Linux Platform Device and Driver,platform_add_devices()->platform_driver_register()

/* 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; 

    

}