Stratix® 10 Hard Processor System Technical Reference Manual

ID 683222
Date 8/15/2024
Public
Document Table of Contents

7.3.3.2. FPGA-to-HPS CCU to SDRAM/OCRAM Memory (Cache Allocate)

If your logic issues a Cache Allocate transaction, the CCU maintains coherency and allocates in the cache. This is useful when you want to maintain coherency and keep data available in the system with minimal latency, so the masters avoid traversing to the external memory for each transaction.

Reads

  • On cache hits, read data is returned by the cache.
  • On cache misses, read data is returned from main memory and allocated (stored) in cache.
ATTRIBUTE VALUE NOTE
ARDOMAIN[1:0] ’b01 Inner Sharable
ARBAR[1:0] ‘b00 Normal access, respecting barriers
ARSNOOP[3:0] ‘b0000 ReadOnce
ARCACHE[3:0] ‘b1111 Write-back Read-allocate
ARPROT[2:0] ‘b011 or ‘b010

Privileged access. Non-Secure access. Data access

(or could be ‘b010 for Unprivileged access)

ARLEN[7:0]

The burst length for:

WRAP burst type must be 1, 2, 4, 8 or 16 transfers.

INCR burst type is 1 to 256 transfers.

ARSIZE[2:0] The number of bytes in a transfer must be equal to the data bus width (128 bits)
ARBURST[1:0] ‘b01 or ‘b10 Must be INCR(‘b01) or WRAP(‘b10)
ARLOCK[1:0] ‘b00 Must be normal access
ARQOS Quality of Service. QoS identifier sent for each transaction. Implemented only in AXI4.

Writes

  • On cache hits, write data is stored in cache.
  • On cache misses, write data is allocated (stored) in cache.
ATTRIBUTE VALUE NOTE
AWDOMAIN[1:0] ’b01 Inner Sharable
AWBAR[1:0] ‘b00 Normal access, respecting barriers
AWSNOOP[2:0] ‘b000 WriteUnique (could be ‘b001 for WriteLineUnique)
AWCACHE[3:0] ‘b1111 Write-back Write-allocate
AWPROT[2:0] ‘b011 or ‘b010

Privileged access. Non-Secure access. Data access

(or could be ‘b010 for Unprivileged access)

AWLEN[7:0]

The burst length for:

WRAP burst type must be 1, 2, 4, 8 or 16 transfers.

INCR burst type is 1 to 256 transfers.

AWSIZE[2:0] The number of bytes in a transfer must be equal to the data bus width (128 bits)
AWBURST[1:0] ‘b01 or ‘b10 Must be INCR(‘b01) or WRAP(‘b10)
AWLOCK[1:0] ‘b00 Must be normal access
AWQOS Quality of Service. QoS identifier sent for each transaction. Implemented only in AXI4.