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ARC: ARCv2: handle DSP presence in HW

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In case of DSP extension presence in HW some instructions
(related to integer multiply, multiply-accumulate, and divide
operation) executes on this DSP execution unit. So their
execution will depend on dsp configuration register (DSP_CTRL)
As we want these instructions to execute the same way regardless
of DSP presence we need to set DSP_CTRL properly.

NOTE:
we do the same adjustments in Linux kernel, see in kernel tree:
commit 4827d0cf744e ("ARC: handle DSP presence in HW")

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
This commit is contained in:
Eugeniy Paltsev 2020-04-22 18:33:21 +03:00 committed by Alexey Brodkin
parent d202f67db0
commit 61c151693b
2 changed files with 16 additions and 0 deletions
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1
arch/arc/include/asm/arcregs.h
View file

@ -100,6 +100,7 @@
/* DSP-extensions related auxiliary registers */
#define ARC_AUX_DSP_BUILD 0x7A
#define ARC_AUX_DSP_CTRL 0x59F
/* ARC Subsystems related auxiliary registers */
#define ARC_AUX_SUBSYS_BUILD 0xF0

15
arch/arc/lib/start.S
View file

@ -61,6 +61,21 @@ ENTRY(_start)
1:
#endif
#ifdef CONFIG_ISA_ARCV2
; In case of DSP extension presence in HW some instructions
; (related to integer multiply, multiply-accumulate, and divide
; operation) executes on this DSP execution unit. So their
; execution will depend on dsp configuration register (DSP_CTRL)
; As we want these instructions to execute the same way regardless
; of DSP presence we need to set DSP_CTRL properly.
lr r5, [ARC_AUX_DSP_BUILD]
bmsk r5, r5, 7
breq r5, 0, 1f
mov r5, 0
sr r5, [ARC_AUX_DSP_CTRL]
1:
#endif
#ifdef __ARC_UNALIGNED__
/*
* Enable handling of unaligned access in the CPU as by default