timed_gpio.c revision 10f62861b4a2f22cbd6412b3c42c76f0bdfbd648
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 28struct 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 37static 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 46static 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 60static 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 84static 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 131err_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 140static 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 154static 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 163module_platform_driver(timed_gpio_driver); 164 165MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>"); 166MODULE_DESCRIPTION("timed gpio driver"); 167MODULE_LICENSE("GPL"); 168