/* arch/arm/mach-s3c2410/devs.c */
/* I2C */
static struct resource s3c_i2c_resource[ ] = {
         [ 0] = {
                   . start = S3C24XX_PA_IIC,
                   . end = S3C24XX_PA_IIC + S3C24XX_SZ_IIC - 1,
                   . flags = IORESOURCE_MEM,
         } ,
         [ 1] = {
                   . start = IRQ_IIC, //S3C2410_IRQ(27)
                   . end = IRQ_IIC,
                   . flags = IORESOURCE_IRQ,
         }
} ;

struct platform_device s3c_device_i2c = {
         . name = "s3c2410-i2c" ,
         . id = - 1,
         . num_resources = ARRAY_SIZE( s3c_i2c_resource) ,
         . resource = s3c_i2c_resource,
} ;

/* arch/arm/mach-3sc2410/cpu.c */
static int __init s3c_arch_init( void )
{
    int ret;
    ……
/* 这里board指针指向在mach-smdk2410.c里的定义的smdk2410_board，里面包含了预先定义的I2C Platform_device等. */
    if ( board ! = NULL ) {
        struct platform_device * * ptr = board- > devices;
        int i;

        for ( i = 0; i < board- > devices_count; i+ + , ptr+ + ) {
            ret = platform_device_register( * ptr) ;      //在这里进行注册

            if ( ret) {
                printk( KERN_ERR "s3c24xx: failed to add board device %s (%d) @%p/n" , ( * ptr) - > name,
ret, * ptr) ;
            }
        }
         /* mask any error, we may not need all these board
         * devices */
        ret = 0;
    }
    return ret;
}


/* device driver for platform bus bits */


static struct platform_driver s3c2410_i2c_driver = {
         . probe = s3c24xx_i2c_probe,
         . remove = s3c24xx_i2c_remove,
         . resume = s3c24xx_i2c_resume,
         . driver = {
                   . owner = THIS_MODULE,
                   . name = "s3c2410-i2c" ,
         } ,
} ;

/* drivers/i2c/busses/i2c-s3c2410.c */

static int s3c24xx_i2c_probe( struct platform_device * pdev)
{
    struct s3c24xx_i2c * i2c = & s3c24xx_i2c;
    struct resource * res;
    int ret;
 
    /* find the clock and enable it */
 
    i2c- > dev = & pdev- > dev;
    i2c- > clk = clk_get( & pdev- > dev, "i2c" ) ;
    if ( IS_ERR( i2c- > clk) ) {
     dev_err( & pdev- > dev, "cannot get clock/n" ) ;
     ret = - ENOENT;
     goto out;
    }

    dev_dbg( & pdev- > dev, "clock source %p/n" , i2c- > clk) ;
    clk_enable( i2c- > clk) ;


    /* map the registers */
    res = platform_get_resource( pdev, IORESOURCE_MEM, 0) ; /* 获取设备的IO资源地址 */
    if ( res = = NULL ) {
     dev_err( & pdev- > dev, "cannot find IO resource/n" ) ;
     ret = - ENOENT;
     goto out;
    }
    
    i2c- > ioarea = request_mem_region( res- > start, ( res- > end- res- > start) + 1, pdev- > name) ; /* 申请这块IO Region */
    
    if ( i2c- > ioarea = = NULL ) {
     dev_err( & pdev- > dev, "cannot request IO/n" ) ;
     ret = - ENXIO;
     goto out;
    }
    
    i2c- > regs = ioremap( res- > start, ( res- > end- res- > start) + 1) ; /* 映射至内核虚拟空间 */
    
    if ( i2c- > regs = = NULL ) {
     dev_err( & pdev- > dev, "cannot map IO/n" ) ;
     ret = - ENXIO;
     goto out;
    }
    
    dev_dbg( & pdev- > dev, "registers %p (%p, %p)/n" , i2c- > regs, i2c- > ioarea, res) ;
    
    /* setup info block for the i2c core */
    i2c- > adap. algo_data = i2c;
    i2c- > adap. dev. parent = & pdev- > dev;
    
    /* initialise the i2c controller */
    ret = s3c24xx_i2c_init( i2c) ;
    if ( ret ! = 0)
     goto out;

    /* find the IRQ for this unit (note, this relies on the init call to ensure no current IRQs pending */
    
    res = platform_get_resource( pdev, IORESOURCE_IRQ, 0) ; /* 获取设备IRQ中断号 */

    if ( res = = NULL ) {
     dev_err( & pdev- > dev, "cannot find IRQ/n" ) ;
     ret = - ENOENT;
     goto out;
    }
    
    ret = request_irq( res- > start, s3c24xx_i2c_irq, IRQF_DISABLED, /* 申请IRQ */
     pdev- > name, i2c) ;
    
    ……

    return ret;
    
}