m68knommu: use user stack pointer hardware on some ColdFire cores

The more modern ColdFire parts (even if based on older version cores)
have separate user and supervisor stack pointers (a7 register).
Modify the ColdFire CPU setup and exception code to enable and use
this on parts that have it.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>

7 files changed, 72 insertions, 55 deletions

diff --git a/arch/m68k/include/asm/cacheflush_no.h b/arch/m68k/include/asm/cacheflush_no.h
index 9246392e1372..e295923020d3 100644
--- a/arch/m68k/include/asm/cacheflush_no.h
+++ b/arch/m68k/include/asm/cacheflush_no.h
@@ -37,7 +37,7 @@ static inline void __flush_cache_all(void)
 {
 #if defined(CONFIG_M523x) || defined(CONFIG_M527x)
         __asm__ __volatile__ (
-                "movel  #0x81400100, %%d0\n\t"
+                "movel  #0x81400110, %%d0\n\t"
                 "movec  %%d0, %%CACR\n\t"
                 "nop\n\t"
                 : : : "d0" );
@@ -65,7 +65,7 @@ static inline void __flush_cache_all(void)
 #endif /* CONFIG_M5249 */
 #ifdef CONFIG_M532x
         __asm__ __volatile__ (
-                "movel  #0x81000200, %%d0\n\t"
+                "movel  #0x81000210, %%d0\n\t"
                 "movec  %%d0, %%CACR\n\t"
                 "nop\n\t"
                 : : : "d0" );
diff --git a/arch/m68k/include/asm/entry_no.h b/arch/m68k/include/asm/entry_no.h
index 26be277394f9..627d69bacc58 100644
--- a/arch/m68k/include/asm/entry_no.h
+++ b/arch/m68k/include/asm/entry_no.h
@@ -42,12 +42,16 @@
  */
 
 #ifdef CONFIG_COLDFIRE
+#ifdef CONFIG_COLDFIRE_SW_A7
 /*
- * This is made a little more tricky on the ColdFire. There is no
- * separate kernel and user stack pointers. Need to artificially
+ * This is made a little more tricky on older ColdFires. There is no
+ * separate supervisor and user stack pointers. Need to artificially
  * construct a usp in software... When doing this we need to disable
- * interrupts, otherwise bad things could happen.
+ * interrupts, otherwise bad things will happen.
  */
+.globl sw_usp
+.globl sw_ksp
+
 .macro SAVE_ALL
         move    #0x2700,%sr             /* disable intrs */
         btst    #5,%sp@(2)              /* from user? */
@@ -74,9 +78,7 @@
         7:
 .endm
 
-.macro RESTORE_ALL
-        btst    #5,%sp@(PT_SR)          /* going user? */
-        bnes    8f                      /* no, skip */
+.macro RESTORE_USER
         move    #0x2700,%sr             /* disable intrs */
         movel   sw_usp,%a0              /* get usp */
         movel   %sp@(PT_OFF_PC),%a0@-   /* copy exception program counter */
@@ -91,19 +93,22 @@
         subql   #8,sw_usp               /* set exception */
         movel   sw_usp,%sp              /* restore usp */
         rte
-        8:
-        moveml  %sp@,%d1-%d5/%a0-%a2
-        lea     %sp@(32),%sp            /* space for 8 regs */
-        movel   %sp@+,%d0
-        addql   #4,%sp                  /* orig d0 */
-        addl    %sp@+,%sp               /* stkadj */
-        rte
 .endm
 
+.macro RDUSP
+        movel   sw_usp,%a2
+.endm
+
+.macro WRUSP
+        movel   %a0,sw_usp
+.endm
+
+#else /* !CONFIG_COLDFIRE_SW_A7 */
 /*
- * Quick exception save, use current stack only.
+ * Modern ColdFire parts have separate supervisor and user stack
+ * pointers. Simple load and restore macros for this case.
  */
-.macro SAVE_LOCAL
+.macro SAVE_ALL
         move    #0x2700,%sr             /* disable intrs */
         clrl    %sp@-                   /* stkadj */
         movel   %d0,%sp@-               /* orig d0 */
@@ -112,7 +117,7 @@
         moveml  %d1-%d5/%a0-%a2,%sp@
 .endm
 
-.macro RESTORE_LOCAL
+.macro RESTORE_USER
         moveml  %sp@,%d1-%d5/%a0-%a2
         lea     %sp@(32),%sp            /* space for 8 regs */
         movel   %sp@+,%d0
@@ -121,6 +126,18 @@
         rte
 .endm
 
+.macro RDUSP
+        /*move  %usp,%a2*/
+        .word   0x4e6a
+.endm
+
+.macro WRUSP
+        /*move  %a0,%usp*/
+        .word   0x4e60
+.endm
+
+#endif /* !CONFIG_COLDFIRE_SW_A7 */
+
 .macro SAVE_SWITCH_STACK
         lea     %sp@(-24),%sp           /* 6 regs */
         moveml  %a3-%a6/%d6-%d7,%sp@
@@ -131,14 +148,6 @@
         lea     %sp@(24),%sp            /* 6 regs */
 .endm
 
-/*
- * Software copy of the user and kernel stack pointers... Ugh...
- * Need these to get around ColdFire not having separate kernel
- * and user stack pointers.
- */
-.globl sw_usp
-.globl sw_ksp
-
 #else /* !CONFIG_COLDFIRE */
 
 /*
@@ -167,6 +176,6 @@
         moveml  %sp@+,%a3-%a6/%d6-%d7
 .endm
 
-#endif /* !CONFIG_COLDFIRE */
+#endif /* !COLDFIRE_SW_A7 */
 #endif /* __ASSEMBLY__ */
 #endif /* __M68KNOMMU_ENTRY_H */
diff --git a/arch/m68k/include/asm/m54xxacr.h b/arch/m68k/include/asm/m54xxacr.h
index 76d64906aa62..12209c68b904 100644
--- a/arch/m68k/include/asm/m54xxacr.h
+++ b/arch/m68k/include/asm/m54xxacr.h
@@ -26,6 +26,7 @@
 #define CACR_IHLCK      0x00000800      /* Intruction cache half lock */
 #define CACR_IDCM       0x00000400      /* Intruction cache inhibit */
 #define CACR_ICINVA     0x00000100      /* Invalidate instr cache */
+#define CACR_EUSP       0x00000020      /* Enable separate user a7 */
 
 #define ACR_BASE_POS    24              /* Address Base */
 #define ACR_MASK_POS    16              /* Address Mask */
@@ -67,7 +68,11 @@
         /* Enable data store buffer */
         /* outside ACRs : No cache, precise */
         /* Enable instruction+branch caches */
+#if defined(CONFIG_M5407)
 #define CACHE_MODE (CACR_DEC+CACR_DESB+CACR_DDCM_P+CACR_BEC+CACR_IEC)
+#else
+#define CACHE_MODE (CACR_DEC+CACR_DESB+CACR_DDCM_P+CACR_BEC+CACR_IEC+CACR_EUSP)
+#endif
 
 #define DATA_CACHE_MODE (ACR_ENABLE+ACR_ANY+ACR_CM_WT)
 
diff --git a/arch/m68k/include/asm/mcfcache.h b/arch/m68k/include/asm/mcfcache.h
index 1b66018461b8..437686b62fea 100644
--- a/arch/m68k/include/asm/mcfcache.h
+++ b/arch/m68k/include/asm/mcfcache.h
@@ -46,7 +46,7 @@
         movec   %d0,%ACR0
         movel   #0x00000000,%d0         /* no other regions cached */
         movec   %d0,%ACR1
-        movel   #0x80400100,%d0         /* configure cache */
+        movel   #0x80400110,%d0         /* configure cache */
         movec   %d0,%CACR               /* enable cache */
         nop
 .endm
@@ -101,7 +101,7 @@
         movec   %d0,%ACR0
         movel   #0x00000000,%d0         /* no other regions cached */
         movec   %d0,%ACR1
-        movel   #0x80000200,%d0         /* setup cache mask */
+        movel   #0x80000210,%d0         /* setup cache mask */
         movec   %d0,%CACR               /* enable cache */
         nop
 .endm
@@ -142,7 +142,7 @@
         movec   %d0,%ACR0
         move.l  #0x00000000,%d0         /* no other regions cached */
         movec   %d0,%ACR1
-        move.l  #0x80400000,%d0         /* enable 8K instruction cache */
+        move.l  #0x80400010,%d0         /* enable 8K instruction cache */
         movec   %d0,%CACR
         nop
 .endm
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index 7a6a7590cc02..278c69bad57a 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -20,23 +20,26 @@
 
 static inline unsigned long rdusp(void)
 {
-#ifdef CONFIG_COLDFIRE
+#ifdef CONFIG_COLDFIRE_SW_A7
         extern unsigned int sw_usp;
         return sw_usp;
 #else
-        unsigned long usp;
-        __asm__ __volatile__("move %/usp,%0" : "=a" (usp));
+        register unsigned long usp __asm__("a0");
+        /* move %usp,%a0 */
+        __asm__ __volatile__(".word 0x4e68" : "=a" (usp));
         return usp;
 #endif
 }
 
 static inline void wrusp(unsigned long usp)
 {
-#ifdef CONFIG_COLDFIRE
+#ifdef CONFIG_COLDFIRE_SW_A7
         extern unsigned int sw_usp;
         sw_usp = usp;
 #else
-        __asm__ __volatile__("move %0,%/usp" : : "a" (usp));
+        register unsigned long a0 __asm__("a0") = usp;
+        /* move %a0,%usp */
+        __asm__ __volatile__(".word 0x4e60" : : "a" (a0) );
 #endif
 }
 
diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig
index 266a39eebcad..e6f482d18d05 100644
--- a/arch/m68knommu/Kconfig
+++ b/arch/m68knommu/Kconfig
@@ -75,6 +75,10 @@ config GENERIC_CLOCKEVENTS
 config NO_IOPORT
         def_bool y
 
+config COLDFIRE_SW_A7
+        bool
+        default n
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"
@@ -107,11 +111,13 @@ config M68360
 
 config M5206
         bool "MCF5206"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5206 processor support.
 
 config M5206e
         bool "MCF5206e"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5206e processor support.
 
@@ -129,6 +135,7 @@ config M523x
 
 config M5249
         bool "MCF5249"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5249 processor support.
 
@@ -139,6 +146,7 @@ config M5271
 
 config M5272
         bool "MCF5272"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5272 processor support.
 
@@ -155,6 +163,7 @@ config M528x
 
 config M5307
         bool "MCF5307"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5307 processor support.
 
@@ -165,6 +174,7 @@ config M532x
 
 config M5407
         bool "MCF5407"
+        select COLDFIRE_SW_A7
         help
           Motorola ColdFire 5407 processor support.
 
diff --git a/arch/m68knommu/platform/coldfire/entry.S b/arch/m68knommu/platform/coldfire/entry.S
index b9ce31966181..f90e6173ccd4 100644
--- a/arch/m68knommu/platform/coldfire/entry.S
+++ b/arch/m68knommu/platform/coldfire/entry.S
@@ -36,13 +36,16 @@
 #include <asm/asm-offsets.h>
 #include <asm/entry.h>
 
+#ifdef CONFIG_COLDFIRE_SW_A7
+/*
+ *      Define software copies of the supervisor and user stack pointers.
+ */
 .bss
-
 sw_ksp:
 .long   0
-
 sw_usp:
 .long   0
+#endif /* CONFIG_COLDFIRE_SW_A7 */
 
 .text
 
@@ -52,6 +55,7 @@ sw_usp:
 .globl ret_from_signal
 .globl sys_call_table
 .globl inthandler
+.globl fasthandler
 
 enosys:
         mov.l   #sys_ni_syscall,%d3
@@ -138,20 +142,7 @@ Luser_return:
         jne     Lwork_to_do             /* still work to do */
 
 Lreturn:
-        move    #0x2700,%sr             /* disable intrs */
-        movel   sw_usp,%a0              /* get usp */
-        movel   %sp@(PT_OFF_PC),%a0@-   /* copy exception program counter */
-        movel   %sp@(PT_OFF_FORMATVEC),%a0@- /* copy exception format/vector/sr */
-        moveml  %sp@,%d1-%d5/%a0-%a2
-        lea     %sp@(32),%sp            /* space for 8 regs */
-        movel   %sp@+,%d0
-        addql   #4,%sp                  /* orig d0 */
-        addl    %sp@+,%sp               /* stk adj */
-        addql   #8,%sp                  /* remove exception */
-        movel   %sp,sw_ksp              /* save ksp */
-        subql   #8,sw_usp               /* set exception */
-        movel   sw_usp,%sp              /* restore usp */
-        rte
+        RESTORE_USER
 
 Lwork_to_do:
         movel   %a0@(TI_FLAGS),%d1      /* get thread_info->flags */
@@ -201,9 +192,8 @@ ENTRY(inthandler)
  */
 ENTRY(resume)
         movel   %a0, %d1                        /* get prev thread in d1 */
-
-        movel   sw_usp,%d0                      /* save usp */
-        movel   %d0,%a0@(TASK_THREAD+THREAD_USP)
+        RDUSP
+        movel   %a2,%a0@(TASK_THREAD+THREAD_USP)
 
         SAVE_SWITCH_STACK
         movel   %sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack pointer */
@@ -211,5 +201,5 @@ ENTRY(resume)
         RESTORE_SWITCH_STACK
 
         movel   %a1@(TASK_THREAD+THREAD_USP),%a0 /* restore thread user stack */
-        movel   %a0, sw_usp
+        WRUSP
         rts