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
syscon_poweroff(void)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
syscon_poweroff_probe(struct platform_device * pdev)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
syscon_poweroff_remove(struct platform_device * pdev)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
syscon_poweroff_register(void)102 static int __init syscon_poweroff_register(void)
103 {
104 return platform_driver_register(&syscon_poweroff_driver);
105 }
106 device_initcall(syscon_poweroff_register);
107
