1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Force-disables a regulator to power down a device
4 *
5 * Michael Klein <michael@fossekall.de>
6 *
7 * Copyright (C) 2020 Michael Klein
8 *
9 * Based on the gpio-poweroff driver.
10 */
11#include <linux/delay.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/pm.h>
16#include <linux/reboot.h>
17#include <linux/regulator/consumer.h>
18
19#define TIMEOUT_MS 3000
20
21static int regulator_poweroff_do_poweroff(struct sys_off_data *data)
22{
23	struct regulator *cpu_regulator = data->cb_data;
24
25	if (cpu_regulator && regulator_is_enabled(cpu_regulator))
26		regulator_force_disable(cpu_regulator);
27
28	/* give it some time */
29	mdelay(TIMEOUT_MS);
30
31	WARN_ON(1);
32
33	return NOTIFY_DONE;
34}
35
36static int regulator_poweroff_probe(struct platform_device *pdev)
37{
38	struct regulator *cpu_regulator;
39
40	cpu_regulator = devm_regulator_get(&pdev->dev, "cpu");
41	if (IS_ERR(cpu_regulator))
42		return PTR_ERR(cpu_regulator);
43
44	/* Set this handler to low priority to not override an existing handler */
45	return devm_register_sys_off_handler(&pdev->dev,
46					     SYS_OFF_MODE_POWER_OFF,
47					     SYS_OFF_PRIO_LOW,
48					     regulator_poweroff_do_poweroff,
49					     cpu_regulator);
50}
51
52static const struct of_device_id of_regulator_poweroff_match[] = {
53	{ .compatible = "regulator-poweroff", },
54	{},
55};
56MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match);
57
58static struct platform_driver regulator_poweroff_driver = {
59	.probe = regulator_poweroff_probe,
60	.driver = {
61		.name = "poweroff-regulator",
62		.of_match_table = of_regulator_poweroff_match,
63	},
64};
65
66module_platform_driver(regulator_poweroff_driver);
67
68MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
69MODULE_DESCRIPTION("Regulator poweroff driver");
70MODULE_ALIAS("platform:poweroff-regulator");
71