treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / power / reset / syscon-poweroff.c
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
20 static struct regmap *map;
21 static u32 offset;
22 static u32 value;
23 static u32 mask;
24
25 static 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
35 static 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
80 static 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
88 static const struct of_device_id syscon_poweroff_of_match[] = {
89         { .compatible = "syscon-poweroff" },
90         {}
91 };
92
93 static 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
102 static int __init syscon_poweroff_register(void)
103 {
104         return platform_driver_register(&syscon_poweroff_driver);
105 }
106 device_initcall(syscon_poweroff_register);