UFS_DEVICE_DESCRIPTOR structure (ufs.h)

UFS_DEVICE_DESCRIPTOR is the main descriptor for Universal Flash Storage (UFS) devices and should be the first descriptor retrieved as it specifies the device class and sub-class and the protocol (command set) to use to access this device and the maximum number of logical units (LUs) contained within the device.

Syntax

typedef struct {
  UCHAR  bLength;
  UCHAR  bDescriptorIDN;
  UCHAR  bDevice;
  UCHAR  bDeviceClass;
  UCHAR  bDeviceSubClass;
  UCHAR  bProtocol;
  UCHAR  bNumberLU;
  UCHAR  bNumberWLU;
  UCHAR  bBootEnable;
  UCHAR  bDescrAccessEn;
  UCHAR  bInitPowerMode;
  UCHAR  bHighPriorityLUN;
  UCHAR  bSecureRemovalType;
  UCHAR  bSecurityLU;
  UCHAR  bBackgroundOpsTermLat;
  UCHAR  bInitActiveICCLevel;
  UCHAR  wSpecVersion[2];
  UCHAR  wManufactureDate[2];
  UCHAR  iManufacturerName;
  UCHAR  iProductName;
  UCHAR  iSerialNumberID;
  UCHAR  iOemID;
  UCHAR  wManufacturerID[2];
  UCHAR  bUD0BaseOffset;
  UCHAR  bUDConfigPLength;
  UCHAR  bDeviceRTTCap;
  UCHAR  wPeriodicRTCUpdate[2];
  UCHAR  bUFSFeaturesSupport;
  UCHAR  bFFUTimeout;
  UCHAR  bQueueDepth;
  UCHAR  wDeviceVersion[2];
  UCHAR  bNumSecureWPArea;
  UCHAR  dPSAMaxDataSize[4];
  UCHAR  dPSAStateTimeout;
  UCHAR  iProductRevisionLevel;
  UCHAR  Reserved[5];
  UCHAR  Reserved2[16];
  USHORT wHPBVersion;
  UCHAR  bHPBControl;
  UCHAR  Reserved3[12];
  UCHAR  dExtendedUFSFeaturesSupport[4];
  UCHAR  bWriteBoosterBufferPreserveUserSpaceEn;
  UCHAR  bWriteBoosterBufferType;
  UCHAR  dNumSharedWriteBoosterBufferAllocUnits[4];
} UFS_DEVICE_DESCRIPTOR, *PUFS_DEVICE_DESCRIPTOR;

Members

bLength

Specifies the length, in bytes, of this descriptor.

bDescriptorIDN

Specifies the type of the descriptor. This descriptor will have a value of UFS_DESC_DEVICE_IDN.

bDevice

Specifies the device type.

Value	Description
0x00	Device
All other values	Reserved for future use

bDeviceClass

Specifies the device class.

Value	Description
0x00	Mass Storage
All other values	Reserved for future use

bDeviceSubClass

Specifies the UFS mass storage subclasses in a bit map as follows:

Bit	Value
0	Bootable or Non-Bootable
1	Embedded or Removable
2	Reserved for JESD220-1 (UME)
All other values	Reserved for future use

bProtocol

Specifies the protocol support by the UFS device.

Value	Description
0x00	SCSI
All other values	Reserved for future use

bNumberLU

Specifies the number of logical units. This does not include the number of well known logical units.

bNumberWLU

Specifies the number of well known logical units.

bBootEnable

Specifies if a device's boot feature is enabled.

Value	Description
0x00	Boot feature disabled
0x01	Boot feature enabled
All other values	Reserved for future use

bDescrAccessEn

Indicates whether the device descriptor can be read after the partial initialization phase of the boot sequence.

Value	Description
0x00	Device Descriptor access disabled
0x01	Device Descriptor access enabled
All other values	Reserved for future use

bInitPowerMode

bInitPowerMode defines the power mode after device initialization or hardware reset.

Value	Description
0x00	UFS-Sleep mode
0x01	Active-mode
All other values	Reserved for future use

bHighPriorityLUN

bHighPriorityLUN defines the high priority logical unit.

bSecureRemovalType

Specifies the secure removal type.

Value	Description
0x00	Information removed by an erase of the physical memory
0x01	Information removed by overwriting the addressed locations with a single character followed by an erase
0x02	Information removed by overwriting the addressed locations with a character, its complement, then a random character
0x03	Information removed using a vendor defined mechanism.
All other values	Reserved for future use

bSecurityLU

Specifies if there is support for security logical units.

Value	Description
0x00	Not supported
0x01	Replay Protected Memory Block (RPMB)
All other values	Reserved for future use

bBackgroundOpsTermLat

bBackgroundOpsTermLat defines the maximum latency for starting data transmission when background operations are ongoing. The termination latency limit applies to two cases:

• When the device receives a COMMAND UFS Protocol Information Units (UPIU) with a transfer request. The device shall start the data transfer and send a DATA IN UPIU or a RTT UPIU within the latency limit.
• When the device receives QUERY REQUEST UPIU to clear the fBackgroundOpsEn Flag. The device is expected to terminate background operations within the latency limit.

bInitActiveICCLevel

bInitActiveICCLevel defines the bActiveICCLevel value after power on or reset. The range of the value is from 0x00 to 0x0F.

wSpecVersion[2]

Indicates the specification version in binary coded decimal (BCD) format.

wManufactureDate[2]

Specifies the manufacturing date in BCD format as 0xMMYY.

iManufacturerName

Contains an index value to the string which contains the manufacturer's name.

iProductName

Contains an index value to the string which contains the product's name.

iSerialNumberID

Contains an index value to the string which contains the serial number.

iOemID

Contains an index value to the string which contains the OEM ID.

wManufacturerID[2]

Specifies the manufacturer ID of the device.

bUD0BaseOffset

Specifies the offset of unit descriptor 0's configurable parameters within the configuration descriptor, UFS_CONFIG_DESCRIPTOR.

bUDConfigPLength

Total size of a UFS_UNIT_CONFIG_DESCRIPTOR's parameters.

bDeviceRTTCap

Specifies the maximum number of outstanding READY TO TRANSFER UPIU'S supported by device. The minimum value is 2.

wPeriodicRTCUpdate[2]

Specifies the frequency and method of real-time clock updates. Bits 10 to 15 are reserved.

bUFSFeaturesSupport

Specifies which features are supported on this device. A feature is supported if its related bit is set to 1.

Bit	Value
0	Field Firmware Update (FFU)
1	Production State Awareness (PSA)
2	Device Life Span
All other values	Reserved for future use

bFFUTimeout

The maximum time, in seconds, to which access to the device is limited or not possible through any ports associated due to execution of a WRITE BUFFER command.

bQueueDepth

Specifies the queue depth. If this member is equal to 0, the device implements the per-LU queuing architecture.

wDeviceVersion[2]

Specifies the device version.

bNumSecureWPArea

Specifies the total number of secure write protect areas supported by the device. The value of this member is between bNumberLU and 32.

dPSAMaxDataSize[4]

Specifies the maximum amount of data that can be written during the pre-soldering phase of the PSA flow.

dPSAStateTimeout

This member corresponds to bPSAStateTimeout (29h) in the JEDEC specification.

iProductRevisionLevel

Specifies the index to the string which contains the product revision level.

Reserved[5]

Reserved for future use.

Reserved2[16]

Reserved for future use.

wHPBVersion

Specifies the host performance booster version.

bHPBControl

Reserved3[12]

Reserved for future use.

dExtendedUFSFeaturesSupport[4]

dExtendedUFSFeaturesSupport is a bitmask indicating which extended features are supported.

bWriteBoosterBufferPreserveUserSpaceEn

Setting bWriteBoosterBufferPreserveUserSpaceEn to 0x01 avoids the reduction of the total user space that can be configured during provisioning, but might result in lower performance. If bWriteBoosterBufferPreserveUserSpaceEn is set to 0x00, the write booster buffer reduces the total user space that can be configured during provisioning.

bWriteBoosterBufferType

bWriteBoosterBufferType configures the the write booster buffer type. A value of 0x00 specifies logical unit dedicated buffer mode. A value of 0x01 specifies shared buffer mode.

dNumSharedWriteBoosterBufferAllocUnits[4]

dNumSharedWriteBoosterBufferAllocUnits specifies the write booster buffer size for a shared write booster buffer configuration.

Remarks

If bBootEnable in the UFS_DEVICE_DESCRIPTOR is set to zero or if the Boot Well Known Logical Unit is not mapped to an enabled logical unit, then the Boot Well Known Logical Unit shall terminate.

UFS_DEVICE_DESCRIPTOR is read only, some of its parameters may be changed by changing the corresponding parameter in UFS_UNIT_CONFIG_DESCRIPTOR.

Requirements

Requirement	Value
Minimum supported client	Windows 10, version 1709
Minimum supported server	Windows Server 2016
Header	ufs.h

See also

• UFS_CONFIG_DESCRIPTOR
• UFS_DEVICE_HEALTH_DESCRIPTOR
• UFS_GEOMETRY_DESCRIPTOR
• UFS_INTERCONNECT_DESCRIPTOR
• UFS_POWER_DESCRIPTOR
• UFS_RPMB_UNIT_DESCRIPTOR
• UFS_STRING_DESCRIPTOR
• UFS_UNIT_CONFIG_DESCRIPTOR
• UFS_UNIT_DESCRIPTOR
• Universal Flash Storage 4.0 specification