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Subject[RFC patch 14/18] MIPS use tsc_sync.c
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 2008-11-07 00:06:06.000000000 -0500
+++ linux.trees.git/arch/mips/kernel/smp.c 2008-11-07 00:16:05.000000000 -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 2008-11-07 00:10:10.000000000 -0500
+++ linux.trees.git/arch/mips/include/asm/timex.h 2008-11-07 00:16:05.000000000 -0500
@@ -56,13 +56,39 @@ static inline cycles_t get_cycles_rate(v
{
return CLOCK_TICK_RATE;
}
+
+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


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