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：

/* 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");