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ARM: 8955/1: virt: Relax arch timer version check during early boot

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Updates to the Generic Timer architecture allow ID_PFR1.GenTimer to
have values other than 0 or 1 while still preserving backward
compatibility. At the moment, Linux is quite strict in the way it
handles this field at early boot and will not configure arch timer if
it doesn't find the value 1.

Since here use ubfx for arch timer version extraction (hyb-stub build
with -march=armv7-a, so it is safe)

To help backports (even though the code was correct at the time of writing)

Fixes: 8ec58be9f3 ("ARM: virt: arch_timers: enable access to physical timers")
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Vladimir Murzin 2020-01-20 15:07:46 +01:00 committed by Russell King
parent 927d780ee3
commit 6849b5eba1
1 changed files with 3 additions and 4 deletions
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7
arch/arm/kernel/hyp-stub.S
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@ -146,10 +146,9 @@ ARM_BE8(orr r7, r7, #(1 << 25)) @ HSCTLR.EE
#if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
@ make CNTP_* and CNTPCT accessible from PL1
mrc p15, 0, r7, c0, c1, 1 @ ID_PFR1
lsr r7, #16
and r7, #0xf
cmp r7, #1
bne 1f
ubfx r7, r7, #16, #4
teq r7, #0
beq 1f
mrc p15, 4, r7, c14, c1, 0 @ CNTHCTL
orr r7, r7, #3 @ PL1PCEN | PL1PCTEN
mcr p15, 4, r7, c14, c1, 0 @ CNTHCTL