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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | /* * Toggles a GPIO pin to power down a device * * Jamie Lentin <jm@lentin.co.uk> * Andrew Lunn <andrew@lunn.ch> * * Copyright (C) 2012 Jamie Lentin * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #include <linux/kernel.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/platform_device.h> #include <linux/gpio.h> #include <linux/of_platform.h> #include <linux/of_gpio.h> #include <linux/module.h> /* * Hold configuration here, cannot be more than one instance of the driver * since pm_power_off itself is global. */ static int gpio_num = -1; static int gpio_active_low; static void gpio_poweroff_do_poweroff(void) { BUG_ON(!gpio_is_valid(gpio_num)); /* drive it active, also inactive->active edge */ gpio_direction_output(gpio_num, !gpio_active_low); mdelay(100); /* drive inactive, also active->inactive edge */ gpio_set_value(gpio_num, gpio_active_low); mdelay(100); /* drive it active, also inactive->active edge */ gpio_set_value(gpio_num, !gpio_active_low); /* give it some time */ mdelay(3000); WARN_ON(1); } static int gpio_poweroff_probe(struct platform_device *pdev) { enum of_gpio_flags flags; bool input = false; int ret; /* If a pm_power_off function has already been added, leave it alone */ if (pm_power_off != NULL) { pr_err("%s: pm_power_off function already registered", __func__); return -EBUSY; } gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags); if (!gpio_is_valid(gpio_num)) return gpio_num; gpio_active_low = flags & OF_GPIO_ACTIVE_LOW; input = of_property_read_bool(pdev->dev.of_node, "input"); ret = gpio_request(gpio_num, "poweroff-gpio"); if (ret) { pr_err("%s: Could not get GPIO %d", __func__, gpio_num); return ret; } if (input) { if (gpio_direction_input(gpio_num)) { pr_err("Could not set direction of GPIO %d to input", gpio_num); goto err; } } else { if (gpio_direction_output(gpio_num, gpio_active_low)) { pr_err("Could not set direction of GPIO %d", gpio_num); goto err; } } pm_power_off = &gpio_poweroff_do_poweroff; return 0; err: gpio_free(gpio_num); return -ENODEV; } static int gpio_poweroff_remove(struct platform_device *pdev) { gpio_free(gpio_num); if (pm_power_off == &gpio_poweroff_do_poweroff) pm_power_off = NULL; return 0; } static const struct of_device_id of_gpio_poweroff_match[] = { { .compatible = "gpio-poweroff", }, {}, }; static struct platform_driver gpio_poweroff_driver = { .probe = gpio_poweroff_probe, .remove = gpio_poweroff_remove, .driver = { .name = "poweroff-gpio", .owner = THIS_MODULE, .of_match_table = of_gpio_poweroff_match, }, }; module_platform_driver(gpio_poweroff_driver); MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>"); MODULE_DESCRIPTION("GPIO poweroff driver"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:poweroff-gpio"); |