Jamie Lentin | 96ff0f5 | 2012-11-17 09:51:04 +0100 | [diff] [blame^] | 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.h> |
| 19 | #include <linux/of_platform.h> |
| 20 | #include <linux/of_gpio.h> |
| 21 | #include <linux/module.h> |
| 22 | |
| 23 | /* |
| 24 | * Hold configuration here, cannot be more than one instance of the driver |
| 25 | * since pm_power_off itself is global. |
| 26 | */ |
| 27 | static int gpio_num = -1; |
| 28 | static int gpio_active_low; |
| 29 | |
| 30 | static void gpio_poweroff_do_poweroff(void) |
| 31 | { |
| 32 | BUG_ON(gpio_num == -1); |
| 33 | |
| 34 | /* drive it active */ |
| 35 | gpio_direction_output(gpio_num, !gpio_active_low); |
| 36 | mdelay(100); |
| 37 | /* rising edge or drive inactive */ |
| 38 | gpio_set_value(gpio_num, gpio_active_low); |
| 39 | mdelay(100); |
| 40 | /* falling edge */ |
| 41 | gpio_set_value(gpio_num, !gpio_active_low); |
| 42 | |
| 43 | /* give it some time */ |
| 44 | mdelay(3000); |
| 45 | |
| 46 | WARN_ON(1); |
| 47 | } |
| 48 | |
| 49 | static int __devinit gpio_poweroff_probe(struct platform_device *pdev) |
| 50 | { |
| 51 | enum of_gpio_flags flags; |
| 52 | bool input = false; |
| 53 | int ret; |
| 54 | |
| 55 | /* If a pm_power_off function has already been added, leave it alone */ |
| 56 | if (pm_power_off != NULL) { |
| 57 | pr_err("%s: pm_power_off function already registered", |
| 58 | __func__); |
| 59 | return -EBUSY; |
| 60 | } |
| 61 | |
| 62 | gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags); |
| 63 | if (gpio_num < 0) { |
| 64 | pr_err("%s: Could not get GPIO configuration: %d", |
| 65 | __func__, gpio_num); |
| 66 | return -ENODEV; |
| 67 | } |
| 68 | gpio_active_low = flags & OF_GPIO_ACTIVE_LOW; |
| 69 | |
| 70 | if (of_get_property(pdev->dev.of_node, "input", NULL)) |
| 71 | input = true; |
| 72 | |
| 73 | ret = gpio_request(gpio_num, "poweroff-gpio"); |
| 74 | if (ret) { |
| 75 | pr_err("%s: Could not get GPIO %d", __func__, gpio_num); |
| 76 | return ret; |
| 77 | } |
| 78 | if (input) { |
| 79 | if (gpio_direction_input(gpio_num)) { |
| 80 | pr_err("Could not set direction of GPIO %d to input", |
| 81 | gpio_num); |
| 82 | goto err; |
| 83 | } |
| 84 | } else { |
| 85 | if (gpio_direction_output(gpio_num, gpio_active_low)) { |
| 86 | pr_err("Could not set direction of GPIO %d", gpio_num); |
| 87 | goto err; |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | pm_power_off = &gpio_poweroff_do_poweroff; |
| 92 | return 0; |
| 93 | |
| 94 | err: |
| 95 | gpio_free(gpio_num); |
| 96 | return -ENODEV; |
| 97 | } |
| 98 | |
| 99 | static int __devexit gpio_poweroff_remove(struct platform_device *pdev) |
| 100 | { |
| 101 | if (gpio_num != -1) |
| 102 | gpio_free(gpio_num); |
| 103 | if (pm_power_off == &gpio_poweroff_do_poweroff) |
| 104 | pm_power_off = NULL; |
| 105 | |
| 106 | return 0; |
| 107 | } |
| 108 | |
| 109 | static const struct of_device_id of_gpio_poweroff_match[] = { |
| 110 | { .compatible = "gpio-poweroff", }, |
| 111 | {}, |
| 112 | }; |
| 113 | |
| 114 | static struct platform_driver gpio_poweroff_driver = { |
| 115 | .probe = gpio_poweroff_probe, |
| 116 | .remove = __devexit_p(gpio_poweroff_remove), |
| 117 | .driver = { |
| 118 | .name = "poweroff-gpio", |
| 119 | .owner = THIS_MODULE, |
| 120 | .of_match_table = of_gpio_poweroff_match, |
| 121 | }, |
| 122 | }; |
| 123 | |
| 124 | module_platform_driver(gpio_poweroff_driver); |
| 125 | |
| 126 | MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>"); |
| 127 | MODULE_DESCRIPTION("GPIO poweroff driver"); |
| 128 | MODULE_LICENSE("GPL"); |
| 129 | MODULE_ALIAS("platform:poweroff-gpio"); |