[PATCH 1/6] ARM: Add inline function smp_cpu() for early init testing

[Tony Lindgren]

* Tony Lindgren <t...@atomide.com> [100902 10:35]:
> * Russell King - ARM Linux <li...@arm.linux.org.uk> [100902 10:00]:
> > On Thu, Sep 02, 2010 at 09:18:47AM -0700, Tony Lindgren wrote:
> > 
> > > --- a/arch/arm/include/asm/smp_plat.h
> > > +++ b/arch/arm/include/asm/smp_plat.h
> > > @@ -39,4 +39,20 @@ static inline int cache_ops_need_broadcast(void)
> > >  #define UP(instr...)     _str(instr)
> > >  #endif
> > >  
> > > +static inline int smp_on_up(void)
> > > +{
> > > +#ifdef CONFIG_SMP_ON_UP
> > > + int smp_on_up;
> > > +
> > > + asm(                                                    \
> > > +         SMP(mov %0, #0)                                 \
> > > +         UP(mov  %0, #1)                                 \
> > > +         : "=r" (smp_on_up));
> > > +
> > > + return smp_on_up;
> > > +#else
> > > + return 0;
> > > +#endif
> > 
> > I think this is the wrong approach - rather than a function which tells us
> > just if we are a SMP kernel running on UP, why not something which returns
> > whether we're running on SMP and use that to eliminate some of these ifdefs?
> 
> Sure. Will has something like this in his patches:
> 
> static inline int cpu_is_part_of_mp_system(void)
> {
>       u32 mpidr;
>       asm volatile("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
>       return (mpidr >> 31) ? !(mpidr >> 30) : 0;
> }
> 
> BTW, so far looks like we should only need this during init to set up things.

Here's this one updated to replace smp_cpu() instead of smp_on_up().

Tony

From: Tony Lindgren <t...@atomide.com>
Date: Mon, 30 Aug 2010 14:00:54 -0700
Subject: [PATCH] ARM: Add inline function smp_cpu() for early init testing

Add inline function smp_cpu() for early init checks, and
change build_mem_type_table to use it.

Inline function copied from cpu_is_part_of_mp_system() by
Will Deacon <will.dea...@arm.com>.

Signed-off-by: Tony Lindgren <t...@atomide.com>

diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
index 8db3512..82bc488 100644
--- a/arch/arm/include/asm/smp_plat.h
+++ b/arch/arm/include/asm/smp_plat.h
@@ -39,4 +39,11 @@ static inline int cache_ops_need_broadcast(void)
 #define UP(instr...)	_str(instr)
 #endif
 
+static inline int smp_cpu(void)
+{
+        u32 mpidr;
+        asm volatile("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
+        return (mpidr >> 31) ? !(mpidr >> 30) : 0;
+}
+
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 6e1c4f6..2bfaefd 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -430,15 +430,17 @@ static void __init build_mem_type_table(void)
 		/*
 		 * Mark memory with the "shared" attribute for SMP systems
 		 */
-		user_pgprot |= L_PTE_SHARED;
-		kern_pgprot |= L_PTE_SHARED;
-		vecs_pgprot |= L_PTE_SHARED;
-		mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
-		mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
-		mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
-		mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
-		mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
-		mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+		if (smp_cpu()) {
+			user_pgprot |= L_PTE_SHARED;
+			kern_pgprot |= L_PTE_SHARED;
+			vecs_pgprot |= L_PTE_SHARED;
+			mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
+			mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
+			mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
+			mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
+			mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+			mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+		}
 #endif
 	}