timed_gpio.c revision 99f41131b8d82cde1a84fec5b93ce31632552f0b
1/* drivers/android/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 <asm/arch/gpio.h> 22 23#include "android_timed_gpio.h" 24 25 26static struct class *timed_gpio_class; 27 28struct timed_gpio_data { 29 struct device *dev; 30 struct hrtimer timer; 31 spinlock_t lock; 32 unsigned gpio; 33 int max_timeout; 34 u8 active_low; 35}; 36 37static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer) 38{ 39 struct timed_gpio_data *gpio_data = container_of(timer, struct timed_gpio_data, timer); 40 41 gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? 1 : 0); 42 return HRTIMER_NORESTART; 43} 44 45static ssize_t gpio_enable_show(struct device *dev, struct device_attribute *attr, char *buf) 46{ 47 struct timed_gpio_data *gpio_data = dev_get_drvdata(dev); 48 int remaining; 49 50 if (hrtimer_active(&gpio_data->timer)) { 51 ktime_t r = hrtimer_get_remaining(&gpio_data->timer); 52 remaining = r.tv.sec * 1000 + r.tv.nsec / 1000000; 53 } else 54 remaining = 0; 55 56 return sprintf(buf, "%d\n", remaining); 57} 58 59static ssize_t gpio_enable_store( 60 struct device *dev, struct device_attribute *attr, 61 const char *buf, size_t size) 62{ 63 struct timed_gpio_data *gpio_data = dev_get_drvdata(dev); 64 int value; 65 unsigned long flags; 66 67 sscanf(buf, "%d", &value); 68 69 spin_lock_irqsave(&gpio_data->lock, flags); 70 71 /* cancel previous timer and set GPIO according to value */ 72 hrtimer_cancel(&gpio_data->timer); 73 gpio_direction_output(gpio_data->gpio, gpio_data->active_low ? !value : !!value); 74 75 if (value > 0) { 76 if (value > gpio_data->max_timeout) 77 value = gpio_data->max_timeout; 78 79 hrtimer_start(&gpio_data->timer, 80 ktime_set(value / 1000, (value % 1000) * 1000000), 81 HRTIMER_MODE_REL); 82 } 83 84 spin_unlock_irqrestore(&gpio_data->lock, flags); 85 86 return size; 87} 88 89static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, gpio_enable_show, gpio_enable_store); 90 91static int android_timed_gpio_probe(struct platform_device *pdev) 92{ 93 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data; 94 struct timed_gpio *cur_gpio; 95 struct timed_gpio_data *gpio_data, *gpio_dat; 96 int i, ret = 0; 97 98 if (!pdata) 99 return -EBUSY; 100 101 gpio_data = kzalloc(sizeof(struct timed_gpio_data) * pdata->num_gpios, GFP_KERNEL); 102 if (!gpio_data) 103 return -ENOMEM; 104 105 for (i = 0; i < pdata->num_gpios; i++) { 106 cur_gpio = &pdata->gpios[i]; 107 gpio_dat = &gpio_data[i]; 108 109 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 110 gpio_dat->timer.function = gpio_timer_func; 111 spin_lock_init(&gpio_dat->lock); 112 113 gpio_dat->gpio = cur_gpio->gpio; 114 gpio_dat->max_timeout = cur_gpio->max_timeout; 115 gpio_dat->active_low = cur_gpio->active_low; 116 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low); 117 118 gpio_dat->dev = device_create(timed_gpio_class, &pdev->dev, 0, "%s", cur_gpio->name); 119 if (unlikely(IS_ERR(gpio_dat->dev))) 120 return PTR_ERR(gpio_dat->dev); 121 122 dev_set_drvdata(gpio_dat->dev, gpio_dat); 123 ret = device_create_file(gpio_dat->dev, &dev_attr_enable); 124 if (ret) 125 return ret; 126 } 127 128 platform_set_drvdata(pdev, gpio_data); 129 130 return 0; 131} 132 133static int android_timed_gpio_remove(struct platform_device *pdev) 134{ 135 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data; 136 struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev); 137 int i; 138 139 for (i = 0; i < pdata->num_gpios; i++) { 140 device_remove_file(gpio_data[i].dev, &dev_attr_enable); 141 device_unregister(gpio_data[i].dev); 142 } 143 144 kfree(gpio_data); 145 146 return 0; 147} 148 149static struct platform_driver android_timed_gpio_driver = { 150 .probe = android_timed_gpio_probe, 151 .remove = android_timed_gpio_remove, 152 .driver = { 153 .name = "android-timed-gpio", 154 .owner = THIS_MODULE, 155 }, 156}; 157 158static int __init android_timed_gpio_init(void) 159{ 160 timed_gpio_class = class_create(THIS_MODULE, "timed_output"); 161 if (IS_ERR(timed_gpio_class)) 162 return PTR_ERR(timed_gpio_class); 163 return platform_driver_register(&android_timed_gpio_driver); 164} 165 166static void __exit android_timed_gpio_exit(void) 167{ 168 class_destroy(timed_gpio_class); 169 platform_driver_unregister(&android_timed_gpio_driver); 170} 171 172module_init(android_timed_gpio_init); 173module_exit(android_timed_gpio_exit); 174 175MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>"); 176MODULE_DESCRIPTION("Android timed gpio driver"); 177MODULE_LICENSE("GPL"); 178