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 29struct timed_gpio_data { 30 struct timed_output_dev dev; 31 struct hrtimer timer; 32 spinlock_t lock; 33 unsigned gpio; 34 int max_timeout; 35 u8 active_low; 36}; 37 38static enum hrtimer_restart gpio_timer_func(struct hrtimer *timer) 39{ 40 struct timed_gpio_data *data = 41 container_of(timer, struct timed_gpio_data, timer); 42 43 gpio_direction_output(data->gpio, data->active_low ? 1 : 0); 44 return HRTIMER_NORESTART; 45} 46 47static int gpio_get_time(struct timed_output_dev *dev) 48{ 49 struct timed_gpio_data *data; 50 ktime_t t; 51 52 data = container_of(dev, struct timed_gpio_data, dev); 53 54 if (!hrtimer_active(&data->timer)) 55 return 0; 56 57 t = hrtimer_get_remaining(&data->timer); 58 59 return ktime_to_ms(t); 60} 61 62static void gpio_enable(struct timed_output_dev *dev, int value) 63{ 64 struct timed_gpio_data *data = 65 container_of(dev, struct timed_gpio_data, dev); 66 unsigned long flags; 67 68 spin_lock_irqsave(&data->lock, flags); 69 70 /* cancel previous timer and set GPIO according to value */ 71 hrtimer_cancel(&data->timer); 72 gpio_direction_output(data->gpio, data->active_low ? !value : !!value); 73 74 if (value > 0) { 75 if (value > data->max_timeout) 76 value = data->max_timeout; 77 78 hrtimer_start(&data->timer, 79 ktime_set(value / 1000, (value % 1000) * 1000000), 80 HRTIMER_MODE_REL); 81 } 82 83 spin_unlock_irqrestore(&data->lock, flags); 84} 85 86static int timed_gpio_probe(struct platform_device *pdev) 87{ 88 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data; 89 struct timed_gpio *cur_gpio; 90 struct timed_gpio_data *gpio_data, *gpio_dat; 91 int i, ret; 92 93 if (!pdata) 94 return -EBUSY; 95 96 gpio_data = devm_kzalloc(&pdev->dev, 97 sizeof(struct timed_gpio_data) * pdata->num_gpios, 98 GFP_KERNEL); 99 if (!gpio_data) 100 return -ENOMEM; 101 102 for (i = 0; i < pdata->num_gpios; i++) { 103 cur_gpio = &pdata->gpios[i]; 104 gpio_dat = &gpio_data[i]; 105 106 hrtimer_init(&gpio_dat->timer, CLOCK_MONOTONIC, 107 HRTIMER_MODE_REL); 108 gpio_dat->timer.function = gpio_timer_func; 109 spin_lock_init(&gpio_dat->lock); 110 111 gpio_dat->dev.name = cur_gpio->name; 112 gpio_dat->dev.get_time = gpio_get_time; 113 gpio_dat->dev.enable = gpio_enable; 114 ret = gpio_request(cur_gpio->gpio, cur_gpio->name); 115 if (ret < 0) 116 goto err_out; 117 ret = timed_output_dev_register(&gpio_dat->dev); 118 if (ret < 0) { 119 gpio_free(cur_gpio->gpio); 120 goto err_out; 121 } 122 123 gpio_dat->gpio = cur_gpio->gpio; 124 gpio_dat->max_timeout = cur_gpio->max_timeout; 125 gpio_dat->active_low = cur_gpio->active_low; 126 gpio_direction_output(gpio_dat->gpio, gpio_dat->active_low); 127 } 128 129 platform_set_drvdata(pdev, gpio_data); 130 131 return 0; 132 133err_out: 134 while (--i >= 0) { 135 timed_output_dev_unregister(&gpio_data[i].dev); 136 gpio_free(gpio_data[i].gpio); 137 } 138 139 return ret; 140} 141 142static int timed_gpio_remove(struct platform_device *pdev) 143{ 144 struct timed_gpio_platform_data *pdata = pdev->dev.platform_data; 145 struct timed_gpio_data *gpio_data = platform_get_drvdata(pdev); 146 int i; 147 148 for (i = 0; i < pdata->num_gpios; i++) { 149 timed_output_dev_unregister(&gpio_data[i].dev); 150 gpio_free(gpio_data[i].gpio); 151 } 152 153 return 0; 154} 155 156static struct platform_driver timed_gpio_driver = { 157 .probe = timed_gpio_probe, 158 .remove = timed_gpio_remove, 159 .driver = { 160 .name = TIMED_GPIO_NAME, 161 }, 162}; 163 164module_platform_driver(timed_gpio_driver); 165 166MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>"); 167MODULE_DESCRIPTION("timed gpio driver"); 168MODULE_LICENSE("GPL"); 169