Visible to Intel only — GUID: xfh1481129239939
Ixiasoft
Visible to Intel only — GUID: xfh1481129239939
Ixiasoft
3.5.10. ACE Bus Interface
The ACE bus interface operates in the mpu_ccu_clk domain, which is mpu_clk/2. This bus provides an AXI3 compatibility mode with support for privilege level accesses through the ARPROTM[0] and AWPROTM[0] signals.
The Cortex* -A53 MPCore processor does not generate any FIXED bursts and all WRAP bursts fetch a complete cache line starting with the critical word first. A burst does not cross a cache line boundary. The cache linefill fetch length is always 64 bytes. The Cortex* -A53 generates only a subset of all possible AXI transactions on the master interface.
For WriteBack transfers the supported transfers are:
- WRAP 4 128-bit for read transfers (linefills).
- INCR 4 128-bit for write transfers (evictions).
- INCR N (N:1, 2, or 4) 128-bit write transfers (read allocate).
For non-cacheable transactions:
- INCR N (N:1, 2, or 4) 128-bit for write transfers.
- INCR N (N:1, 2, or 4) 128-bit for read transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit for read transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit for write transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit for exclusive write transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit for exclusive read transfers.
For Device transactions:
- INCR N (N:1, 2, or 4) 128-bit read transfers.
- INCR N (N:1, 2, or 4) 128-bit write transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit read transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit write transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit exclusive read transfers.
- INCR 1 8-bit, 16-bit, 32-bit, 64-bit, and 128-bit exclusive write transfers.
For translation table walk transactions INCR 1 32-bit, and 64-bit read transfers.
The following characteristics apply to AXI transactions:
- WRAP bursts are only 128-bit.
- INCR 1 can be any size for read or write.
- INCR burst, more than one transfer, are only 128-bit.
- No transaction is marked as FIXED.
- Write transfers with all, some or no byte strobes HIGH can occur.