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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 #include <linux/ktime.h>
 24 
 25 #include "timed_output.h"
 26 #include "timed_gpio.h"
 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         ktime_t t;
 50 
 51         data = container_of(dev, struct timed_gpio_data, dev);
 52 
 53         if (!hrtimer_active(&data->timer))
 54                 return 0;
 55 
 56         t = hrtimer_get_remaining(&data->timer);
 57 
 58         return ktime_to_ms(t);
 59 }
 60 
 61 static void gpio_enable(struct timed_output_dev *dev, int value)
 62 {
 63         struct timed_gpio_data *data =
 64                 container_of(dev, struct timed_gpio_data, dev);
 65         unsigned long flags;
 66 
 67         spin_lock_irqsave(&data->lock, flags);
 68 
 69         /* cancel previous timer and set GPIO according to value */
 70         hrtimer_cancel(&data->timer);
 71         gpio_direction_output(data->gpio, data->active_low ? !value : !!value);
 72 
 73         if (value > 0) {
 74                 if (value > data->max_timeout)
 75                         value = data->max_timeout;
 76 
 77                 hrtimer_start(&data->timer,
 78                               ktime_set(value / 1000, (value % 1000) * 1000000),
 79                               HRTIMER_MODE_REL);
 80         }
 81 
 82         spin_unlock_irqrestore(&data->lock, flags);
 83 }
 84 
 85 static int timed_gpio_probe(struct platform_device *pdev)
 86 {
 87         struct timed_gpio_platform_data *pdata = pdev->dev.platform_data;
 88         struct timed_gpio *cur_gpio;
 89         struct timed_gpio_data *gpio_data, *gpio_dat;
 90         int i, ret;
 91 
 92         if (!pdata)
 93                 return -EBUSY;
 94 
 95         gpio_data = devm_kcalloc(&pdev->dev, pdata->num_gpios,
 96                                  sizeof(*gpio_data), 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         },
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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