1. How to Write an ATAport Miniport

2. Outline Current ATA Environment ATAport Solution ATAport Features
ATAport Model
Best Known Practices

3. Industry Activities Many Vendor ATA drivers are Scsiport miniports
Creating an inconsistent behavior around ATA command handling
Emphasis on consumer RAID
The introduction of SATA interconnect
Requires new feature support
Has a richer host controller interface
Still uses ATA, which is a duplicate of a significant portion of the ATA driver infrastructure

4. ATAport Goals Extensibility Compatibility Flexibility Diagnosability
Support innovations in the ATA industry
Compatibility
Accommodates existing and new hardware
Flexibility
Enables Vendor value add
Diagnosability

5. ATAport Features ATA/ATAPI 7 support SATA support Command Queuing
Forced Unit Access
Advanced Power Management
SATA support
Support for greater than 2 channels/controller
Support for greater than 2 devices/channel
Command Queuing
Channel-based queuing
Device-based queuing

6. ATAport Features Support for Message Signal Interrupts Hotplug
Provides greater flexibility and stability in interrupts
Hotplug
More granular Power Management control
ATAport provides a flexible miniport interface for vendor value add

7. ATAport Model: Port Services
Translation of upper OS storage requests into ATA protocol
Automatic Generation of Sense Data for ATA devices
Push model as opposed to a Pull model
Improved IDE Request Block that more accurately maps to the underlying hardware model

8. ATAport Model: Port Services
Asynchronous device reset management
Hierarchical reset (device and channel)
Asynchronous device power management
Per-channel granularity
Power, resets, queuing, interrupts
I/O is concurrent

9. ATAport Model: Miniport Capabilities
Negotiation of Device parameters
Transfer mode
Bytes/Sector
Sectors/block
LBA sectors/disk
Removable media
Decide on channel- or device-based command queuing
Control the timeout on a per-request basis
Request the mapping of data buffers on a per request basis
Miniport can participate in the queuing policy
Selection of depth, freezing,retry

10. ATAport Interface Illustration
Default Miniport
ATAport
Channel 0
Channel 1
Disk
Channel Interface
Disk
Controller
Interface
Port IO
Pciidex
Vendor Miniport
Hardware CS
BAR

11. Controller Interface ATAport Miniport Driver Entry AtaPortInitializeEx
Start Controller
AdapterControl w/ IdeStart
AtaControllerIntitialize
Enumerate Channels
ControllerChannelEnabled
AtaControllerChannelEnabled
ChannelInitialize

12. Channel Interface ATAport Miniport Initialize Channel
ChannelInitialize
ChannelInitialize
Start Channel
HwControl w/ IdeStart
AtaChannelControl
Configure Devices
AtaHwIntitialize
HwIntitialize
I/O
HwBuildIO
AtaHwBuildIO
HwStartIO
AtaHwStartIO
HwInterrupt
AtaHwInterrupt

13. Keep track of extensions in global variables
Trick: Extensions
Keep track of extensions in global variables
Finding Channel Extensions
!devstack 0x8245dbf8
!DevObj !DrvObj !DevExt ObjectName
8246a030 \Driver\disk a0e8 disk
8245c478 \Driver\ACPI ac a
8245dbf8 \Driver\msahci dcb0 ataport
Channel extension is DevExt +0x84
Finding the Controller Extension
8246a030 \Driver\msahci a0e8 PciIde2
8245dbf8 \Driver\pci dcb0 NTPNP_PCI0012
Controller Extension is DevExt +0x88
No device objects during crashdump

14. Best Known Practices: CrashDump/Hybernate
Creates an unused copy of the miniport at boot time
Has no driver stack, runs single threaded, processes 1 IO at a time
Can be identified by ChannelConfiguration.ChannelMode
Cannot touch PCI config space
Cannot use more than 30KB of uncached extension per channel

15. AtaPortStallExecution
Trick: Stalling
AtaPortStallExecution
Spinlocks the CPU for x microseconds
Should not be used for greater than 1 millisecond delays
AtaPortRequestTimer
Causes the port driver to trigger a callback routine after x microseconds
Should be used for greater than 1 millisecond delays
Best when used with multiphase functions
Remember crashdump is single-threaded

16. Best Known Practices: Memory Allocation
Uncached Extension allocation can only be done during Start Channel
AtaPortGetPhysicalAddress retrieves physical address for:
IRB's data buffer
IRB's IrbExtension
Miniport's uncached extension
SGList Entries and Page Breaks

17. Best Known Practices: Queuing
Per Channel
Use IDE_UNTAGGED for TargetID on QueueTag function calls
Per Device
Use TargetID on QueueTag function calls
Always, Always pause the queue with AtaPortDeviceBusy when failing an IRB with IRB_STATUS_BUSY

18. Best Known Practices: Bus Configuration Changes
ChannelEnable is optional and only used to validate the channel
Critical hardware operations should not be done in ChannelEnable
ChannelEnable will only be called during QueryDeviceRelations
Use AtaPortBusChangeDetected to reenumerate a channel
Use AtaPortDeviceArrived and AtaPortDeviceRemoved for device hotplug

19. Best Known Practices: IO Error Reporting
STATUS_BUSY
Host is busy
Make sure to pause the queues with AtaPortDeviceBusy
SELECTION_TIMEOUT
Device busy
Not necessarily retried
IRB AtaStatus and Error fields
Only valid on Selection_Timeout, and Error

20. Summary
ATAport is an improved port-miniport interface for ATA-based controllers
ATAport supports the latest ATA and architecture features

21. Additional Resources ATA Miniport Interface List of Specifications
Documented in the WDK
List of Specifications
ATA -
SATA -
SCSI -
AHCI -

22. © 2005 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.