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>

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" );

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 */

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)
 

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

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
 }
 

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.
 

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