nuttx/Documentation/components
Justin Hammond 69386aa6c0
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drivers/power: Describe the regulators through procfs.
The regulator framework has no way out to userspace: consumers reach a
rail by name from inside the kernel, which is the right interface for
controlling one, but it leaves a board with regulators offering no way
to see what they are doing, and a newly written regulator driver cannot
be looked at without writing a consumer for it first.

Adds /proc/regulator, behind REGULATOR_PROCFS, listing every registered
regulator: its present voltage, the range it will accept, whether it is
enabled, how many consumers hold and enable it, its supply, and whether
it is always on or expected on at boot.  Lines carry the same key:value
tokens in the same order, so the file is machine parseable.  The last
two are worth reading beside the consumer count, since a rail enabled
with no consumers is expected rather than suspect when either is set.

A part usually measures more than the framework has fields for, so
struct regulator_ops_s gains an optional describe method: it writes
key:value text and the renderer appends it to that rail's line.  This is
how a driver reports what only it knows, an input voltage, an output
current, a temperature or a fault word, without the framework growing a
field per part or the driver growing procfs code of its own.  It is
called with the list mutex held and never from interrupt context, so
reading the part over a bus is allowed.

The voltage and the enabled state are read back from the hardware rather
than recalled, so a rail the boot loader set and nothing has touched
since reads as it actually is.  Both calls can fail, and a failure
reports - rather than an errno formatted as a voltage or a rail that
looks switched on.

Reading the hardware is also why this takes the list mutex directly
rather than calling regulator_list_lock(), which additionally disables
interrupts so that callers in interrupt or idle context are safe.
Asking a regulator on a bus what it is doing means a transfer, and a
transfer waits; a task reading a file can afford to wait and an
interrupt handler cannot.

procfs_register() appends without checking for duplicates, so the entry
is claimed once for the lifetime of the system rather than whenever the
list is empty.  It also needs FS_PROCFS_REGISTER, which the option now
depends on rather than only FS_PROCFS.

Documents the framework, which had no page at all: the consumer
interface and what counted enables mean, what a driver supplies, and the
new entry.

The entry is read only.  What voltage a rail may be is knowledge its
consumers hold, and arranging the order between them is what the
framework is for, so moving one from a shell would step around the part
that matters.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
2026-08-18 17:28:02 +08:00
..
arch Documentation: update organization.rst 2023-10-30 20:29:54 +08:00
audio Documentation/audio: document the audio upper half interface 2026-08-05 07:58:53 +02:00
concurrency Documentation: Add documentation for seqcount. 2025-12-22 10:22:06 -03:00
drivers drivers/power: Describe the regulators through procfs. 2026-08-18 17:28:02 +08:00
filesystem !arch/arm: Use r9 as the PIC base register. 2026-08-06 01:38:23 +08:00
libs include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
mm mm/iob: add iob_init method to support external buffer init as iob structure 2025-12-25 10:08:49 +08:00
net Documentation/net: document lower-half driver performance tuning 2026-07-13 11:53:26 +02:00
nxgraphics !boards/boardctl: Remove BOARDIOC_INIT 2026-05-26 09:57:29 +08:00
tools sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
binfmt.rst style: fix typos 2025-04-30 13:45:46 +08:00
boards.rst Documentation/components/boards.rst: fix typo 2026-06-04 09:58:42 +08:00
cmake.rst Documentation: initialize cmake doc 2023-10-27 13:21:40 -03:00
crypto.rst crypto: Support SHA2_224_HMAC 2026-07-04 14:15:17 +08:00
index.rst Documentation: Add documentation for seqcount. 2025-12-22 10:22:06 -03:00
nxflat.rst Documentation/nxflat: Document the in-tree mknxflat and the ABI marker. 2026-08-06 01:38:23 +08:00
openamp.rst Documentation: add dummy pages for missing top directories 2023-10-27 13:21:40 -03:00
paging.rst style: fix typos 2025-04-30 13:45:46 +08:00
syscall.rst Documentation: fix spelling 2025-05-15 11:33:41 +08:00
video.rst Documentation: add dummy pages for missing top directories 2023-10-27 13:21:40 -03:00
wireless.rst Documentation: add dummy pages for missing top directories 2023-10-27 13:21:40 -03:00