arm 驱动进阶：编写输入子系统的驱动程序

编写输入子系统的驱动程序步骤：

 

驱动程序代码实现：

buttons.c

/* 参考drivers\input\keyboard\gpio_keys.c */



#include <linux/module.h>

#include <linux/version.h>



#include <linux/init.h>

#include <linux/fs.h>

#include <linux/interrupt.h>

#include <linux/irq.h>

#include <linux/sched.h>

#include <linux/pm.h>

#include <linux/sysctl.h>

#include <linux/proc_fs.h>

#include <linux/delay.h>

#include <linux/platform_device.h>

#include <linux/input.h>

#include <linux/irq.h>



#include <asm/gpio.h>

#include <asm/io.h>

#include <asm/arch/regs-gpio.h>



struct pin_desc{

    int irq;

    char *name;

    unsigned int pin;

    unsigned int key_val;

};



struct pin_desc pins_desc[4] = {

    {IRQ_EINT0,  "S2", S3C2410_GPF0,   KEY_L},

    {IRQ_EINT2,  "S3", S3C2410_GPF2,   KEY_S},

    {IRQ_EINT11, "S4", S3C2410_GPG3,   KEY_ENTER},

    {IRQ_EINT19, "S5",  S3C2410_GPG11, KEY_LEFTSHIFT},

};



static struct input_dev *buttons_dev;

static struct pin_desc *irq_pd;

static struct timer_list buttons_timer;



static irqreturn_t buttons_irq(int irq, void *dev_id)

{

    /* 10ms后启动定时器 */

    irq_pd = (struct pin_desc *)dev_id;

    mod_timer(&buttons_timer, jiffies+HZ/100);

    return IRQ_RETVAL(IRQ_HANDLED);

}



static void buttons_timer_function(unsigned long data)

{

    struct pin_desc * pindesc = irq_pd;

    unsigned int pinval;



    if (!pindesc)

        return;

    

    pinval = s3c2410_gpio_getpin(pindesc->pin);



    if (pinval)

    {

        /* 松开 : 最后一个参数: 0-松开, 1-按下 */

        input_event(buttons_dev, EV_KEY, pindesc->key_val, 0);

        input_sync(buttons_dev);

    }

    else

    {

        /* 按下 */

        input_event(buttons_dev, EV_KEY, pindesc->key_val, 1);

        input_sync(buttons_dev);

    }

}



static int buttons_init(void)

{

    int i;

    

    /* 1. 分配一个input_dev结构体 */

    buttons_dev = input_allocate_device();;



    /* 2. 设置 */

    /* 2.1 能产生哪类事件 */

    set_bit(EV_KEY, buttons_dev->evbit);

    set_bit(EV_REP, buttons_dev->evbit);

    

    /* 2.2 能产生这类操作里的哪些事件: L,S,ENTER,LEFTSHIT */

    set_bit(KEY_L, buttons_dev->keybit);

    set_bit(KEY_S, buttons_dev->keybit);

    set_bit(KEY_ENTER, buttons_dev->keybit);

    set_bit(KEY_LEFTSHIFT, buttons_dev->keybit);



    /* 3. 注册 */

    input_register_device(buttons_dev);

    

    /* 4. 硬件相关的操作 */

    init_timer(&buttons_timer);

    buttons_timer.function = buttons_timer_function;

    add_timer(&buttons_timer);

    

    for (i = 0; i < 4; i++)

    {

        request_irq(pins_desc[i].irq, buttons_irq, IRQT_BOTHEDGE, pins_desc[i].name, &pins_desc[i]);

    }

    

    return 0;

}



static void buttons_exit(void)

{

    int i;

    for (i = 0; i < 4; i++)

    {

        free_irq(pins_desc[i].irq, &pins_desc[i]);

    }



    del_timer(&buttons_timer);

    input_unregister_device(buttons_dev);

    input_free_device(buttons_dev);    

}



module_init(buttons_init);



module_exit(buttons_exit);



MODULE_LICENSE("GPL");