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 WARN_ON(1); 48 49 return NOTIFY_DONE; 50 } 51 52 static int gpio_poweroff_probe(struct platform_device *pdev) 53 { 54 struct gpio_poweroff *gpio_poweroff; 55 bool input = false; 56 enum gpiod_flags flags; 57 int priority = SYS_OFF_PRIO_DEFAULT; 58 int ret; 59 60 gpio_poweroff = devm_kzalloc(&pdev->dev, sizeof(*gpio_poweroff), GFP_KERNEL); 61 if (!gpio_poweroff) 62 return -ENOMEM; 63 64 input = device_property_read_bool(&pdev->dev, "input"); 65 if (input) 66 flags = GPIOD_IN; 67 else 68 flags = GPIOD_OUT_LOW; 69 70 71 gpio_poweroff->active_delay_ms = 100; 72 gpio_poweroff->inactive_delay_ms = 100; 73 gpio_poweroff->timeout_ms = DEFAULT_TIMEOUT_MS; 74 75 device_property_read_u32(&pdev->dev, "active-delay-ms", &gpio_poweroff->active_delay_ms); 76 device_property_read_u32(&pdev->dev, "inactive-delay-ms", 77 &gpio_poweroff->inactive_delay_ms); 78 device_property_read_u32(&pdev->dev, "timeout-ms", &gpio_poweroff->timeout_ms); 79 device_property_read_u32(&pdev->dev, "priority", &priority); 80 if (priority > 255) { 81 dev_err(&pdev->dev, "Invalid priority property: %u\n", priority); 82 return -EINVAL; 83 } 84 85 gpio_poweroff->reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags); 86 if (IS_ERR(gpio_poweroff->reset_gpio)) 87 return PTR_ERR(gpio_poweroff->reset_gpio); 88 89 ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF, 90 priority, gpio_poweroff_do_poweroff, gpio_poweroff); 91 if (ret) 92 return dev_err_probe(&pdev->dev, ret, "Cannot register poweroff handler\n"); 93 94 return 0; 95 } 96 97 static const struct of_device_id of_gpio_poweroff_match[] = { 98 { .compatible = "gpio-poweroff", }, 99 {}, 100 }; 101 MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match); 102 103 static struct platform_driver gpio_poweroff_driver = { 104 .probe = gpio_poweroff_probe, 105 .driver = { 106 .name = "poweroff-gpio", 107 .of_match_table = of_gpio_poweroff_match, 108 }, 109 }; 110 111 module_platform_driver(gpio_poweroff_driver); 112 113 MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>"); 114 MODULE_DESCRIPTION("GPIO poweroff driver"); 115 MODULE_ALIAS("platform:poweroff-gpio"); 116