MN10300: AM34 erratum requires MMUCTR read and write on exception entry

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@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>

3 files changed, 37 insertions, 6 deletions

diff --git a/arch/mn10300/Kconfig b/arch/mn10300/Kconfig
index 21e2a534d98e..dd7b5700358b 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 b82ce7b47fcb..355f68176771 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 7095147dcb8b..ccf622999a5b 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