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>
After adding a pinctrl flag to gpio-mmio we can use it
for driving gpio-vf610.
The existing code has the same semantics and the generic
gpio-mmio, including reading from the data out register
when the direction is set to input, and it can also handle
the absence of the direction register better than the
current driver: we get the direction from the shadow
direction registers in gpio-mmio instead.
Since gpio-mmio has an internal spinlock we can drop the
direction-protecting spinlock from the driver.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Tested-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/20250219-vf610-mmio-v3-2-588b64f0b689@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Both gpio-sim and gpio-virtuser share a mechanism to instantiate a
platform device, wait for probe completion, and retrieve the probe
success or error status synchronously. With gpio-aggregator planned to
adopt this approach for its configfs interface, it's time to factor
out the common code.
Add dev-sync-probe.[ch] to house helper functions used by all such
implementations.
No functional change.
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/20250221133501.2203897-2-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Pull gpio updates from Bartosz Golaszewski:
"Thanks to little activity in December, this is really tiny. Just a few
updates to drivers and device-tree bindings.
Driver improvements:
- support a new model in gpio-mpc8xxx
- refactor gpio-tqmx86 and add support for direction setting
- allow building gpio-omap with COMPILE_TEST=y
- use gpiochip_get_data() instead of dev_get_drvdata() in
gpio-twl6040
- drop unued field from driver data in gpio-altera
- use generic request/free callbacks in gpio-regmap for better
integration with pinctrl
- use dev_err_probe() where applicable in gpio-pca953x
- use existing dedicated GPIO defines in gpio-tps65219 instead of
custom ones
DT bindings:
- document a new model in fsl,qoriq-gpio
- explain the chip's latch clock pin and how it works like
chip-select in fairchild,74hc595
- enable the gpio-line-names property for gpio-brcmstb"
* tag 'gpio-updates-for-v6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
gpio: regmap: Use generic request/free ops
gpio: altera: Drop .mapped_irq from driver data
gpio: mpc8xxx: Add MPC8314 support
dt-bindings: gpio: fsl,qoriq-gpio: Add compatible string fsl,mpc8314-gpio
dt-bindings: gpio: fairchild,74hc595: Document chip select vs. latch clock
gpio: tps65219: Use existing kernel gpio macros
gpio: pca953x: log an error when failing to get the reset GPIO
dt-bindings: gpio: brcmstb: permit gpio-line-names property
gpio: tqmx86: add support for changing GPIO directions
gpio: tqmx86: introduce tqmx86_gpio_clrsetbits() helper
gpio: tqmx86: use cleanup guards for spinlock
gpio: tqmx86: consistently refer to IRQs by hwirq numbers
gpio: tqmx86: add macros for interrupt configuration
gpio: omap: allow building the module with COMPILE_TEST=y
gpio: twl4030: use gpiochip_get_data
FTDI FT2232H is a USB to GPIO chip. Sealevel produces some devices
with this chip. FT2232H presents itself as a composite device with two
interfaces (each is an "MPSSE"). Each MPSSE has two banks (high and low)
of 8 GPIO each. I believe some MPSSE's have only one bank, but I don't
know how to identify them (I don't have any for testing) and as a result
are unsupported for the time being.
Additionally, this driver provides software polling-based interrupts for
edge detection. For the Sealevel device I have to test with, this works
well because there is hardware debouncing. From talking to Sealevel's
people, this is their preferred way to do edge detection.
Signed-off-by: Mary Strodl <mstrodl@csh.rit.edu>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241009131131.1618329-1-mstrodl@csh.rit.edu
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Pull gpio updates from Bartosz Golaszewski:
"The majority of added lines are two new modules: the GPIO virtual
consumer module that improves our ability to add automated tests for
the kernel API and the "sloppy" logic analyzer module that uses the
GPIO API to implement a coarse-grained debugging tool for useful for
remote development.
Other than that we have the usual assortment of various driver
extensions, improvements to the core GPIO code, DT-bindings and other
documentation updates as well as an extension to the interrupt
simulator:
GPIOLIB core:
- rework kfifo handling rework in the character device code
- improve the labeling of GPIOs requested as interrupts and show more
info on interrupt-only GPIOs in debugfs
- remove unused APIs
- unexport interfaces that are only used from the core GPIO code
- drop the return value from gpiochip_set_desc_names() as it cannot
fail
- move a string array definition out of a header and into a specific
compilation unit
- convert the last user of gpiochip_get_desc() other than GPIO core
to using a safer alternative
- use array_index_nospec() where applicable
New drivers:
- add a "virtual GPIO consumer" module that allows requesting GPIOs
from actual hardware and driving tests of the in-kernel GPIO API
from user-space over debugfs
- add a GPIO-based "sloppy" logic analyzer module useful for "first
glance" debugging on remote boards
Driver improvements:
- add support for a new model to gpio-pca953x
- lock GPIOs as interrupts in gpio-sim when the lines are requested
as irqs via the simulator domain + some other minor improvements
- improve error reporting in gpio-syscon
- convert gpio-ath79 to using dynamic GPIO base and range
- use pcibios_err_to_errno() for converting PCIBIOS error codes to
errno vaues in gpio-amd8111 and gpio-rdc321x
- allow building gpio-brcmstb for the BCM2835 architecture
DT bindings:
- convert DT bindings for lsi,zevio, mpc8xxx, and atmel to DT schema
- document new properties for aspeed,gpio, fsl,qoriq-gpio and
gpio-vf610
- document new compatibles for pca953x and fsl,qoriq-gpio
Documentation:
- document stricter behavior of the GPIO character device uAPI with
regards to reconfiguring requested line without direction set
- clarify the effect of the active-low flag on line values and edges
- remove documentation for the legacy GPIO API in order to stop
tempting people to use it
- document the preference for using pread() for reading edge events
in the sysfs API
Other:
- add an extended initializer to the interrupt simulator allowing to
specify a number of callbacks callers can use to be notified about
irqs being requested and released"
* tag 'gpio-updates-for-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (41 commits)
gpio: mc33880: Convert comma to semicolon
gpio: virtuser: actually use the "trimmed" local variable
dt-bindings: gpio: convert Atmel GPIO to json-schema
gpio: virtuser: new virtual testing driver for the GPIO API
dt-bindings: gpio: vf610: Allow gpio-line-names to be set
gpio: sim: lock GPIOs as interrupts when they are requested
genirq/irq_sim: add an extended irq_sim initializer
dt-bindings: gpio: fsl,qoriq-gpio: Add compatible string fsl,ls1046a-gpio
gpiolib: unexport gpiochip_get_desc()
gpio: add sloppy logic analyzer using polling
Documentation: gpio: Reconfiguration with unset direction (uAPI v2)
Documentation: gpio: Reconfiguration with unset direction (uAPI v1)
dt-bindings: gpio: fsl,qoriq-gpio: add common property gpio-line-names
gpio: ath79: convert to dynamic GPIO base allocation
pinctrl: da9062: replace gpiochip_get_desc() with gpio_device_get_desc()
gpiolib: put gpio_suffixes in a single compilation unit
Documentation: gpio: Clarify effect of active low flag on line edges
Documentation: gpio: Clarify effect of active low flag on line values
gpiolib: Remove data-less gpiochip_add() function
gpio: sim: use devm_mutex_init()
...
The GPIO subsystem used to have a serious problem with undefined behavior
and use-after-free bugs on hot-unplug of GPIO chips. This can be
considered a corner-case by some as most GPIO controllers are enabled
early in the boot process and live until the system goes down but most
GPIO drivers do allow unbind over sysfs, many are loadable modules that
can be (force) unloaded and there are also GPIO devices that can be
dynamically detached, for instance CP2112 which is a USB GPIO expender.
Bugs can be triggered both from user-space as well as by in-kernel users.
We have the means of testing it from user-space via the character device
but the issues manifest themselves differently in the kernel.
This is a proposition of adding a new virtual driver - a configurable
GPIO consumer that can be configured over configfs (similarly to
gpio-sim) or described on the device-tree.
This driver is aimed as a helper in spotting any regressions in
hot-unplug handling in GPIOLIB.
Link: https://lore.kernel.org/r/20240708142912.120570-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
