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ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 9-23
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9.5 Enabling or disabling AXI slave accesses
This section describes how to enable or disable AXI slave accesses to the cache RAMs. When
caches are accessible by the AXI slave interface, the caches are considered to be cache-off from
the processor. After turning the interface on or off, an
ISB
instruction must flush the pipeline so
that all subsequent instruction fetches return valid data.
The following code is an example of enabling AXI slave accesses to the cache RAMs:
MRC p15, 0, R1, c1, c0, 1 ; Read Auxiliary Control Register
ORR R1, R1, #0x1 <<24
DSB
MCR p15, 0, R1, c1, c0, 1 ; enabled AXI slave accesses to the cache RAMs
ISB
; Clean entire data cache. This routine will depend on the data cache size. It can be
omitted if it is known that the data cache has no dirty data
Fetch from uncached memory
Fetch from uncached memory
Fetch from uncached memory
Fetch from uncached memory
The following code is an example of disabling AXI slave accesses to the cache RAMs. No cache
invalidation is performed because it is assumed that, after accessing the cache RAMs, the AXI
slave interface restored the previously valid data to them.
MRC p15, 0, R1, c1, c0, 1 ; Read Auxiliary Control Register
BIC R1, R1, #0x1 <<24
DSB
MCR p15, 0, R1, c1, c0, 1 ; disabled AXI slave accesses to the cache RAMs
ISB
Fetch from cached memory
Fetch from cached memory
Fetch from cached memory
Fetch from cached memory