Merge tag 'gpio-updates-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux
Pull gpio updates from Bartosz Golaszewski:
"The gpio-sim module is back, this time without any changes to
configfs. This results in a less elegant user-space interface but I
never got any follow-up on the committable items and didn't want to
delay this module for several more months.
Other than that we have support for several new models and some
support going away. We started working on converting GPIO drivers to
using fwnode exclusively in order to limit references to OF symbols to
gpiolib-of.c exclusively. We also have regular tweaks and improvements
all over the place.
Summary:
- new testing module: gpio-sim that is scheduled to replace
gpio-mockup
- initial changes aiming at converting all GPIO drivers to using the
fwnode interface and limiting any references to OF symbols to
gpiolib-of.c
- add support for Tegra234 and Tegra241 to gpio-tegra186
- add support for new models (SSD201 and SSD202D) to gpio-msc313
- add basic support for interrupts to gpio-aggregator
- add support for AMDIF031 HID device to gpio-amdpt
- drop support for unused platforms in gpio-xlp
- cleanup leftovers from the removal of the legacy Samsung Exynos
GPIO driver
- use raw spinlocks in gpio-aspeed and gpio-aspeed-sgpio to make
PREEMPT_RT happy
- generalize the common 'ngpios' device property by reading it in the
core gpiolib code so that we can remove duplicate reads from
drivers
- allow line names from device properties to override names set by
drivers
- code shrink in gpiod_add_lookup_table()
- add new model to the DT bindings for gpio-vf610
- convert DT bindings for tegra devices to YAML
- improvements to interrupt handling in gpio-rcar and gpio-rockchip
- updates to intel drivers from Andy (details in the merge commit)
- some minor tweaks, improvements and coding-style fixes all around
the subsystem"
* tag 'gpio-updates-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (59 commits)
gpio: rcar: Propagate errors from devm_request_irq()
gpio: rcar: Use platform_get_irq() to get the interrupt
gpio: ts5500: Use platform_get_irq() to get the interrupt
gpio: dwapb: Switch to use fwnode instead of of_node
gpiolib: acpi: make fwnode take precedence in struct gpio_chip
dt-bindings: gpio: samsung: drop unused bindings
gpio: max3191x: Use bitmap_free() to free bitmap
gpio: regmap: Switch to use fwnode instead of of_node
gpio: tegra186: Add support for Tegra241
dt-bindings: gpio: Add Tegra241 support
gpio: brcmstb: Use local variable to access OF node
gpio: Remove unused local OF node pointers
gpio: sim: add missing fwnode_handle_put() in gpio_sim_probe()
gpio: msc313: Add support for SSD201 and SSD202D
gpio: msc313: Code clean ups
dt-bindings: gpio: msc313: Add offsets for ssd20xd
dt-bindings: gpio: msc313: Add compatible for ssd20xd
gpio: sim: fix uninitialized ret variable
gpio: Propagate firmware node from a parent device
gpio: Setup parent device and get rid of unnecessary of_node assignment
...
This commit is contained in:
Linus Torvalds
134
Documentation/admin-guide/gpio/gpio-sim.rst
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134
Documentation/admin-guide/gpio/gpio-sim.rst
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.. SPDX-License-Identifier: GPL-2.0-or-later
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Configfs GPIO Simulator
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=======================
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The configfs GPIO Simulator (gpio-sim) provides a way to create simulated GPIO
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chips for testing purposes. The lines exposed by these chips can be accessed
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using the standard GPIO character device interface as well as manipulated
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using sysfs attributes.
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Creating simulated chips
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------------------------
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The gpio-sim module registers a configfs subsystem called ``'gpio-sim'``. For
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details of the configfs filesystem, please refer to the configfs documentation.
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The user can create a hierarchy of configfs groups and items as well as modify
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values of exposed attributes. Once the chip is instantiated, this hierarchy
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will be translated to appropriate device properties. The general structure is:
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**Group:** ``/config/gpio-sim``
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This is the top directory of the gpio-sim configfs tree.
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**Group:** ``/config/gpio-sim/gpio-device``
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**Attribute:** ``/config/gpio-sim/gpio-device/dev_name``
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**Attribute:** ``/config/gpio-sim/gpio-device/live``
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This is a directory representing a GPIO platform device. The ``'dev_name'``
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attribute is read-only and allows the user-space to read the platform device
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name (e.g. ``'gpio-sim.0'``). The ``'live'`` attribute allows to trigger the
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actual creation of the device once it's fully configured. The accepted values
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are: ``'1'`` to enable the simulated device and ``'0'`` to disable and tear
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it down.
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**Group:** ``/config/gpio-sim/gpio-device/gpio-bankX``
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**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/chip_name``
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**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/num_lines``
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This group represents a bank of GPIOs under the top platform device. The
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``'chip_name'`` attribute is read-only and allows the user-space to read the
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device name of the bank device. The ``'num_lines'`` attribute allows to specify
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the number of lines exposed by this bank.
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**Group:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY``
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**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/name``
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This group represents a single line at the offset Y. The 'name' attribute
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allows to set the line name as represented by the 'gpio-line-names' property.
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**Item:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog``
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**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog/name``
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**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog/direction``
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This item makes the gpio-sim module hog the associated line. The ``'name'``
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attribute specifies the in-kernel consumer name to use. The ``'direction'``
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attribute specifies the hog direction and must be one of: ``'input'``,
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``'output-high'`` and ``'output-low'``.
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Inside each bank directory, there's a set of attributes that can be used to
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configure the new chip. Additionally the user can ``mkdir()`` subdirectories
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inside the chip's directory that allow to pass additional configuration for
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specific lines. The name of those subdirectories must take the form of:
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``'line<offset>'`` (e.g. ``'line0'``, ``'line20'``, etc.) as the name will be
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used by the module to assign the config to the specific line at given offset.
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Once the confiuration is complete, the ``'live'`` attribute must be set to 1 in
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order to instantiate the chip. It can be set back to 0 to destroy the simulated
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chip. The module will synchronously wait for the new simulated device to be
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successfully probed and if this doesn't happen, writing to ``'live'`` will
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result in an error.
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Simulated GPIO chips can also be defined in device-tree. The compatible string
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must be: ``"gpio-simulator"``. Supported properties are:
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``"gpio-sim,label"`` - chip label
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Other standard GPIO properties (like ``"gpio-line-names"``, ``"ngpios"`` or
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``"gpio-hog"``) are also supported. Please refer to the GPIO documentation for
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details.
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An example device-tree code defining a GPIO simulator:
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.. code-block :: none
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gpio-sim {
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compatible = "gpio-simulator";
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bank0 {
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gpio-controller;
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#gpio-cells = <2>;
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ngpios = <16>;
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gpio-sim,label = "dt-bank0";
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gpio-line-names = "", "sim-foo", "", "sim-bar";
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};
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bank1 {
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gpio-controller;
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#gpio-cells = <2>;
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ngpios = <8>;
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gpio-sim,label = "dt-bank1";
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line3 {
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gpio-hog;
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gpios = <3 0>;
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output-high;
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line-name = "sim-hog-from-dt";
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};
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};
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};
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Manipulating simulated lines
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----------------------------
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Each simulated GPIO chip creates a separate sysfs group under its device
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directory for each exposed line
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(e.g. ``/sys/devices/platform/gpio-sim.X/gpiochipY/``). The name of each group
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is of the form: ``'sim_gpioX'`` where X is the offset of the line. Inside each
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group there are two attibutes:
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``pull`` - allows to read and set the current simulated pull setting for
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every line, when writing the value must be one of: ``'pull-up'``,
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``'pull-down'``
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``value`` - allows to read the current value of the line which may be
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different from the pull if the line is being driven from
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user-space
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