linux 输入子系统

最新推荐文章于 2023-04-29 20:52:23 发布

weixin_34204057

最新推荐文章于 2023-04-29 20:52:23 发布

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/wszdezh/p/8735304.html

本文详细介绍了一个基于Linux内核的GPIO按键驱动程序实现方法。通过具体的C语言代码示例，展示了如何配置GPIO引脚、注册中断处理函数、创建定时器及输入设备等关键步骤，并实现了按键的按下与释放事件检测。

  1 #include <linux/module.h>
  2 #include <linux/init.h>
  3 
  4 //#include <linux/kernel.h>
  5 //#include <linux/fs.h>
  6 #include <linux/interrupt.h>
  7 #include <linux/irq.h>
  8 //#include <linux/sched.h>
  9 //#include <linux/pm.h>
 10 //#include <linux/slab.h>
 11 //#include <linux/sysctl.h>
 12 //#include <linux/proc_fs.h>
 13 //#include <linux/delay.h>
 14 //#include <linux/platform_device.h>
 15 #include <linux/input.h>
 16 //#include <linux/workqueue.h>
 17 
 18 #include <linux/gpio.h>
 19 #include <plat/gpio-cfg.h>
 20 
 21 
 22 struct pin_desc{
 23     int irq;
 24     char *name;
 25     unsigned int pin;
 26     unsigned int key_val;
 27 };
 28 
 29 struct pin_desc pins_desc[4] = {
 30     {IRQ_EINT(9),  "K1", EXYNOS4_GPX1(1), KEY_L},
 31     {IRQ_EINT(10), "K2", EXYNOS4_GPX1(2), KEY_S},
 32     {IRQ_EINT(16), "K3", EXYNOS4_GPX2(0), KEY_ENTER},
 33     {IRQ_EINT(17), "K4", EXYNOS4_GPX2(1), KEY_LEFTSHIFT},
 34 };
 35 
 36 
 37 static struct input_dev *key_dev;
 38 static struct pin_desc *irq_pd;
 39 static struct timer_list buttons_timer;
 40 
 41 
 42 
 43 static irqreturn_t buttons_irq(int irq, void *dev_id)
 44 {
 45     irq_pd = (struct pin_desc *)dev_id;
 46     //input_event(key_dev, EV_KEY, irq_pd->key_val, 1);
 47     //input_sync(key_dev);
 48     //input_event(key_dev, EV_KEY, irq_pd->key_val, 0);
 49     //input_sync(key_dev);
 50     
 51     mod_timer(&buttons_timer, jiffies+HZ/100);
 52     return IRQ_RETVAL(IRQ_HANDLED);
 53 }
 54 
 55 static void buttons_timer_function(unsigned long data)
 56 {
 57     struct pin_desc * pindesc = irq_pd;
 58     unsigned int pinval;
 59 
 60     if (!pindesc)
 61         return;
 62     
 63     pinval = gpio_get_value(pindesc->pin);
 64 
 65     if (pinval)
 66     {
 67         /* 松开 : 最后一个参数: 0-松开, 1-按下 */
 68         input_event(key_dev, EV_KEY, irq_pd->key_val, 0);
 69         input_sync(key_dev);
 70     }
 71     else
 72     {
 73         /* 按下 */
 74         input_event(key_dev, EV_KEY, irq_pd->key_val, 1);
 75         input_sync(key_dev);
 76 
 77     }
 78 }
 79 
 80 
 81 static int __init key_input_init(void)
 82 {
 83     int i;
 84     int ret;
 85     printk("hello wsz\n");
 86     key_dev = input_allocate_device();
 87     if(!key_dev)
 88     {
 89         printk("key_dev allocate fail\n");
 90         return -ENOMEM;
 91     }
 92 
 93     set_bit(EV_KEY, key_dev->evbit);
 94     /*能产生这类事件的哪些具体事件*/
 95     set_bit(KEY_L, key_dev->keybit);
 96     set_bit(KEY_S, key_dev->keybit);
 97     set_bit(KEY_ENTER, key_dev->keybit);
 98     set_bit(KEY_LEFTSHIFT, key_dev->keybit);
 99 
100     ret = input_register_device(key_dev);
101     if(ret) 
102     {
103         printk("request_irq faild\n");
104         return ret;
105     }
106 
107     /* 4. 硬件相关的操作 */
108     init_timer(&buttons_timer);
109     buttons_timer.function = buttons_timer_function;
110     add_timer(&buttons_timer);
111     
112     for (i = 0; i < 4; i++)
113     {
114         s3c_gpio_setpull(pins_desc[i].pin, S3C_GPIO_PULL_NONE);
115         ret = request_irq(pins_desc[i].irq, buttons_irq, IRQ_TYPE_EDGE_BOTH, pins_desc[i].name, &pins_desc[i]);
116         if(ret) 
117         {
118             printk("request_irq faild\n");
119             return ret;
120         }
121     }
122     return 0;
123 }
124 
125 static void __exit key_input_exit(void)
126 {
127     int i;
128     for (i = 0; i < 4; i++)
129     {
130         free_irq(pins_desc[i].irq, &pins_desc[i]);
131     }
132     
133     del_timer(&buttons_timer);
134     input_unregister_device(key_dev);
135     input_free_device(key_dev);    
136 }
137 
138 
139 module_init(key_input_init);
140 module_exit(key_input_exit);
141 
142 MODULE_LICENSE("GPL");