From d8005e6b95268cbb50db3773d5f180c32a9434fe Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 18 Jan 2013 15:12:18 +0530 Subject: 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_CNT to TIMER_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 Cc: Thomas Gleixner --- arch/arc/include/asm/clk.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 arch/arc/include/asm/clk.h (limited to 'arch/arc/include/asm/clk.h') diff --git a/arch/arc/include/asm/clk.h b/arch/arc/include/asm/clk.h new file mode 100644 index 000000000000..61956436c75c --- /dev/null +++ b/arch/arc/include/asm/clk.h @@ -0,0 +1,20 @@ +/* + * 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. + */ + +#ifndef _ASM_ARC_CLK_H +#define _ASM_ARC_CLK_H + +/* Although we can't really hide core_freq, the accessor is still better way */ +extern unsigned long core_freq; + +static inline unsigned long arc_get_core_freq(void) +{ + return core_freq; +} + +#endif -- cgit v1.2.3