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/regulator/consumer.h> 17 18 #define TIMEOUT_MS 3000 19 20 /* 21 * Hold configuration here, cannot be more than one instance of the driver 22 * since pm_power_off itself is global. 23 */ 24 static struct regulator *cpu_regulator; 25 26 static void regulator_poweroff_do_poweroff(void) 27 { 28 if (cpu_regulator && regulator_is_enabled(cpu_regulator)) 29 regulator_force_disable(cpu_regulator); 30 31 /* give it some time */ 32 mdelay(TIMEOUT_MS); 33 34 WARN_ON(1); 35 } 36 37 static int regulator_poweroff_probe(struct platform_device *pdev) 38 { 39 /* If a pm_power_off function has already been added, leave it alone */ 40 if (pm_power_off != NULL) { 41 dev_err(&pdev->dev, 42 "%s: pm_power_off function already registered\n", 43 __func__); 44 return -EBUSY; 45 } 46 47 cpu_regulator = devm_regulator_get(&pdev->dev, "cpu"); 48 if (IS_ERR(cpu_regulator)) 49 return PTR_ERR(cpu_regulator); 50 51 pm_power_off = ®ulator_poweroff_do_poweroff; 52 return 0; 53 } 54 55 static int regulator_poweroff_remove(__maybe_unused struct platform_device *pdev) 56 { 57 if (pm_power_off == ®ulator_poweroff_do_poweroff) 58 pm_power_off = NULL; 59 60 return 0; 61 } 62 63 static const struct of_device_id of_regulator_poweroff_match[] = { 64 { .compatible = "regulator-poweroff", }, 65 {}, 66 }; 67 MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match); 68 69 static struct platform_driver regulator_poweroff_driver = { 70 .probe = regulator_poweroff_probe, 71 .remove = regulator_poweroff_remove, 72 .driver = { 73 .name = "poweroff-regulator", 74 .of_match_table = of_regulator_poweroff_match, 75 }, 76 }; 77 78 module_platform_driver(regulator_poweroff_driver); 79 80 MODULE_AUTHOR("Michael Klein <michael@fossekall.de>"); 81 MODULE_DESCRIPTION("Regulator poweroff driver"); 82 MODULE_LICENSE("GPL v2"); 83 MODULE_ALIAS("platform:poweroff-regulator"); 84