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	struct device *dev = &pdev->dev;
36	int mask_err, value_err;
37
38	map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
39	if (IS_ERR(map)) {
40		map = syscon_node_to_regmap(dev->parent->of_node);
41		if (IS_ERR(map)) {
42			dev_err(dev, "unable to get syscon");
43			return PTR_ERR(map);
44		}
45	}
46
47	if (of_property_read_u32(dev->of_node, "offset", &offset)) {
48		dev_err(dev, "unable to read 'offset'");
49		return -EINVAL;
50	}
51
52	value_err = of_property_read_u32(dev->of_node, "value", &value);
53	mask_err = of_property_read_u32(dev->of_node, "mask", &mask);
54	if (value_err && mask_err) {
55		dev_err(dev, "unable to read 'value' and 'mask'");
56		return -EINVAL;
57	}
58
59	if (value_err) {
60		/* support old binding */
61		value = mask;
62		mask = 0xFFFFFFFF;
63	} else if (mask_err) {
64		/* support value without mask*/
65		mask = 0xFFFFFFFF;
66	}
67
68	if (pm_power_off) {
69		dev_err(dev, "pm_power_off already claimed for %ps",
70			pm_power_off);
71		return -EBUSY;
72	}
73
74	pm_power_off = syscon_poweroff;
75
76	return 0;
77}
78
79static void syscon_poweroff_remove(struct platform_device *pdev)
80{
81	if (pm_power_off == syscon_poweroff)
82		pm_power_off = NULL;
83}
84
85static const struct of_device_id syscon_poweroff_of_match[] = {
86	{ .compatible = "syscon-poweroff" },
87	{}
88};
89
90static struct platform_driver syscon_poweroff_driver = {
91	.probe = syscon_poweroff_probe,
92	.remove_new = syscon_poweroff_remove,
93	.driver = {
94		.name = "syscon-poweroff",
95		.of_match_table = syscon_poweroff_of_match,
96	},
97};
98builtin_platform_driver(syscon_poweroff_driver);