tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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 int syscon_poweroff_remove(struct platform_device *pdev)
80{
81 if (pm_power_off == syscon_poweroff)
82 pm_power_off = NULL;
83
84 return 0;
85}
86
87static const struct of_device_id syscon_poweroff_of_match[] = {
88 { .compatible = "syscon-poweroff" },
89 {}
90};
91
92static struct platform_driver syscon_poweroff_driver = {
93 .probe = syscon_poweroff_probe,
94 .remove = syscon_poweroff_remove,
95 .driver = {
96 .name = "syscon-poweroff",
97 .of_match_table = syscon_poweroff_of_match,
98 },
99};
100builtin_platform_driver(syscon_poweroff_driver);