drivers/staging/android/timed_gpio.c

   1 /* drivers/misc/timed_gpio.c
   2  *
   3  * Copyright (C) 2008 Google, Inc.
   4  * Author: Mike Lockwood <lockwood@android.com>
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/err.h>
  21 #include <linux/gpio.h>
  22
  23 #include "timed_gpio.h"
  24
  25
  26 static struct class *timed_gpio_class;
  27
  28 struct timed_gpio_data {
  29         struct device *dev;
  30         struct hrtimer timer;
  31         spinlock_t lock;
  32         unsigned        gpio;
  33         int             max_timeout;
  34         u8              active_low;
  35 };
  36
  37 static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer)
  38 {
  39         struct timed_gpio_data *gpio_data = container_of(timer, struct timed_gpio_data, timer);
  40
  41         gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? 1 : 0);
  42         return HRTIMER_NORESTART;
  43 }
  44
  45 static ssize_t gpio_enable_show(struct device *dev, struct device_attribute *attr, char *buf)
  46 {
  47         struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
  48         int remaining;
  49
  50         if (hrtimer_active(&gpio_data->timer)) {
  51                 ktime_t r = hrtimer_get_remaining(&gpio_data->timer);
  52                 remaining = r.tv.sec * 1000 + r.tv.nsec / 1000000;
  53         } else
  54                 remaining = 0;
  55
  56         return sprintf(buf, "%d\n", remaining);
  57 }
  58
  59 static ssize_t gpio_enable_store(
  60                 struct device *dev, struct device_attribute *attr,
  61                 const char *buf, size_t size)
  62 {
  63         struct timed_gpio_data *gpio_data = dev_get_drvdata(dev);
  64         int value;
  65         unsigned long   flags;
  66
  67         sscanf(buf, "%d", &value);
  68
  69         spin_lock_irqsave(&gpio_data->lock, flags);
  70
  71         /* cancel previous timer and set GPIO according to value */
  72         hrtimer_cancel(&gpio_data->timer);
  73         gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? !value : !!value);
  74
  75         if (value > 0) {
  76                 if (value > gpio_data->max_timeout)
  77                         value = gpio_data->max_timeout;
  78
  79                 hrtimer_start(&gpio_data->timer,
  80                                                 ktime_set(value / 1000, (value % 1000) * 1000000),
  81                                                 HRTIMER_MODE_REL);
  82         }
  83
  84         spin_unlock_irqrestore(&gpio_data->lock, flags);
  85
  86         return size;
  87 }
  88
  89 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, gpio_enable_show, gpio_enable_store);
  90
  91 static int timed_gpio_probe(struct platform_device *pdev)
  92 {
  93         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
  94         struct timed_gpio *cur_gpio;
  95         struct timed_gpio_data *gpio_data, *gpio_dat;
  96         int i, ret = 0;
  97
  98         if (!pdata)
  99                 return -EBUSY;
 100
 101         gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios, GFP_KERNEL);
 102         if (!gpio_data)
 103                 return -ENOMEM;
 104
 105         for (i = 0; i < pdata->num_gpios; i++) {
 106                 cur_gpio = &pdata->gpios[i];
 107                 gpio_dat = &gpio_data[i];
 108
 109                 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 110                 gpio_dat->timer.function = gpio_timer_func;
 111                 spin_lock_init(&gpio_dat->lock);
 112
 113                 gpio_dat->gpio = cur_gpio->gpio;
 114                 gpio_dat->max_timeout = cur_gpio->max_timeout;
 115                 gpio_dat->active_low = cur_gpio->active_low;
 116                 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
 117
 118                 gpio_dat->dev = device_create(timed_gpio_class, &pdev->dev, 0, "%s", cur_gpio->name);
 119                 if (unlikely(IS_ERR(gpio_dat->dev)))
 120                         return PTR_ERR(gpio_dat->dev);
 121
 122                 dev_set_drvdata(gpio_dat->dev, gpio_dat);
 123                 ret = device_create_file(gpio_dat->dev, &dev_attr_enable);
 124                 if (ret)
 125                         return ret;
 126         }
 127
 128         platform_set_drvdata(pdev, gpio_data);
 129
 130         return 0;
 131 }
 132
 133 static int timed_gpio_remove(struct platform_device *pdev)
 134 {
 135         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
 136         struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
 137         int i;
 138
 139         for (i = 0; i < pdata->num_gpios; i++) {
 140                 device_remove_file(gpio_data[i].dev, &dev_attr_enable);
 141                 device_unregister(gpio_data[i].dev);
 142         }
 143
 144         kfree(gpio_data);
 145
 146         return 0;
 147 }
 148
 149 static struct platform_driver timed_gpio_driver = {
 150         .probe          = timed_gpio_probe,
 151         .remove         = timed_gpio_remove,
 152         .driver         = {
 153                 .name           = "timed-gpio",
 154                 .owner          = THIS_MODULE,
 155         },
 156 };
 157
 158 static int __init timed_gpio_init(void)
 159 {
 160         timed_gpio_class = class_create(THIS_MODULE, "timed_output");
 161         if (IS_ERR(timed_gpio_class))
 162                 return PTR_ERR(timed_gpio_class);
 163         return platform_driver_register(&timed_gpio_driver);
 164 }
 165
 166 static void __exit timed_gpio_exit(void)
 167 {
 168         class_destroy(timed_gpio_class);
 169         platform_driver_unregister(&timed_gpio_driver);
 170 }
 171
 172 module_init(timed_gpio_init);
 173 module_exit(timed_gpio_exit);
 174
 175 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 176 MODULE_DESCRIPTION("timed gpio driver");
 177 MODULE_LICENSE("GPL");