Quotin the ARM datasheet "When set, coherent linefill requests are
sent speculatively to the L2C-310 in parallel with the tag look-up. If
the tag look-up misses, the confirmed linefill is sent to the L2C-310
and gets RDATA earlier because the data request was already initiated
by the speculative request. "
Some SoC (such as the Armada 375/38x) can benefit of this feature. As
this is something related to the Cortex A9 and not specific to a SoC,
we can expose it in a common place.
Signed-off-by: Gregory CLEMENT <gregory.clem...@free-electrons.com>
---
arch/arm/include/asm/smp_scu.h | 3 +++
arch/arm/kernel/smp_scu.c | 22 ++++++++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
index 0393fbab8dd5..d9650dce48c7 100644
--- a/arch/arm/include/asm/smp_scu.h
+++ b/arch/arm/include/asm/smp_scu.h
@@ -26,6 +26,7 @@ static inline unsigned long scu_a9_get_base(void)
#ifdef CONFIG_HAVE_ARM_SCU
unsigned int scu_get_core_count(void __iomem *);
int scu_power_mode(void __iomem *, unsigned int);
+void scu_spec_linefills_enable(void __iomem *scu_base, bool enable);
#else
static inline unsigned int scu_get_core_count(void __iomem *scu_base)
{
@@ -35,6 +36,8 @@ static inline int scu_power_mode(void __iomem *scu_base,
unsigned int mode)
{
return -EINVAL;
}
+static inline void scu_spec_linefills_enable(void __iomem *scu_base,
+ bool enable) {}
#endif
#if defined(CONFIG_SMP) && defined(CONFIG_HAVE_ARM_SCU)
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index cfea41b41ad0..3fd21a495028 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -18,6 +18,7 @@
#define SCU_CTRL 0x00
#define SCU_CTRL_ENABLE BIT(1)
+#define SCU_CTRL_SPEC_LINEFILLS BIT(3)
#define SCU_CONFIG 0x04
#define SCU_CPU_STATUS 0x08
#define SCU_INVALIDATE 0x0c
@@ -88,3 +89,24 @@ int scu_power_mode(void __iomem *scu_base, unsigned int mode)
return 0;
}
+
+/*
+ * When enabled, coherent linefill requests are sent speculatively to
+ * the L2C-310 in parallel with the tag look-up
+ *
+ */
+void scu_spec_linefills_enable(void __iomem *scu_base, bool enable)
+{
+ u32 scu_ctrl;
+
+ scu_ctrl = readl_relaxed(scu_base + SCU_CTRL);
+ /* already enabled? */
+ if (scu_ctrl & SCU_CTRL_ENABLE)
+ return;
+ if (enable)
+ scu_ctrl |= SCU_CTRL_SPEC_LINEFILLS;
+ else
+ scu_ctrl &= ~SCU_CTRL_SPEC_LINEFILLS;
+
+ writel_relaxed(scu_ctrl, scu_base + SCU_CTRL);
+}
--
1.8.1.2
--
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