linux按键platform驱动样例学习

按键驱动platform的编写流程和led驱动的差不了太多，只是多了一个中断机制和延时消抖的过程，延时消抖可以用内置定时器来做。

platform_device

首先来看设备结构体

static struct platform_device s3c_button_device = {  
    .name    = "s3c_button",  
    .id      = 1,  
    .dev     =   
    {  
        .platform_data = &s3c_button_data,   
        .release = platform_button_release,  
    },  
};  

name成员设为s3c_button，.dev->platform_data依旧是以自定义的s3c_button_platform_data类型的结构体传入，还有就是relese函数的处理。

struct s3c_button_info  
{  
    unsigned char           num;       /*Button nubmer  按键号*/    
    char *                  name;      /*Button nubmer  按键名*/  
    int                     nIRQ;      /*Button IRQ number 中断号*/  
    unsigned int            setting;   /*Button IRQ Pin Setting 中断引脚配置*/  
    unsigned int            gpio;      /*Button GPIO port 对应的IO引脚*/  
};  
  
/* The button plaotform device private data structure */  
struct s3c_button_platform_data //按键数据结构体  
{  
    struct s3c_button_info *buttons; //用来访问按键硬件信息的指针  
    int                     nbuttons;//按键数量  
};  
  
/* Button hardware informtation data*/ //具体的相应按键信息  
static struct s3c_button_info  s3c_buttons[] = {  
    [0] = {  
        .num = 1,  
        .name = "KEY1",  
        .nIRQ = IRQ_EINT0,//中断号  
        .gpio = S3C2410_GPF(0),  
        .setting = S3C2410_GPF0_EINT0,//datasheet手册上对应的IO中断口  
    },  
    [1] = {  
        .num = 2,  
        .name = "KEY2",  
        .nIRQ = IRQ_EINT2,  
        .gpio = S3C2410_GPF(2),  
        .setting = S3C2410_GPF2_EINT2,  
    },  
    [2] = {  
        .num = 3,  
        .name = "KEY3",  
        .nIRQ = IRQ_EINT3,  
        .gpio = S3C2410_GPF(3),  
        .setting = S3C2410_GPF3_EINT3,  
    },  
    [3] = {  
        .num = 4,  
        .name = "KEY4",  
        .nIRQ = IRQ_EINT4,  
        .gpio = S3C2410_GPF(4),  
        .setting = S3C2410_GPF4_EINT4,  
    },  
};  
  
/* The button platform device private data */  
static struct s3c_button_platform_data s3c_button_data = {  
    .buttons = s3c_buttons,  
    .nbuttons = ARRAY_SIZE(s3c_buttons),  
};  
struct button_device  
{  
    unsigned char                      *status;      /* The buttons Push down or up status */  
    struct s3c_button_platform_data    *data;        /* The buttons hardware information data */  
  
    struct timer_list                  *timers;      /* The buttons remove dithering timers */  
    wait_queue_head_t                  waitq;           /* Wait queue for poll()  */  
    volatile int                       ev_press;     /* Button pressed event */  
  
    struct cdev                        cdev;             
    struct class                       *dev_class;   
} button_device;

自定义了s3c_button_info结构体数组用来存放不同按键的基本信息，s3c_button_platform_data这个结构体包含了s3c_button_info成员，还有成员的数量，总线数据嘛，顾名思义。

与LED驱动不同的是，按键多自定义了一个结构体button_device来存放设备更多的信息，包括定时器结构体，按键事件，同时还包括了总线信息s3c_button_platform_data，可以说button_device是信息最全的包含设备的信息。

platform_driver

static struct platform_driver s3c_button_driver = {   
    .probe      = s3c_bu