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ARM: implement some Cortex-A9 errata workarounds

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Various errata exist in the Cortex-A9 CPU, and may be worked around by
setting some bits in a CP15 diagnostic register. Add code to implement
the workarounds, enabled by new CONFIG_ options.

This code was taken from the Linux kernel, v3.8, arch/arm/mm/proc-v7.S,
and modified to remove the logic to conditionally apply the WAR (since we
know exactly which CPU we're running on given the U-Boot configuration),
and use r0 instead of r10 for consistency with the rest of U-Boot's
cpu_init_cp15().

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Stephen Warren 2013-02-26 12:28:27 +00:00 committed by Albert ARIBAUD
parent ef123c5253
commit 0678587fb6
2 changed files with 29 additions and 0 deletions
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10
README
View file

@ -485,6 +485,16 @@ The following options need to be configured:
Thumb2 this flag will result in Thumb2 code generated by
GCC.
CONFIG_ARM_ERRATA_742230
CONFIG_ARM_ERRATA_743622
CONFIG_ARM_ERRATA_751472
If set, the workarounds for these ARM errata are applied early
during U-Boot startup. Note that these options force the
workarounds to be applied; no CPU-type/version detection
exists, unlike the similar options in the Linux kernel. Do not
set these options unless they apply!
- Linux Kernel Interface:
CONFIG_CLOCKS_IN_MHZ

19
arch/arm/cpu/armv7/start.S
View file

@ -309,6 +309,25 @@ ENTRY(cpu_init_cp15)
orr r0, r0, #0x00001000 @ set bit 12 (I) I-cache
#endif
mcr p15, 0, r0, c1, c0, 0
#ifdef CONFIG_ARM_ERRATA_742230
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 4 @ set bit #4
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_743622
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 6 @ set bit #6
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_751472
mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register
orr r0, r0, #1 << 11 @ set bit #11
mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
#endif
mov pc, lr @ back to my caller
ENDPROC(cpu_init_cp15)