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_output.h"
  24 #include "timed_gpio.h"
  25
  26
  27 struct timed_gpio_data {
  28         struct timed_output_dev dev;
  29         struct hrtimer timer;
  30         spinlock_t lock;
  31         unsigned        gpio;
  32         int             max_timeout;
  33         u8              active_low;
  34 };
  35
  36 static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer)
  37 {
  38         struct timed_gpio_data *data =
  39                 container_of(timer, struct timed_gpio_data, timer);
  40
  41         gpio_direction_output(data->gpio, data->active_low ? 1 : 0);
  42         return HRTIMER_NORESTART;
  43 }
  44
  45 static int gpio_get_time(struct timed_output_dev *dev)
  46 {
  47         struct timed_gpio_data  *data =
  48                 container_of(dev, struct timed_gpio_data, dev);
  49
  50         if (hrtimer_active(&data->timer)) {
  51                 ktime_t r = hrtimer_get_remaining(&data->timer);
  52                 struct timeval t = ktime_to_timeval(r);
  53                 return t.tv_sec * 1000 + t.tv_usec / 1000;
  54         } else
  55                 return 0;
  56 }
  57
  58 static void gpio_enable(struct timed_output_dev *dev, int value)
  59 {
  60         struct timed_gpio_data  *data =
  61                 container_of(dev, struct timed_gpio_data, dev);
  62         unsigned long   flags;
  63
  64         spin_lock_irqsave(&data->lock, flags);
  65
  66         /* cancel previous timer and set GPIO according to value */
  67         hrtimer_cancel(&data->timer);
  68         gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
  69
  70         if (value > 0) {
  71                 if (value > data->max_timeout)
  72                         value = data->max_timeout;
  73
  74                 hrtimer_start(&data->timer,
  75                         ktime_set(value / 1000, (value % 1000) * 1000000),
  76                         HRTIMER_MODE_REL);
  77         }
  78
  79         spin_unlock_irqrestore(&data->lock, flags);
  80 }
  81
  82 static int timed_gpio_probe(struct platform_device *pdev)
  83 {
  84         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
  85         struct timed_gpio *cur_gpio;
  86         struct timed_gpio_data *gpio_data, *gpio_dat;
  87         int i, j, ret = 0;
  88
  89         if (!pdata)
  90                 return -EBUSY;
  91
  92         gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios,
  93                         GFP_KERNEL);
  94         if (!gpio_data)
  95                 return -ENOMEM;
  96
  97         for (i = 0; i < pdata->num_gpios; i++) {
  98                 cur_gpio = &pdata->gpios[i];
  99                 gpio_dat = &gpio_data[i];
 100
 101                 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
 102                                 HRTIMER_MODE_REL);
 103                 gpio_dat->timer.function = gpio_timer_func;
 104                 spin_lock_init(&gpio_dat->lock);
 105
 106                 gpio_dat->dev.name = cur_gpio->name;
 107                 gpio_dat->dev.get_time = gpio_get_time;
 108                 gpio_dat->dev.enable = gpio_enable;
 109                 ret = timed_output_dev_register(&gpio_dat->dev);
 110                 if (ret < 0) {
 111                         for (j = 0; j < i; j++)
 112                                 timed_output_dev_unregister(&gpio_data[i].dev);
 113                         kfree(gpio_data);
 114                         return ret;
 115                 }
 116
 117                 gpio_dat->gpio = cur_gpio->gpio;
 118                 gpio_dat->max_timeout = cur_gpio->max_timeout;
 119                 gpio_dat->active_low = cur_gpio->active_low;
 120                 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
 121         }
 122
 123         platform_set_drvdata(pdev, gpio_data);
 124
 125         return 0;
 126 }
 127
 128 static int timed_gpio_remove(struct platform_device *pdev)
 129 {
 130         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
 131         struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
 132         int i;
 133
 134         for (i = 0; i < pdata->num_gpios; i++)
 135                 timed_output_dev_unregister(&gpio_data[i].dev);
 136
 137         kfree(gpio_data);
 138
 139         return 0;
 140 }
 141
 142 static struct platform_driver timed_gpio_driver = {
 143         .probe          = timed_gpio_probe,
 144         .remove         = timed_gpio_remove,
 145         .driver         = {
 146                 .name           = TIMED_GPIO_NAME,
 147                 .owner          = THIS_MODULE,
 148         },
 149 };
 150
 151 static int __init timed_gpio_init(void)
 152 {
 153         return platform_driver_register(&timed_gpio_driver);
 154 }
 155
 156 static void __exit timed_gpio_exit(void)
 157 {
 158         platform_driver_unregister(&timed_gpio_driver);
 159 }
 160
 161 module_init(timed_gpio_init);
 162 module_exit(timed_gpio_exit);
 163
 164 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 165 MODULE_DESCRIPTION("timed gpio driver");
 166 MODULE_LICENSE("GPL");