diff options
author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2008-10-09 21:31:56 +0100 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2008-10-09 21:31:56 +0100 |
commit | 6a4690c22f5da1eb1c898b61b6a80da52fbd976f (patch) | |
tree | a03891a32abe0da191fb765fe669a597e07423c6 /arch/blackfin/include/asm/time.h | |
parent | 90bb28b0644f7324f8bd1feb27b35146e6785ba2 (diff) | |
parent | 8ec53663d2698076468b3e1edc4e1b418bd54de3 (diff) |
Merge branch 'ptebits' into devel
Conflicts:
arch/arm/Kconfig
Diffstat (limited to 'arch/blackfin/include/asm/time.h')
-rw-r--r-- | arch/blackfin/include/asm/time.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/arch/blackfin/include/asm/time.h b/arch/blackfin/include/asm/time.h new file mode 100644 index 00000000000..ddc43ce3853 --- /dev/null +++ b/arch/blackfin/include/asm/time.h @@ -0,0 +1,40 @@ +/* + * asm-blackfin/time.h: + * + * Copyright 2004-2008 Analog Devices Inc. + * + * Licensed under the GPL-2 or later. + */ + +#ifndef _ASM_BLACKFIN_TIME_H +#define _ASM_BLACKFIN_TIME_H + +/* + * The way that the Blackfin core timer works is: + * - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE) + * - Every time TSCALE ticks, a 32bit is counted down (TCOUNT) + * + * If you take the fastest clock (1ns, or 1GHz to make the math work easier) + * 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter + * (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need + * to use TSCALE, and program it to zero (which is pass CCLK through). + * If you feel like using it, try to keep HZ * TIMESCALE to some + * value that divides easy (like power of 2). + */ + +#ifndef CONFIG_CPU_FREQ +#define TIME_SCALE 1 +#define __bfin_cycles_off (0) +#define __bfin_cycles_mod (0) +#else +/* + * Blackfin CPU frequency scaling supports max Core Clock 1, 1/2 and 1/4 . + * Whenever we change the Core Clock frequency changes we immediately + * adjust the Core Timer Presale Register. This way we don't lose time. + */ +#define TIME_SCALE 4 +extern unsigned long long __bfin_cycles_off; +extern unsigned int __bfin_cycles_mod; +#endif + +#endif |