1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Toggles a GPIO pin to power down a device 4 * 5 * Jamie Lentin <jm@lentin.co.uk> 6 * Andrew Lunn <andrew@lunn.ch> 7 * 8 * Copyright (C) 2012 Jamie Lentin 9 */ 10 #include <linux/kernel.h> 11 #include <linux/init.h> 12 #include <linux/delay.h> 13 #include <linux/platform_device.h> 14 #include <linux/property.h> 15 #include <linux/gpio/consumer.h> 16 #include <linux/mod_devicetable.h> 17 #include <linux/module.h> 18 #include <linux/reboot.h> 19 20 #define DEFAULT_TIMEOUT_MS 3000 21 22 struct gpio_poweroff { 23 struct gpio_desc *reset_gpio; 24 u32 timeout_ms; 25 u32 active_delay_ms; 26 u32 inactive_delay_ms; 27 }; 28 29 static int gpio_poweroff_do_poweroff(struct sys_off_data *data) 30 { 31 struct gpio_poweroff *gpio_poweroff = data->cb_data; 32 33 /* drive it active, also inactive->active edge */ 34 gpiod_direction_output(gpio_poweroff->reset_gpio, 1); 35 mdelay(gpio_poweroff->active_delay_ms); 36 37 /* drive inactive, also active->inactive edge */ 38 gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 0); 39 mdelay(gpio_poweroff->inactive_delay_ms); 40 41 /* drive it active, also inactive->active edge */ 42 gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 1); 43 44 /* give it some time */ 45 mdelay(gpio_poweroff->timeout_ms); 46 47 /* 48 * If code reaches this point, it means that gpio-poweroff has failed 49 * to actually power off the system. 50 * Warn the user that the attempt to poweroff via gpio-poweroff 51 * has gone wrong. 52 */ 53 WARN(1, "Failed to poweroff via gpio-poweroff mechanism\n"); 54 55 return NOTIFY_DONE; 56 } 57 58 static int gpio_poweroff_probe(struct platform_device *pdev) 59 { 60 struct gpio_poweroff *gpio_poweroff; 61 bool input = false; 62 enum gpiod_flags flags; 63 int priority = SYS_OFF_PRIO_DEFAULT; 64 int ret; 65 66 gpio_poweroff = devm_kzalloc(&pdev->dev, sizeof(*gpio_poweroff), GFP_KERNEL); 67 if (!gpio_poweroff) 68 return -ENOMEM; 69 70 input = device_property_read_bool(&pdev->dev, "input"); 71 if (input) 72 flags = GPIOD_IN; 73 else 74 flags = GPIOD_OUT_LOW; 75 76 77 gpio_poweroff->active_delay_ms = 100; 78 gpio_poweroff->inactive_delay_ms = 100; 79 gpio_poweroff->timeout_ms = DEFAULT_TIMEOUT_MS; 80 81 device_property_read_u32(&pdev->dev, "active-delay-ms", &gpio_poweroff->active_delay_ms); 82 device_property_read_u32(&pdev->dev, "inactive-delay-ms", 83 &gpio_poweroff->inactive_delay_ms); 84 device_property_read_u32(&pdev->dev, "timeout-ms", &gpio_poweroff->timeout_ms); 85 device_property_read_u32(&pdev->dev, "priority", &priority); 86 if (priority > 255) { 87 dev_err(&pdev->dev, "Invalid priority property: %u\n", priority); 88 return -EINVAL; 89 } 90 91 gpio_poweroff->reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags); 92 if (IS_ERR(gpio_poweroff->reset_gpio)) 93 return PTR_ERR(gpio_poweroff->reset_gpio); 94 95 ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF, 96 priority, gpio_poweroff_do_poweroff, gpio_poweroff); 97 if (ret) 98 return dev_err_probe(&pdev->dev, ret, "Cannot register poweroff handler\n"); 99 100 return 0; 101 } 102 103 static const struct of_device_id of_gpio_poweroff_match[] = { 104 { .compatible = "gpio-poweroff", }, 105 {}, 106 }; 107 MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match); 108 109 static struct platform_driver gpio_poweroff_driver = { 110 .probe = gpio_poweroff_probe, 111 .driver = { 112 .name = "poweroff-gpio", 113 .of_match_table = of_gpio_poweroff_match, 114 }, 115 }; 116 117 module_platform_driver(gpio_poweroff_driver); 118 119 MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>"); 120 MODULE_DESCRIPTION("GPIO poweroff driver"); 121 MODULE_ALIAS("platform:poweroff-gpio"); 122