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 
18 static struct regmap *map;
19 static u32 offset;
20 static u32 value;
21 static u32 mask;
22 
23 static 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 
33 static 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 
75 static 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 
83 static const struct of_device_id syscon_poweroff_of_match[] = {
84 	{ .compatible = "syscon-poweroff" },
85 	{}
86 };
87 
88 static 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 
97 static int __init syscon_poweroff_register(void)
98 {
99 	return platform_driver_register(&syscon_poweroff_driver);
100 }
101 device_initcall(syscon_poweroff_register);
102