2bd8040174
Pull GPIO updates from Linus Walleij:
"This is the bulk of GPIO changes for the v4.12 kernel cycle.
Core changes:
- Return NULL from gpiod_get_optional() when GPIOLIB is disabled.
This was a much discussed change. It affects use cases where people
write drivers that might or might not be using GPIO resources. I
have decided that this is the lesser evil right now.
- Make gpiod_count() behave consistently across different hardware
descriptions.
- Fix the syntax around open drain/open source to not infer active
high/low semantics.
New drivers:
- A new single-register fixed-direction framework driver for hardware
that have lines controlled by a single register that just work in
one direction (out or in), including IRQ support.
- Support the Fintek F71889A GPIO SuperIO controller.
- Support the National NI 169445 MMIO GPIO.
- Support for the X-Gene derivative of the DWC GPIO controller
- Support for the Rohm BD9571MWV-M PMIC GPIO controller.
- Refactor the Gemini GPIO driver to a generic Faraday FTGPIO driver
and replace both the Gemini and the Moxa ART custom drivers with
this driver.
Driver improvements:
- A whole slew of drivers have their spinlocks chaned to raw
spinlocks as they provide irqchips, and thus we are progressing on
realtime compliance.
- Use devm_irq_alloc_descs() in a slew of drivers, getting managed
resources.
- Support for the embedded PWM controller inside the MVEBU driver.
- Debounce, open source and open drain support for the Aspeed driver.
- Misc smaller fixes like spelling and syntax and whatnot"
* tag 'gpio-v4.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (77 commits)
gpio: f7188x: Add a missing break
gpio: omap: return error if requested debounce time is not possible
gpio: Add ROHM BD9571MWV-M PMIC GPIO driver
gpio: gpio-wcove: fix GPIO IRQ status mask
gpio: DT bindings, move tca9554 from pcf857x to pca953x
gpio: move tca9554 from pcf857x to pca953x
gpio: arizona: Correct check whether the pin is an input
gpio: Add XRA1403 DTS binding documentation
dt-bindings: add exar to vendor prefixes list
gpio: gpio-wcove: fix irq pending status bit width
gpio: dwapb: use dwapb_read instead of readl_relaxed
gpio: aspeed: Add open-source and open-drain support
gpio: aspeed: Add debounce support
gpio: aspeed: dt: Add optional clocks property
gpio: aspeed: dt: Fix description alignment in bindings document
gpio: mvebu: Add limited PWM support
gpio: Use unsigned int for interrupt numbers
gpio: f7188x: Add F71889A GPIO support.
gpio: core: Decouple open drain/source flag with active low/high
gpio: arizona: Correct handling for reading input GPIOs
...
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.