[PATCH v4 15/15] ARM: vexpress: Select multi-cluster SMP operation if required

[Nicolas Pitre]

On Fri, 5 Apr 2013, Olof Johansson wrote:

> On Tue, Feb 05, 2013 at 12:22:12AM -0500, Nicolas Pitre wrote:
> > From: Jon Medhurst <tixy at linaro.org>
> > 
> > Signed-off-by: Jon Medhurst <tixy at linaro.org>
> > Signed-off-by: Nicolas Pitre <nicolas.pitre at linaro.org>
> > Reviewed-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
> > ---
> >  arch/arm/mach-vexpress/core.h    |  2 ++
> >  arch/arm/mach-vexpress/platsmp.c | 12 ++++++++++++
> >  arch/arm/mach-vexpress/v2m.c     |  2 +-
> >  3 files changed, 15 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/mach-vexpress/core.h b/arch/arm/mach-vexpress/core.h
> > index f134cd4a85..3a761fd76c 100644
> > --- a/arch/arm/mach-vexpress/core.h
> > +++ b/arch/arm/mach-vexpress/core.h
> > @@ -6,6 +6,8 @@
> >  
> >  void vexpress_dt_smp_map_io(void);
> >  
> > +void vexpress_smp_init_ops(void);
> > +
> >  extern struct smp_operations	vexpress_smp_ops;
> >  
> >  extern void vexpress_cpu_die(unsigned int cpu);
> > diff --git a/arch/arm/mach-vexpress/platsmp.c b/arch/arm/mach-vexpress/platsmp.c
> > index c5d70de9bb..667344b479 100644
> > --- a/arch/arm/mach-vexpress/platsmp.c
> > +++ b/arch/arm/mach-vexpress/platsmp.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/errno.h>
> >  #include <linux/smp.h>
> >  #include <linux/io.h>
> > +#include <linux/of.h>
> >  #include <linux/of_fdt.h>
> >  #include <linux/vexpress.h>
> >  
> > @@ -206,3 +207,14 @@ struct smp_operations __initdata vexpress_smp_ops = {
> >  	.cpu_die		= vexpress_cpu_die,
> >  #endif
> >  };
> > +
> > +void __init vexpress_smp_init_ops(void)
> > +{
> > +	struct smp_operations *ops = &vexpress_smp_ops;
> > +#ifdef CONFIG_CLUSTER_PM
> > +	extern struct smp_operations mcpm_smp_ops;
> 
> Seems appropriate to put this prototype in a header file instead.
> 
> > +	if(of_find_compatible_node(NULL, NULL, "arm,cci"))
> 
> Another checkpatch error on if() whitespace.
> 
> Also, while bindings haven't been ironed out, checking for whether the
> node/device is enabled or disabled could be appropriate here?

Right.

I've amended this patch slightly so to:

1) Keep the default .smp = &vexpress_smp_ops and only perform an 
   override in vexpress_smp_init_ops() when appropriate.  This should
   remove one potential issue with Xen support that was highlighted 
   recently.

2) Add a mcpm_smp_set_ops() instead of installing mcpm_smp_ops directly
   for better abstraction.

3) Added a comment about and checked for the CCI node being enabled.

That results in the patch below.  Given those are minor changes, I kept 
the existing review tags.

From: Jon Medhurst <tixy at linaro.org>
Date: Wed, 30 Jan 2013 09:12:55 +0000
Subject: [PATCH] ARM: vexpress: Select multi-cluster SMP operation if required

Signed-off-by: Jon Medhurst <tixy at linaro.org>
Signed-off-by: Nicolas Pitre <nicolas.pitre at linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
Acked-by: Pawel Moll <pawel.moll at arm.com>

diff --git a/arch/arm/common/mcpm_platsmp.c b/arch/arm/common/mcpm_platsmp.c
index 34f236af09..cc82040877 100644
--- a/arch/arm/common/mcpm_platsmp.c
+++ b/arch/arm/common/mcpm_platsmp.c
@@ -85,3 +85,8 @@ struct smp_operations __initdata mcpm_smp_ops = {
 	.cpu_die		= mcpm_cpu_die,
 #endif
 };
+
+void __init mcpm_smp_set_ops(void)
+{
+	smp_set_ops(&mcpm_smp_ops);
+}
diff --git a/arch/arm/include/asm/mcpm_entry.h b/arch/arm/include/asm/mcpm_entry.h
index 814623e6a1..34dfb86ff5 100644
--- a/arch/arm/include/asm/mcpm_entry.h
+++ b/arch/arm/include/asm/mcpm_entry.h
@@ -190,5 +190,7 @@ int __mcpm_cluster_state(unsigned int cluster);
 int __init mcpm_sync_init(
 	void (*power_up_setup)(unsigned int affinity_level));
 
+void __init mcpm_smp_set_ops(void);
+
 #endif /* ! __ASSEMBLY__ */
 #endif
diff --git a/arch/arm/mach-vexpress/core.h b/arch/arm/mach-vexpress/core.h
index f134cd4a85..3a761fd76c 100644
--- a/arch/arm/mach-vexpress/core.h
+++ b/arch/arm/mach-vexpress/core.h
@@ -6,6 +6,8 @@
 
 void vexpress_dt_smp_map_io(void);
 
+void vexpress_smp_init_ops(void);
+
 extern struct smp_operations	vexpress_smp_ops;
 
 extern void vexpress_cpu_die(unsigned int cpu);
diff --git a/arch/arm/mach-vexpress/platsmp.c b/arch/arm/mach-vexpress/platsmp.c
index dc1ace55d5..06317bc714 100644
--- a/arch/arm/mach-vexpress/platsmp.c
+++ b/arch/arm/mach-vexpress/platsmp.c
@@ -12,9 +12,11 @@
 #include <linux/errno.h>
 #include <linux/smp.h>
 #include <linux/io.h>
+#include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/vexpress.h>
 
+#include <asm/mcpm_entry.h>
 #include <asm/smp_scu.h>
 #include <asm/mach/map.h>
 
@@ -203,3 +205,18 @@ struct smp_operations __initdata vexpress_smp_ops = {
 	.cpu_die		= vexpress_cpu_die,
 #endif
 };
+
+void __init vexpress_smp_init_ops(void)
+{
+#ifdef CONFIG_MCPM
+	/*
+	 * The best way to detect a multi-cluster configuration at the moment
+	 * is to look for the presence of a CCI in the system.
+	 * Override the default vexpress_smp_ops if so.
+	 */
+	struct device_node *node;
+	node = of_find_compatible_node(NULL, NULL, "arm,cci");
+	if (node && of_device_is_available(node))
+		mcpm_smp_set_ops();
+#endif
+}
diff --git a/arch/arm/mach-vexpress/v2m.c b/arch/arm/mach-vexpress/v2m.c
index 915683cb67..16b42c10e0 100644
--- a/arch/arm/mach-vexpress/v2m.c
+++ b/arch/arm/mach-vexpress/v2m.c
@@ -476,6 +476,7 @@ static const char * const v2m_dt_match[] __initconst = {
 DT_MACHINE_START(VEXPRESS_DT, "ARM-Versatile Express")
 	.dt_compat	= v2m_dt_match,
 	.smp		= smp_ops(vexpress_smp_ops),
+	.smp_init	= smp_init_ops(vexpress_smp_init_ops),
 	.map_io		= v2m_dt_map_io,
 	.init_early	= v2m_dt_init_early,
 	.init_irq	= irqchip_init,