
76
77 ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
78 if (IS_ERR(ctx->map)) {
79 ctx->map = syscon_node_to_regmap(dev->parent->of_node);
80 if (IS_ERR(ctx->map))
81 return PTR_ERR(ctx->map);
82 }
83
84 if (of_property_read_u32(pdev->dev.of_node, "priority", &priority))
85 priority = 192;
86
87 ctx->rd = of_device_get_match_data(dev);
88 if (!ctx->rd) {
89 int mask_err, value_err;
90
91 if (of_property_read_u32(pdev->dev.of_node, "offset",
92 &ctx->catchall.offset) &&
93 of_property_read_u32(pdev->dev.of_node, "reg",
94 &ctx->catchall.offset))
95 return -EINVAL;
96
97 value_err = of_property_read_u32(pdev->dev.of_node, "value",
98 &ctx->catchall.value);
99 mask_err = of_property_read_u32(pdev->dev.of_node, "mask",
100 &ctx->catchall.mask);
101 if (value_err && mask_err) {
102 dev_err(dev, "unable to read 'value' and 'mask'");
103 return -EINVAL;
104 }
105
106 if (value_err) {
107 /* support old binding */
108 ctx->catchall.value = ctx->catchall.mask;
109 ctx->catchall.mask = 0xFFFFFFFF;
110 } else if (mask_err) {
111 /* support value without mask */
112 ctx->catchall.mask = 0xFFFFFFFF;
113 }
114 }
115
116 ctx->restart_handler.notifier_call = syscon_restart_handle;
117 ctx->restart_handler.priority = priority;
118 err = register_restart_handler(&ctx->restart_handler);
119 if (err)
120 dev_err(dev, "can't register restart notifier (err=%d)\n", err);
121
122 return err;
123}
124
125static const struct reboot_data gs101_reboot_data = {
126 .mode_bits = {
127 [REBOOT_WARM] = {
128 .offset = 0x3a00, /* SYSTEM_CONFIGURATION */
129 .mask = 0x00000002, /* SWRESET_SYSTEM */
130 .value = 0x00000002,
131 .valid = true,
132 },
133 [REBOOT_SOFT] = {
134 .offset = 0x3a00, /* SYSTEM_CONFIGURATION */
135 .mask = 0x00000002, /* SWRESET_SYSTEM */
136 .value = 0x00000002,
137 .valid = true,
138 },
139 },
140 .catchall = {
141 .offset = 0x3e9c, /* PAD_CTRL_PWR_HOLD */
142 .mask = 0x00000100,
143 .value = 0x00000000,
144 },
145};
146
147static const struct of_device_id syscon_reboot_of_match[] = {
148 { .compatible = "google,gs101-reboot", .data = &gs101_reboot_data },
149 { .compatible = "syscon-reboot" },
150 {}
151};
152
153static struct platform_driver syscon_reboot_driver = {
154 .probe = syscon_reboot_probe,
155 .driver = {
156 .name = "syscon-reboot",
157 .of_match_table = syscon_reboot_of_match,
158 },
159};
160builtin_platform_driver(syscon_reboot_driver);