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+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==========================
+Samsung Galaxy Book Driver
+==========================
+
+Joshua Grisham <josh@joshuagrisham.com>
+
+This is a Linux x86 platform driver for Samsung Galaxy Book series notebook
+devices which utilizes Samsung's ``SCAI`` ACPI device in order to control
+extra features and receive various notifications.
+
+Supported devices
+=================
+
+Any device with one of the supported ACPI device IDs should be supported. This
+covers most of the "Samsung Galaxy Book" series notebooks that are currently
+available as of this writing, and could include other Samsung notebook devices
+as well.
+
+Status
+======
+
+The following features are currently supported:
+
+- :ref:`Keyboard backlight <keyboard-backlight>` control
+- :ref:`Performance mode <performance-mode>` control implemented using the
+  platform profile interface
+- :ref:`Battery charge control end threshold
+  <battery-charge-control-end-threshold>` (stop charging battery at given
+  percentage value) implemented as a battery hook
+- :ref:`Firmware Attributes <firmware-attributes>` to allow control of various
+  device settings
+- :ref:`Handling of Fn hotkeys <keyboard-hotkey-actions>` for various actions
+- :ref:`Handling of ACPI notifications and hotkeys
+  <acpi-notifications-and-hotkey-actions>`
+
+Because different models of these devices can vary in their features, there is
+logic built within the driver which attempts to test each implemented feature
+for a valid response before enabling its support (registering additional devices
+or extensions, adding sysfs attributes, etc). Therefore, it can be important to
+note that not all features may be supported for your particular device.
+
+The following features might be possible to implement but will require
+additional investigation and are therefore not supported at this time:
+
+- "Dolby Atmos" mode for the speakers
+- "Outdoor Mode" for increasing screen brightness on models with ``SAM0427``
+- "Silent Mode" on models with ``SAM0427``
+
+.. _keyboard-backlight:
+
+Keyboard backlight
+==================
+
+A new LED class named ``samsung-galaxybook::kbd_backlight`` is created which
+will then expose the device using the standard sysfs-based LED interface at
+``/sys/class/leds/samsung-galaxybook::kbd_backlight``. Brightness can be
+controlled by writing the desired value to the ``brightness`` sysfs attribute or
+with any other desired userspace utility.
+
+.. note::
+  Most of these devices have an ambient light sensor which also turns
+  off the keyboard backlight under well-lit conditions. This behavior does not
+  seem possible to control at this time, but can be good to be aware of.
+
+.. _performance-mode:
+
+Performance mode
+================
+
+This driver implements the
+Documentation/userspace-api/sysfs-platform_profile.rst interface for working
+with the "performance mode" function of the Samsung ACPI device.
+
+Mapping of each Samsung "performance mode" to its respective platform profile is
+performed dynamically by the driver, as not all models support all of the same
+performance modes. Your device might have one or more of the following mappings:
+
+- "Silent" maps to ``low-power``
+- "Quiet" maps to ``quiet``
+- "Optimized" maps to ``balanced``
+- "High performance" maps to ``performance``
+
+The result of the mapping can be printed in the kernel log when the module is
+loaded. Supported profiles can also be retrieved from
+``/sys/firmware/acpi/platform_profile_choices``, while
+``/sys/firmware/acpi/platform_profile`` can be used to read or write the
+currently selected profile.
+
+The ``balanced`` platform profile will be set during module load if no profile
+has been previously set.
+
+.. _battery-charge-control-end-threshold:
+
+Battery charge control end threshold
+====================================
+
+This platform driver will add the ability to set the battery's charge control
+end threshold, but does not have the ability to set a start threshold.
+
+This feature is typically called "Battery Saver" by the various Samsung
+applications in Windows, but in Linux we have implemented the standardized
+"charge control threshold" sysfs interface on the battery device to allow for
+controlling this functionality from the userspace.
+
+The sysfs attribute
+``/sys/class/power_supply/BAT1/charge_control_end_threshold`` can be used to
+read or set the desired charge end threshold.
+
+If you wish to maintain interoperability with the Samsung Settings application
+in Windows, then you should set the value to 100 to represent "off", or enable
+the feature using only one of the following values: 50, 60, 70, 80, or 90.
+Otherwise, the driver will accept any value between 1 and 100 as the percentage
+that you wish the battery to stop charging at.
+
+.. note::
+  Some devices have been observed as automatically "turning off" the charge
+  control end threshold if an input value of less than 30 is given.
+
+.. _firmware-attributes:
+
+Firmware Attributes
+===================
+
+The following enumeration-typed firmware attributes are set up by this driver
+and should be accessible under
+``/sys/class/firmware-attributes/samsung-galaxybook/attributes/`` if your device
+supports them:
+
+- ``power_on_lid_open`` (device should power on when the lid is opened)
+- ``usb_charging``  (USB ports can deliver power to connected devices even when
+  the device is powered off or in a low sleep state)
+- ``block_recording`` (blocks access to camera and microphone)
+
+All of these attributes are simple boolean-like enumeration values which use 0
+to represent "off" and 1 to represent "on". Use the ``current_value`` attribute
+to get or change the setting on the device.
+
+Note that when ``block_recording`` is updated, the input device "Samsung Galaxy
+Book Lens Cover" will receive a ``SW_CAMERA_LENS_COVER`` switch event which
+reflects the current state.
+
+.. _keyboard-hotkey-actions:
+
+Keyboard hotkey actions (i8042 filter)
+======================================
+
+The i8042 filter will swallow the keyboard events for the Fn+F9 hotkey (Multi-
+level keyboard backlight toggle) and Fn+F10 hotkey (Block recording toggle)
+and instead execute their actions within the driver itself.
+
+Fn+F9 will cycle through the brightness levels of the keyboard backlight. A
+notification will be sent using ``led_classdev_notify_brightness_hw_changed``
+so that the userspace can be aware of the change. This mimics the behavior of
+other existing devices where the brightness level is cycled internally by the
+embedded controller and then reported via a notification.
+
+Fn+F10 will toggle the value of the "block recording" setting, which blocks
+or allows usage of the built-in camera and microphone (and generates the same
+Lens Cover switch event mentioned above).
+
+.. _acpi-notifications-and-hotkey-actions:
+
+ACPI notifications and hotkey actions
+=====================================
+
+ACPI notifications will generate ACPI netlink events under the device class
+``samsung-galaxybook`` and bus ID matching the Samsung ACPI device ID found on
+your device. The events can be received using userspace tools such as
+``acpi_listen`` and ``acpid``.
+
+The Fn+F11 Performance mode hotkey will be handled by the driver; each keypress
+will cycle to the next available platform profile.