Staging: android: add timed_gpio driver

driver for GPIOs that turn back off after a delay

From: Mike Lockwood <lockwood@android.com>
Signed-off-by: Brian Swetland <swetland@google.com>
Cc: Robert Love <rlove@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/android/Kconfig

@@ -72,4 +72,9 @@ config ANDROID_RAM_CONSOLE_EARLY_SIZE
 	default 0
 	depends on ANDROID_RAM_CONSOLE_EARLY_INIT
 
+config ANDROID_TIMED_GPIO
+	tristate "Android timed gpio driver"
+	depends on GENERIC_GPIO
+	default n
+
 endmenu

drivers/staging/android/Makefile

@@ -2,3 +2,4 @@ obj-$(CONFIG_ANDROID)			+= android.o
 obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o
 obj-$(CONFIG_ANDROID_LOGGER)		+= logger.o
 obj-$(CONFIG_ANDROID_RAM_CONSOLE)	+= ram_console.o
+obj-$(CONFIG_ANDROID_TIMED_GPIO)	+= timed_gpio.o

drivers/staging/android/android_timed_gpio.h

+/* include/linux/android_timed_gpio.h
+ *
+ * Copyright (C) 2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+*/
+
+#ifndef _LINUX_ANDROID_TIMED_GPIO_H
+#define _LINUX_ANDROID_TIMED_GPIO_H
+
+struct timed_gpio {
+	const char *name;
+	unsigned 	gpio;
+	int     max_timeout;
+	u8 		active_low;
+};
+
+struct timed_gpio_platform_data {
+	int 		num_gpios;
+	struct timed_gpio *gpios;
+};
+
+#endif

drivers/staging/android/timed_gpio.c

+/* drivers/android/timed_gpio.c
+ *
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/hrtimer.h>
+#include <linux/err.h>
+#include <asm/arch/gpio.h>
+
+#include "android_timed_gpio.h"
+
+
+static struct class *timed_gpio_class;
+
+struct timed_gpio_data {
+	struct device *dev;
+	struct hrtimer timer;
+	spinlock_t lock;
+	unsigned 	gpio;
+	int 		max_timeout;
+	u8 		active_low;
+};
+
+static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer)
+{
+	struct timed_gpio_data *gpio_data = container_of(timer, struct timed_gpio_data, timer);
+
+	gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? 1 : 0);
+	return HRTIMER_NORESTART;
+}
+
+static ssize_t gpio_enable_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
+	int remaining;
+
+	if (hrtimer_active(&gpio_data->timer)) {
+		ktime_t r = hrtimer_get_remaining(&gpio_data->timer);
+		remaining = r.tv.sec * 1000 + r.tv.nsec / 1000000;
+	} else
+		remaining = 0;
+
+	return sprintf(buf, "%d\n", remaining);
+}
+
+static ssize_t gpio_enable_store(
+		struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t size)
+{
+	struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
+	int value;
+	unsigned long	flags;
+
+	sscanf(buf, "%d", &value);
+
+	spin_lock_irqsave(&gpio_data->lock, flags);
+
+	/* cancel previous timer and set GPIO according to value */
+	hrtimer_cancel(&gpio_data->timer);
+	gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? !value : !!value);
+
+	if (value > 0) {
+		if (value > gpio_data->max_timeout)
+			value = gpio_data->max_timeout;
+
+		hrtimer_start(&gpio_data->timer,
+						ktime_set(value / 1000, (value % 1000) * 1000000),
+						HRTIMER_MODE_REL);
+	}
+
+	spin_unlock_irqrestore(&gpio_data->lock, flags);
+
+	return size;
+}
+
+static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, gpio_enable_show, gpio_enable_store);
+
+static int android_timed_gpio_probe(struct platform_device *pdev)
+{
+	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
+	struct timed_gpio *cur_gpio;
+	struct timed_gpio_data *gpio_data, *gpio_dat;
+	int i, ret = 0;
+
+	if (!pdata)
+		return -EBUSY;
+
+	gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios, GFP_KERNEL);
+	if (!gpio_data)
+		return -ENOMEM;
+
+	for (i = 0; i < pdata->num_gpios; i++) {
+		cur_gpio = &pdata->gpios[i];
+		gpio_dat = &gpio_data[i];
+
+		hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		gpio_dat->timer.function = gpio_timer_func;
+		spin_lock_init(&gpio_dat->lock);
+
+		gpio_dat->gpio = cur_gpio->gpio;
+		gpio_dat->max_timeout = cur_gpio->max_timeout;
+		gpio_dat->active_low = cur_gpio->active_low;
+		gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
+
+		gpio_dat->dev = device_create(timed_gpio_class, &pdev->dev, 0, "%s", cur_gpio->name);
+		if (unlikely(IS_ERR(gpio_dat->dev)))
+			return PTR_ERR(gpio_dat->dev);
+
+		dev_set_drvdata(gpio_dat->dev, gpio_dat);
+		ret = device_create_file(gpio_dat->dev, &dev_attr_enable);
+		if (ret)
+			return ret;
+	}
+
+	platform_set_drvdata(pdev, gpio_data);
+
+	return 0;
+}
+
+static int android_timed_gpio_remove(struct platform_device *pdev)
+{
+	struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
+	struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < pdata->num_gpios; i++) {
+		device_remove_file(gpio_data[i].dev, &dev_attr_enable);
+		device_unregister(gpio_data[i].dev);
+	}
+
+	kfree(gpio_data);
+
+	return 0;
+}
+
+static struct platform_driver android_timed_gpio_driver = {
+	.probe		= android_timed_gpio_probe,
+	.remove		= android_timed_gpio_remove,
+	.driver		= {
+		.name		= "android-timed-gpio",
+		.owner		= THIS_MODULE,
+	},
+};
+
+static int __init android_timed_gpio_init(void)
+{
+	timed_gpio_class = class_create(THIS_MODULE, "timed_output");
+	if (IS_ERR(timed_gpio_class))
+		return PTR_ERR(timed_gpio_class);
+	return platform_driver_register(&android_timed_gpio_driver);
+}
+
+static void __exit android_timed_gpio_exit(void)
+{
+	class_destroy(timed_gpio_class);
+	platform_driver_unregister(&android_timed_gpio_driver);
+}
+
+module_init(android_timed_gpio_init);
+module_exit(android_timed_gpio_exit);
+
+MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
+MODULE_DESCRIPTION("Android timed gpio driver");
+MODULE_LICENSE("GPL");