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/delay.h>
10#include <linux/io.h>
11#include <linux/notifier.h>
12#include <linux/mfd/syscon.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/pm.h>
16#include <linux/regmap.h>
17
18static struct regmap *map;
19static u32 offset;
20static u32 value;
21static u32 mask;
22
23static void syscon_poweroff(void)
24{
25	/* Issue the poweroff */
26	regmap_update_bits(map, offset, mask, value);
27
28	mdelay(1000);
29
30	pr_emerg("Unable to poweroff system\n");
31}
32
33static int syscon_poweroff_probe(struct platform_device *pdev)
34{
35	int mask_err, value_err;
36
37	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
38	if (IS_ERR(map)) {
39		dev_err(&pdev->dev, "unable to get syscon");
40		return PTR_ERR(map);
41	}
42
43	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
44		dev_err(&pdev->dev, "unable to read 'offset'");
45		return -EINVAL;
46	}
47
48	value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
49	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
50	if (value_err && mask_err) {
51		dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
52		return -EINVAL;
53	}
54
55	if (value_err) {
56		/* support old binding */
57		value = mask;
58		mask = 0xFFFFFFFF;
59	} else if (mask_err) {
60		/* support value without mask*/
61		mask = 0xFFFFFFFF;
62	}
63
64	if (pm_power_off) {
65		dev_err(&pdev->dev, "pm_power_off already claimed for %ps",
66			pm_power_off);
67		return -EBUSY;
68	}
69
70	pm_power_off = syscon_poweroff;
71
72	return 0;
73}
74
75static int syscon_poweroff_remove(struct platform_device *pdev)
76{
77	if (pm_power_off == syscon_poweroff)
78		pm_power_off = NULL;
79
80	return 0;
81}
82
83static const struct of_device_id syscon_poweroff_of_match[] = {
84	{ .compatible = "syscon-poweroff" },
85	{}
86};
87
88static struct platform_driver syscon_poweroff_driver = {
89	.probe = syscon_poweroff_probe,
90	.remove = syscon_poweroff_remove,
91	.driver = {
92		.name = "syscon-poweroff",
93		.of_match_table = syscon_poweroff_of_match,
94	},
95};
96
97static int __init syscon_poweroff_register(void)
98{
99	return platform_driver_register(&syscon_poweroff_driver);
100}
101device_initcall(syscon_poweroff_register);
102