Merge tag 'gpio-updates-for-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio updates from Bartosz Golaszewski:
 "For this merge window we have two new drivers: support for
  GPIO-signalled ACPI events on Intel platforms and a generic
  GPIO-over-pinctrl driver using the ARM SCMI protocol for
  controlling pins.

  Several things have been reworked in GPIO core: we unduplicated GPIO
  hog handling, reduced the number of SRCU locks and dereferences,
  improved support for software-node-based lookup and removed more
  legacy code after converting remaining users to modern alternatives.

  There's also a number of driver reworks and refactoring, documentation
  updates, some bug-fixes and new tests.

  GPIO core:
   - defer probe on software node lookups when the remote software node
     exists but has not been registered as a firmware node yet
   - unify GPIO hog handling by moving code duplicated in OF and ACPI
     modules into GPIO core and allow setting up hogs with software
     nodes
   - allow matching GPIO controllers by secondary firmware node if
     matching by primary does not succeed
   - demote deferral warnings to debug level as they are quite normal
     when using software nodes which don't support fw_devlink yet
   - disable the legacy GPIO character device uAPI v1 supprt in Kconfig
     by default
   - rework several core functions in preparation for the upcoming
     Revocable helper library for protecting resources against sudden
     removal, this reduces the number of SRCU dereferences in GPIO core
   - simplify file descriptor logic in GPIO character device code by
     using FD_PREPARE()
   - introduce a header defining symbols used by both GPIO consumers and
     providers to avoid having to include provider-specific headers from
     drivers which only consume GPIOs
   - replace snprintf() with strscpy() where formatting is not required

  New drivers:
   - add the gpio-by-pinctrl generic driver using the ARM SCMI protocol
     to control GPIOs (along with SCMI changes pulled from the pinctrl
     tree)
   - add a driver providing support for handling of platform events via
     GPIO-signalled ACPI events (used on Intel Nova Lake and later
     platforms)

  Driver changes:
   - extend the gpio-kempld driver with support for more recent models,
     interrupts and setting/getting multiple values at once
   - improve interrupt handling in gpio-brcmstb
   - add support for multi-SoC systems in gpio-tegra186
   - make sure we return correct values from the .get() callbacks in
     several GPIO drivers by normalizing any values other than 0, 1 or
     negative error numbers
   - use flexible arrays in several drivers to reduce the number of
     required memory allocations
   - simplify synchronous waiting for virtual drivers to probe and
     remove the dedicated, a bit overengineered helper library
     dev-sync-probe
   - remove unneeded Kconfig dependencies on OF_GPIO in several drivers
     and subsystems
   - convert the two remaining users of of_get_named_gpio() to using
     GPIO descriptors and remove the (no longer used) function along
     with the header that declares it
   - add missing includes in gpio-mmio
   - shrink and simplify code in gpio-max732x by using guard(mutex)
   - remove duplicated code handling the 'ngpios' property from
     gpio-ts4800, it's already handled in GPIO core
   - use correct variable type in gpio-aspeed
   - add support for a new model in gpio-realtek-otto
   - allow to specify the active-low setting of simulated hogs over the
     configfs interface (in addition to existing devicetree support) in
     gpio-sim

  Bug fixes:
   - clear the OF_POPULATED flag on hog nodes in GPIO chip remove path
     on OF systems
   - fix resource leaks in error path in gpiochip_add_data_with_key()
   - drop redundant device reference in gpio-mpsse

  Tests:
   - add selftests for use-after-free cases in GPIO character device
     code

  DT bindings:
   - add a DT binding document for SCMI based, gpio-over-pinctrl devices
   - fix interrupt description in microchip,mpfs-gpio
   - add new compatible for gpio-realtek-otto
   - describe the resets of the mpfs-gpio controller
   - fix maintainer's email in gpio-delay bindings
   - remove the binding document for cavium,thunder-8890 as the
     corresponding device is bound over PCI and not firmware nodes

  Documentation:
   - update the recommended way of converting legacy boards to using
     software nodes for GPIO description
   - describe GPIO line value semantics
   - misc updates to kerneldocs

  Misc:
   - convert OMAP1 ams-delta board to using GPIO hogs described with
     software nodes"

* tag 'gpio-updates-for-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (79 commits)
  gpio: swnode: defer probe on references to unregistered software nodes
  dt-bindings: gpio: cavium,thunder-8890: Remove DT binding
  Documentation: gpio: update the preferred method for using software node lookup
  gpio: gpio-by-pinctrl: s/used to do/is used to do/
  gpio: aspeed: fix unsigned long int declaration
  gpio: rockchip: convert to dynamic GPIO base allocation
  gpio: remove dev-sync-probe
  gpio: virtuser: stop using dev-sync-probe
  gpio: aggregator: stop using dev-sync-probe
  gpio: sim: stop using dev-sync-probe
  gpio: Add Intel Nova Lake ACPI GPIO events driver
  gpiolib: Make deferral warnings debug messages
  gpiolib: fix hogs with multiple lines
  gpio: fix up CONFIG_OF dependencies
  gpio: gpio-by-pinctrl: add pinctrl based generic GPIO driver
  gpio: dt-bindings: Add GPIO on top of generic pin control
  firmware: arm_scmi: Allow PINCTRL_REQUEST to return EOPNOTSUPP
  pinctrl: scmi: ignore PIN_CONFIG_PERSIST_STATE
  pinctrl: scmi: Delete PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS support
  pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE
  ...

Documentation/driver-api/gpio/board.rst

@@ -108,9 +108,8 @@ macro, which ties a software node representing the GPIO controller with
 consumer device. It allows consumers to use regular gpiolib APIs, such as
 gpiod_get(), gpiod_get_optional().
 
-The software node representing a GPIO controller need not be attached to the
-GPIO controller device. The only requirement is that the node must be
-registered and its name must match the GPIO controller's label.
+The software node representing a GPIO controller must be attached to the
+GPIO controller device - either as the primary or the secondary firmware node.
 
 For example, here is how to describe a single GPIO-connected LED. This is an
 alternative to using platform_data on legacy systems.
@@ -122,8 +121,7 @@ alternative to using platform_data on legacy systems.
 	#include <linux/gpio/property.h>
 
 	/*
-	 * 1. Define a node for the GPIO controller. Its .name must match the
-	 *    controller's label.
+	 * 1. Define a node for the GPIO controller.
 	 */
 	static const struct software_node gpio_controller_node = {
 		.name = "gpio-foo",
@@ -153,6 +151,21 @@ alternative to using platform_data on legacy systems.
 	};
 	software_node_register_node_group(swnodes);
 
+	/*
+	 * 5. Attach the GPIO controller's software node to the device and
+	 *    register it.
+	 */
+	 static void gpio_foo_register(void)
+	 {
+		struct platform_device_info pdev_info = {
+			.name = "gpio-foo",
+			.id = PLATFORM_DEVID_NONE,
+			.swnode = &gpio_controller_node
+		};
+
+		platform_device_register_full(&pdev_info);
+	 }
+
 	// Then register a platform_device for "leds-gpio" and associate
 	// it with &led_device_swnode via .fwnode.
 
@@ -239,22 +252,6 @@ mapping and is thus transparent to GPIO consumers.
 A set of functions such as gpiod_set_value() is available to work with
 the new descriptor-oriented interface.
 
-Boards using platform data can also hog GPIO lines by defining GPIO hog tables.
-
-.. code-block:: c
-
-        struct gpiod_hog gpio_hog_table[] = {
-                GPIO_HOG("gpio.0", 10, "foo", GPIO_ACTIVE_LOW, GPIOD_OUT_HIGH),
-                { }
-        };
-
-And the table can be added to the board code as follows::
-
-        gpiod_add_hogs(gpio_hog_table);
-
-The line will be hogged as soon as the gpiochip is created or - in case the
-chip was created earlier - when the hog table is registered.
-
 Arrays of pins
 --------------
 In addition to requesting pins belonging to a function one by one, a device may

Documentation/driver-api/gpio/driver.rst

@@ -87,6 +87,33 @@ atomic context on realtime kernels (inside hard IRQ handlers and similar
 contexts). Normally this should not be required.
 
 
+GPIO level semantics
+--------------------
+
+The gpip_chip .get/set[_multiple]() line values are clamped to the boolean
+space [0, 1], low level or high level.
+
+Low and high values are defined as physical low on the line in/out to the
+connector such as a physical pad, pin or rail.
+
+The GPIO library has internal logic to handle lines that are active low, such
+as indicated by overstrike or #name in a schematic, and the driver should not
+try to second-guess the logic value of a line.
+
+The way GPIO values are handled by the consumers is that the library present
+the *logical* value to the consumer. A line is *asserted* if its *logical*
+value is 1, and *de-asserted* if its logical value is 0. If inversion is
+required, this is handled by gpiolib and configured using hardware descriptions
+such as device tree or ACPI that can clearly indicate if a line is active
+high or low.
+
+Since electronics commonly insert inverters as driving stages or protection
+buffers in front of a GPIO line it is necessary that this semantic is part
+of the hardware description, so that consumers such as kernel drivers need
+not worry about this, and can for example assert a RESET line tied to a GPIO
+pin by setting it to logic 1 even if it is physically active low.
+
+
 GPIO electrical configuration
 -----------------------------
 

Documentation/driver-api/gpio/legacy-boards.rst

@@ -36,12 +36,10 @@ Requirements for GPIO Properties
 When using software nodes to describe GPIO connections, the following
 requirements must be met for the GPIO core to correctly resolve the reference:
 
-1.  **The GPIO controller's software node "name" must match the controller's
-    "label".** The gpiolib core uses this name to find the corresponding
-    struct gpio_chip at runtime.
-    This software node has to be registered, but need not be attached to the
-    device representing the GPIO controller that is providing the GPIO in
-    question. It may be left as a "free floating" node.
+1.  **The GPIO controller's software node must be registered and attached to
+    the controller's ``struct device`` either as its primary or secondary
+    firmware node.** The gpiolib core uses the address of the firmware node to
+    find the corresponding ``struct gpio_chip`` at runtime.
 
 2.  **The GPIO property must be a reference.** The ``PROPERTY_ENTRY_GPIO()``
     macro handles this as it is an alias for ``PROPERTY_ENTRY_REF()``.
@@ -121,13 +119,21 @@ A typical legacy board file might look like this:
   /* Device registration */
   static int __init myboard_init(void)
   {
+  	struct platform_device_info pdev_info = {
+  		.name = MYBOARD_GPIO_CONTROLLER,
+  		.id = PLATFORM_DEVID_NONE,
+  		.swnode = &gpio_controller_node
+  	};
+
   	gpiod_add_lookup_table(&myboard_leds_gpios);
   	gpiod_add_lookup_table(&myboard_buttons_gpios);
 
+  	platform_device_register_full(&pdev_info);
   	platform_device_register_data(NULL, "leds-gpio", -1,
   				      &myboard_leds_pdata, sizeof(myboard_leds_pdata));
   	platform_device_register_data(NULL, "gpio-keys", -1,
-  				      &myboard_buttons_pdata, sizeof(myboard_buttons_pdata));
+  				      &myboard_buttons_pdata,
+  				      sizeof(myboard_buttons_pdata));
 
   	return 0;
   }
@@ -141,8 +147,7 @@ Step 1: Define the GPIO Controller Node
 ***************************************
 
 First, define a software node that represents the GPIO controller that the
-LEDs and buttons are connected to. The ``name`` of this node must match the
-name of the driver for the GPIO controller (e.g., "gpio-foo").
+LEDs and buttons are connected to. The ``name`` of this node is optional.
 
 .. code-block:: c
 
@@ -257,6 +262,16 @@ software nodes using the ``fwnode`` field in struct platform_device_info.
   	if (error)
   		return error;
 
+  	memset(&pdev_info, 0, sizeof(pdev_info));
+  	pdev_info.name = MYBOARD_GPIO_CONTROLLER;
+  	pdev_info.id = PLATFORM_DEVID_NONE;
+  	pdev_info.swnode = &myboard_gpio_controller_node;
+  	gpio_pdev = platform_device_register_full(&pdev_info);
+  	if (IS_ERR(gpio_pdev)) {
+  		error = PTR_ERR(gpio_pdev);
+  		goto err_unregister_nodes;
+  	}
+
   	memset(&pdev_info, 0, sizeof(pdev_info));
   	pdev_info.name = "leds-gpio";
   	pdev_info.id = PLATFORM_DEVID_NONE;
@@ -264,6 +279,7 @@ software nodes using the ``fwnode`` field in struct platform_device_info.
   	leds_pdev = platform_device_register_full(&pdev_info);
   	if (IS_ERR(leds_pdev)) {
   		error = PTR_ERR(leds_pdev);
+  		platform_device_unregister(gpio_pdev);
   		goto err_unregister_nodes;
   	}
 
@@ -274,6 +290,7 @@ software nodes using the ``fwnode`` field in struct platform_device_info.
   	keys_pdev = platform_device_register_full(&pdev_info);
   	if (IS_ERR(keys_pdev)) {
   		error = PTR_ERR(keys_pdev);
+  		platform_device_unregister(gpio_pdev);
   		platform_device_unregister(leds_pdev);
   		goto err_unregister_nodes;
   	}
@@ -289,6 +306,7 @@ software nodes using the ``fwnode`` field in struct platform_device_info.
   {
   	platform_device_unregister(keys_pdev);
   	platform_device_unregister(leds_pdev);
+  	platform_device_unregister(gpio_pdev);
   	software_node_unregister_node_group(myboard_swnodes);
   }