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Subject[PATCH 2/3] ARC: ARCv2: support loop buffer (LPB) disabling
Date
On HS cores, loop buffer (LPB) is programmable in runtime and can
be optionally disabled.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
arch/arc/Kconfig | 6 ++++++
arch/arc/kernel/head.S | 8 ++++++++
2 files changed, 14 insertions(+)

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 2d4f85dc914e..270504d4fdf5 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -471,6 +471,12 @@ config ARC_IRQ_NO_AUTOSAVE
This is programmable and can be optionally disabled in which case
software INTERRUPT_PROLOGUE/EPILGUE do the needed work

+config ARC_LPB_DISABLE
+ bool "Disable loop buffer (LPB)"
+ help
+ On HS cores, loop buffer (LPB) is programmable in runtime and can
+ be optionally disabled.
+
endif # ISA_ARCV2

endmenu # "ARC CPU Configuration"
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 6eb23f1545ee..17fd1ed700cc 100644
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -59,6 +59,14 @@
bclr r5, r5, STATUS_AD_BIT
#endif
kflag r5
+
+#ifdef CONFIG_ARC_LPB_DISABLE
+ lr r5, [ARC_REG_LPB_BUILD]
+ breq r5, 0, 1f ; LPB doesn't exist
+ mov r5, 1
+ sr r5, [ARC_REG_LPB_CTRL]
+1:
+#endif /* CONFIG_ARC_LPB_DISABLE */
#endif
; Config DSP_CTRL properly, so kernel may use integer multiply,
; multiply-accumulate, and divide operations
--
2.21.3
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