| /* drivers/misc/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 <linux/gpio.h> |
| |
| #include "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); |
| struct timeval t = ktime_to_timeval(r); |
| remaining = t.tv_sec * 1000 + t.tv_usec / 1000; |
| } 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 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 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 timed_gpio_driver = { |
| .probe = timed_gpio_probe, |
| .remove = timed_gpio_remove, |
| .driver = { |
| .name = "timed-gpio", |
| .owner = THIS_MODULE, |
| }, |
| }; |
| |
| static int __init 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(&timed_gpio_driver); |
| } |
| |
| static void __exit timed_gpio_exit(void) |
| { |
| class_destroy(timed_gpio_class); |
| platform_driver_unregister(&timed_gpio_driver); |
| } |
| |
| module_init(timed_gpio_init); |
| module_exit(timed_gpio_exit); |
| |
| MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>"); |
| MODULE_DESCRIPTION("timed gpio driver"); |
| MODULE_LICENSE("GPL"); |