Merge tag 'gpio-v4.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
 "Here is the bulk of GPIO changes for the v4.4 development cycle.

  The only changes hitting outside drivers/gpio are in the pin control
  subsystem and these seem to have settled nicely in linux-next.

  Development mistakes and catfights are nicely documented in the
  reverts as you can see.  The outcome of the ABI fight is that we're
  working on a chardev ABI for GPIO now, where hope to show results for
  the v4.5 kernel.

  Summary of changes:

  GPIO core:
   - Define and handle flags for open drain/open collector and open
     source/open emitter, also know as "single-ended" configurations.
   - Generic request/free operations that handle calling out to the
     (optional) pin control backend.
   - Some refactoring related to an ABI change that did not happen, yet
     provide useful.
   - Added a real-time compliance checklist.  Many GPIO chips have
     irqchips, and need to think this over with the RT patches going
     upstream.
   - Restructure, fix and clean up Kconfig menus a bit.

  New drivers:
   - New driver for AMD Promony.
   - New driver for ACCES 104-IDIO-16, a port-mapped I/O card,
     ISA-style.  Very retro.

  Subdriver changes:
   - OMAP changes to handle real time requirements.
   - Handle trigger types for edge and level IRQs on PL061 properly.  As
     this hardware is very common it needs to set a proper example for
     others to follow.
   - Some container_of() cleanups.
   - Delete the unused MSM driver in favor of the driver that is
     embedded inside the pin control driver.
   - Cleanup of the ath79 GPIO driver used by many, many OpenWRT router
     targets.
   - A consolidated IT87xx driver replacing the earlier very specific
     IT8761e driver.
   - Handle the TI TCA9539 in the PCA953x driver.  Also handle ACPI
     devices in this subdriver.
   - Drop xilinx arch dependencies as these FPGAs seem to profilate over
     a few different architectures.  MIPS and ARM come to mind"

* tag 'gpio-v4.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (57 commits)
  gpio: fix up SPI submenu
  gpio: drop surplus I2C dependencies
  gpio: drop surplus X86 dependencies
  gpio: dt-bindings: document the official use of "ngpios"
  gpio: MAINTAINERS: Add an entry for the ATH79 GPIO driver
  gpio / ACPI: Allow shared GPIO event to be read via operation region
  gpio: group port-mapped I/O drivers in a menu
  gpio: Add ACCES 104-IDIO-16 driver maintainer entry
  gpio: zynq: Document interrupt-controller DT binding
  gpio: xilinx: Drop architecture dependencies
  gpio: generic: Revert to old error handling in bgpio_map
  gpio: add a real time compliance notes
  Revert "gpio: add a real time compliance checklist"
  gpio: Add GPIO support for the ACCES 104-IDIO-16
  gpio: driver for AMD Promontory
  gpio: xlp: Convert to use gpiolib irqchip helpers
  gpio: add a real time compliance checklist
  gpio/xilinx: enable for MIPS
  gpiolib: Add and use OF_GPIO_SINGLE_ENDED flag
  gpiolib: Split GPIO flags parsing and GPIO configuration
  ...

1 files changed, 39 insertions, 2 deletions

diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 82d40e2505f6..069cdf6f9dac 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -54,9 +54,13 @@ only uses one.
 
 gpio-specifier may encode: bank, pin position inside the bank,
 whether pin is open-drain and whether pin is logically inverted.
+
 Exact meaning of each specifier cell is controller specific, and must
-be documented in the device tree binding for the device. Use the macros
-defined in include/dt-bindings/gpio/gpio.h whenever possible:
+be documented in the device tree binding for the device.
+
+Most controllers are however specifying a generic flag bitfield
+in the last cell, so for these, use the macros defined in
+include/dt-bindings/gpio/gpio.h whenever possible:
 
 Example of a node using GPIOs:
 
@@ -67,6 +71,15 @@ Example of a node using GPIOs:
 GPIO_ACTIVE_HIGH is 0, so in this example gpio-specifier is "18 0" and encodes
 GPIO pin number, and GPIO flags as accepted by the "qe_pio_e" gpio-controller.
 
+Optional standard bitfield specifiers for the last cell:
+
+- Bit 0: 0 means active high, 1 means active low
+- Bit 1: 1 means single-ended wiring, see:
+           https://en.wikipedia.org/wiki/Single-ended_triode
+	   When used with active-low, this means open drain/collector, see:
+           https://en.wikipedia.org/wiki/Open_collector
+	   When used with active-high, this means open source/emitter
+
 1.1) GPIO specifier best practices
 ----------------------------------
 
@@ -118,6 +131,30 @@ Every GPIO controller node must contain both an empty "gpio-controller"
 property, and a #gpio-cells integer property, which indicates the number of
 cells in a gpio-specifier.
 
+Optionally, a GPIO controller may have a "ngpios" property. This property
+indicates the number of in-use slots of available slots for GPIOs. The
+typical example is something like this: the hardware register is 32 bits
+wide, but only 18 of the bits have a physical counterpart. The driver is
+generally written so that all 32 bits can be used, but the IP block is reused
+in a lot of designs, some using all 32 bits, some using 18 and some using
+12. In this case, setting "ngpios = <18>;" informs the driver that only the
+first 18 GPIOs, at local offset 0 .. 17, are in use.
+
+If these GPIOs do not happen to be the first N GPIOs at offset 0...N-1, an
+additional bitmask is needed to specify which GPIOs are actually in use,
+and which are dummies. The bindings for this case has not yet been
+specified, but should be specified if/when such hardware appears.
+
+Example:
+
+gpio-controller@00000000 {
+	compatible = "foo";
+	reg = <0x00000000 0x1000>;
+	gpio-controller;
+	#gpio-cells = <2>;
+	ngpios = <18>;
+}
+
 The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
 providing automatic GPIO request and configuration as part of the
 gpio-controller's driver probe function.