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
  55                 return t.tv_sec * 1000 + t.tv_usec / 1000;
  56         } else
  57                 return 0;
  58 }
  59
  60 static void gpio_enable(struct timed_output_dev *dev, int value)
  61 {
  62         struct timed_gpio_data  *data =
  63                 container_of(dev, struct timed_gpio_data, dev);
  64         unsigned long   flags;
  65
  66         spin_lock_irqsave(&data->lock, flags);
  67
  68         /* cancel previous timer and set GPIO according to value */
  69         hrtimer_cancel(&data->timer);
  70         gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
  71
  72         if (value > 0) {
  73                 if (value > data->max_timeout)
  74                         value = data->max_timeout;
  75
  76                 hrtimer_start(&data->timer,
  77                         ktime_set(value / 1000, (value % 1000) * 1000000),
  78                         HRTIMER_MODE_REL);
  79         }
  80
  81         spin_unlock_irqrestore(&data->lock, flags);
  82 }
  83
  84 static int timed_gpio_probe(struct platform_device *pdev)
  85 {
  86         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
  87         struct timed_gpio *cur_gpio;
  88         struct timed_gpio_data *gpio_data, *gpio_dat;
  89         int i, ret;
  90
  91         if (!pdata)
  92                 return -EBUSY;
  93
  94         gpio_data = devm_kzalloc(&pdev->dev,
  95                         sizeof(struct timed_gpio_data) * pdata->num_gpios,
  96                         GFP_KERNEL);
  97         if (!gpio_data)
  98                 return -ENOMEM;
  99
 100         for (i = 0; i < pdata->num_gpios; i++) {
 101                 cur_gpio = &pdata->gpios[i];
 102                 gpio_dat = &gpio_data[i];
 103
 104                 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
 105                                 HRTIMER_MODE_REL);
 106                 gpio_dat->timer.function = gpio_timer_func;
 107                 spin_lock_init(&gpio_dat->lock);
 108
 109                 gpio_dat->dev.name = cur_gpio->name;
 110                 gpio_dat->dev.get_time = gpio_get_time;
 111                 gpio_dat->dev.enable = gpio_enable;
 112                 ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
 113                 if (ret < 0)
 114                         goto err_out;
 115                 ret = timed_output_dev_register(&gpio_dat->dev);
 116                 if (ret < 0) {
 117                         gpio_free(cur_gpio->gpio);
 118                         goto err_out;
 119                 }
 120
 121                 gpio_dat->gpio = cur_gpio->gpio;
 122                 gpio_dat->max_timeout = cur_gpio->max_timeout;
 123                 gpio_dat->active_low = cur_gpio->active_low;
 124                 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
 125         }
 126
 127         platform_set_drvdata(pdev, gpio_data);
 128
 129         return 0;
 130
 131 err_out:
 132         while (--i >= 0) {
 133                 timed_output_dev_unregister(&gpio_data[i].dev);
 134                 gpio_free(gpio_data[i].gpio);
 135         }
 136
 137         return ret;
 138 }
 139
 140 static int timed_gpio_remove(struct platform_device *pdev)
 141 {
 142         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
 143         struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
 144         int i;
 145
 146         for (i = 0; i < pdata->num_gpios; i++) {
 147                 timed_output_dev_unregister(&gpio_data[i].dev);
 148                 gpio_free(gpio_data[i].gpio);
 149         }
 150
 151         return 0;
 152 }
 153
 154 static struct platform_driver timed_gpio_driver = {
 155         .probe          = timed_gpio_probe,
 156         .remove         = timed_gpio_remove,
 157         .driver         = {
 158                 .name           = TIMED_GPIO_NAME,
 159                 .owner          = THIS_MODULE,
 160         },
 161 };
 162
 163 module_platform_driver(timed_gpio_driver);
 164
 165 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
 166 MODULE_DESCRIPTION("timed gpio driver");
 167 MODULE_LICENSE("GPL");