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/slab.h>
  20 #include <linux/hrtimer.h>
  21 #include <linux/err.h>
  22 #include <linux/gpio.h>
  23
  24 #include "timed_output.h"
  25 #include "timed_gpio.h"
  26
  27
  28 struct timed_gpio_data {
  29         struct timed_output_dev 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 *data =
  40                 container_of(timer, struct timed_gpio_data, timer);
  41
  42         gpio_direction_output(data->gpio, data->active_low ? 1 : 0);
  43         return HRTIMER_NORESTART;
  44 }
  45
  46 static int gpio_get_time(struct timed_output_dev *dev)
  47 {
  48         struct timed_gpio_data  *data =
  49                 container_of(dev, struct timed_gpio_data, dev);
  50
  51         if (hrtimer_active(&data->timer)) {
  52                 ktime_t r = hrtimer_get_remaining(&data->timer);
  53                 struct timeval t = ktime_to_timeval(r);
  54                 return t.tv_sec * 1000 + t.tv_usec / 1000;
  55         } else
  56                 return 0;
  57 }
  58
  59 static void gpio_enable(struct timed_output_dev *dev, int value)
  60 {
  61         struct timed_gpio_data  *data =
  62                 container_of(dev, struct timed_gpio_data, dev);
  63         unsigned long   flags;
  64
  65         spin_lock_irqsave(&data->lock, flags);
  66
  67         /* cancel previous timer and set GPIO according to value */
  68         hrtimer_cancel(&data->timer);
  69         gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
  70
  71         if (value > 0) {
  72                 if (value > data->max_timeout)
  73                         value = data->max_timeout;
  74
  75                 hrtimer_start(&data->timer,
  76                         ktime_set(value / 1000, (value % 1000) * 1000000),
  77                         HRTIMER_MODE_REL);
  78         }
  79
  80         spin_unlock_irqrestore(&data->lock, flags);
  81 }
  82
  83 static int timed_gpio_probe(struct platform_device *pdev)
  84 {
  85         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
  86         struct timed_gpio *cur_gpio;
  87         struct timed_gpio_data *gpio_data, *gpio_dat;
  88         int i, j, ret = 0;
  89
  90         if (!pdata)
  91                 return -EBUSY;
  92
  93         gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios,
  94                         GFP_KERNEL);
  95         if (!gpio_data)
  96                 return -ENOMEM;
  97
  98         for (i = 0; i < pdata->num_gpios; i++) {
  99                 cur_gpio = &pdata->gpios[i];
 100                 gpio_dat = &gpio_data[i];
 101
 102                 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
 103                                 HRTIMER_MODE_REL);
 104                 gpio_dat->timer.function = gpio_timer_func;
 105                 spin_lock_init(&gpio_dat->lock);
 106
 107                 gpio_dat->dev.name = cur_gpio->name;
 108                 gpio_dat->dev.get_time = gpio_get_time;
 109                 gpio_dat->dev.enable = gpio_enable;
 110                 ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
 111                 if (ret >= 0) {
 112                         ret = timed_output_dev_register(&gpio_dat->dev);
 113                         if (ret < 0)
 114                                 gpio_free(cur_gpio->gpio);
 115                 }
 116                 if (ret < 0) {
 117                         for (j = 0; j < i; j++) {
 118                                 timed_output_dev_unregister(&gpio_data[i].dev);
 119                                 gpio_free(gpio_data[i].gpio);
 120                         }
 121                         kfree(gpio_data);
 122                         return ret;
 123                 }
 124
 125                 gpio_dat->gpio = cur_gpio->gpio;
 126                 gpio_dat->max_timeout = cur_gpio->max_timeout;
 127                 gpio_dat->active_low = cur_gpio->active_low;
 128                 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
 129         }
 130
 131         platform_set_drvdata(pdev, gpio_data);
 132
 133         return 0;
 134 }
 135
 136 static int timed_gpio_remove(struct platform_device *pdev)
 137 {
 138         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
 139         struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
 140         int i;
 141
 142         for (i = 0; i < pdata->num_gpios; i++) {
 143                 timed_output_dev_unregister(&gpio_data[i].dev);
 144                 gpio_free(gpio_data[i].gpio);
 145         }
 146
 147         kfree(gpio_data);
 148
 149         return 0;
 150 }
 151
 152 static struct platform_driver timed_gpio_driver = {
 153         .probe          = timed_gpio_probe,
 154         .remove         = timed_gpio_remove,
 155         .driver         = {
 156                 .name           = TIMED_GPIO_NAME,
 157                 .owner          = THIS_MODULE,
 158         },
 159 };
 160
 161 static int __init timed_gpio_init(void)
 162 {
 163         return platform_driver_register(&timed_gpio_driver);
 164 }
 165
 166 static void __exit timed_gpio_exit(void)
 167 {
 168         platform_driver_unregister(&timed_gpio_driver);
 169 }
 170
 171 module_init(timed_gpio_init);
 172 module_exit(timed_gpio_exit);
 173
 174 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 175 MODULE_DESCRIPTION("timed gpio driver");
 176 MODULE_LICENSE("GPL");