5fd518a27c
The port could only run with a periodic ARM SysTick tick. Add an alarm/ oneshot lower-half backed by an RP2350 system timer block so the scheduler can run tickless, waking the CPU only when a timer actually expires. rp23xx_oneshot.c implements the ONESHOT_COUNT lower-half (mirroring the RISC-V mtimer driver). A timer block is a free-running 64-bit microsecond counter (clocked by the TICKS block, independent of the SysTick), which serves directly as the monotonic time base returned by current(), so timekeeping is exact to 1 us. The one adaptation versus a full 64-bit compare timer is that the RP2350 ALARM registers match only the low 32 bits of the counter: max_delay() is therefore capped below 2^32 counts (~71.5 minutes) so the scheduler never asks for a longer interval, and any deadline that is already due -- or that the counter reaches while the alarm is being armed -- is raised immediately through the INTF force register instead of waiting a full 32-bit wrap for the compare to match again. Enabled with CONFIG_RP23XX_SYSTIMER_TICKLESS (mutually exclusive with RP23XX_SYSTIMER_SYSTICK), which selects ONESHOT, ONESHOT_COUNT and ALARM_ARCH; up_timer_initialize() then hands the oneshot to up_alarm_set_lowerhalf(). ARCH_CHIP_RP23XX now selects ARCH_HAVE_TICKLESS. The block is selectable with CONFIG_RP23XX_SYSTIMER_TICKLESS_TIMER0 (default) or _TIMER1; the chosen block is claimed exclusively by the scheduler and is excluded from the /dev/timer driver (CONFIG_RP23XX_TIMER) in Kconfig, so the tickless clock and a /dev/timer device can coexist on different blocks. Tested on Pimoroni Pico Plus 2 (RP2350B) hardware with CONFIG_SCHED_TICKLESS and CONFIG_SCHED_TICKLESS_ALARM: the image boots to nsh and keeps accurate time -- "uptime" advances at real-time rate (17 s over a measured 17.4 s) and "sleep 4" blocks for 4.25 s of wall time -- confirming the oneshot both drives the scheduler and provides a correct 1 MHz monotonic clock. Assisted-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> |
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| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.