powerpc/8xx: add CONFIG_PIN_TLB_IMMR

CONFIG_PIN_TLB maps IMMR area and the first 24 Mbytes of memory.
In some circunstances it might be more interesting to not map
IMMR but map 32 Mbytes of memory instead.

Therefore we add config option CONFIG_PIN_TLB_IMMR to select if
IMMR shall be pinned or not, hence whether we pin 24 or 32 Mbytes of RAM

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>

arch/powerpc/kernel/head_8xx.S

@@ -414,11 +414,11 @@ DataStoreTLBMiss:
 	 */
 	mfspr	r11, SPRN_MD_EPN
 	rlwinm	r11, r11, 16, 0xfff8
-#ifndef CONFIG_PIN_TLB
+#ifndef CONFIG_PIN_TLB_IMMR
 	cmpli	cr0, r11, VIRT_IMMR_BASE@h
 #endif
 	cmpli	cr7, r11, PAGE_OFFSET@h
-#ifndef CONFIG_PIN_TLB
+#ifndef CONFIG_PIN_TLB_IMMR
 _ENTRY(DTLBMiss_jmp)
 	beq-	DTLBMissIMMR
 #endif
@@ -819,7 +819,6 @@ initial_mmu:
 
 #ifdef CONFIG_PIN_TLB
 	oris	r10, r10, MD_RSV4I@h
-	ori	r10, r10, 0x1c00
 	mtspr	SPRN_MD_CTR, r10	/* Set data TLB control */
 #endif
 
@@ -843,7 +842,10 @@ initial_mmu:
 	/* Map a 512k page for the IMMR to get the processor
 	 * internal registers (among other things).
 	 */
-#ifdef CONFIG_PIN_TLB
+#ifdef CONFIG_PIN_TLB_IMMR
+	ori	r10, r10, 0x1c00
+	mtspr	SPRN_MD_CTR, r10
+
 	mfspr	r9, 638			/* Get current IMMR */
 	andis.	r9, r9, 0xfff8		/* Get 512 kbytes boundary */