EDK II UEFI Driver Writer's Guide
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EDK II UEFI Driver Writer's Guide
Introduction
Tables
Figures
Examples
Acknowledgements
1 Introduction
2 UEFI Driver Implementation Checklist
3 Foundation
4 General Driver Design Guidelines
5 UEFI Services
6 UEFI Driver Categories
7 Driver Entry Point
8 Private Context Data Structures
9 Driver Binding Protocol
10 UEFI Service Binding Protocol
11 UEFI Driver and Controller Names
12 UEFI Driver Configuration
13 UEFI Driver Diagnostics
14 Driver Health Protocol
15 Driver Family Override Protocol
16 Driver Supported EFI Version Protocol
17 Bus-Specific Driver Override Protocol
18 PCI Driver Design Guidelines
19 USB Driver Design Guidelines
20 SCSI Driver Design Guidelines
20.1 SCSI Host Controller Driver
20.1.1 Single-Channel SCSI Adapters
20.1.2 Multi-Channel SCSI Adapters
20.1.3 SCSI Adapters with RAID
20.1.4 Implementing driver binding protocol
20.1.5 Implementing Extended SCSI Pass Thru Protocol
20.1.6 SCSI command set device considerations
20.1.7 Discover a SCSI channel
20.1.8 SCSI Device Path
20.2 SCSI Bus Driver
20.3 SCSI Device Driver
21 ATA Driver Design Guidelines
22 Text Console Driver Design Guidelines
23 Graphics Driver Design Guidelines
24 Mass Storage Driver Design Guidelines
25 Network Driver Design Guidelines
26 User Credential Driver Design Guidelines
27 Load File Driver Design Guidelines
28 IPF Platform Porting Considerations
29 EFI Byte Code Porting Considerations
30 Building UEFI Drivers
31 Testing and Debugging UEFI Drivers
32 Distributing UEFI Drivers
Appendix A EDK II File Templates
Appendix B EDK II Sample Drivers
Appendix C Glossary
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20.1.4 Implementing driver binding protocol
A SCSI host controller driver follows the UEFI driver model, so the image entry point of a SCSI host controller driver installs the Driver Binding Protocol instance on the image handle. All three of the services in the Driver Binding Protocol-Supported(), Start(), and Stop()-must be implemented by a SCSI host controller driver.

20.1.4.1 Supported()

The Supported() function tests to see if a given controller handle is SCSI adapter the driver knows how to manage. In this function, a SCSI host controller driver checks to see if the EFI_DEVICE_PATH_PROTOCOL and EFI_PCI_IO_PROTOCOL are present to ensure the handle that is passed in represents a PCI device. In addition, a SCSI host controller driver checks the ClassCode, VendorId, and DeviceId from the device's PCI configuration header to see if it is a conformant SCSI adapter that can be managed by the SCSI host controller driver.

20.1.4.2 Start()

The Start() function tells the SCSI host controller driver to start managing the SCSI host controller. In this function, a single channel SCSI host controller driver uses chipspecific knowledge to perform the following tasks:
  • Initialize the SCSI host controller.
  • Enable the PCI device.
  • Allocate resources.
  • Construct data structures for the driver to use.
  • Install the Extended SCSI Pass Thru Protocol instance on the same handle that
    has the PCI I/O Protocol.
If the SCSI adapter is a multi-channel adapter, then the driver should also do the following:
  • Enumerate the SCSI channels that are supported by the SCSI host controller.
  • Create child handles for each physical SCSI channel.
  • Append the device path for each channel handle.
  • Install the Device Path Protocol and Extended SCSI Pass Thru Protocol on
    every newly created channel handle.

20.1.4.3 Stop()

The Stop() function performs the opposite operations as Start(). Generally speaking, a SCSI driver is required to do the following:
  • Disable the SCSI adapter.
  • Release all resources that were allocated for this driver.
  • Close the protocol instances that were opened in the Start()function.
  • Uninstall the protocol interfaces that were attached on the host controller
    handle.
In general, if it is possible to design a SCSI host controller driver to create one child at a time, it should do so to support the rapid boot capability in the UEFI driver model.
Each of the channel child handles created in Start() must contain a Device Path Protocol instance and a Extended SCSI Pass Thru abstraction layer.
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20.1.3 SCSI Adapters with RAID
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20.1.5 Implementing Extended SCSI Pass Thru Protocol
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Outline
20.1.4.1 Supported()
20.1.4.2 Start()
20.1.4.3 Stop()