linux platform设备与驱动

　　

 struct platform_driver {
     int (*probe)(struct platform_device *);
     int (*remove)(struct platform_device *);
     void (*shutdown)(struct platform_device *);
     int (*suspend)(struct platform_device *, pm_message_t state);
     int (*resume)(struct platform_device *);
     struct device_driver driver;
     const struct platform_device_id *id_table;
     bool prevent_deferred_probe;
 };

  struct device_driver {
      const char      *name;
      struct bus_type     *bus;

      struct module       *owner;
      const char      *mod_name;  /* used for built-in modules */

      bool suppress_bind_attrs;   /* disables bind/unbind via sysfs */
      enum probe_type probe_type;

      const struct of_device_id   *of_match_table;　　　　//device tree通过这个去匹配
      const struct acpi_device_id *acpi_match_table;

      int (*probe) (struct device *dev);
      int (*remove) (struct device *dev);
      void (*shutdown) (struct device *dev);
      int (*suspend) (struct device *dev, pm_message_t state);
      int (*resume) (struct device *dev);
      const struct attribute_group **groups;

      const struct dev_pm_ops *pm;

      struct driver_private *p;
  };

  struct platform_device {
      const char  *name;
      int     id;
      bool        id_auto;
      struct device   dev;
      u32     num_resources;
      struct resource *resource;

      const struct platform_device_id *id_entry;
      char *driver_override; /* Driver name to force a match */

      /* MFD cell pointer */
      struct mfd_cell *mfd_cell;

      /* arch specific additions */
      struct pdev_archdata    archdata;
  };

以上是头文件的结构体定义

 static const struct of_device_id dw_spi_mmio_of_match[] = {
     { .compatible = "snps,dw-apb-ssi", },
     { /* end of table */}
 };
 MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);

 static struct platform_driver dw_spi_mmio_driver = {
     .probe      = dw_spi_mmio_probe,
     .remove     = dw_spi_mmio_remove,
     .driver     = {
         .name   = DRIVER_NAME,
         .of_match_table = dw_spi_mmio_of_match,
     },
 };
 module_platform_driver(dw_spi_mmio_driver);

 MODULE_AUTHOR("Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>");
 MODULE_DESCRIPTION("Memory-mapped I/O interface driver for DW SPI Core");
 MODULE_LICENSE("GPL v2");

以前的写法　：　

    struct platform_device s3c_device_usb = {
             .name    = "s3c2410-ohci",  //s3c6410-usb
             .id    = -,
             .num_resources   = ARRAY_SIZE(s3c_usb_resource),
             .resource   = s3c_usb_resource,
             .dev              = {
                     .dma_mask = &s3c_device_usb_dmamask,
                     .coherent_dma_mask = 0xffffffffUL
                 }
    };  

有了platform_device就可以调用函数platform_add_devices向系统中添加该设备了。系统中的设备资源都可以采用这种方式列举在一起，然后成一个指针数组，如：

static struct platform_device *smdk6410_devices[] __initdata = {

......

 &s3c_device_usbgadget,
 &s3c_device_usb,  //jeff add.

......

}
   static struct platform_driver ohci_hcd_s3c2410_driver = {
         .probe  = ohci_hcd_s3c2410_drv_probe,
         .remove  = ohci_hcd_s3c2410_drv_remove,
         .shutdown = usb_hcd_platform_shutdown,
         /*.suspend = ohci_hcd_s3c2410_drv_suspend, */
         /*.resume = ohci_hcd_s3c2410_drv_resume, */
         .driver  = {
              .owner = THIS_MODULE,
              .name = "s3c2410-ohci",
            },
    };  

（）在内核初始化时kernel_init()->do_basic_setup()->driver_init()->platform_bus_init()初始化platform_bus(虚拟总线)；

（2）设备注册的时候platform_device_register()->platform_device_add()->(pdev->dev.bus = &platform_bus_type)把设备挂在虚拟的platform bus下；

（）驱动注册的时候platform_driver_register()->driver_register()->bus_add_driver()->driver_attach()->bus_for_each_dev()，对每个挂在虚拟的
 platform bus的设备作__driver_attach()->driver_probe_device()，判断drv->bus->match()是否存在并且是否执行成功，此时通过指针执行platform_match，
 比较strncmp(pdev->name, drv->name, BUS_ID_SIZE)，如果相符就调用really_probe（实际就是执行的相应设备的platform_driver->probe(platform_device)，
 注意platform_drv_probe的_dev参数是由bus_for_each_dev的next_device获得）开始真正的探测加载，如果probe成功则绑定该设备到该驱动。

      当进入probe函数后，需要获取设备的资源信息，根据参数type所指定类型，例如IORESOURCE_MEM，来分别获取指定的资源。
struct resource * platform_get_resource(struct platform_device *dev, unsigned int type, unsigned int num);当然，也可以固定资源类型，
如获取资源中的中断号：struct int platform_get_irq(struct platform_device *dev, unsigned int num);

      probe函数一般完成硬件设备使能，struct resource的获取以及虚拟地址的动态映射和具体类型设备的注册（因为平台设备只是一种虚拟的设备类型);
remove函数完成硬件设备的关闭，struct resource以及虚拟地址的动态映射的释放和具体类型设备的注销。只要和内核本身运行依赖性不大的外围设备
 ( 换句话说只要不在内核运行所需的一个最小系统之内的设备 ), 相对独立的拥有各自独自的资源 (addresses and IRQs) ，都可以用platform_driver 实现。
如：lcd,usb,uart 等，都可以用platfrom_driver 写，而timer,irq等最小系统之内的设备则最好不用platfrom_driver 机制，实际上内核实现也是这样的。

http://blog.csdn.net/zhandoushi1982/article/details/5130207

http://blog.csdn.net/lichengtongxiazai/article/details/38941997    ＤＴ书写规范

http://www.right.com.cn/forum/thread-146260-1-1.html　　　ＤＴ（２）　

http://blog.csdn.net/zengxianyang/article/details/50732929　　ＤＴ驱动写法

http://blog.csdn.net/21cnbao/article/details/8457546　　ＤＴ宋宝华

http://www.cnblogs.com/dyllove98/archive/2013/07/03/3170178.html　获取ＤＴ资源

http://blog.csdn.net/zqixiao_09/article/details/50888795  　　　 platform_device字符驱动