Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18

Linux/drivers/power/reset/gpio-poweroff.c

  1 /*
  2  * Toggles a GPIO pin to power down a device
  3  *
  4  * Jamie Lentin <jm@lentin.co.uk>
  5  * Andrew Lunn <andrew@lunn.ch>
  6  *
  7  * Copyright (C) 2012 Jamie Lentin
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2 as
 11  * published by the Free Software Foundation.
 12  *
 13  */
 14 #include <linux/kernel.h>
 15 #include <linux/init.h>
 16 #include <linux/delay.h>
 17 #include <linux/platform_device.h>
 18 #include <linux/gpio/consumer.h>
 19 #include <linux/of_platform.h>
 20 #include <linux/module.h>
 21 
 22 /*
 23  * Hold configuration here, cannot be more than one instance of the driver
 24  * since pm_power_off itself is global.
 25  */
 26 static struct gpio_desc *reset_gpio;
 27 
 28 static void gpio_poweroff_do_poweroff(void)
 29 {
 30         BUG_ON(!reset_gpio);
 31 
 32         /* drive it active, also inactive->active edge */
 33         gpiod_direction_output(reset_gpio, 1);
 34         mdelay(100);
 35         /* drive inactive, also active->inactive edge */
 36         gpiod_set_value(reset_gpio, 0);
 37         mdelay(100);
 38 
 39         /* drive it active, also inactive->active edge */
 40         gpiod_set_value(reset_gpio, 1);
 41 
 42         /* give it some time */
 43         mdelay(3000);
 44 
 45         WARN_ON(1);
 46 }
 47 
 48 static int gpio_poweroff_probe(struct platform_device *pdev)
 49 {
 50         bool input = false;
 51 
 52         /* If a pm_power_off function has already been added, leave it alone */
 53         if (pm_power_off != NULL) {
 54                 dev_err(&pdev->dev,
 55                         "%s: pm_power_off function already registered",
 56                        __func__);
 57                 return -EBUSY;
 58         }
 59 
 60         reset_gpio = devm_gpiod_get(&pdev->dev, NULL);
 61         if (IS_ERR(reset_gpio))
 62                 return PTR_ERR(reset_gpio);
 63 
 64         input = of_property_read_bool(pdev->dev.of_node, "input");
 65 
 66         if (input) {
 67                 if (gpiod_direction_input(reset_gpio)) {
 68                         dev_err(&pdev->dev,
 69                                 "Could not set direction of reset GPIO to input\n");
 70                         return -ENODEV;
 71                 }
 72         } else {
 73                 if (gpiod_direction_output(reset_gpio, 0)) {
 74                         dev_err(&pdev->dev,
 75                                 "Could not set direction of reset GPIO\n");
 76                         return -ENODEV;
 77                 }
 78         }
 79 
 80         pm_power_off = &gpio_poweroff_do_poweroff;
 81         return 0;
 82 }
 83 
 84 static int gpio_poweroff_remove(struct platform_device *pdev)
 85 {
 86         if (pm_power_off == &gpio_poweroff_do_poweroff)
 87                 pm_power_off = NULL;
 88 
 89         return 0;
 90 }
 91 
 92 static const struct of_device_id of_gpio_poweroff_match[] = {
 93         { .compatible = "gpio-poweroff", },
 94         {},
 95 };
 96 
 97 static struct platform_driver gpio_poweroff_driver = {
 98         .probe = gpio_poweroff_probe,
 99         .remove = gpio_poweroff_remove,
100         .driver = {
101                 .name = "poweroff-gpio",
102                 .owner = THIS_MODULE,
103                 .of_match_table = of_gpio_poweroff_match,
104         },
105 };
106 
107 module_platform_driver(gpio_poweroff_driver);
108 
109 MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
110 MODULE_DESCRIPTION("GPIO poweroff driver");
111 MODULE_LICENSE("GPL v2");
112 MODULE_ALIAS("platform:poweroff-gpio");
113 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us