power: Add simple poweroff-gpio driver
Given appropriate devicetree bindings, this driver registers a
pm_power_off function to set a GPIO line high/low to power down
your board.
Signed-off-by: Jamie Lentin <jm@lentin.co.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by:Simon Baatz <gmbnomis@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c
new file mode 100644
index 0000000..0491e53
--- /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");