[patch 14/17] MIPS use tsc_sync.c

[Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>]

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tsc-sync.c is now available to test if TSC is synchronized across cores. Given
I currently don't have access to a MIPS board myself, help trying to use it
when CPUs go online and testing the implementation would be welcome.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Ralf Baechle <ralf@linux-mips.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/mips/include/asm/timex.h |   26 ++++++++++++++++++++++++++
 arch/mips/kernel/smp.c        |    1 +
 2 files changed, 27 insertions(+)

Index: linux.trees.git/arch/mips/kernel/smp.c
===================================================================
--- linux.trees.git.orig/arch/mips/kernel/smp.c	2008-11-12 18:15:47.000000000 -0500
+++ linux.trees.git/arch/mips/kernel/smp.c	2008-11-26 06:57:38.000000000 -0500
@@ -178,6 +178,7 @@ void __init smp_cpus_done(unsigned int m
 {
 	mp_ops->cpus_done();
 	synchronise_count_master();
+	test_tsc_synchronization();
 }
 
 /* called from main before smp_init() */
Index: linux.trees.git/arch/mips/include/asm/timex.h
===================================================================
--- linux.trees.git.orig/arch/mips/include/asm/timex.h	2008-11-26 06:49:34.000000000 -0500
+++ linux.trees.git/arch/mips/include/asm/timex.h	2008-11-26 06:57:38.000000000 -0500
@@ -58,13 +58,39 @@ static inline cycles_t get_cycles_rate(v
 {
 	return mips_hpt_frequency;
 }
+
+extern int test_tsc_synchronization(void);
+extern int _tsc_is_sync;
+static inline int tsc_is_sync(void)
+{
+	return _tsc_is_sync;
+}
 #else
 static inline cycles_t get_cycles(void)
 {
 	return 0;
 }
+static inline int test_tsc_synchronization(void)
+{
+	return 0;
+}
+static inline int tsc_is_sync(void)
+{
+	return 0;
+}
 #endif
 
+#define DELAY_INTERRUPT 100
+/*
+ * Only updates 32 LSB.
+ */
+static inline void write_tsc(u32 val1, u32 val2)
+{
+	write_c0_count(val1);
+	/* Arrange for an interrupt in a short while */
+	write_c0_compare(read_c0_count() + DELAY_INTERRUPT);
+}
+
 #endif /* __KERNEL__ */
 
 #endif /*  _ASM_TIMEX_H */

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68