FDT bindings document for gpio-i2c devices.
Using the gpio_pin_* functions to acquire/release/manipulate gpio pins
removes the constraint that both gpio pins must belong to the same gpio
controller/bank, and that the gpioiic instance must be a child of gpiobus.
Removing those constraints allows the driver to be fully compatible with
the modern dts bindings for a gpio bitbanged i2c bus.
For hinted attachment, the two gpio pins still must be on the same gpiobus,
and the device instance must be a child of that bus. This preserves
compatibility for existing installations that have use gpioiic(4) with hints.
Some controllers cannot preset future output value while the pin is in
input mode. This adds a fallback for those controllers. The new code
assumes that a controller reports an error in that case.
For example, all hardware supported by nctgpio behaves in that way.
This is a temporary measure. In the future we will use
GPIO_PIN_PRESET_LOW / GPIO_PIN_PRESET_HIGH to preset the output either
in hardware, if supported, or in software (e.g., in
gpiobus_pin_setflags).
While here, I extracted common functionality of gpioiic_set{sda,scl} and
gpioiic_get{sda,scl} to gpioiic_setpin and gpioiic_getpin respectively.
MFC after: 2 weeks
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
The GPIO hardware should not be owned by a single device, this defeats any
chance of use of the GPIO controller as an interrupt source.
ow(4) is now the only consumer of this 'feature' before we can remove it
for good.
Discussed with: ian, bsdimp
"how" argument is passed as value of int* pointer to callback
function but dereferenced as char* so only one byte taken into
into account. On little-endian systems it happens to work because
first byte is LSB that contains actual value, on big-endian it's
MSB and in this case it's always equal zero
PR: 207786
Submitted by: chadf@triularity.org
hold the gpiobus lock between the gpio calls.
gpiobus_acquire_lock() now accepts a third parameter which tells gpiobus
what to do when the bus is already busy.
When GPIOBUS_WAIT wait is used, the calling thread will be put to sleep
until the bus became free.
With GPIOBUS_DONTWAIT the calling thread will receive EWOULDBLOCK right
away and then it can act upon.
This fixes the gpioiic(4) locking issues that arises when doing multiple
concurrent access on the bus.
At attach, print the SCL and SDA pin numbers.
Remove a stray blank line.
Remove the GPIOBUS locking from gpioiic_reset(), it is already called with
this lock held. This fixes a crash when you try to scan the iicbus with
i2c(8).
gpioled(4).
Tested on RPi and BBB (using the hardware I2C controller and gpioiic(4) for
the I2C tests). It was also verified for regressions on RSPRO (MIPS/ar71xx)
used as reference for a non OFW-based system.
Update the gpioled(4) and gpioiic(4) man pages with some details and
examples about the FDT/OFW support.
Some compatibility details pointed out by imp@ will follow in subsequent
commits.
Approved by: adrian (mentor, implicit)
performance issues.
* Access to the GPIO bus is already locked by requesting
and releasing the bus - thus the lock isn't really needed
for each GPIO pin change.
* Don't lock and unlock the GPIO bus for -each- i2c access -
the i2c bus code is already doing this by calling the upper
layer callback to request/release the bus. This thus locks
the bus for the entirety of the transaction.
TODO:
* Further verify that everything is correctly requesting/
releasing the GPIO bus.
* Look at how to lock the GPIO pin configuration stuff,
potentially by locking/unlocking the bus at the gpiobus
layer.
pins, rather than defaulting to 0 and 1.
This way the pin order can be reversed. It is reversed with the
TP-Link TL-WR1043nd.
Submitted by: Stefan Bethke <stb@lassitu.de>
- license clause now contains "AUTHOR AND CONTRIBUTORS"
instead of just "AUTHOR"
- Add license/copyright to gpioc.c
Spotted by: Edward Tomasz Napierala, Andrew Turner
- GPIO bus controller interface
- GPIO bus interface
- Implementation of GPIO led(4) compatible device
- Implementation of iic(4) bus over GPIO (author: Luiz Otavio O Souza)
Tested by: Luiz Otavio O Souza, Alexandr Rybalko
