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authorChris Metcalf <cmetcalf@tilera.com>2011-02-28 13:21:52 -0500
committerChris Metcalf <cmetcalf@tilera.com>2011-03-01 16:20:04 -0500
commit13371731487896a6ef158b1cd74297f40a3da4bb (patch)
treeaf09fca3fd8811340b373faaddcdb528f8a07669 /arch/tile/include/asm/timex.h
parent04f7a3f12e10032ee3d44df1a509dbf5b2001fce (diff)
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blackbird-op-linux-13371731487896a6ef158b1cd74297f40a3da4bb.zip
arch/tile: fix __ndelay etc to work better
The current implementations of __ndelay and __udelay call a hypervisor service to delay, but the hypervisor service isn't actually implemented very well, and the consensus is that Linux should handle figuring this out natively and not use a hypervisor service. By converting nanoseconds to cycles, and then spinning until the cycle counter reaches the desired cycle, we get several benefits: first, we are sensitive to the actual clock speed; second, we use less power by issuing a slow SPR read once every six cycles while we delay; and third, we properly handle the case of an interrupt by exiting at the target time rather than after some number of cycles. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/include/asm/timex.h')
-rw-r--r--arch/tile/include/asm/timex.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/tile/include/asm/timex.h b/arch/tile/include/asm/timex.h
index 3baf5fc4c0a1..29921f0b86da 100644
--- a/arch/tile/include/asm/timex.h
+++ b/arch/tile/include/asm/timex.h
@@ -38,6 +38,9 @@ static inline cycles_t get_cycles(void)
cycles_t get_clock_rate(void);
+/* Convert nanoseconds to core clock cycles. */
+cycles_t ns2cycles(unsigned long nsecs);
+
/* Called at cpu initialization to set some low-level constants. */
void setup_clock(void);
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