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GITS_CWRITER, ITS Write Register

The GITS_CWRITER characteristics are:

Purpose

Specifies the offset from GITS_CBASER where software writes the next ITS command.

Configuration

RW fields in this register reset to architecturally UNKNOWN values.

Bits [63:32] and bits [31:0] are accessible separately.

Attributes

GITS_CWRITER is a 64-bit register.

Field descriptions

The GITS_CWRITER bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0OffsetRES0Retry
313029282726252423222120191817161514131211109876543210

Bits [63:20]

Reserved, RES0.

Offset, bits [19:5]

Bits [19:5] of the offset from GITS_CBASER. Bits [4:0] of the offset are zero.

This field resets to an architecturally UNKNOWN value.

Bits [4:1]

Reserved, RES0.

Retry, bit [0]

Writing this bit has the following effects:

RetryMeaning
0b0

No effect on the processing commands by the ITS.

0b1

Restarts the processing of commands by the ITS if it stalled because of a command error.

Note

If the processing of commands is not stalled because of a command error, writing 1 to this bit has no effect.

When read, this bit is RES0.

See The ITS Command Interface for more information.

If GITS_CWRITER is written with a value outside of the valid range specified by GITS_CBASER.Physical_Address and GITS_CBASER.Size, behavior is a CONSTRAINED UNPREDICTABLE choice, as follows:

  • The command queue is considered invalid, and no further commands are processed until GITS_CWRITER is written with a value that is in the valid range.
  • The value is treated as a valid UNKNOWN value.

An implementation might choose to report a system error in an IMPLEMENTATION DEFINED manner.

Accessing the GITS_CWRITER

GITS_CWRITER can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
GIC ITS control0x0088GITS_CWRITER

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0b0 access to this register is RW.
  • When IsAccessSecure() access to this register is RW.
  • When !IsAccessSecure() access to this register is RW.


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