input子系统学习之三：设备层

设备层：直接操作硬件，所有事件上报核心层或者通过核心层得到需要硬件执行什么操作

 

input子系统按键驱动实例：

  1 /* 参考drivers\input\keyboard\gpio_keys.c */
  2 
  3 #include <linux/module.h>
  4 #include <linux/version.h>
  5 
  6 #include <linux/init.h>
  7 #include <linux/fs.h>
  8 #include <linux/interrupt.h>
  9 #include <linux/irq.h>
 10 #include <linux/sched.h>
 11 #include <linux/pm.h>
 12 #include <linux/sysctl.h>
 13 #include <linux/proc_fs.h>
 14 #include <linux/delay.h>
 15 #include <linux/platform_device.h>
 16 #include <linux/input.h>
 17 #include <linux/irq.h>
 18 
 19 #include <asm/gpio.h>
 20 #include <asm/io.h>
 21 #include <asm/arch/regs-gpio.h>
 22 
 23 struct pin_desc{
 24     int irq;
 25     char *name;
 26     unsigned int pin;
 27     unsigned int key_val;
 28 };
 29 
 30 struct pin_desc pins_desc[4] = {
 31     {IRQ_EINT8,  "S2", S3C2410_GPG(0),   KEY_L},
 32     {IRQ_EINT11,  "S3", S3C2410_GPG(3),   KEY_S},
 33     {IRQ_EINT13, "S4", S3C2410_GPG(5),   KEY_ENTER},
 34     {IRQ_EINT14, "S5",  S3C2410_GPG(6), KEY_LEFTSHIFT},
 35 };
 36 
 37 static struct input_dev *buttons_dev;
 38 static struct pin_desc *irq_pd;
 39 static struct timer_list buttons_timer;
 40 
 41 static irqreturn_t buttons_irq(int irq, void *dev_id)
 42 {
 43     /* 10ms后启动定时器 */
 44     irq_pd = (struct pin_desc *)dev_id;
 45     mod_timer(&buttons_timer, jiffies+HZ/100);
 46     return IRQ_RETVAL(IRQ_HANDLED);
 47 }
 48 
 49 static void buttons_timer_function(unsigned long data)
 50 {
 51     struct pin_desc * pindesc = irq_pd;
 52     unsigned int pinval;
 53 
 54     if (!pindesc)
 55         return;
 56     
 57     pinval = s3c2410_gpio_getpin(pindesc->pin);
 58 
 59     if (pinval)
 60     {
 61         /* 松开 : 最后一个参数: 0-松开, 1-按下 */
 62         input_event(buttons_dev, EV_KEY, pindesc->key_val, 0);
 63         input_sync(buttons_dev);
 64     }
 65     else
 66     {
 67         /* 按下 */
 68         input_event(buttons_dev, EV_KEY, pindesc->key_val, 1);
 69         input_sync(buttons_dev);
 70     }
 71 }
 72 
 73 static int buttons_init(void)
 74 {
 75     int i;
 76     
 77     /* 1. 分配一个input_dev结构体 */
 78     buttons_dev = input_allocate_device();;
 79 
 80     /* 2. 设置 */
 81     /* 2.1 能产生哪类事件 */
 82     set_bit(EV_KEY, buttons_dev->evbit);
 83     set_bit(EV_REP, buttons_dev->evbit);
 84     
 85     /* 2.2 能产生这类操作里的哪些事件: L,S,ENTER,LEFTSHIT */
 86     set_bit(KEY_L, buttons_dev->keybit);
 87     set_bit(KEY_S, buttons_dev->keybit);
 88     set_bit(KEY_ENTER, buttons_dev->keybit);
 89     set_bit(KEY_LEFTSHIFT, buttons_dev->keybit);
 90 
 91     /* 3. 注册 */
 92     input_register_device(buttons_dev);
 93     
 94     /* 4. 硬件相关的操作 */
 95     init_timer(&buttons_timer);
 96     buttons_timer.function = buttons_timer_function;
 97     add_timer(&buttons_timer);
 98     
 99     for (i = 0; i < 4; i++)
100     {
101         request_irq(pins_desc[i].irq, buttons_irq, IRQ_TYPE_EDGE_BOTH, pins_desc[i].name, &pins_desc[i]);
102     }
103     
104     return 0;
105 }
106 
107 static void buttons_exit(void)
108 {
109     int i;
110     for (i = 0; i < 4; i++)
111     {
112         free_irq(pins_desc[i].irq, &pins_desc[i]);
113     }
114 
115     del_timer(&buttons_timer);
116     input_unregister_device(buttons_dev);
117     input_free_device(buttons_dev);    
118 }
119 
120 module_init(buttons_init);
121 
122 module_exit(buttons_exit);
123 
124 MODULE_LICENSE("GPL");

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