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
  ...

5 files changed, 129 insertions, 28 deletions

diff --git a/Documentation/devicetree/bindings/gpio/gpio-msm.txt b/Documentation/devicetree/bindings/gpio/gpio-msm.txt
deleted file mode 100644
index ac20e68a004e..000000000000
--- a/Documentation/devicetree/bindings/gpio/gpio-msm.txt
+++ /dev/null
@@ -1,26 +0,0 @@
-MSM GPIO controller bindings
-
-Required properties:
-- compatible:
-  - "qcom,msm-gpio" for MSM controllers
-- #gpio-cells : Should be two.
-  - first cell is the pin number
-  - second cell is used to specify optional parameters (unused)
-- gpio-controller : Marks the device node as a GPIO controller.
-- #interrupt-cells : Should be 2.
-- interrupt-controller: Mark the device node as an interrupt controller
-- interrupts : Specify the TLMM summary interrupt number
-- ngpio : Specify the number of MSM GPIOs
-
-Example:
-
-	msmgpio: gpio@fd510000 {
-		compatible = "qcom,msm-gpio";
-		gpio-controller;
-		#gpio-cells = <2>;
-		interrupt-controller;
-		#interrupt-cells = <2>;
-		reg = <0xfd510000 0x4000>;
-		interrupts = <0 208 0>;
-		ngpio = <150>;
-	};
diff --git a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
index b9a42f294dd0..13df9933f4cd 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
@@ -24,6 +24,7 @@ Required properties:
 	ti,tca6408
 	ti,tca6416
 	ti,tca6424
+	ti,tca9539
 	exar,xra1202
 
 Example:
diff --git a/Documentation/devicetree/bindings/gpio/gpio-zynq.txt b/Documentation/devicetree/bindings/gpio/gpio-zynq.txt
index db4c6a663c03..7b542657f259 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-zynq.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-zynq.txt
@@ -12,6 +12,13 @@ Required properties:
 - interrupts		: Interrupt specifier (see interrupt bindings for
 			  details)
 - interrupt-parent	: Must be core interrupt controller
+- interrupt-controller	: Marks the device node as an interrupt controller.
+- #interrupt-cells 	: Should be 2.  The first cell is the GPIO number.
+			  The second cell bits[3:0] is used to specify trigger type and level flags:
+			      1 = low-to-high edge triggered.
+			      2 = high-to-low edge triggered.
+			      4 = active high level-sensitive.
+			      8 = active low level-sensitive.
 - reg			: Address and length of the register set for the device
 
 Example:
@@ -22,5 +29,7 @@ Example:
 		gpio-controller;
 		interrupt-parent = <&intc>;
 		interrupts = <0 20 4>;
+		interrupt-controller;
+		#interrupt-cells = <2>;
 		reg = <0xe000a000 0x1000>;
 	};
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.
diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt
index 90d0f6aba7a6..12a61948ec91 100644
--- a/Documentation/gpio/driver.txt
+++ b/Documentation/gpio/driver.txt
@@ -62,6 +62,11 @@ Any debugfs dump method should normally ignore signals which haven't been
 requested as GPIOs. They can use gpiochip_is_requested(), which returns either
 NULL or the label associated with that GPIO when it was requested.
 
+RT_FULL: GPIO driver should not use spinlock_t or any sleepable APIs
+(like PM runtime) in its gpio_chip implementation (.get/.set and direction
+control callbacks) if it is expected to call GPIO APIs from atomic context
+on -RT (inside hard IRQ handlers and similar contexts). Normally this should
+not be required.
 
 GPIO drivers providing IRQs
 ---------------------------
@@ -73,6 +78,13 @@ The IRQ portions of the GPIO block are implemented using an irqchip, using
 the header <linux/irq.h>. So basically such a driver is utilizing two sub-
 systems simultaneously: gpio and irq.
 
+RT_FULL: GPIO driver should not use spinlock_t or any sleepable APIs
+(like PM runtime) as part of its irq_chip implementation on -RT.
+- spinlock_t should be replaced with raw_spinlock_t [1].
+- If sleepable APIs have to be used, these can be done from the .irq_bus_lock()
+  and .irq_bus_unlock() callbacks, as these are the only slowpath callbacks
+  on an irqchip. Create the callbacks if needed [2].
+
 GPIO irqchips usually fall in one of two categories:
 
 * CHAINED GPIO irqchips: these are usually the type that is embedded on
@@ -93,6 +105,38 @@ GPIO irqchips usually fall in one of two categories:
   Chained GPIO irqchips typically can NOT set the .can_sleep flag on
   struct gpio_chip, as everything happens directly in the callbacks.
 
+  RT_FULL: Note, chained IRQ handlers will not be forced threaded on -RT.
+  As result, spinlock_t or any sleepable APIs (like PM runtime) can't be used
+  in chained IRQ handler.
+  if required (and if it can't be converted to the nested threaded GPIO irqchip)
+  - chained IRQ handler can be converted to generic irq handler and this way
+  it will be threaded IRQ handler on -RT and hard IRQ handler on non-RT
+  (for example, see [3]).
+  Know W/A: The generic_handle_irq() is expected to be called with IRQ disabled,
+  so IRQ core will complain if it will be called from IRQ handler wich is forced
+  thread. The "fake?" raw lock can be used to W/A this problem:
+
+	raw_spinlock_t wa_lock;
+	static irqreturn_t omap_gpio_irq_handler(int irq, void *gpiobank)
+		unsigned long wa_lock_flags;
+		raw_spin_lock_irqsave(&bank->wa_lock, wa_lock_flags);
+		generic_handle_irq(irq_find_mapping(bank->chip.irqdomain, bit));
+		raw_spin_unlock_irqrestore(&bank->wa_lock, wa_lock_flags);
+
+* GENERIC CHAINED GPIO irqchips: these are the same as "CHAINED GPIO irqchips",
+  but chained IRQ handlers are not used. Instead GPIO IRQs dispatching is
+  performed by generic IRQ handler which is configured using request_irq().
+  The GPIO irqchip will then end up calling something like this sequence in
+  its interrupt handler:
+
+  static irqreturn_t gpio_rcar_irq_handler(int irq, void *dev_id)
+	for each detected GPIO IRQ
+		generic_handle_irq(...);
+
+  RT_FULL: Such kind of handlers will be forced threaded on -RT, as result IRQ
+  core will complain that generic_handle_irq() is called with IRQ enabled and
+  the same W/A as for "CHAINED GPIO irqchips" can be applied.
+
 * NESTED THREADED GPIO irqchips: these are off-chip GPIO expanders and any
   other GPIO irqchip residing on the other side of a sleeping bus. Of course
   such drivers that need slow bus traffic to read out IRQ status and similar,
@@ -133,6 +177,13 @@ To use the helpers please keep the following in mind:
   the irqchip can initialize. E.g. .dev and .can_sleep shall be set up
   properly.
 
+- Nominally set all handlers to handle_bad_irq() in the setup call and pass
+  handle_bad_irq() as flow handler parameter in gpiochip_irqchip_add() if it is
+  expected for GPIO driver that irqchip .set_type() callback have to be called
+  before using/enabling GPIO IRQ. Then set the handler to handle_level_irq()
+  and/or handle_edge_irq() in the irqchip .set_type() callback depending on
+  what your controller supports.
+
 It is legal for any IRQ consumer to request an IRQ from any irqchip no matter
 if that is a combined GPIO+IRQ driver. The basic premise is that gpio_chip and
 irq_chip are orthogonal, and offering their services independent of each
@@ -169,6 +220,31 @@ When implementing an irqchip inside a GPIO driver, these two functions should
 typically be called in the .startup() and .shutdown() callbacks from the
 irqchip.
 
+Real-Time compliance for GPIO IRQ chips
+---------------------------------------
+
+Any provider of irqchips needs to be carefully tailored to support Real Time
+preemption. It is desireable that all irqchips in the GPIO subsystem keep this
+in mind and does the proper testing to assure they are real time-enabled.
+So, pay attention on above " RT_FULL:" notes, please.
+The following is a checklist to follow when preparing a driver for real
+time-compliance:
+
+- ensure spinlock_t is not used as part irq_chip implementation;
+- ensure that sleepable APIs are not used as part irq_chip implementation.
+  If sleepable APIs have to be used, these can be done from the .irq_bus_lock()
+  and .irq_bus_unlock() callbacks;
+- Chained GPIO irqchips: ensure spinlock_t or any sleepable APIs are not used
+  from chained IRQ handler;
+- Generic chained GPIO irqchips: take care about generic_handle_irq() calls and
+  apply corresponding W/A;
+- Chained GPIO irqchips: get rid of chained IRQ handler and use generic irq
+  handler if possible :)
+- regmap_mmio: Sry, but you are in trouble :( if MMIO regmap is used as for
+  GPIO IRQ chip implementation;
+- Test your driver with the appropriate in-kernel real time test cases for both
+  level and edge IRQs.
+
 
 Requesting self-owned GPIO pins
 -------------------------------
@@ -190,3 +266,7 @@ gpiochip_free_own_desc().
 These functions must be used with care since they do not affect module use
 count. Do not use the functions to request gpio descriptors not owned by the
 calling driver.
+
+[1] http://www.spinics.net/lists/linux-omap/msg120425.html
+[2] https://lkml.org/lkml/2015/9/25/494
+[3] https://lkml.org/lkml/2015/9/25/495