1/*
2 * Generic Syscon Reboot Driver
3 *
4 * Copyright (c) 2013, Applied Micro Circuits Corporation
5 * Author: Feng Kan <fkan@apm.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 */
17#include <linux/delay.h>
18#include <linux/io.h>
19#include <linux/notifier.h>
20#include <linux/mfd/syscon.h>
21#include <linux/of_address.h>
22#include <linux/of_device.h>
23#include <linux/platform_device.h>
24#include <linux/reboot.h>
25#include <linux/regmap.h>
26
27struct syscon_reboot_context {
28	struct regmap *map;
29	u32 offset;
30	u32 mask;
31	struct notifier_block restart_handler;
32};
33
34static int syscon_restart_handle(struct notifier_block *this,
35					unsigned long mode, void *cmd)
36{
37	struct syscon_reboot_context *ctx =
38			container_of(this, struct syscon_reboot_context,
39					restart_handler);
40
41	/* Issue the reboot */
42	regmap_write(ctx->map, ctx->offset, ctx->mask);
43
44	mdelay(1000);
45
46	pr_emerg("Unable to restart system\n");
47	return NOTIFY_DONE;
48}
49
50static int syscon_reboot_probe(struct platform_device *pdev)
51{
52	struct syscon_reboot_context *ctx;
53	struct device *dev = &pdev->dev;
54	int err;
55
56	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
57	if (!ctx)
58		return -ENOMEM;
59
60	ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
61	if (IS_ERR(ctx->map))
62		return PTR_ERR(ctx->map);
63
64	if (of_property_read_u32(pdev->dev.of_node, "offset", &ctx->offset))
65		return -EINVAL;
66
67	if (of_property_read_u32(pdev->dev.of_node, "mask", &ctx->mask))
68		return -EINVAL;
69
70	ctx->restart_handler.notifier_call = syscon_restart_handle;
71	ctx->restart_handler.priority = 192;
72	err = register_restart_handler(&ctx->restart_handler);
73	if (err)
74		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
75
76	return err;
77}
78
79static const struct of_device_id syscon_reboot_of_match[] = {
80	{ .compatible = "syscon-reboot" },
81	{}
82};
83
84static struct platform_driver syscon_reboot_driver = {
85	.probe = syscon_reboot_probe,
86	.driver = {
87		.name = "syscon-reboot",
88		.of_match_table = syscon_reboot_of_match,
89	},
90};
91builtin_platform_driver(syscon_reboot_driver);
92