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21cdd133ca
It is not safe to compare timer values directly. On 32-bit systems, for example, timer_get_us() wraps around every 72 min. (2 ^ 32 / 1000000 =~ 4295 sec =~ 72 min). Depending on the get_ticks() implementation, it may wrap more frequently. The 72 min might be possible on the use of U-Boot. Let's borrow time_after, time_before, and friends to solve the wrap-around problem. These macros were copied from include/linux/jiffies.h of Linux 4.9. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Simon Glass <sjg@chromium.org>
58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
/*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#ifndef _TIME_H
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#define _TIME_H
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#include <linux/typecheck.h>
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unsigned long get_timer(unsigned long base);
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/*
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* Return the current value of a monotonically increasing microsecond timer.
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* Granularity may be larger than 1us if hardware does not support this.
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*/
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unsigned long timer_get_us(void);
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/*
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* These inlines deal with timer wrapping correctly. You are
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* strongly encouraged to use them
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* 1. Because people otherwise forget
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* 2. Because if the timer wrap changes in future you won't have to
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* alter your driver code.
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*
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* time_after(a,b) returns true if the time a is after time b.
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*
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* Do this with "<0" and ">=0" to only test the sign of the result. A
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* good compiler would generate better code (and a really good compiler
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* wouldn't care). Gcc is currently neither.
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*/
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#define time_after(a,b) \
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(typecheck(unsigned long, a) && \
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typecheck(unsigned long, b) && \
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((long)((b) - (a)) < 0))
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#define time_before(a,b) time_after(b,a)
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#define time_after_eq(a,b) \
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(typecheck(unsigned long, a) && \
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typecheck(unsigned long, b) && \
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((long)((a) - (b)) >= 0))
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#define time_before_eq(a,b) time_after_eq(b,a)
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/*
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* Calculate whether a is in the range of [b, c].
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*/
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#define time_in_range(a,b,c) \
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(time_after_eq(a,b) && \
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time_before_eq(a,c))
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/*
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* Calculate whether a is in the range of [b, c).
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*/
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#define time_in_range_open(a,b,c) \
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(time_after_eq(a,b) && \
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time_before(a,c))
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#endif /* _TIME_H */
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