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 Pieralisilorenzo.pieralisi@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);
+}