diff options
Diffstat (limited to 'drivers/power/reset/gpio-poweroff.c')
| -rw-r--r-- | drivers/power/reset/gpio-poweroff.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c new file mode 100644 index 000000000000..0491e5335d02 --- /dev/null +++ b/drivers/power/reset/gpio-poweroff.c @@ -0,0 +1,129 @@ +/* + * 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_num == -1); + + /* drive it active */ + gpio_direction_output(gpio_num, !gpio_active_low); + mdelay(100); + /* rising edge or drive inactive */ + gpio_set_value(gpio_num, gpio_active_low); + mdelay(100); + /* falling edge */ + gpio_set_value(gpio_num, !gpio_active_low); + + /* give it some time */ + mdelay(3000); + + WARN_ON(1); +} + +static int __devinit 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_num < 0) { + pr_err("%s: Could not get GPIO configuration: %d", + __func__, gpio_num); + return -ENODEV; + } + gpio_active_low = flags & OF_GPIO_ACTIVE_LOW; + + if (of_get_property(pdev->dev.of_node, "input", NULL)) + input = true; + + 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 __devexit gpio_poweroff_remove(struct platform_device *pdev) +{ + if (gpio_num != -1) + 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 = __devexit_p(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"); +MODULE_ALIAS("platform:poweroff-gpio"); |