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0b5bf6c2c5
NuttX builtin up_udelay function uses BOARD_LOOPSPERMSEC configuration value to determine how many loops need to be done to cause requested delay. This does not match well with AVR DA/DB microcontrollers because the CPU clock frequency is configurable. A board configuration could therefore provide BOARD_LOOPSPERMSEC valid for one frequency but for other frequencies, the user would be required to calibrate the value and would still get incorrect result when changing the clock speed during runtime. This patch therefore implements dynamic architecture-specific up_udelay function which determines current clock settings and infers required loop count from that. New function was tested by simple application that used up_udelay to put delays between printf calls. Signed-off-by: Kerogit <kr.git@kerogit.eu>
122 lines
4.2 KiB
ReStructuredText
122 lines
4.2 KiB
ReStructuredText
=====
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Sleep
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=====
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NuttX provides three different types of sleep interfaces.
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Common Sleep Interfaces
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=======================
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Scheduled Sleep Interfaces (tick-based)
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---------------------------------------
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Suspend the calling thread for a specified amount of time until the time expires
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or the thread is explicitly woken up through scheduler operations.
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.. c:function:: void nxsched_abstick_sleep(clock_t ticks)
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Suspends the calling thread from execution until the specified absolute time in clock ticks.
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:param ticks: Absolute time in clock ticks.
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.. c:function:: void nxsched_ticksleep(unsigned int ticks)
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Suspends the calling thread from execution for the specified number of system ticks.
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:param ticks: The number of system ticks to sleep.
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.. c:function:: void nxsched_usleep(useconds_t usec)
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Suspends the calling thread from execution for the specified number of microseconds.
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:param usec: The number of microseconds to sleep.
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.. c:function:: void nxsched_msleep(unsigned int msec)
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Suspends the calling thread from execution for the specified number of milliseconds.
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:param msec: The number of milliseconds to sleep.
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.. c:function:: void nxsched_sleep(unsigned int sec)
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Suspends the calling thread from execution for the specified number of seconds.
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:param sec: The number of seconds to sleep.
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.. c:function:: int nxsched_nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
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Suspends the calling thread from execution for the specified rqtp argument. This
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function will return the remaining time via updating rmtp if the sleep is interrupted
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by a signal.
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:param rqtp: The amount of time to be suspended from execution.
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:param rmtp: If the rmtp argument is non-NULL, the timespec structure referenced
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by it is updated to contain the amount of time remaining.
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:return: 0 (OK), or negated errno if unsuccessful.
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.. c:function:: void nxsched_wakeup(struct tcb_s *tcb)
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This function is used to wake up a thread that is currently in sleeping state
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before its timeout expires.
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:param tcb: Pointer to the TCB of the task to be awakened.
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Signal-based Sleep Interfaces (timespec-based)
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----------------------------------------------
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Suspend the calling thread for a specified amount of time until the
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time expires or a signal is delivered to the calling thread.
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.. note::
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Implementations are dependent on the signal framework and based on standard
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timespec conversion.
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.. c:function:: void nxsig_usleep(useconds_t usec)
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Suspends the calling thread from execution for the specified number of microseconds.
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:param usec: The number of microseconds to sleep.
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.. c:function:: void nxsig_sleep(unsigned int sec)
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Suspends the calling thread from execution for the specified number of seconds.
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:param sec: The number of seconds to sleep.
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.. c:function:: int nxsig_nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
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Suspends the calling thread from execution for the specified rqtp argument. This
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function will return the remaining time via updating rmtp if the sleep is interrupted
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by a signal.
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:param rqtp: The amount of time to be suspended from execution.
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:param rmtp: If the rmtp argument is non-NULL, the timespec structure referenced
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by it is updated to contain the amount of time remaining.
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:return: 0 (OK), or negated errno if unsuccessful.
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Busy Sleep Interfaces
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---------------------
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Spin in a loop for the requested duration and never yield the CPU. The delay accuracy depends on
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``CONFIG_BOARD_LOOPSPERMSEC`` (unless the architecture/board code replaces these
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function(s) with an implementation that does not use the value.)
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.. c:function:: void up_mdelay(unsigned int milliseconds)
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Delay inline for the requested number of milliseconds.
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:param milliseconds: The number of milliseconds to delay.
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.. c:function:: void up_udelay(useconds_t microseconds)
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Delay inline for the requested number of microseconds.
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:param microseconds: The number of microseconds to delay.
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.. c:function:: void up_ndelay(unsigned long nanoseconds)
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Delay inline for the requested number of nanoseconds.
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:param nanoseconds: The number of nanoseconds to delay.
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