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author | Vineet Gupta <vgupta@synopsys.com> | 2013-01-18 15:12:18 +0530 |
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committer | Vineet Gupta <vgupta@synopsys.com> | 2013-02-11 20:00:39 +0530 |
commit | d8005e6b95268cbb50db3773d5f180c32a9434fe (patch) | |
tree | 1e27f00970c3612521a4d29146948ef4cec05586 /arch/arc/kernel/clk.c | |
parent | bf90e1eab682dcb79b7765989fb65835ce9d6165 (diff) | |
download | blackbird-op-linux-d8005e6b95268cbb50db3773d5f180c32a9434fe.tar.gz blackbird-op-linux-d8005e6b95268cbb50db3773d5f180c32a9434fe.zip |
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/kernel/clk.c')
-rw-r--r-- | arch/arc/kernel/clk.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/arc/kernel/clk.c b/arch/arc/kernel/clk.c new file mode 100644 index 000000000000..64925db9eb5e --- /dev/null +++ b/arch/arc/kernel/clk.c @@ -0,0 +1,11 @@ +/* + * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <asm/clk.h> + +unsigned long core_freq = CONFIG_ARC_PLAT_CLK; |