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| author | Vineet Gupta <vgupta@synopsys.com> | 2013-01-18 13:42:18 +0400 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2013-02-11 18:30:39 +0400 |
| commit | d8005e6b95268cbb50db3773d5f180c32a9434fe (patch) | |
| tree | 1e27f00970c3612521a4d29146948ef4cec05586 /arch/arc/include/asm/irq.h | |
| parent | bf90e1eab682dcb79b7765989fb65835ce9d6165 (diff) | |
| download | linux-d8005e6b95268cbb50db3773d5f180c32a9434fe.tar.xz | |
ARC: Timers/counters/delay management
ARC700 includes 2 in-core 32bit timers TIMER0 and TIMER1.
Both have exactly same capabilies.
* programmable to count from TIMER<n>_CNT to TIMER<n>_LIMIT
* for count 0 and LIMIT ~1, provides a free-running counter by
auto-wrapping when limit is reached.
* optionally interrupt when LIMIT is reached (oneshot event semantics)
* rearming the interrupt provides periodic semantics
* run at CPU clk
ARC Linux uses TIMER0 for clockevent (periodic/oneshot) and TIMER1 for
clocksource (free-running clock).
Newer cores provide RTSC insn which gives a 64bit cpu clk snapshot hence
is more apt for clocksource when available.
SMP poses a bit of challenge for global timekeeping clocksource /
sched_clock() backend:
-TIMER1 based local clocks are out-of-sync hence can't be used
(thus we default to jiffies based cs as well as sched_clock() one/both
of which platform can override with it's specific hardware assist)
-RTSC is only allowed in SMP if it's cross-core-sync (Kconfig glue
ensures that) and thus usable for both requirements.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/arc/include/asm/irq.h')
| -rw-r--r-- | arch/arc/include/asm/irq.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arc/include/asm/irq.h b/arch/arc/include/asm/irq.h index ca4aeba1eed3..514b30287445 100644 --- a/arch/arc/include/asm/irq.h +++ b/arch/arc/include/asm/irq.h @@ -19,4 +19,6 @@ extern void __init arc_init_IRQ(void); extern void __init plat_init_IRQ(void); extern int __init get_hw_config_num_irq(void); +void __cpuinit arc_local_timer_setup(unsigned int cpu); + #endif |