// SPDX-License-Identifier: GPL-2.0-only /* * Force-disables a regulator to power down a device * * Michael Klein <michael@fossekall.de> * * Copyright (C) 2020 Michael Klein * * Based on the gpio-poweroff driver. */ #include <linux/delay.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/pm.h> #include <linux/regulator/consumer.h> #define TIMEOUT_MS 3000 /* * Hold configuration here, cannot be more than one instance of the driver * since pm_power_off itself is global. */ static struct regulator *cpu_regulator; static void regulator_poweroff_do_poweroff(void) { if (cpu_regulator && regulator_is_enabled(cpu_regulator)) regulator_force_disable(cpu_regulator); /* give it some time */ mdelay(TIMEOUT_MS); WARN_ON(1); } static int regulator_poweroff_probe(struct platform_device *pdev) { /* If a pm_power_off function has already been added, leave it alone */ if (pm_power_off != NULL) { dev_err(&pdev->dev, "%s: pm_power_off function already registered\n", __func__); return -EBUSY; } cpu_regulator = devm_regulator_get(&pdev->dev, "cpu"); if (IS_ERR(cpu_regulator)) return PTR_ERR(cpu_regulator); pm_power_off = ®ulator_poweroff_do_poweroff; return 0; } static int regulator_poweroff_remove(__maybe_unused struct platform_device *pdev) { if (pm_power_off == ®ulator_poweroff_do_poweroff) pm_power_off = NULL; return 0; } static const struct of_device_id of_regulator_poweroff_match[] = { { .compatible = "regulator-poweroff", }, {}, }; MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match); static struct platform_driver regulator_poweroff_driver = { .probe = regulator_poweroff_probe, .remove = regulator_poweroff_remove, .driver = { .name = "poweroff-regulator", .of_match_table = of_regulator_poweroff_match, }, }; module_platform_driver(regulator_poweroff_driver); MODULE_AUTHOR("Michael Klein <michael@fossekall.de>"); MODULE_DESCRIPTION("Regulator poweroff driver"); MODULE_ALIAS("platform:poweroff-regulator");