[POWERPC] Merge CPU features pertaining to icache coherency

Currently the powerpc kernel has a 64-bit only feature,
COHERENT_ICACHE used for those CPUS which maintain icache/dcache
coherency in hardware (POWER5, essentially).  It also has a feature,
SPLIT_ID_CACHE, which is used on CPUs which have separate i and
d-caches, which is to say everything except 601 and Freescale E200.

In nearly all the places we check the SPLIT_ID_CACHE, what we actually
care about is whether the i and d-caches are coherent (which they will
be, trivially, if they're the same cache).

This tries to clarify the situation a little.  The COHERENT_ICACHE
feature becomes availble on 32-bit and is set for all CPUs where i and
d-cache are effectively coherent, whether this is due to special logic
(POWER5) or because they're unified.  We check this, instead of
SPLIT_ID_CACHE nearly everywhere.

The SPLIT_ID_CACHE feature itself is replaced by a UNIFIED_ID_CACHE
feature with reversed sense, set only on 601 and Freescale E200.  In
the two places (one Freescale BookE specific) where we really care
whether it's a unified cache, not whether they're coherent, we check
this feature.  The CPUs with unified cache are so few, we could
consider replacing this feature bit with explicit checks against the
PVR.

This will make unifying the 32-bit and 64-bit cache flush code a
little more straightforward.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 10 insertions, 12 deletions

diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 98decf8ebff4..e708ab7ca9e8 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -392,7 +392,7 @@ BEGIN_FTR_SECTION
 	mtspr   SPRN_L1CSR0,r3
 	isync
 	blr
-END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
+END_FTR_SECTION_IFSET(CPU_FTR_UNIFIED_ID_CACHE)
 	mfspr	r3,SPRN_L1CSR1
 	ori	r3,r3,L1CSR1_ICFI|L1CSR1_ICLFR
 	mtspr	SPRN_L1CSR1,r3
@@ -419,7 +419,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
 _GLOBAL(__flush_icache_range)
 BEGIN_FTR_SECTION
 	blr				/* for 601, do nothing */
-END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
+END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	li	r5,L1_CACHE_BYTES-1
 	andc	r3,r3,r5
 	subf	r4,r3,r4
@@ -514,8 +514,8 @@ _GLOBAL(invalidate_dcache_range)
  */
 _GLOBAL(__flush_dcache_icache)
 BEGIN_FTR_SECTION
-	blr					/* for 601, do nothing */
-END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
+	blr
+END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	rlwinm	r3,r3,0,0,19			/* Get page base address */
 	li	r4,4096/L1_CACHE_BYTES	/* Number of lines in a page */
 	mtctr	r4
@@ -543,7 +543,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
 _GLOBAL(__flush_dcache_icache_phys)
 BEGIN_FTR_SECTION
 	blr					/* for 601, do nothing */
-END_FTR_SECTION_IFCLR(CPU_FTR_SPLIT_ID_CACHE)
+END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
 	mfmsr	r10
 	rlwinm	r0,r10,0,28,26			/* clear DR */
 	mtmsr	r0
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 35f8f443c14f..7ec6ba56d83d 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -262,13 +262,11 @@ void __init setup_arch(char **cmdline_p)
 	 * Systems with OF can look in the properties on the cpu node(s)
 	 * for a possibly more accurate value.
 	 */
-	if (cpu_has_feature(CPU_FTR_SPLIT_ID_CACHE)) {
-		dcache_bsize = cur_cpu_spec->dcache_bsize;
-		icache_bsize = cur_cpu_spec->icache_bsize;
-		ucache_bsize = 0;
-	} else
-		ucache_bsize = dcache_bsize = icache_bsize
-			= cur_cpu_spec->dcache_bsize;
+	dcache_bsize = cur_cpu_spec->dcache_bsize;
+	icache_bsize = cur_cpu_spec->icache_bsize;
+	ucache_bsize = 0;
+	if (cpu_has_feature(CPU_FTR_UNIFIED_ID_CACHE))
+		ucache_bsize = icache_bsize = dcache_bsize;
 
 	/* reboot on panic */
 	panic_timeout = 180;