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| author | Che-Liang Chiou <clchiou@chromium.org> | 2013-03-28 04:32:17 +0000 |
|---|---|---|
| committer | Minkyu Kang <mk7.kang@samsung.com> | 2013-04-01 14:02:08 +0900 |
| commit | f24869d3a8f6646c2d207057719e6fa0a8f31eb0 (patch) | |
| tree | d14942201488f330c95e3bc141dc12bcefe43c33 /arch/arm/cpu/armv7/s5p-common | |
| parent | 3d00c0cb96ff93a929700b80d89cb905e5ab5315 (diff) | |
| download | u-boot-f24869d3a8f6646c2d207057719e6fa0a8f31eb0.tar.gz | |
Exynos: Add timer_get_us function
timer_get_us returns the time in microseconds since a certain reference
point of history. However, it does not guarantee to return an accurate
time after a long period; instead, it wraps around (that is, the
reference point is reset to some other point of history) after some
periods. The frequency of wrapping around is about an hour (or 2^32
microseconds).
Test with command "sf probe 1:0; time sf read 40008000 0 1000".
Try with different numbers of bytes and see that sane values are obtained
Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
Diffstat (limited to 'arch/arm/cpu/armv7/s5p-common')
| -rw-r--r-- | arch/arm/cpu/armv7/s5p-common/timer.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/arm/cpu/armv7/s5p-common/timer.c b/arch/arm/cpu/armv7/s5p-common/timer.c index c48a297702..de6140516c 100644 --- a/arch/arm/cpu/armv7/s5p-common/timer.c +++ b/arch/arm/cpu/armv7/s5p-common/timer.c @@ -90,6 +90,21 @@ unsigned long get_timer(unsigned long base) return gd->arch.timer_reset_value / 1000 - base; } +unsigned long timer_get_us(void) +{ + static unsigned long base_time_us; + + struct s5p_timer *const timer = + (struct s5p_timer *)samsung_get_base_timer(); + unsigned long now_downward_us = readl(&timer->tcnto4); + + if (!base_time_us) + base_time_us = now_downward_us; + + /* Note that this timer counts downward. */ + return base_time_us - now_downward_us; +} + /* delay x useconds */ void __udelay(unsigned long usec) { |