mirror of
https://github.com/torvalds/linux.git
synced 2026-07-30 11:11:26 +02:00
Linux kernel source tree
86f162e73d
The existing sysfs 'new_device' interface has several limitations:
* No way to determine when GPIO aggregator creation is complete.
* No way to retrieve errors when creating a GPIO aggregator.
* No way to trace a GPIO line of an aggregator back to its
corresponding physical device.
* The 'new_device' echo does not indicate which virtual gpiochip<N>
was created.
* No way to assign names to GPIO lines exported through an aggregator.
Introduce the new configfs interface for gpio-aggregator to address
these limitations. It provides a more streamlined, modern, and
extensible configuration method. For backward compatibility, the
'new_device' interface and its behavior is retained for now.
This commit implements basic functionalities:
/config/gpio-aggregator/<name-of-your-choice>/
/config/gpio-aggregator/<name-of-your-choice>/live
/config/gpio-aggregator/<name-of-your-choice>/dev_name
/config/gpio-aggregator/<name-of-your-choice>/<lineY>/
/config/gpio-aggregator/<name-of-your-choice>/<lineY>/key
/config/gpio-aggregator/<name-of-your-choice>/<lineY>/offset
/config/gpio-aggregator/<name-of-your-choice>/<lineY>/name
Basic setup flow is:
1. Create a directory for a GPIO aggregator.
2. Create subdirectories for each line you want to instantiate.
3. In each line directory, configure the key and offset.
The key/offset semantics are as follows:
* If offset is >= 0:
- key specifies the name of the chip this GPIO belongs to
- offset specifies the line offset within that chip.
* If offset is <0:
- key needs to specify the GPIO line name.
4. Return to the aggregator's root directory and write '1' to the live
attribute.
For example, the command in the existing kernel doc:
echo 'e6052000.gpio 19 e6050000.gpio 20-21' > new_device
is equivalent to:
mkdir /sys/kernel/config/gpio-aggregator/<custom-name>
# Change <custom-name> to name of your choice (e.g. "aggr0")
cd /sys/kernel/config/gpio-aggregator/<custom-name>
mkdir line0 line1 line2 # Only "line<Y>" naming allowed.
echo e6052000.gpio > line0/key
echo 19 > line0/offset
echo e6050000.gpio > line1/key
echo 20 > line1/offset
echo e6050000.gpio > line2/key
echo 21 > line2/offset
echo 1 > live
The corresponding gpio_device id can be identified as follows:
cd /sys/kernel/config/gpio-aggregator/<custom-name>
ls -d /sys/devices/platform/`cat dev_name`/gpiochip*
Also, via configfs, custom GPIO line name can be set like this:
cd /sys/kernel/config/gpio-aggregator/<custom-name>
echo "abc" > line1/name
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/20250407043019.4105613-5-koichiro.den@canonical.com
[Bartosz: remove stray newlines]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.