diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2020-12-15 15:09:28 +0000 |
|---|---|---|
| committer | Philippe Mathieu-Daudé <f4bug@amsat.org> | 2021-01-04 23:24:44 +0100 |
| commit | de6a65f11d7e5a2a93f2b75c0d434ab6ed7f68c8 (patch) | |
| tree | eda8b610ef97a0cec2c25aa05535c00104a0f417 /docs | |
| parent | 0ac1fb256742f665449c3dd02dd0ed7a5112cea1 (diff) | |
clock: Remove clock_get_ns()
Remove the now-unused clock_get_ns() API and the CLOCK_PERIOD_TO_NS()
macro that only it was using.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20201215150929.30311-4-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/devel/clocks.rst | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/docs/devel/clocks.rst b/docs/devel/clocks.rst index c2e70e64db..2d317ff32f 100644 --- a/docs/devel/clocks.rst +++ b/docs/devel/clocks.rst @@ -238,8 +238,17 @@ object during device instance init. For example: Fetching clock frequency/period ------------------------------- -To get the current state of a clock, use the functions ``clock_get()``, -``clock_get_ns()`` or ``clock_get_hz()``. +To get the current state of a clock, use the functions ``clock_get()`` +or ``clock_get_hz()``. + +``clock_get()`` returns the period of the clock in its fully precise +internal representation, as an unsigned 64-bit integer in units of +2^-32 nanoseconds. (For many purposes ``clock_ticks_to_ns()`` will +be more convenient; see the section below on expiry deadlines.) + +``clock_get_hz()`` returns the frequency of the clock, rounded to the +next lowest integer. This implies some inaccuracy due to the rounding, +so be cautious about using it in calculations. It is also possible to register a callback on clock frequency changes. Here is an example: @@ -254,8 +263,8 @@ Here is an example: */ /* do something with the new period */ - fprintf(stdout, "device new period is %" PRIu64 "ns\n", - clock_get_ns(dev->my_clk_input)); + fprintf(stdout, "device new period is %" PRIu64 "* 2^-32 ns\n", + clock_get(dev->my_clk_input)); } Calculating expiry deadlines |