Linux device driver Development-platform device driver

A new device driver model-platform (platform) device driver, platform device driver (platform_device) and platform driver (Platform_driver) is introduced into the Linux2.6 kernel, The introduction of platform devices makes Linux device drivers more portable.

First, platform equipment
Platform Device structure:

1 structPlatform_device {2     Const Char* NAME;/*Device Name*/3     intID;4     structDevice Dev;/*Device Structural Body*/5U32 num_resources;/*number of device resources*/6     structResource * resource;/*Equipment Resources*/7 8     Const structPLATFORM_DEVICE_ID *Id_entry;9 Ten     /*Arch Specific Additions*/ One     structPdev_archdata Archdata; A};

Platform equipment is mainly to provide equipment resources and platform data to the platform driver, resource as an array of equipment resources, types have ioresource_io, Ioresource_mem, IORESOURCE_IRQ, IORESOURCE_DMA, Ioresource_dma. The following is a network card chip DM9000 Peripheral resources:

1 Static structResource dm9000_resources[] = {2[0] = {3. Start =s3c64xx_pa_dm9000,4. end = s3c64xx_pa_dm9000 +3,5. Flags =Ioresource_mem,6     },7[1] = {8. Start = s3c64xx_pa_dm9000 +4,9. end = s3c64xx_pa_dm9000 + s3c64xx_sz_dm9000-1,Ten. Flags =Ioresource_mem, One     }, A[2] = { -. Start = Irq_eint (7), -. End = Irq_eint (7), the. Flags = IORESOURCE_IRQ |Irqf_trigger_high, -     }, -};

Dm9000_resources There are three device resources, the first is the Ioresource_mem type, indicating that the first resource memory start address is s3c64xx_pa_dm9000 End address is s3c64xx_pa_dm9000 + 3, the second is also the Ioresource_mem type, indicating that the second resource memory start address is s3c64xx_pa_dm9000 + 4 End address is s3c64xx_pa_dm9000 + s3c64xx_sz_dm9000- 1, the third is a IORESOURCE_IRQ type, indicating that the interrupt number is Irq_eint (7).

1 structDevice {2     structDevice *parent;3 4     structDevice_private *p;5 6     structKobject kobj;7     Const Char*init_name;/*Initial name of the device*/8     structDevice_type *type;9 Ten     structMutex mutex;/*Mutex to synchronize calls to One * its driver. A                      */ -  -     structBus_type *bus;/*type of bus device is on*/ the     structDevice_driver *driver;/*which driver have allocated this - Device*/ -     void*platform_data;/*Platform specific data, device - core doesn ' t touch it*/ +     ... -};

The struct device structure has an important member Platform_data, which is an important member of platform device and platform driver for data transfer.

Platform Device Registration:

1 int platform_device_register (struct platform_device *pdev);

Platform_device_register () invokes the Platform_device_register () function to add it to the subsystem after the platform device has been initialized accordingly.

Platform Device Logoff:

1 void platform_device_unregister (struct platform_device *pdev);

The Platform_device_unregister () function removes the device resource from the subsystem after it has been freed.

Platform Device templates:

1 Static structResource Xxx_resource =2 {3[0] =4     {5. Start = ...,6. end = ...,7. Flags = ...,8     },9[1] =Ten     { One         ... A     } -     ... - }; the  - Static structXxx_plat_data Xxx_data = - { -     ... + }; -  + Static structPlatform_device Xxx_platform_device = A { at. Name =NAME, -. num_resources =array_size (xxx_resource), -. Resource =Xxx_resource, -. Dev = -     { -. Platform_data = &Xxx_data, in     } - }; to  + Static int__init Xxx_device_init (void) - { the     ... *     /*Registering platform Devices*/ $Platform_device_register (&xxx_platform_device);Panax Notoginseng     ... - } the  + Static void__exit Xxx_device_exit (void) A { the     ... +     /*Unregister platform Devices*/ -Platform_device_unregister (&xxx_platform_device); $     ... $}

Second, platform-driven
Platform-driven structure:

1 structPlatform_driver {2     int(*probe) (structPlatform_device *);3     int(*remove) (structPlatform_device *);4     void(*shutdown) (structPlatform_device *);5     int(*suspend) (structPlatform_device *, pm_message_t state);6     int(*resume) (structPlatform_device *);7     structDevice_driver driver;8     Const structPLATFORM_DEVICE_ID *id_table;9};

The name of the platform-driven structure driver member must be identical to the name member inside the platform device structure, and when the system registers a device, it is matched by the name member inside the device structure and the name member in the platform driver driver. When the match succeeds, the platform-driven probe function is called,
It is common to get the resources and private data of the platform device and initialize the device in the probe function.

Get Device resources:

1 struct resource *platform_get_resource (structintint num);

The Platform_get_resource () function is used to obtain resources for platform devices, dev for platform device, type for platform device resource, num for Platform resource number (two for resource number 0, 1 for a resource).

Platform-driven registration:

1 int platform_driver_register (struct platform_driver *drv);

The Platform_driver_register () function completes the platform-driven registration, which is called when the driver module is loaded.

Platform-driven logoff:

1 void platform_driver_unregister (struct platform_driver *drv);

The Platform_driver_unregister () function completes the platform-driven logoff, which is called when the driver module is unloaded.

Platform-driven templates:

1 Static int__devinit Xxx_probe (structPlatform_device *Pdev)2 {3     structXxx_plat_data *pdata = pdev->dev.platform_data;/*Get Private Data*/4Platform_get_resource (PDEV,XXX,X);/*Get device Resources*/5     ...6 }7 8 Static structPlatform_driver Xxx_platform_driver =9 {Ten. Probe =Xxx_probe, One. remove =__devexit_p (xxx_remove), A. Driver = -     { -. Name = Name,/*consistent with platform device name*/ the         ... -     }, -     ... - }; +  - Static int__init Xxx_driver_init (void) + { A     ... at     /*Driver Registration*/ -Platform_driver_register (&xxx_platform_driver); -     ... - } -  - Static void__exit Xxx_driver_exit (void) in { -     ... to     /*Driver Logoff*/ +Platform_driver_unregister (&xxx_platform_driver); -     ... the}

Linux device driver Development-platform device driver