[PATCH 25/43] MN10300: AM34 erratum requires MMUCTR read and writeon exception entry

[David Howells]

From: Akira Takeuchi <takeuchi.akr@xxxxxxxxxxxxxxxx>

An AM34 erratum requires MMUCTR read and write on entry to certain exceptions,
prior to EPSW.NMID being cleared to allow NMIs to happen.

Signed-off-by: Akira Takeuchi <takeuchi.akr@xxxxxxxxxxxxxxxx>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@xxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 arch/mn10300/Kconfig          |    3 +++
 arch/mn10300/kernel/entry.S   |    8 ++++++++
 arch/mn10300/mm/tlb-mn10300.S |   32 ++++++++++++++++++++++++++------
 3 files changed, 37 insertions(+), 6 deletions(-)


diff --git a/arch/mn10300/Kconfig b/arch/mn10300/Kconfig
index 21e2a53..dd7b570 100644
--- a/arch/mn10300/Kconfig
+++ b/arch/mn10300/Kconfig
@@ -20,6 +20,9 @@ config AM34_2
 	select MN10300_HAS_ATOMIC_OPS_UNIT
 	select MN10300_HAS_CACHE_SNOOP
 
+config ERRATUM_NEED_TO_RELOAD_MMUCTR
+	def_bool y if AM33_3 || AM34_2
+
 config MMU
 	def_bool y
 
diff --git a/arch/mn10300/kernel/entry.S b/arch/mn10300/kernel/entry.S
index b82ce7b..355f681 100644
--- a/arch/mn10300/kernel/entry.S
+++ b/arch/mn10300/kernel/entry.S
@@ -251,6 +251,10 @@ double_fault_loop:
 ENTRY(raw_bus_error)
 	add	-4,sp
 	mov	d0,(sp)
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d0
+	mov	d0,(MMUCTR)
+#endif
 	mov	(BCBERR),d0		# what
 	btst	BCBERR_BEMR_DMA,d0	# see if it was an external bus error
 	beq	__common_exception_aux	# it wasn't
@@ -282,6 +286,10 @@ ENTRY(nmi_handler)
 ENTRY(__common_exception)
 	add	-4,sp
 	mov	d0,(sp)
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d0
+	mov	d0,(MMUCTR)
+#endif
 
 __common_exception_aux:
 	mov	(TBR),d0
diff --git a/arch/mn10300/mm/tlb-mn10300.S b/arch/mn10300/mm/tlb-mn10300.S
index 7095147..ccf6229 100644
--- a/arch/mn10300/mm/tlb-mn10300.S
+++ b/arch/mn10300/mm/tlb-mn10300.S
@@ -27,7 +27,6 @@
 ###############################################################################
 	.type	itlb_miss,@function
 ENTRY(itlb_miss)
-	and	~EPSW_NMID,epsw
 #ifdef CONFIG_GDBSTUB
 	movm	[d2,d3,a2],(sp)
 #else
@@ -38,6 +37,12 @@ ENTRY(itlb_miss)
 	nop
 #endif
 
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d2
+	mov	d2,(MMUCTR)
+#endif
+
+	and	~EPSW_NMID,epsw
 	mov	(IPTEU),d3
 	mov	(PTBR),a2
 	mov	d3,d2
@@ -79,7 +84,6 @@ itlb_miss_fault:
 ###############################################################################
 	.type	dtlb_miss,@function
 ENTRY(dtlb_miss)
-	and	~EPSW_NMID,epsw
 #ifdef CONFIG_GDBSTUB
 	movm	[d2,d3,a2],(sp)
 #else
@@ -90,6 +94,12 @@ ENTRY(dtlb_miss)
 	nop
 #endif
 
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d2
+	mov	d2,(MMUCTR)
+#endif
+
+	and	~EPSW_NMID,epsw
 	mov	(DPTEU),d3
 	mov	(PTBR),a2
 	mov	d3,d2
@@ -130,9 +140,15 @@ dtlb_miss_fault:
 ###############################################################################
 	.type	itlb_aerror,@function
 ENTRY(itlb_aerror)
-	and	~EPSW_NMID,epsw
 	add	-4,sp
 	SAVE_ALL
+
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d1
+	mov	d1,(MMUCTR)
+#endif
+
+	and	~EPSW_NMID,epsw
 	add	-4,sp				# need to pass three params
 
 	# calculate the fault code
@@ -148,7 +164,6 @@ ENTRY(itlb_aerror)
 	clr	d0
 	mov	d0,(IPTEL)
 
-	and	~EPSW_NMID,epsw
 	or	EPSW_IE,epsw
 	mov	fp,d0
 	call	do_page_fault[],0		# do_page_fault(regs,code,addr
@@ -163,10 +178,16 @@ ENTRY(itlb_aerror)
 ###############################################################################
 	.type	dtlb_aerror,@function
 ENTRY(dtlb_aerror)
-	and	~EPSW_NMID,epsw
 	add	-4,sp
 	SAVE_ALL
+
+#if defined(CONFIG_ERRATUM_NEED_TO_RELOAD_MMUCTR)
+	mov	(MMUCTR),d1
+	mov	d1,(MMUCTR)
+#endif
+
 	add	-4,sp				# need to pass three params
+	and	~EPSW_NMID,epsw
 
 	# calculate the fault code
 	movhu	(MMUFCR_DFC),d1
@@ -180,7 +201,6 @@ ENTRY(dtlb_aerror)
 	clr	d0
 	mov	d0,(DPTEL)
 
-	and	~EPSW_NMID,epsw
 	or	EPSW_IE,epsw
 	mov	fp,d0
 	call	do_page_fault[],0		# do_page_fault(regs,code,addr

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