Re: [PATCH 4/5] ARM: scu: Move register defines to header file

Russell King - ARM Linux
2011-02-04T11:31:14Z

On Fri, Feb 04, 2011 at 04:16:07PM +0530, Santosh Shilimkar wrote:
> > -----Original Message-----
> > From: Russell King - ARM Linux [mailto:linux@arm.linux.org.uk]
> > Sent: Friday, February 04, 2011 4:11 PM
> > To: Santosh Shilimkar
> > Cc: catalin.marinas@arm.com; linus.ml.walleij@gmail.com; linux-
> > omap@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> > ccross@android.com
> > Subject: Re: [PATCH 4/5] ARM: scu: Move register defines to header
> > file
> >
> > On Tue, Jan 25, 2011 at 11:53:35PM +0530, Santosh Shilimkar wrote:
> > > After fixing the 3rd version for base address break, I was able to
> > > use this patch and test it. Seems to work. SMC related stuff can
> > > be ignored because OMAP4 ES1.0 doesn't have functional PM hardware
> > > support.
> >
> > I think I'd prefer to do as the other functions do, and pass in the
> > scu base address from the platform code. It's potentially more
> > efficient for platforms which have a fixed SCU base address.
> Ok. I can fix that

8<------
Subject: [PATCH] ARM: smp: add function to set WFI low-power mode for SMP CPUs

Add a function to set the SCU low-power mode for SMP CPUs. This
centralizes this functionality rather than having to expose the
SCU register definitions to each platform.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/include/asm/smp_scu.h | 5 +++++
arch/arm/kernel/smp_scu.c | 24 ++++++++++++++++++++++++
2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
index 2376835..800860d 100644
--- a/arch/arm/include/asm/smp_scu.h
+++ b/arch/arm/include/asm/smp_scu.h
@@ -1,7 +1,12 @@
#ifndef __ASMARM_ARCH_SCU_H
#define __ASMARM_ARCH_SCU_H

+#define SCU_PM_NORMAL 0
+#define SCU_PM_DORMANT 2
+#define SCU_PM_POWEROFF 3
+
unsigned int scu_get_core_count(void __iomem *);
void scu_enable(void __iomem *);
+int scu_power_mode(void __iomem *, unsigned int);

#endif
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index 9ab4149..0ba329a 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -50,3 +50,27 @@ void __init scu_enable(void __iomem *scu_base)
*/
flush_cache_all();
}
+
+/*
+ * Set the executing CPUs power mode as defined. This will be in
+ * preparation for it executing a WFI instruction.
+ *
+ * This function must be called with preemption disabled, and as it
+ * 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)
+{
+ unsigned int val;
+ int cpu = smp_processor_id();
+ int shift;
+
+ if (mode > 3 || mode == 1 || cpu > 3)
+ return -EINVAL;
+
+ val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
+ val |= mode;
+ __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
+
+ return 0;
+}
--
1.6.2.5