drivers/power/reset/regulator-poweroff.c

   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
  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
  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");