On 7/7/2011 8:50 AM, Lorenzo Pieralisi wrote:
When a CLUSTER is powered down the SCU must be reinitialized on
warm-boot.
This patch adds a hook to reset the SCU, which implies invalidating
TAG RAMs and renabling it.
The scu virtual address is saved in a static variable when the SCU
is first enabled at boot; this allows common idle code to be
generic and avoid relying on platform code to get the address at
run-time.
On warm-boot the SCU TAG RAM is invalidated and the SCU enabled if
it is not already enabled.
The reset can be skipped altogether thanks to save/restore
framework flags.
Flushing D$ cache is cumbersome since the system just comes out of
reset, which invalidates caches in the process if needed (A9), that
is why the scu_enable function is not reused as it is to reset the SCU.
If the init function is extended, there might not be a need for
a SCU specific hook, since the init function can be reused to
reinitialize the SCU at boot provided it is removed from the init
section and kept in memory.
Signed-off-by: Lorenzo Pieralisi<lorenzo.pieral...@arm.com>
---
arch/arm/include/asm/smp_scu.h | 3 ++-
arch/arm/kernel/smp_scu.c | 33 ++++++++++++++++++++++++++++++---
2 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
index 4eb6d00..cfaa68e 100644
--- a/arch/arm/include/asm/smp_scu.h
+++ b/arch/arm/include/asm/smp_scu.h
@@ -8,7 +8,8 @@
#ifndef __ASSEMBLER__
unsigned int scu_get_core_count(void __iomem *);
void scu_enable(void __iomem *);
-int scu_power_mode(void __iomem *, unsigned int);
+int scu_power_mode(unsigned int);
+void scu_reset(void);
#endif
#endif
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index a1e757c..980ced9 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -20,6 +20,7 @@
#define SCU_INVALIDATE 0x0c
#define SCU_FPGA_REVISION 0x10
+static void __iomem *scu_va;
Change log and patch doesn't seems to match. I remember suggesting
this change to Russell when "scu_power_mode()" was introduced.
His preference was to have scu_base passed as part of the API.
/*
* Get the number of CPU cores from the SCU configuration
*/
@@ -36,6 +37,7 @@ void __init scu_enable(void __iomem *scu_base)
{
u32 scu_ctrl;
+ scu_va = scu_base;
scu_ctrl = __raw_readl(scu_base + SCU_CTRL);
/* already enabled? */
if (scu_ctrl& 1)
@@ -59,7 +61,7 @@ void __init scu_enable(void __iomem *scu_base)
* has the side effect of disabling coherency, caches must have been
* flushed. Interrupts must also have been disabled.
*/
-int scu_power_mode(void __iomem *scu_base, unsigned int mode)
+int scu_power_mode(unsigned int mode)
{
unsigned int val;
int cpu = smp_processor_id();
@@ -67,9 +69,34 @@ int scu_power_mode(void __iomem *scu_base, unsigned int mode)
if (mode> 3 || mode == 1 || cpu> 3)
return -EINVAL;
- val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu)& ~0x03;
+ val = __raw_readb(scu_va + SCU_CPU_STATUS + cpu)& ~0x03;
val |= mode;
- __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
+ __raw_writeb(val, scu_va + SCU_CPU_STATUS + cpu);
return 0;
}
+
+/*
+ * Reinitialise the SCU after power-down
+ */
+
+void scu_reset(void)
+{
+ u32 scu_ctrl;
+
+ scu_ctrl = __raw_readl(scu_va + SCU_CTRL);
+ /* already enabled? */
+ if (scu_ctrl& 1)
+ return;
+ /*
+ * SCU TAGS should be invalidated on boot-up
+ */
+ __raw_writel(0xffff, scu_va + SCU_INVALIDATE);
+ /*
+ * Coming out of reset, dcache invalidated
+ * no need to go through the whole hog again
+ * just enable the SCU and pop out
+ */
+ scu_ctrl |= 1;
+ __raw_writel(scu_ctrl, scu_va + SCU_CTRL);
+}
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