1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Generic Syscon Poweroff Driver
4 *
5 * Copyright (c) 2015, National Instruments Corp.
6 * Author: Moritz Fischer <moritz.fischer@ettus.com>
7 */
8
9#include <linux/kallsyms.h>
10#include <linux/delay.h>
11#include <linux/io.h>
12#include <linux/notifier.h>
13#include <linux/mfd/syscon.h>
14#include <linux/of_address.h>
15#include <linux/of_device.h>
16#include <linux/platform_device.h>
17#include <linux/pm.h>
18#include <linux/regmap.h>
19
20static struct regmap *map;
21static u32 offset;
22static u32 value;
23static u32 mask;
24
25static void syscon_poweroff(void)
26{
27	/* Issue the poweroff */
28	regmap_update_bits(map, offset, mask, value);
29
30	mdelay(1000);
31
32	pr_emerg("Unable to poweroff system\n");
33}
34
35static int syscon_poweroff_probe(struct platform_device *pdev)
36{
37	char symname[KSYM_NAME_LEN];
38	int mask_err, value_err;
39
40	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
41	if (IS_ERR(map)) {
42		dev_err(&pdev->dev, "unable to get syscon");
43		return PTR_ERR(map);
44	}
45
46	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
47		dev_err(&pdev->dev, "unable to read 'offset'");
48		return -EINVAL;
49	}
50
51	value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
52	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
53	if (value_err && mask_err) {
54		dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
55		return -EINVAL;
56	}
57
58	if (value_err) {
59		/* support old binding */
60		value = mask;
61		mask = 0xFFFFFFFF;
62	} else if (mask_err) {
63		/* support value without mask*/
64		mask = 0xFFFFFFFF;
65	}
66
67	if (pm_power_off) {
68		lookup_symbol_name((ulong)pm_power_off, symname);
69		dev_err(&pdev->dev,
70		"pm_power_off already claimed %p %s",
71		pm_power_off, symname);
72		return -EBUSY;
73	}
74
75	pm_power_off = syscon_poweroff;
76
77	return 0;
78}
79
80static int syscon_poweroff_remove(struct platform_device *pdev)
81{
82	if (pm_power_off == syscon_poweroff)
83		pm_power_off = NULL;
84
85	return 0;
86}
87
88static const struct of_device_id syscon_poweroff_of_match[] = {
89	{ .compatible = "syscon-poweroff" },
90	{}
91};
92
93static struct platform_driver syscon_poweroff_driver = {
94	.probe = syscon_poweroff_probe,
95	.remove = syscon_poweroff_remove,
96	.driver = {
97		.name = "syscon-poweroff",
98		.of_match_table = syscon_poweroff_of_match,
99	},
100};
101
102static int __init syscon_poweroff_register(void)
103{
104	return platform_driver_register(&syscon_poweroff_driver);
105}
106device_initcall(syscon_poweroff_register);
107