Merge remote-tracking branch 'gpio/for-next'

4 files changed, 83 insertions, 17 deletions

diff --git a/Documentation/devicetree/bindings/gpio/cortina,gemini-gpio.txt b/Documentation/devicetree/bindings/gpio/cortina,gemini-gpio.txt
new file mode 100644
index 000000000000..5c9246c054e5
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/cortina,gemini-gpio.txt
@@ -0,0 +1,24 @@
+Cortina Systems Gemini GPIO Controller
+
+Required properties:
+
+- compatible : Must be "cortina,gemini-gpio"
+- reg : Should contain registers location and length
+- interrupts : Should contain the interrupt line for the GPIO block
+- gpio-controller : marks this as a GPIO controller
+- #gpio-cells : Should be 2, see gpio/gpio.txt
+- interrupt-controller : marks this as an interrupt controller
+- #interrupt-cells : a standard two-cell interrupt flag, see
+  interrupt-controller/interrupts.txt
+
+Example:
+
+gpio@4d000000 {
+	compatible = "cortina,gemini-gpio";
+	reg = <0x4d000000 0x100>;
+	interrupts = <22 IRQ_TYPE_LEVEL_HIGH>;
+	gpio-controller;
+	#gpio-cells = <2>;
+	interrupt-controller;
+	#interrupt-cells = <2>;
+};
diff --git a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
index 08dd15f89ba9..e63935710011 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
@@ -29,6 +29,10 @@ Required properties:
 	onsemi,pca9654
 	exar,xra1202
 
+Optional properties:
+ - reset-gpios: GPIO specification for the RESET input. This is an
+		active low signal to the PCA953x.
+
 Example:
 
 
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 68d28f62a6f4..84ede036f73d 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -187,10 +187,10 @@ gpio-controller's driver probe function.
 
 Each GPIO hog definition is represented as a child node of the GPIO controller.
 Required properties:
-- gpio-hog:   A property specifying that this child node represent a GPIO hog.
-- gpios:      Store the GPIO information (id, flags, ...). Shall contain the
-	      number of cells specified in its parent node (GPIO controller
-	      node).
+- gpio-hog:   A property specifying that this child node represents a GPIO hog.
+- gpios:      Store the GPIO information (id, flags, ...) for each GPIO to
+	      affect. Shall contain an integer multiple of the number of cells
+	      specified in its parent node (GPIO controller node).
 Only one of the following properties scanned in the order shown below.
 This means that when multiple properties are present they will be searched
 in the order presented below and the first match is taken as the intended
diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt
index 747c721776ed..fc1d2f83564d 100644
--- a/Documentation/gpio/driver.txt
+++ b/Documentation/gpio/driver.txt
@@ -41,34 +41,71 @@ In the gpiolib framework each GPIO controller is packaged as a "struct
 gpio_chip" (see linux/gpio/driver.h for its complete definition) with members
 common to each controller of that type:
 
- - methods to establish GPIO direction
- - methods used to access GPIO values
- - method to return the IRQ number associated to a given GPIO
+ - methods to establish GPIO line direction
+ - methods used to access GPIO line values
+ - method to set electrical configuration to a a given GPIO line
+ - method to return the IRQ number associated to a given GPIO line
  - flag saying whether calls to its methods may sleep
+ - optional line names array to identify lines
  - optional debugfs dump method (showing extra state like pullup config)
  - optional base number (will be automatically assigned if omitted)
- - label for diagnostics and GPIOs mapping using platform data
+ - optional label for diagnostics and GPIO chip mapping using platform data
 
 The code implementing a gpio_chip should support multiple instances of the
 controller, possibly using the driver model. That code will configure each
-gpio_chip and issue gpiochip_add(). Removing a GPIO controller should be rare;
-use gpiochip_remove() when it is unavoidable.
+gpio_chip and issue gpiochip_add[_data]() or devm_gpiochip_add_data().
+Removing a GPIO controller should be rare; use [devm_]gpiochip_remove() when
+it is unavoidable.
 
-Most often a gpio_chip is part of an instance-specific structure with state not
+Often a gpio_chip is part of an instance-specific structure with states not
 exposed by the GPIO interfaces, such as addressing, power management, and more.
-Chips such as codecs will have complex non-GPIO state.
+Chips such as audio codecs will have complex non-GPIO states.
 
 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
+RT_FULL: the 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 electrical configuration
+-----------------------------
+
+GPIOs can be configured for several electrical modes of operation by using the
+.set_config() callback. Currently this API supports setting debouncing and
+single-ended modes (open drain/open source). These settings are described
+below.
+
+The .set_config() callback uses the same enumerators and configuration
+semantics as the generic pin control drivers. This is not a coincidence: it is
+possible to assign the .set_config() to the function gpiochip_generic_config()
+which will result in pinctrl_gpio_set_config() being called and eventually
+ending up in the pin control back-end "behind" the GPIO controller, usually
+closer to the actual pins. This way the pin controller can manage the below
+listed GPIO configurations.
+
+
+GPIOs with debounce support
+---------------------------
+
+Debouncing is a configuration set to a pin indicating that it is connected to
+a mechanical switch or button, or similar that may bounce. Bouncing means the
+line is pulled high/low quickly at very short intervals for mechanical
+reasons. This can result in the value being unstable or irqs fireing repeatedly
+unless the line is debounced.
+
+Debouncing in practice involves setting up a timer when something happens on
+the line, wait a little while and then sample the line again, so see if it
+still has the same value (low or high). This could also be repeated by a clever
+state machine, waiting for a line to become stable. In either case, it sets
+a certain number of milliseconds for debouncing, or just "on/off" if that time
+is not configurable.
+
+
 GPIOs with open drain/source support
 ------------------------------------
 
@@ -146,10 +183,11 @@ a pull-up resistor is needed on the outgoing rail to complete the circuit, and
 in the second case, a pull-down resistor is needed on the rail.
 
 Hardware that supports open drain or open source or both, can implement a
-special callback in the gpio_chip: .set_single_ended() that takes an enum flag
-telling whether to configure the line as open drain, open source or push-pull.
-This will happen in response to the GPIO_OPEN_DRAIN or GPIO_OPEN_SOURCE flag
-set in the machine file, or coming from other hardware descriptions.
+special callback in the gpio_chip: .set_config() that takes a generic
+pinconf packed value telling whether to configure the line as open drain,
+open source or push-pull. This will happen in response to the
+GPIO_OPEN_DRAIN or GPIO_OPEN_SOURCE flag set in the machine file, or coming
+from other hardware descriptions.
 
 If this state can not be configured in hardware, i.e. if the GPIO hardware does
 not support open drain/open source in hardware, the GPIO library will instead