powerpc/8xx: Better readibility of ERRATA CPU6 handling

This patch hiddes that SPR address needed for CPU6 ERRATA handling in the macro.
Then we don't have to worry about this address directly in the code.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <scottwood@freescale.com>

arch/powerpc/kernel/head_8xx.S

@@ -33,12 +33,19 @@
 
 /* Macro to make the code more readable. */
 #ifdef CONFIG_8xx_CPU6
-#define DO_8xx_CPU6(val, reg)	\
-	li	reg, val;	\
-	stw	reg, 12(r0);	\
-	lwz	reg, 12(r0);
+#define SPRN_MI_TWC_ADDR	0x2b80
+#define SPRN_MI_RPN_ADDR	0x2d80
+#define SPRN_MD_TWC_ADDR	0x3b80
+#define SPRN_MD_RPN_ADDR	0x3d80
+
+#define MTSPR_CPU6(spr, reg, treg)	\
+	li	treg, spr##_ADDR;	\
+	stw	treg, 12(r0);		\
+	lwz	treg, 12(r0);		\
+	mtspr	spr, reg
 #else
-#define DO_8xx_CPU6(val, reg)
+#define MTSPR_CPU6(spr, reg, treg)	\
+	mtspr	spr, reg
 #endif
 
 /*
@@ -336,8 +343,7 @@ InstructionTLBMiss:
 	 * for this "segment."
 	 */
 	ori	r11,r11,1		/* Set valid bit */
-	DO_8xx_CPU6(0x2b80, r3)
-	mtspr	SPRN_MI_TWC, r11	/* Set segment attributes */
+	MTSPR_CPU6(SPRN_MI_TWC, r11, r3)	/* Set segment attributes */
 	mfspr	r11, SPRN_SRR0	/* Get effective address of fault */
 	/* Extract level 2 index */
 	rlwinm	r11, r11, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
@@ -356,8 +362,7 @@ InstructionTLBMiss:
 	 */
 	li	r11, RPN_PATTERN
 	rlwimi	r10, r11, 0, 0x07f8	/* Set 24-27, clear 21-23,28 */
-	DO_8xx_CPU6(0x2d80, r3)
-	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */
+	MTSPR_CPU6(SPRN_MI_RPN, r10, r3)	/* Update TLB entry */
 
 	/* Restore registers */
 #ifdef CONFIG_8xx_CPU6
@@ -426,8 +431,7 @@ DataStoreTLBMiss:
 	 * It is bit 25 in the Linux PTE and bit 30 in the TWC
 	 */
 	rlwimi	r11, r10, 32-5, 30, 30
-	DO_8xx_CPU6(0x3b80, r3)
-	mtspr	SPRN_MD_TWC, r11
+	MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
 
 	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
 	 * We also need to know if the insn is a load/store, so:
@@ -460,8 +464,7 @@ DataStoreTLBMiss:
 	 */
 2:	li	r11, RPN_PATTERN
 	rlwimi	r10, r11, 0, 24, 28	/* Set 24-27, clear 28 */
-	DO_8xx_CPU6(0x3d80, r3)
-	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
+	MTSPR_CPU6(SPRN_MD_RPN, r10, r3)	/* Update TLB entry */
 
 	/* Restore registers */
 #ifdef CONFIG_8xx_CPU6