timecounter: provide a macro to initialize the cyclecounter mask field.

There is no need for users of the timecounter/cyclecounter code to include
clocksource.h just for a single macro.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Richard Cochran 2015-01-02 20:22:03 +01:00 committed by David S. Miller
parent b422da7c36
commit 1891172aa5
1 changed files with 4 additions and 1 deletions

View File

@ -19,6 +19,9 @@
#include <linux/types.h>
/* simplify initialization of mask field */
#define CYCLECOUNTER_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
/**
* struct cyclecounter - hardware abstraction for a free running counter
* Provides completely state-free accessors to the underlying hardware.
@ -29,7 +32,7 @@
* @read: returns the current cycle value
* @mask: bitmask for two's complement
* subtraction of non 64 bit counters,
* see CLOCKSOURCE_MASK() helper macro
* see CYCLECOUNTER_MASK() helper macro
* @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
*/