From a79fead50f06886311f37777d03b20b058749ce1 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 19 Dec 2016 19:21:34 +0100 Subject: gpio: of: Add support for multiple GPIOs in a single GPIO hog When listing multiple GPIOs in the "gpios" property of a GPIO hog, only the first GPIO is affected. The user is left clueless about the dysfunctioning of the other GPIOs specified. Fix this by adding and documenting support for specifying multiple GPIOs in a single GPIO hog. Signed-off-by: Geert Uytterhoeven Acked-by: Rob Herring Signed-off-by: Linus Walleij --- Documentation/devicetree/bindings/gpio/gpio.txt | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'Documentation') 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 -- cgit v1.2.3 From 054ccdef8b2850be3aee8cbd49000e6d61f837b2 Mon Sep 17 00:00:00 2001 From: Steve Longerbeam Date: Tue, 10 Jan 2017 11:29:51 -0800 Subject: gpio: pca953x: Add optional reset gpio control Add optional reset-gpios pin control. If present, de-assert the specified reset gpio pin to bring the chip out of reset. v2: - Specify that reset signal to PCA953x chip is active low, in binding doc. - reorder includes in gpio-pca953x.c. - remove dev_err() on devm_gpiod_get_optional() error return. Cc: Alexandre Courbot Cc: linux-gpio@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Steve Longerbeam Reviewed-by: Andy Shevchenko Reviewed-by: Vladimir Zapolskiy Signed-off-by: Linus Walleij --- Documentation/devicetree/bindings/gpio/gpio-pca953x.txt | 4 ++++ drivers/gpio/gpio-pca953x.c | 9 +++++++++ 2 files changed, 13 insertions(+) (limited to 'Documentation') 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/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index d5d72d84b719..d44232aadb6c 100644 --- a/drivers/gpio/gpio-pca953x.c +++ b/drivers/gpio/gpio-pca953x.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -754,8 +755,16 @@ static int pca953x_probe(struct i2c_client *client, invert = pdata->invert; chip->names = pdata->names; } else { + struct gpio_desc *reset_gpio; + chip->gpio_start = -1; irq_base = 0; + + /* See if we need to de-assert a reset pin */ + reset_gpio = devm_gpiod_get_optional(&client->dev, "reset", + GPIOD_OUT_LOW); + if (IS_ERR(reset_gpio)) + return PTR_ERR(reset_gpio); } chip->client = client; -- cgit v1.2.3 From 284864f990ac3e186fb5beb4b0d5b3188fe8f225 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 22 Jan 2017 13:18:30 +0100 Subject: gpio: add DT bindings for Cortina Gemini GPIO This adds fairly standard DT bindings for the Cortina Systems Gemini GPIO controller. Cc: Janos Laube Cc: Paulius Zaleckas Cc: Hans Ulli Kroll Cc: Florian Fainelli Cc: devicetree@vger.kernel.org Acked-by: Rob Herring Signed-off-by: Linus Walleij --- .../bindings/gpio/cortina,gemini-gpio.txt | 24 ++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/cortina,gemini-gpio.txt (limited to 'Documentation') 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>; +}; -- cgit v1.2.3 From 7354740666cd07b089af81eb91f0d4a8f1253eb9 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 31 Jan 2017 15:43:05 +0100 Subject: gpio: random documentation update Updated and proofread the documentation for GPIO drivers a bit when looking over the changes for generic configuration. Signed-off-by: Linus Walleij --- Documentation/gpio/driver.txt | 55 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 46 insertions(+), 9 deletions(-) (limited to 'Documentation') diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt index ad8f0c0cd13f..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 ------------------------------------ -- cgit v1.2.3