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 <fkan@apm.com>
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 syscon_reboot_context {
18	struct regmap *map;
19	u32 offset;
20	u32 value;
21	u32 mask;
22	struct notifier_block restart_handler;
23};
24
25static int syscon_restart_handle(struct notifier_block *this,
26					unsigned long mode, void *cmd)
27{
28	struct syscon_reboot_context *ctx =
29			container_of(this, struct syscon_reboot_context,
30					restart_handler);
31
32	/* Issue the reboot */
33	regmap_update_bits(ctx->map, ctx->offset, ctx->mask, ctx->value);
34
35	mdelay(1000);
36
37	pr_emerg("Unable to restart system\n");
38	return NOTIFY_DONE;
39}
40
41static int syscon_reboot_probe(struct platform_device *pdev)
42{
43	struct syscon_reboot_context *ctx;
44	struct device *dev = &pdev->dev;
45	int mask_err, value_err;
46	int priority;
47	int err;
48
49	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
50	if (!ctx)
51		return -ENOMEM;
52
53	ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
54	if (IS_ERR(ctx->map)) {
55		ctx->map = syscon_node_to_regmap(dev->parent->of_node);
56		if (IS_ERR(ctx->map))
57			return PTR_ERR(ctx->map);
58	}
59
60	if (of_property_read_s32(pdev->dev.of_node, "priority", &priority))
61		priority = 192;
62
63	if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
64		return -EINVAL;
65
66	value_err = of_property_read_u32(pdev->dev.of_node, "value", &ctx->value);
67	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask);
68	if (value_err && mask_err) {
69		dev_err(dev, "unable to read 'value' and 'mask'");
70		return -EINVAL;
71	}
72
73	if (value_err) {
74		/* support old binding */
75		ctx->value = ctx->mask;
76		ctx->mask = 0xFFFFFFFF;
77	} else if (mask_err) {
78		/* support value without mask*/
79		ctx->mask = 0xFFFFFFFF;
80	}
81
82	ctx->restart_handler.notifier_call = syscon_restart_handle;
83	ctx->restart_handler.priority = priority;
84	err = register_restart_handler(&ctx->restart_handler);
85	if (err)
86		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
87
88	return err;
89}
90
91static const struct of_device_id syscon_reboot_of_match[] = {
92	{ .compatible = "syscon-reboot" },
93	{}
94};
95
96static struct platform_driver syscon_reboot_driver = {
97	.probe = syscon_reboot_probe,
98	.driver = {
99		.name = "syscon-reboot",
100		.of_match_table = syscon_reboot_of_match,
101	},
102};
103builtin_platform_driver(syscon_reboot_driver);
104