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Subject[PATCH 4/7] [RFC] enable L1_WRITETHROUGH mode for BG/P
Date
BG/P nodes need to be configured for writethrough to work in SMP
configurations. This patch adds the right hooks in the MMU code
to make sure L1_WRITETHROUGH configurations are setup for BG/P.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
---
arch/powerpc/include/asm/mmu-44x.h | 2 ++
arch/powerpc/kernel/head_44x.S | 24 ++++++++++++++++++++++--
arch/powerpc/kernel/misc_32.S | 15 +++++++++++++++
arch/powerpc/lib/copy_32.S | 10 ++++++++++
arch/powerpc/mm/44x_mmu.c | 7 +++++--
arch/powerpc/platforms/Kconfig | 5 +++++
arch/powerpc/platforms/Kconfig.cputype | 4 ++++
7 files changed, 63 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu-44x.h b/arch/powerpc/include/asm/mmu-44x.h
index bf52d70..ca1b90c 100644
--- a/arch/powerpc/include/asm/mmu-44x.h
+++ b/arch/powerpc/include/asm/mmu-44x.h
@@ -8,6 +8,7 @@

#define PPC44x_MMUCR_TID 0x000000ff
#define PPC44x_MMUCR_STS 0x00010000
+#define PPC44x_MMUCR_U2 0x00200000

#define PPC44x_TLB_PAGEID 0
#define PPC44x_TLB_XLAT 1
@@ -32,6 +33,7 @@

/* Storage attribute and access control fields */
#define PPC44x_TLB_ATTR_MASK 0x0000ff80
+#define PPC44x_TLB_WL1 0x00100000 /* Write-through L1 */
#define PPC44x_TLB_U0 0x00008000 /* User 0 */
#define PPC44x_TLB_U1 0x00004000 /* User 1 */
#define PPC44x_TLB_U2 0x00002000 /* User 2 */
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 5e12b74..1f7ae60 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -429,7 +429,16 @@ finish_tlb_load_44x:
andi. r10,r12,_PAGE_USER /* User page ? */
beq 1f /* nope, leave U bits empty */
rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */
-1: tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */
+1:
+#ifdef CONFIG_L1_WRITETHROUGH
+ andi. r10, r11, PPC44x_TLB_I
+ bne 2f
+ oris r11,r11,PPC44x_TLB_WL1@h /* Add coherency for */
+ /* non-inhibited */
+ ori r11,r11,PPC44x_TLB_U2|PPC44x_TLB_M
+2:
+#endif /* CONFIG_L1_WRITETHROUGH */
+ tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */

/* Done...restore registers and get out of here.
*/
@@ -799,7 +808,11 @@ skpinv: addi r4,r4,1 /* Increment */
sync

/* Initialize MMUCR */
+#ifdef CONFIG_L1_WRITETHROUGH
+ lis r5, PPC44x_MMUCR_U2@h
+#else
li r5,0
+#endif /* CONFIG_L1_WRITETHROUGH */
mtspr SPRN_MMUCR,r5
sync

@@ -814,7 +827,14 @@ skpinv: addi r4,r4,1 /* Increment */
/* attrib fields */
/* Added guarded bit to protect against speculative loads/stores */
li r5,0
- ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)
+#ifdef CONFIG_L1_WRITETHROUGH
+ ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | \
+ PPC44x_TLB_G | PPC44x_TLB_U2)
+ oris r5,r5,PPC44x_TLB_WL1@h
+#else
+ ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | \
+ PPC44x_TLB_G)
+#endif /* CONFIG_L1_WRITETHROUGH

li r0,63 /* TLB slot 63 */

diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 094bd98..d88369b 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -506,7 +506,20 @@ _GLOBAL(clear_pages)
li r0,PAGE_SIZE/L1_CACHE_BYTES
slw r0,r0,r4
mtctr r0
+#ifdef CONFIG_L1_WRITETHROUGH
+ /* assuming 32 byte cacheline */
+ li r4, 0
+1: stw r4, 0(r3)
+ stw r4, 4(r3)
+ stw r4, 8(r3)
+ stw r4, 12(r3)
+ stw r4, 16(r3)
+ stw r4, 20(r3)
+ stw r4, 24(r3)
+ stw r4, 28(r3)
+#else
1: dcbz 0,r3
+#endif /* CONFIG_L1_WRITETHROUGH */
addi r3,r3,L1_CACHE_BYTES
bdnz 1b
blr
@@ -550,7 +563,9 @@ _GLOBAL(copy_page)
mtctr r0
1:
dcbt r11,r4
+#ifndef CONFIG_L1_WRITETHROUGH
dcbz r5,r3
+#endif
COPY_16_BYTES
#if L1_CACHE_BYTES >= 32
COPY_16_BYTES
diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 55f19f9..98a07e3 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -98,7 +98,11 @@ _GLOBAL(cacheable_memzero)
bdnz 4b
3: mtctr r9
li r7,4
+#ifdef CONFIG_L1_WRITETHROUGH
+10:
+#else
10: dcbz r7,r6
+#endif /* CONFIG_L1_WRITETHROUGH */
addi r6,r6,CACHELINE_BYTES
bdnz 10b
clrlwi r5,r8,32-LG_CACHELINE_BYTES
@@ -187,7 +191,9 @@ _GLOBAL(cacheable_memcpy)
mtctr r0
beq 63f
53:
+#ifndef CONFIG_L1_WRITETHROUGH
dcbz r11,r6
+#endif /* CONFIG_L1_WRITETHROUGH */
COPY_16_BYTES
#if L1_CACHE_BYTES >= 32
COPY_16_BYTES
@@ -368,7 +374,11 @@ _GLOBAL(__copy_tofrom_user)
mtctr r8

53: dcbt r3,r4
+#ifdef CONFIG_L1_WRITETHROUGH
+54:
+#else
54: dcbz r11,r6
+#endif
.section __ex_table,"a"
.align 2
.long 54b,105f
diff --git a/arch/powerpc/mm/44x_mmu.c b/arch/powerpc/mm/44x_mmu.c
index 024acab..b684c8a 100644
--- a/arch/powerpc/mm/44x_mmu.c
+++ b/arch/powerpc/mm/44x_mmu.c
@@ -80,9 +80,12 @@ static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
:
#ifdef CONFIG_PPC47x
: "r" (PPC47x_TLB2_S_RWX),
-#else
+#elseif CONFIG_L1_WRITETHROUGH
+ : "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_WL1 \
+ | PPC44x_TLB_U2 | PPC44x_TLB_M),
+#else /* neither CONFIG_PPC47x or CONFIG_L1_WRITETHROUGH */
: "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),
-#endif
+#endif /* CONFIG_PPC47x */
"r" (phys),
"r" (virt | PPC44x_TLB_VALID | PPC44x_TLB_256M),
"r" (entry),
diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index f7b0772..684a281 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -348,4 +348,9 @@ config XILINX_PCI
bool "Xilinx PCI host bridge support"
depends on PCI && XILINX_VIRTEX

+config L1_WRITETHROUGH
+ bool "Blue Gene/P enabled writethrough mode"
+ depends on BGP
+ default y
+
endmenu
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 111138c..3a3c711 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -329,9 +329,13 @@ config NOT_COHERENT_CACHE
bool
depends on 4xx || 8xx || E200 || PPC_MPC512x || GAMECUBE_COMMON
default n if PPC_47x
+ default n if BGP
default y

config CHECK_CACHE_COHERENCY
bool

+config L1_WRITETHROUGH
+ bool
+
endmenu
--
1.7.4.1


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