From 41c594ab65fc89573af296d192aa5235d09717ab Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 5 Apr 2006 09:45:45 +0100
Subject: [MIPS] MT: Improved multithreading support.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
 include/asm-mips/mipsregs.h | 133 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)

(limited to 'include/asm-mips/mipsregs.h')

diff --git a/include/asm-mips/mipsregs.h b/include/asm-mips/mipsregs.h
index e85a42e2ea0..a2ef579f6b1 100644
--- a/include/asm-mips/mipsregs.h
+++ b/include/asm-mips/mipsregs.h
@@ -861,7 +861,19 @@ do {									\
 #define write_c0_compare3(val)	__write_32bit_c0_register($11, 7, val)
 
 #define read_c0_status()	__read_32bit_c0_register($12, 0)
+#ifdef CONFIG_MIPS_MT_SMTC
+#define write_c0_status(val)						\
+do {									\
+	__write_32bit_c0_register($12, 0, val);				\
+	__ehb();							\
+} while (0)
+#else
+/*
+ * Legacy non-SMTC code, which may be hazardous
+ * but which might not support EHB
+ */
 #define write_c0_status(val)	__write_32bit_c0_register($12, 0, val)
+#endif /* CONFIG_MIPS_MT_SMTC */
 
 #define read_c0_cause()		__read_32bit_c0_register($13, 0)
 #define write_c0_cause(val)	__write_32bit_c0_register($13, 0, val)
@@ -1004,6 +1016,9 @@ do {									\
 #define read_c0_taglo()		__read_32bit_c0_register($28, 0)
 #define write_c0_taglo(val)	__write_32bit_c0_register($28, 0, val)
 
+#define read_c0_dtaglo()	__read_32bit_c0_register($28, 2)
+#define write_c0_dtaglo(val)	__write_32bit_c0_register($28, 2, val)
+
 #define read_c0_taghi()		__read_32bit_c0_register($29, 0)
 #define write_c0_taghi(val)	__write_32bit_c0_register($29, 0, val)
 
@@ -1357,6 +1372,11 @@ static inline void tlb_write_random(void)
 /*
  * Manipulate bits in a c0 register.
  */
+#ifndef CONFIG_MIPS_MT_SMTC
+/*
+ * SMTC Linux requires shutting-down microthread scheduling
+ * during CP0 register read-modify-write sequences.
+ */
 #define __BUILD_SET_C0(name)					\
 static inline unsigned int					\
 set_c0_##name(unsigned int set)					\
@@ -1395,6 +1415,119 @@ change_c0_##name(unsigned int change, unsigned int new)		\
 	return res;						\
 }
 
+#else /* SMTC versions that manage MT scheduling */
+
+#include <asm/interrupt.h>
+
+/*
+ * This is a duplicate of dmt() in mipsmtregs.h to avoid problems with
+ * header file recursion.
+ */
+static inline unsigned int __dmt(void)
+{
+	int res;
+
+	__asm__ __volatile__(
+	"	.set	push						\n"
+	"	.set	mips32r2					\n"
+	"	.set	noat						\n"
+	"	.word	0x41610BC1			# dmt $1	\n"
+	"	ehb							\n"
+	"	move	%0, $1						\n"
+	"	.set	pop						\n"
+	: "=r" (res));
+
+	instruction_hazard();
+
+	return res;
+}
+
+#define __VPECONTROL_TE_SHIFT	15
+#define __VPECONTROL_TE		(1UL << __VPECONTROL_TE_SHIFT)
+
+#define __EMT_ENABLE		__VPECONTROL_TE
+
+static inline void __emt(unsigned int previous)
+{
+	if ((previous & __EMT_ENABLE))
+		__asm__ __volatile__(
+		"	.set	noreorder				\n"
+		"	.set	mips32r2				\n"
+		"	.word	0x41600be1		# emt		\n"
+		"	ehb						\n"
+		"	.set	mips0					\n"
+		"	.set	reorder					\n");
+}
+
+static inline void __ehb(void)
+{
+	__asm__ __volatile__(
+	"	ehb							\n");
+}
+
+/*
+ * Note that local_irq_save/restore affect TC-specific IXMT state,
+ * not Status.IE as in non-SMTC kernel.
+ */
+
+#define __BUILD_SET_C0(name)					\
+static inline unsigned int					\
+set_c0_##name(unsigned int set)					\
+{								\
+	unsigned int res;					\
+	unsigned int omt;					\
+	unsigned int flags;					\
+								\
+	local_irq_save(flags);					\
+	omt = __dmt();						\
+	res = read_c0_##name();					\
+	res |= set;						\
+	write_c0_##name(res);					\
+	__emt(omt);						\
+	local_irq_restore(flags);				\
+								\
+	return res;						\
+}								\
+								\
+static inline unsigned int					\
+clear_c0_##name(unsigned int clear)				\
+{								\
+	unsigned int res;					\
+	unsigned int omt;					\
+	unsigned int flags;					\
+								\
+	local_irq_save(flags);					\
+	omt = __dmt();						\
+	res = read_c0_##name();					\
+	res &= ~clear;						\
+	write_c0_##name(res);					\
+	__emt(omt);						\
+	local_irq_restore(flags);				\
+								\
+	return res;						\
+}								\
+								\
+static inline unsigned int					\
+change_c0_##name(unsigned int change, unsigned int new)		\
+{								\
+	unsigned int res;					\
+	unsigned int omt;					\
+	unsigned int flags;					\
+								\
+	local_irq_save(flags);					\
+								\
+	omt = __dmt();						\
+	res = read_c0_##name();					\
+	res &= ~change;						\
+	res |= (new & change);					\
+	write_c0_##name(res);					\
+	__emt(omt);						\
+	local_irq_restore(flags);				\
+								\
+	return res;						\
+}
+#endif
+
 __BUILD_SET_C0(status)
 __BUILD_SET_C0(cause)
 __BUILD_SET_C0(config)
-- 
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