[PATCH 3/16] powerpc/4xx: Extended DCR support v2

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

This adds supports to the "extended" DCR addressing via
the indirect mfdcrx/mtdcrx instructions supported by some
4xx cores (440H6 and later)

I enabled the feature for now only on AMCC 460 chips

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

This variant uses "440x6" instead of "440H6". I made no other
changes to the code as I think the codegen is the less bad I've
had so far and I rely on Josh further work on cleaning up the
type of 440core selection at Kconfig time so the feature are
properly reflected in the POSSIBLE and ALWAYS masks based on
the core selection. That way, if only one core type is selected
the feature test should resolve at compile time.


 arch/powerpc/include/asm/cputable.h   |    7 ++-
 arch/powerpc/include/asm/dcr-native.h |   63 +++++++++++++++++++++++++++-------
 arch/powerpc/kernel/cputable.c        |    4 +-
 arch/powerpc/sysdev/dcr-low.S         |    8 +++-
 4 files changed, 65 insertions(+), 17 deletions(-)

--- linux-work.orig/arch/powerpc/include/asm/cputable.h	2008-12-08 15:56:42.000000000 +1100
+++ linux-work/arch/powerpc/include/asm/cputable.h	2008-12-09 14:04:44.000000000 +1100
@@ -164,6 +164,7 @@ extern const char *powerpc_base_platform
 #define CPU_FTR_NEED_PAIRED_STWCX	ASM_CONST(0x0000000004000000)
 #define CPU_FTR_LWSYNC			ASM_CONST(0x0000000008000000)
 #define CPU_FTR_NOEXECUTE		ASM_CONST(0x0000000010000000)
+#define CPU_FTR_INDEXED_DCR		ASM_CONST(0x0000000020000000)
 
 /*
  * Add the 64-bit processor unique features in the top half of the word;
@@ -369,6 +370,8 @@ extern const char *powerpc_base_platform
 #define CPU_FTRS_8XX	(CPU_FTR_USE_TB)
 #define CPU_FTRS_40X	(CPU_FTR_USE_TB | CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
 #define CPU_FTRS_44X	(CPU_FTR_USE_TB | CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE)
+#define CPU_FTRS_440x6	(CPU_FTR_USE_TB | CPU_FTR_NODSISRALIGN | CPU_FTR_NOEXECUTE | \
+	    CPU_FTR_INDEXED_DCR)
 #define CPU_FTRS_E200	(CPU_FTR_USE_TB | CPU_FTR_SPE_COMP | \
 	    CPU_FTR_NODSISRALIGN | CPU_FTR_COHERENT_ICACHE | \
 	    CPU_FTR_UNIFIED_ID_CACHE | CPU_FTR_NOEXECUTE)
@@ -455,7 +458,7 @@ enum {
 	    CPU_FTRS_40X |
 #endif
 #ifdef CONFIG_44x
-	    CPU_FTRS_44X |
+	    CPU_FTRS_44X | CPU_FTRS_440x6 |
 #endif
 #ifdef CONFIG_E200
 	    CPU_FTRS_E200 |
@@ -495,7 +498,7 @@ enum {
 	    CPU_FTRS_40X &
 #endif
 #ifdef CONFIG_44x
-	    CPU_FTRS_44X &
+	    CPU_FTRS_44X & CPU_FTRS_440x6 &
 #endif
 #ifdef CONFIG_E200
 	    CPU_FTRS_E200 &
Index: linux-work/arch/powerpc/include/asm/dcr-native.h
===================================================================
--- linux-work.orig/arch/powerpc/include/asm/dcr-native.h	2008-09-29 14:21:37.000000000 +1000
+++ linux-work/arch/powerpc/include/asm/dcr-native.h	2008-12-08 15:56:43.000000000 +1100
@@ -23,6 +23,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/spinlock.h>
+#include <asm/cputable.h>
 
 typedef struct {
 	unsigned int base;
@@ -39,23 +40,45 @@ static inline bool dcr_map_ok_native(dcr
 #define dcr_read_native(host, dcr_n)		mfdcr(dcr_n + host.base)
 #define dcr_write_native(host, dcr_n, value)	mtdcr(dcr_n + host.base, value)
 
-/* Device Control Registers */
-void __mtdcr(int reg, unsigned int val);
-unsigned int __mfdcr(int reg);
+/* Table based DCR accessors */
+extern void __mtdcr(unsigned int reg, unsigned int val);
+extern unsigned int __mfdcr(unsigned int reg);
+
+/* mfdcrx/mtdcrx instruction based accessors. We hand code
+ * the opcodes in order not to depend on newer binutils
+ */
+static inline unsigned int mfdcrx(unsigned int reg)
+{
+	unsigned int ret;
+	asm volatile(".long 0x7c000206 | (%0 << 21) | (%1 << 16)"
+		     : "=r" (ret) : "r" (reg));
+	return ret;
+}
+
+static inline void mtdcrx(unsigned int reg, unsigned int val)
+{
+	asm volatile(".long 0x7c000306 | (%0 << 21) | (%1 << 16)"
+		     : : "r" (val), "r" (reg));
+}
+
 #define mfdcr(rn)						\
 	({unsigned int rval;					\
-	if (__builtin_constant_p(rn))				\
+	if (__builtin_constant_p(rn) && rn < 1024)		\
 		asm volatile("mfdcr %0," __stringify(rn)	\
 		              : "=r" (rval));			\
+	else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR)))	\
+		rval = mfdcrx(rn);				\
 	else							\
 		rval = __mfdcr(rn);				\
 	rval;})
 
 #define mtdcr(rn, v)						\
 do {								\
-	if (__builtin_constant_p(rn))				\
+	if (__builtin_constant_p(rn) && rn < 1024)		\
 		asm volatile("mtdcr " __stringify(rn) ",%0"	\
 			      : : "r" (v)); 			\
+	else if (likely(cpu_has_feature(CPU_FTR_INDEXED_DCR)))	\
+		mtdcrx(rn, v);					\
 	else							\
 		__mtdcr(rn, v);					\
 } while (0)
@@ -69,8 +92,13 @@ static inline unsigned __mfdcri(int base
 	unsigned int val;
 
 	spin_lock_irqsave(&dcr_ind_lock, flags);
-	__mtdcr(base_addr, reg);
-	val = __mfdcr(base_data);
+	if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+		mtdcrx(base_addr, reg);
+		val = mfdcrx(base_data);
+	} else {
+		__mtdcr(base_addr, reg);
+		val = __mfdcr(base_data);
+	}
 	spin_unlock_irqrestore(&dcr_ind_lock, flags);
 	return val;
 }
@@ -81,8 +109,13 @@ static inline void __mtdcri(int base_add
 	unsigned long flags;
 
 	spin_lock_irqsave(&dcr_ind_lock, flags);
-	__mtdcr(base_addr, reg);
-	__mtdcr(base_data, val);
+	if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+		mtdcrx(base_addr, reg);
+		mtdcrx(base_data, val);
+	} else {
+		__mtdcr(base_addr, reg);
+		__mtdcr(base_data, val);
+	}
 	spin_unlock_irqrestore(&dcr_ind_lock, flags);
 }
 
@@ -93,9 +126,15 @@ static inline void __dcri_clrset(int bas
 	unsigned int val;
 
 	spin_lock_irqsave(&dcr_ind_lock, flags);
-	__mtdcr(base_addr, reg);
-	val = (__mfdcr(base_data) & ~clr) | set;
-	__mtdcr(base_data, val);
+	if (cpu_has_feature(CPU_FTR_INDEXED_DCR)) {
+		mtdcrx(base_addr, reg);
+		val = (mfdcrx(base_data) & ~clr) | set;
+		mtdcrx(base_data, val);
+	} else {
+		__mtdcr(base_addr, reg);
+		val = (__mfdcr(base_data) & ~clr) | set;
+		__mtdcr(base_data, val);
+	}
 	spin_unlock_irqrestore(&dcr_ind_lock, flags);
 }
 
Index: linux-work/arch/powerpc/sysdev/dcr-low.S
===================================================================
--- linux-work.orig/arch/powerpc/sysdev/dcr-low.S	2008-07-07 13:45:04.000000000 +1000
+++ linux-work/arch/powerpc/sysdev/dcr-low.S	2008-12-08 15:56:43.000000000 +1100
@@ -11,14 +11,20 @@
 
 #include <asm/ppc_asm.h>
 #include <asm/processor.h>
+#include <asm/bug.h>
 
 #define DCR_ACCESS_PROLOG(table) \
+	cmpli	cr0,r3,1024;	 \
 	rlwinm  r3,r3,4,18,27;   \
 	lis     r5,table@h;      \
 	ori     r5,r5,table@l;   \
 	add     r3,r3,r5;        \
+	bge-	1f;		 \
 	mtctr   r3;              \
-	bctr
+	bctr;			 \
+1:	trap;			 \
+	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,0;	\
+	blr
 
 _GLOBAL(__mfdcr)
 	DCR_ACCESS_PROLOG(__mfdcr_table)
Index: linux-work/arch/powerpc/kernel/cputable.c
===================================================================
--- linux-work.orig/arch/powerpc/kernel/cputable.c	2008-11-24 14:48:55.000000000 +1100
+++ linux-work/arch/powerpc/kernel/cputable.c	2008-12-09 14:04:44.000000000 +1100
@@ -1506,7 +1506,7 @@ static struct cpu_spec __initdata cpu_sp
 		.pvr_mask		= 0xffff0002,
 		.pvr_value		= 0x13020002,
 		.cpu_name		= "460EX",
-		.cpu_features		= CPU_FTRS_44X,
+		.cpu_features		= CPU_FTRS_440x6,
 		.cpu_user_features	= COMMON_USER_BOOKE | PPC_FEATURE_HAS_FPU,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
@@ -1518,7 +1518,7 @@ static struct cpu_spec __initdata cpu_sp
 		.pvr_mask		= 0xffff0002,
 		.pvr_value		= 0x13020000,
 		.cpu_name		= "460GT",
-		.cpu_features		= CPU_FTRS_44X,
+		.cpu_features		= CPU_FTRS_440x6,
 		.cpu_user_features	= COMMON_USER_BOOKE | PPC_FEATURE_HAS_FPU,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,