platform _device和platform_driver注册过程

platform _device和platform_driver注册过程

作者：Dongas

日期：08-06-28

 

platform_device_register()注册过程
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/* arch/arm/mach-s3c2410/mach-smdk2410.c */

struct platform_device s3c_device_i2c = {

         .name                  = "s3c2410-i2c",

         .id                = -1,

         .num_resources         = ARRAY_SIZE(s3c_i2c_resource),

         .resource   = s3c_i2c_resource,

};

 

/*

* platform_device_register - add a platform-level device

* @pdev: platform device we're adding

*

*/

int platform_device_register(struct platform_device * pdev)

{

    device_initialize(&pdev->dev);        //初始化设备结构

    return platform_device_add(pdev); //添加一个片上的设备到设备层

}

 

 

/**

 * platform_device_add - add a platform device to device hierarchy

 * @pdev: platform device we're adding

 *

 * This is part 2 of platform_device_register(), though may be called

 * separately _iff_ pdev was allocated by platform_device_alloc().

 */

int platform_device_add(struct platform_device *pdev)

{

         int i, ret = 0;

 

         if (!pdev)

                  return -EINVAL;

 

         if (!pdev->dev.parent)

                   pdev->dev.parent = &platform_bus;

 

         pdev->dev.bus = &platform_bus_type;

 

         if (pdev->id != -1)

                   snprintf(pdev->dev.bus_id, BUS_ID_SIZE, "%s.%d", pdev->name,

                             pdev->id);       /* 若支持同类多个设备，则用pdev->name和pdev->id在总线上标识该设备  */

         else

                   strlcpy(pdev->dev.bus_id, pdev->name, BUS_ID_SIZE); /* 否则，用pdev->name(如"s3c2410-i2c")在总线上标识该设备 */

 

         for (i = 0; i < pdev->num_resources; i++) {       /*  遍历资源数，并为各自在总线地址空间请求分配 */

                   struct resource *p, *r = &pdev->resource[i];

 

                   if (r->name == NULL)

                            r->name = pdev->dev.bus_id;

 

                   p = r->parent;

                   if (!p) {

                            if (r->flags & IORESOURCE_MEM)

                                     p = &iomem_resource;   /*  作为IO内存资源分配   */

                            else if (r->flags & IORESOURCE_IO)

                                     p = &ioport_resource;     /*  作为IO Port资源分配   */

                   }

 

                  if (p && insert_resource(p, r)) {       /*   将新的resource插入内核resource tree */

                            printk(KERN_ERR

                                   "%s: failed to claim resource %d\n",

                                   pdev->dev.bus_id, i);

                            ret = -EBUSY;

                            goto failed;

                   }

         }

 

         pr_debug("Registering platform device '%s'. Parent at %s\n",

                    pdev->dev.bus_id, pdev->dev.parent->bus_id);

 

         ret = device_add(&pdev->dev);

         if (ret == 0)

                   return ret;

 

 failed:

         while (--i >= 0)

                   if (pdev->resource[i].flags & (IORESOURCE_MEM|IORESOURCE_IO))

                            release_resource(&pdev->resource[i]);

         return ret;

}

这里发现，添加device到内核最终还是调用的device_add函数。Platform_device_add和device_add最主要的区别是多了一步insert_resource(p, r)即将platform资源(resource)添加进内核，由内核统一管理。

 

 

 

 

platform_driver_register()注册过程

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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",

         },

};

 

platform_driver_register(&s3c2410fb_driver)----->
driver_register(&drv->driver)----->
bus_add_driver(drv)----->
driver_attach(drv)----->
bus_for_each_dev(drv->bus, NULL, drv, __driver_attach)----->
__driver_attach(struct device * dev, void * data)----->
driver_probe_device(drv, dev)----->
really_probe(dev, drv)----->

在really_probe()中：为设备指派管理该设备的驱动：dev->driver = drv, 调用probe()函数初始化设备：drv->probe(dev)

 

注：Platform_device和Platform_driver的使用请参考这篇文章:
《Linux Platform Device and Driver》
http://blog.chinaunix.net/u2/60011/showart.php?id=1018502