gpio: consumer: new virtual driver

new file mode 100644
index 000000000000..50ec57088e5a
@@ -0,0 +1,111 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Virtual GPIO Consumer
+=====================
+
+The virtual GPIO Consumer module allows users to create dynamic GPIO lookup
+tables using the exposed configfs interface and instantiate virtual GPIO
+consumer devices that retrieve and use GPIOs using these tables.
+
+Creating GPIO consumers
+-----------------------
+
+The gpio-consumer module registers a configfs subsystem called
+``'gpio-consumer'``. For details of the configfs filesystem, please refer to
+the configfs documentation.
+
+The user can create a hierarchy of configfs groups and items as well as modify
+values of exposed attributes. Once the consumer is instantiated, this hierarchy
+will be translated to appropriate device properties. The general structure is:
+
+**Group:** ``/config/gpio-consumer``
+
+This is the top directory of the gpio-consumer configfs tree.
+
+**Group:** ``/config/gpio-consumer/consumer-device``
+
+**Attribute:** ``/config/gpio-consumer/gpio-device/function``
+
+**Attribute:** ``/config/gpio-consumer/gpio-device/live``
+
+This is a directory representing a GPIO consumer device. The ``'function'``
+attribute defines how the device will use requested GPIOs. It takes the
+following values: ``'active'`` - GPIOs will be requested as output-high and
+kept in this state until the device is unbound, ``'toggle'`` - GPIOs will
+be requested in output mode and then toggled periodically (every second)
+between 1 and 0, ``'monitor'`` - GPIOs will be requested in input mode, then
+requested as interrupts and their firing reported in the kernel log.
+
+The ``'live'`` attribute allows to trigger the actual creation of the device
+once it's fully configured. The accepted values are: ``'1'`` to enable the
+virtual device and ``'0'`` to disable and tear it down.
+
+Creating GPIO lookup tables
+---------------------------
+
+User can create a number of configfs groups under the device group with the
+following properties:
+
+**Group:** ``/config/gpio-consumer/consumer-device/lookupX``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/key``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/offset``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/drive``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/pull``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/active_low``
+
+**Attribute:** ``/config/gpio-consumer/consumer-device/lookupX/transitory``
+
+This group represents a single entry in the GPIO lookup table. The name of the
+sub-directory maps to the ``'con_id'`` field of ``'struct gpiod_lookup'``. The
+``'key'`` attribute represents either the name of the chip this GPIO belongs to
+or the GPIO line name. This depends on the value of the ``'offset'`` attribute:
+if its value is >= 0, then ``'key'`` represents the label of the chip to lookup
+while ``'offset'`` represents the offset of the line in that chip. If
+``'offset'`` is < 0, then ``'key'`` represents the name of the line.
+
+The remaining attributes map to the ``'flags'`` field of the GPIO lookup struct.
+The first two take string values as arguments:
+
+**``'drive'``:** ``'push-pull'``, ``'open-drain'``, ``'open-source'``
+**``'pull'``:** ``'pull-up'``, ``'pull-down'``, ``'pull-disabled'``, ``'as-is'``
+
+``'active_low'`` and ``'transitory'`` are boolean attributes.
+
+Activating GPIO consumers
+-------------------------
+
+Once the confiuration is complete, the ``'live'`` attribute must be set to 1 in
+order to instantiate the consumer. It can be set back to 0 to destroy the
+virtual devices. The module will synchronously wait for the new simulated device
+to be successfully probed and if this doesn't happen, writing to ``'live'`` will
+result in an error.
+
+Device-tree
+-----------
+
+Virtual GPIO consumers can also be defined in device-tree. The compatible string
+must be: ``"gpio-virtual-consumer"``. Supported properties are:
+
+  ``"gpio-virtual-consumer,function"`` - function of the virtual device
+  ``"gpio-virtual-consumer,lines"`` - list of lookup keys
+
+An example device-tree code defining a virtual GPIO consumer:
+
+.. code-block :: none
+
+    gpio-virt-consumer {
+        compatible = "gpio-virtual-consumer";
+
+        foo-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
+        bar-gpios = <&gpio0 6 0>;
+
+        gpio-virtual-consumer,function = "toggle";
+        gpio-virtual-consumer,lines = "foo", "bar";
+    };
+
+.. SPDX-License-Identifier: GPL-2.0-or-later

index e382dfebad7c..c152fcf6c54f 100644
@@ -1762,6 +1762,13 @@ config GPIO_AGGREGATOR
 	      industrial control context, to be operated from userspace using
 	      the GPIO chardev interface.
 
+config GPIO_CONSUMER
+	tristate "GPIO Consumer Testing Module"
+	select CONFIGFS_FS
+	help
+	  This enables the configurable, configfs-based virtual GPIO consumer
+	  testing driver.
+
 config GPIO_LATCH
 	tristate "GPIO latch driver"
 	help

index c3ac51d47aa9..268e8f65f3c8 100644
@@ -46,6 +46,7 @@ obj-$(CONFIG_GPIO_BT8XX)		+= gpio-bt8xx.o
 obj-$(CONFIG_GPIO_CADENCE)		+= gpio-cadence.o
 obj-$(CONFIG_GPIO_CLPS711X)		+= gpio-clps711x.o
 obj-$(CONFIG_GPIO_SNPS_CREG)		+= gpio-creg-snps.o
+obj-$(CONFIG_GPIO_CONSUMER)		+= gpio-consumer.o
 obj-$(CONFIG_GPIO_CRYSTAL_COVE)		+= gpio-crystalcove.o
 obj-$(CONFIG_GPIO_CS5535)		+= gpio-cs5535.o
 obj-$(CONFIG_GPIO_DA9052)		+= gpio-da9052.o