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Justin Hammond 9b7c7717f8 drivers/devfreq: Document the frequency table contract.
A driver author had to read the core to learn what a frequency table may
contain: the rules live in devfreq_table_validate() and in the four other
places that skip DEVFREQ_ENTRY_INVALID.  State them where the special
values are defined instead.  A table ascends, DEVFREQ_ENTRY_END terminates
it, DEVFREQ_ENTRY_INVALID stands in for a frequency the device cannot use
and is skipped by every consumer, and devfreq_register() rejects a table
whose usable entries do not ascend.

Say on get_table that it is called once, by devfreq_register(), which
keeps the returned table for the life of the device.  That is a real
constraint on the caller, since the table cannot be on its stack, and
consumers outside the core retain the same pointer.

Comments only, no functional change.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
2026-08-18 09:46:47 -03:00
.github ci: do not trigger Build on PR description edits 2026-08-16 19:08:58 -04:00
arch arch/arm/stm32: use common SYSTICK_HCLKd8 symbol 2026-08-18 09:34:58 +08:00
audio audio: limit the buffer count guard to shared ring requests 2026-08-05 07:58:53 +02:00
binfmt sched: add supplementary group IDs (setgroups/getgroups/initgroups) 2026-08-12 16:06:03 -03:00
boards sim/thermal: Exercise the devfreq cooling path. 2026-08-18 09:46:47 -03:00
cmake sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
crypto tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
Documentation sim/thermal: Exercise the devfreq cooling path. 2026-08-18 09:46:47 -03:00
drivers drivers/thermal: Cool a devfreq device instead of a cpufreq policy. 2026-08-18 09:46:47 -03:00
dummy build: add initial cmake build system 2023-07-08 13:50:48 +08:00
fs sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
graphics tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
include drivers/devfreq: Document the frequency table contract. 2026-08-18 09:46:47 -03:00
libs libs/libc/machine/risc-v: Compare a register at a time on equal offsets. 2026-08-17 12:24:06 +02:00
mm cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
net net/arp: do not resolve an address to another interface's MAC 2026-08-17 11:28:45 +08:00
openamp cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
pass1 tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
sched sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
syscall sched: add supplementary group IDs (setgroups/getgroups/initgroups) 2026-08-12 16:06:03 -03:00
tools sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
video tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
wireless wireless/bluetooth/bt_hcicore.c: Balance conn and buffer refs in hci_acl(). 2026-08-15 11:51:19 +08:00
.asf.yaml github: master branch protection tune. 2025-05-07 18:37:13 -05:00
.codespell-ignore-lines arch/arm: Reserve r10 via ARCHCFLAGS and hoist the PIC module flags. 2026-07-24 23:09:08 +08:00
.codespellrc arch/arm/rp23xx: Add hardware TRNG driver for /dev/random. 2026-07-25 15:06:56 +08:00
.editorconfig .editorconfig: fix character encoding property specification 2025-11-28 19:12:13 +08:00
.gitignore git: Specify multiple build directories in .gitignore. 2026-05-20 03:06:58 +08:00
.gitmessage docs/contributing: Add a commit message template 2025-06-03 17:33:24 +08:00
.pre-commit-config.yaml pre-commit: enable codespell checks 2025-05-05 12:34:39 +08:00
.yamllint feat: add a GitHub action to lint the YAML files 2020-12-15 09:52:04 -06:00
AUTHORS AUTHORS: add Eren Terzioglu 2026-05-20 15:17:00 +08:00
CMakeLists.txt Revert "cmake: normalize .config on reconfigure" 2026-08-13 07:54:00 +02:00
CONTRIBUTING.md contributing: Add requirement for 'Assisted-by' commit field 2026-07-12 09:42:28 +08:00
INVIOLABLES.md
Kconfig drivers/clk: Add debug output levels. 2026-08-16 23:23:04 +08:00
LICENSE libs/libdsp: Add Matrix operations 2026-07-11 14:55:59 -03:00
Makefile !boards: enforce secure ROMFS passwd and TEA key setup 2026-07-09 22:41:11 +08:00
NOTICE Remove the double blank line from source files 2022-02-20 20:10:14 +01:00
README.md ci/testing: Add MemBrowse Integration 2026-06-18 12:07:41 -03:00
ReleaseNotes Documentation: move ReleaseNotes 2023-09-26 20:41:00 +08:00

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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.