1/*
2 * Generic Syscon Poweroff Driver
3 *
4 * Copyright (c) 2015, National Instruments Corp.
5 * Author: Moritz Fischer <moritz.fischer@ettus.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
18#include <linux/kallsyms.h>
19#include <linux/delay.h>
20#include <linux/io.h>
21#include <linux/notifier.h>
22#include <linux/mfd/syscon.h>
23#include <linux/of_address.h>
24#include <linux/of_device.h>
25#include <linux/platform_device.h>
26#include <linux/pm.h>
27#include <linux/regmap.h>
28
29static struct regmap *map;
30static u32 offset;
31static u32 mask;
32
33void syscon_poweroff(void)
34{
35	/* Issue the poweroff */
36	regmap_write(map, offset, mask);
37
38	mdelay(1000);
39
40	pr_emerg("Unable to poweroff system\n");
41}
42
43static int syscon_poweroff_probe(struct platform_device *pdev)
44{
45	char symname[KSYM_NAME_LEN];
46
47	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
48	if (IS_ERR(map)) {
49		dev_err(&pdev->dev, "unable to get syscon");
50		return PTR_ERR(map);
51	}
52
53	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
54		dev_err(&pdev->dev, "unable to read 'offset'");
55		return -EINVAL;
56	}
57
58	if (of_property_read_u32(pdev->dev.of_node, "mask", &mask)) {
59		dev_err(&pdev->dev, "unable to read 'mask'");
60		return -EINVAL;
61	}
62
63	if (pm_power_off) {
64		lookup_symbol_name((ulong)pm_power_off, symname);
65		dev_err(&pdev->dev,
66		"pm_power_off already claimed %p %s",
67		pm_power_off, symname);
68		return -EBUSY;
69	}
70
71	pm_power_off = syscon_poweroff;
72
73	return 0;
74}
75
76static int syscon_poweroff_remove(struct platform_device *pdev)
77{
78	if (pm_power_off == syscon_poweroff)
79		pm_power_off = NULL;
80
81	return 0;
82}
83
84static const struct of_device_id syscon_poweroff_of_match[] = {
85	{ .compatible = "syscon-poweroff" },
86	{}
87};
88
89static struct platform_driver syscon_poweroff_driver = {
90	.probe = syscon_poweroff_probe,
91	.remove = syscon_poweroff_remove,
92	.driver = {
93		.name = "syscon-poweroff",
94		.of_match_table = syscon_poweroff_of_match,
95	},
96};
97
98static int __init syscon_poweroff_register(void)
99{
100	return platform_driver_register(&syscon_poweroff_driver);
101}
102device_initcall(syscon_poweroff_register);
103