3.3 Protection control translation

For protection control, the AHB5 to AXI5 bridge maps the hprot and hnonseq AHB signals to the axprot and axcache AXI signals. The bridge also maps hprot[6] to axdomain[1:0].

The following table shows how the AHB5 to AXI5 bridge generates the AXI5 signals from the AHB5 signals.

Table 3-3 AHB5 to AXI5 protection control mapping

AXI signals AXI bit number, function Value is derived from AHB signal:
arprot[2:0] and awprot[2:0] Bit[2], Opcode/Data !hprot[0]
Bit[1], Secure hnonsec
Bit[0], Privileged hprot[1]
arcache[3:0] Bit[3], Other Allocate Either:
  • hprot[4] for Non-exclusive accesses.
  • arcache[3] is set LOW for Exclusive accesses.
Bit[2], Allocate Either:
  • hprot[5] for Non-exclusive accesses.
  • arcache[2] is set LOW for Exclusive accesses.
Bit[1], Modifiable hprot[3]
Bit[0], Bufferable hprot[2]
awcache[3:0] Bit[3], Allocate Either:
  • hprot[5] for Non-exclusive accesses.
  • awcache[3] is set LOW for Exclusive accesses.
Bit[2], Other Allocate Either:
  • hprot[4] for Non-exclusive accesses.
  • awcache[2] is set LOW for Exclusive accesses.
Bit[1], Modifiable hprot[3]
Bit[0], Bufferable hprot[2]
ardomain[1:0] and awdomain[1:0] Bits[1:0], shareability domain

hprot[6]. The AXI signal is set to:

  • 0b11 when hprot[6] is LOW.
  • 0b01 when hprot[6] is HIGH.

ardomain[1:0] and awdomain[1:0] do not exist in the AXI protocol. The ACE protocol uses a concept that is called shareability domains and the axdomain[1:0] signals indicate the shareability domain of a transaction. See the Arm® AMBA® AXI and ACE Protocol Specification for more information.

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