From 96ff0f5c7efd4a2205c48a76a6a1fcd2731e6128 Mon Sep 17 00:00:00 2001
From: Jamie Lentin <jm@lentin.co.uk>
Date: Sat, 17 Nov 2012 09:51:04 +0100
Subject: 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>
---
 drivers/power/reset/gpio-poweroff.c | 129 ++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 drivers/power/reset/gpio-poweroff.c

(limited to 'drivers/power/reset/gpio-poweroff.c')

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");
-- 
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