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>

3 files changed, 19 insertions, 8 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 394f9dc7be08..fcfe5332416f 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1056,6 +1056,11 @@ config CONSISTENT_SIZE
 config PIN_TLB
         bool "Pinned Kernel TLBs (860 ONLY)"
         depends on ADVANCED_OPTIONS && 8xx
+
+config PIN_TLB_IMMR
+        bool "Pinned TLB for IMMR"
+        depends on PIN_TLB
+        default y
 endmenu
 
 if PPC64
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 00cc9df7d322..43ddaae42baf 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/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 */
 
diff --git a/arch/powerpc/mm/8xx_mmu.c b/arch/powerpc/mm/8xx_mmu.c
index 0f0a83ed7a20..6c5025e81236 100644
--- a/arch/powerpc/mm/8xx_mmu.c
+++ b/arch/powerpc/mm/8xx_mmu.c
@@ -61,11 +61,15 @@ void __init MMU_init_hw(void)
 #ifdef CONFIG_PIN_TLB
         unsigned long ctr = mfspr(SPRN_MD_CTR) & 0xfe000000;
         unsigned long flags = 0xf0 | MD_SPS16K | _PAGE_SHARED | _PAGE_DIRTY;
-        int i;
+#ifdef CONFIG_PIN_TLB_IMMR
+        int i = 29;
+#else
+        int i = 28;
+#endif
         unsigned long addr = 0;
         unsigned long mem = total_lowmem;
 
-        for (i = 29; i < 32 && mem >= LARGE_PAGE_SIZE_8M; i++) {
+        for (; i < 32 && mem >= LARGE_PAGE_SIZE_8M; i++) {
                 mtspr(SPRN_MD_CTR, ctr | (i << 8));
                 mtspr(SPRN_MD_EPN, (unsigned long)__va(addr) | MD_EVALID);
                 mtspr(SPRN_MD_TWC, MD_PS8MEG | MD_SVALID);
@@ -88,7 +92,7 @@ static void mmu_mapin_immr(void)
 }
 
 /* Address of instructions to patch */
-#ifndef CONFIG_PIN_TLB
+#ifndef CONFIG_PIN_TLB_IMMR
 extern unsigned int DTLBMiss_jmp;
 #endif
 extern unsigned int DTLBMiss_cmp, FixupDAR_cmp;
@@ -109,7 +113,7 @@ unsigned long __init mmu_mapin_ram(unsigned long top)
         if (__map_without_ltlbs) {
                 mapped = 0;
                 mmu_mapin_immr();
-#ifndef CONFIG_PIN_TLB
+#ifndef CONFIG_PIN_TLB_IMMR
                 patch_instruction(&DTLBMiss_jmp, PPC_INST_NOP);
 #endif
         } else {