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
regulator_poweroff_do_poweroff(struct sys_off_data * data)21 static 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
regulator_poweroff_probe(struct platform_device * pdev)36 static 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
52 static const struct of_device_id of_regulator_poweroff_match[] = {
53 { .compatible = "regulator-poweroff", },
54 {},
55 };
56 MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match);
57
58 static 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
66 module_platform_driver(regulator_poweroff_driver);
67
68 MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
69 MODULE_DESCRIPTION("Regulator poweroff driver");
70 MODULE_ALIAS("platform:poweroff-regulator");
71