[POWERPC] Add DSCR SPR to sysfs

POWER6 adds a new SPR, the data stream control register (DSCR). It can
be used to adjust how agressive the prefetch mechanisms are.

Its possible we may want to context switch this, but for now just export
it to userspace via sysfs so we can adjust it.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index 6fe5c9d..782adbf 100644
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h
@@ -152,6 +152,7 @@
 #define CPU_FTR_PURR			LONG_ASM_CONST(0x0000400000000000)
 #define CPU_FTR_CELL_TB_BUG		LONG_ASM_CONST(0x0000800000000000)
 #define CPU_FTR_SPURR			LONG_ASM_CONST(0x0001000000000000)
+#define CPU_FTR_DSCR			LONG_ASM_CONST(0x0002000000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -330,13 +331,14 @@
 	    CPU_FTR_HPTE_TABLE | CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
 	    CPU_FTR_COHERENT_ICACHE | CPU_FTR_LOCKLESS_TLBIE | \
-	    CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE)
+	    CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
+	    CPU_FTR_DSCR)
 #define CPU_FTRS_POWER6X (CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_USE_TB | \
 	    CPU_FTR_HPTE_TABLE | CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_MMCRA | CPU_FTR_SMT | \
 	    CPU_FTR_COHERENT_ICACHE | CPU_FTR_LOCKLESS_TLBIE | \
 	    CPU_FTR_PURR | CPU_FTR_CI_LARGE_PAGE | \
-	    CPU_FTR_SPURR | CPU_FTR_REAL_LE)
+	    CPU_FTR_SPURR | CPU_FTR_REAL_LE | CPU_FTR_DSCR)
 #define CPU_FTRS_CELL	(CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_USE_TB | \
 	    CPU_FTR_HPTE_TABLE | CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
 	    CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \