127 lines
2.9 KiB
C
127 lines
2.9 KiB
C
/*
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* Toggles a GPIO pin to power down a device
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*
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* Jamie Lentin <jm@lentin.co.uk>
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* Andrew Lunn <andrew@lunn.ch>
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*
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* Copyright (C) 2012 Jamie Lentin
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/platform_device.h>
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#include <linux/gpio.h>
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#include <linux/of_platform.h>
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#include <linux/of_gpio.h>
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#include <linux/module.h>
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/*
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* Hold configuration here, cannot be more than one instance of the driver
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* since pm_power_off itself is global.
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*/
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static int gpio_num = -1;
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static int gpio_active_low;
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static void gpio_poweroff_do_poweroff(void)
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{
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BUG_ON(!gpio_is_valid(gpio_num));
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/* drive it active, also inactive->active edge */
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gpio_direction_output(gpio_num, !gpio_active_low);
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mdelay(100);
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/* drive inactive, also active->inactive edge */
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gpio_set_value(gpio_num, gpio_active_low);
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mdelay(100);
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/* drive it active, also inactive->active edge */
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gpio_set_value(gpio_num, !gpio_active_low);
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/* give it some time */
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mdelay(3000);
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WARN_ON(1);
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}
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static int gpio_poweroff_probe(struct platform_device *pdev)
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{
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enum of_gpio_flags flags;
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bool input = false;
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int ret;
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/* If a pm_power_off function has already been added, leave it alone */
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if (pm_power_off != NULL) {
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pr_err("%s: pm_power_off function already registered",
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__func__);
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return -EBUSY;
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}
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gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
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if (!gpio_is_valid(gpio_num))
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return gpio_num;
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gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
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input = of_property_read_bool(pdev->dev.of_node, "input");
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ret = gpio_request(gpio_num, "poweroff-gpio");
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if (ret) {
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pr_err("%s: Could not get GPIO %d", __func__, gpio_num);
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return ret;
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}
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if (input) {
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if (gpio_direction_input(gpio_num)) {
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pr_err("Could not set direction of GPIO %d to input",
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gpio_num);
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goto err;
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}
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} else {
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if (gpio_direction_output(gpio_num, gpio_active_low)) {
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pr_err("Could not set direction of GPIO %d", gpio_num);
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goto err;
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}
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}
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pm_power_off = &gpio_poweroff_do_poweroff;
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return 0;
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err:
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gpio_free(gpio_num);
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return -ENODEV;
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}
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static int gpio_poweroff_remove(struct platform_device *pdev)
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{
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gpio_free(gpio_num);
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if (pm_power_off == &gpio_poweroff_do_poweroff)
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pm_power_off = NULL;
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return 0;
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}
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static const struct of_device_id of_gpio_poweroff_match[] = {
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{ .compatible = "gpio-poweroff", },
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{},
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};
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static struct platform_driver gpio_poweroff_driver = {
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.probe = gpio_poweroff_probe,
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.remove = gpio_poweroff_remove,
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.driver = {
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.name = "poweroff-gpio",
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.owner = THIS_MODULE,
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.of_match_table = of_gpio_poweroff_match,
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},
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};
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module_platform_driver(gpio_poweroff_driver);
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MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
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MODULE_DESCRIPTION("GPIO poweroff driver");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:poweroff-gpio");
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