From 61c151693ba7129fbe7864a8486bca4e36046d19 Mon Sep 17 00:00:00 2001 From: Eugeniy Paltsev Date: Wed, 22 Apr 2020 18:33:21 +0300 Subject: [PATCH] ARC: ARCv2: handle DSP presence in HW 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 Signed-off-by: Alexey Brodkin --- arch/arc/include/asm/arcregs.h | 1 + arch/arc/lib/start.S | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h index fff6591c68..f3cd4a889a 100644 --- a/arch/arc/include/asm/arcregs.h +++ b/arch/arc/include/asm/arcregs.h @@ -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 diff --git a/arch/arc/lib/start.S b/arch/arc/lib/start.S index 8c744f5be7..016ae85be2 100644 --- a/arch/arc/lib/start.S +++ b/arch/arc/lib/start.S @@ -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 -- 2.25.1