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Linux/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, ret;
 89 
 90         if (!pdata)
 91                 return -EBUSY;
 92 
 93         gpio_data = devm_kzalloc(&pdev->dev,
 94                                 sizeof(struct timed_gpio_data) * pdata->num_gpios,
 95                                 GFP_KERNEL);
 96         if (!gpio_data)
 97                 return -ENOMEM;
 98 
 99         for (i = 0; i < pdata->num_gpios; i++) {
100                 cur_gpio = &pdata->gpios[i];
101                 gpio_dat = &gpio_data[i];
102 
103                 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC,
104                                 HRTIMER_MODE_REL);
105                 gpio_dat->timer.function = gpio_timer_func;
106                 spin_lock_init(&gpio_dat->lock);
107 
108                 gpio_dat->dev.name = cur_gpio->name;
109                 gpio_dat->dev.get_time = gpio_get_time;
110                 gpio_dat->dev.enable = gpio_enable;
111                 ret = gpio_request(cur_gpio->gpio, cur_gpio->name);
112                 if (ret < 0)
113                         goto err_out;
114                 ret = timed_output_dev_register(&gpio_dat->dev);
115                 if (ret < 0) {
116                         gpio_free(cur_gpio->gpio);
117                         goto err_out;
118                 }
119 
120                 gpio_dat->gpio = cur_gpio->gpio;
121                 gpio_dat->max_timeout = cur_gpio->max_timeout;
122                 gpio_dat->active_low = cur_gpio->active_low;
123                 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low);
124         }
125 
126         platform_set_drvdata(pdev, gpio_data);
127 
128         return 0;
129 
130 err_out:
131         while (--i >= 0) {
132                 timed_output_dev_unregister(&gpio_data[i].dev);
133                 gpio_free(gpio_data[i].gpio);
134         }
135 
136         return ret;
137 }
138 
139 static int timed_gpio_remove(struct platform_device *pdev)
140 {
141         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
142         struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev);
143         int i;
144 
145         for (i = 0; i < pdata->num_gpios; i++) {
146                 timed_output_dev_unregister(&gpio_data[i].dev);
147                 gpio_free(gpio_data[i].gpio);
148         }
149 
150         return 0;
151 }
152 
153 static struct platform_driver timed_gpio_driver = {
154         .probe          = timed_gpio_probe,
155         .remove         = timed_gpio_remove,
156         .driver         = {
157                 .name           = TIMED_GPIO_NAME,
158                 .owner          = THIS_MODULE,
159         },
160 };
161 
162 module_platform_driver(timed_gpio_driver);
163 
164 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
165 MODULE_DESCRIPTION("timed gpio driver");
166 MODULE_LICENSE("GPL");
167 

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