Re: [PATCH] platform/x86: samsung-galaxybook: Add samsung-galaxybook driver

[Ilpo Järvinen]

On Mon, 9 Dec 2024, Joshua Grisham wrote:

> This patch will add a new driver for Samsung Galaxy Book series notebook
> devices. This should hopefully include all suggestions from my original
> mailing list feedback thread [1], as well as a first version for
> associated updates to the documentation, Kconfig, Makefile, and the
> MAINTAINERS file related to this new driver.
> 
> I have tested the driver both using m and y in the config, as well as
> with various other options mentioned in the patch checklist of the
> documentation.
> 
> Other users with other device IDs have also tested successfully using
> a version of these same driver updates which I have maintained in a
> separate branch of my GitHub repository [2].
> 
> I have made an attempt with the coding style to find a balance between what
> is written in the kernel documentation and what actually exists in current
> x86 platform drivers, but any feedback on this (or anything else) is
> certainly welcome!
> 
> [1]: https://lore.kernel.org/platform-driver-x86/CAMF+KeYus9dW00WNJMLVxLLHdG9JgCfrGJ491fu7NM8GAEqqCg@xxxxxxxxxxxxxx/
> [2]: https://github.com/joshuagrisham/samsung-galaxybook-extras/pull/44
> 
> Signed-off-by: Joshua Grisham <josh@xxxxxxxxxxxxxxxxx>
> ---
>  Documentation/admin-guide/laptops/index.rst   |    1 +
>  .../laptops/samsung-galaxybook.rst            |  301 +++
>  MAINTAINERS                                   |    6 +
>  drivers/platform/x86/Kconfig                  |   19 +
>  drivers/platform/x86/Makefile                 |    5 +-
>  drivers/platform/x86/samsung-galaxybook.c     | 1972 +++++++++++++++++
>  6 files changed, 2302 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/admin-guide/laptops/samsung-galaxybook.rst
>  create mode 100644 drivers/platform/x86/samsung-galaxybook.c
> 
> diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst
> index cd9a1c269..e71c8984c 100644
> --- a/Documentation/admin-guide/laptops/index.rst
> +++ b/Documentation/admin-guide/laptops/index.rst
> @@ -11,6 +11,7 @@ Laptop Drivers
>     disk-shock-protection
>     laptop-mode
>     lg-laptop
> +   samsung-galaxybook
>     sony-laptop
>     sonypi
>     thinkpad-acpi
> diff --git a/Documentation/admin-guide/laptops/samsung-galaxybook.rst b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
> new file mode 100644
> index 000000000..ab12f0001
> --- /dev/null
> +++ b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
> @@ -0,0 +1,301 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +==========================
> +Samsung Galaxy Book Extras
> +==========================
> +
> +December 9, 2024
> +
> +Joshua Grisham <josh@xxxxxxxxxxxxxxxxx>
> +
> +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
> +=================
> +
> +"SAMSUNG ELECTRONICS CO., LTD." devices of type "Notebook" which have 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 device extension
> +- :ref:`Fan speed <fan-speed>` monitoring via ``fan_speed_rpm`` sysfs attribute
> +  plus a new hwmon device
> +- :ref:`Settings Attributes <settings-attributes>` to allow control of various
> +  device settings
> +- :ref:`Handling of Fn hotkeys <keyboard-hotkey-actions>` for various 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``
> +
> +
> +Parameters
> +==========
> +
> +The driver includes a list of boolean parameters that allow for manually
> +enabling or disabling various features:
> +
> +- ``kbd_backlight``: Enable Keyboard Backlight control (default on)
> +- ``performance_mode``: Enable Performance Mode control (default on)
> +- ``battery_threshold``: Enable battery charge threshold control (default on)
> +- ``fan_speed``: Enable fan speed (default on)
> +- ``allow_recording``: Enable control to allow or block access to camera and
> +  microphone (default on)
> +- ``i8042_filter``: Enable capture and execution of keyboard-based hotkey events
> +  (default on)
> +
> +.. note::
> +  Even if you explicitly try to enable a feature using its parameter, support
> +  for it will still be evaluated by the driver, and the feature will be
> +  disabled if it does not appear to be supported on your device.
> +
> +The availability of various sysfs file-based "settings" attributes
> +(``usb_charge``, ``start_on_lid_open``, etc) will be determined automatically
> +and cannot be manually disabled at this time.
> +
> +
> +.. _keyboard-backlight:
> +
> +Keyboard backlight
> +==================
> +
> +Controlled by parameter: ``kbd_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 values 0 to 3 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
> +================
> +
> +Controlled by parameter: ``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
> +done dynamically based on a list of the supported modes reported by the device
> +itself. Preference is given to always try and map ``low-power``, ``balanced``,
> +and ``performance`` profiles, as these seem to be the most common profiles
> +utilized (and sometimes even required) by various userspace tools.
> +
> +The result of the mapping will 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
> +====================================
> +
> +Controlled by parameter: ``battery_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 Windows, then you should set the
> +value to 80 to represent "on", or 0 to represent "off", as these are the values
> +currently recognized by the various Windows-based Samsung applications and
> +services as "on" or "off". Otherwise, the device will accept any value between 0
> +(off) and 99 as the percentage that you wish the battery to stop charging at.
> +
> +.. note::
> +  If you try to set a value of 100, the driver will also accept this input, but
> +  will set the attribute value to 0 (i.e. 100% will "remove" the end threshold).
> +
> +
> +.. _fan-speed:
> +
> +Fan speed
> +=========
> +
> +Controlled by parameter: ``fan_speed``
> +
> +The number and type of fans on these devices can vary, and different methods
> +must be used in order to be able to successfully read their status.
> +
> +In cases where Samsung has implemented the standard ACPI method ``_FST`` for a
> +fan device, the other methods in the ACPI specification which would cause
> +the kernel to automatically add the ``fan_speed_rpm`` attribute are not always
> +present. On top of this, it seems that there are some bugs in the firmware that
> +throw an exception when the ``_FST`` method is executed.
> +
> +This platform driver attempts to resolve all PNP fans that are present in the
> +ACPI of supported devices, and add support for reading their speed using the
> +following decision tree:
> +
> +1. Do all 4 required methods exist so that the fan speed should be reported
> +   out-of-the-box by ACPI? If yes, then assume this fan is already set up and
> +   available.
> +
> +2. Does the method ``_FST`` exist and appears to be working (returns a speed
> +   value greater than 0)? If yes, add an attribute ``fan_speed_rpm`` to this fan
> +   device and add a fan input channel for it to the hwmon device. The returned
> +   value will be directly read from the ``_FST`` method.
> +
> +3. Does the field ``FANS`` (fan speed level) exist on the embedded controller,
> +   and the table ``FANT`` (fan speed level table) exist on the fan device? If
> +   yes, add the ``fan_speed_rpm`` attribute to this fan device and add a fan
> +   input channel for it to the hwmon device. The returned value will be based
> +   on a match of the current value of ``FANS`` compared to a list of level
> +   speeds from the ``FANT`` table.
> +
> +The fan speed for all supported fans can be monitored using hwmon sensors or by
> +reading the ``fan_speed_rpm`` sysfs attribute of each fan device.
> +
> +
> +.. _settings-attributes:
> +
> +Settings Attributes
> +===================
> +
> +Various hardware settings can be controlled by the following sysfs attributes:
> +
> +- ``allow_recording`` (allows or blocks usage of built-in camera and microphone)
> +- ``start_on_lid_open`` (power on automatically when opening the lid)
> +- ``usb_charge`` (allows USB ports to provide power even when device is off)
> +
> +These attributes will be available under the path for your supported ACPI Device
> +ID's platform device (``SAM0428``, ``SAM0429``, etc), and can most reliably
> +be found by seeing which device has been bound to the ``samsung-galaxybook``
> +driver. Here are some examples: ::
> +
> +  # find which device ID has been bound to the driver
> +  ls /sys/bus/platform/drivers/samsung-galaxybook/ | grep SAM
> +
> +  # see SAM0429 attributes
> +  ls /sys/bus/platform/drivers/samsung-galaxybook/SAM0429\:00
> +
> +  # see attributes no matter the device ID (using wildcard expansion)
> +  ls /sys/bus/platform/drivers/samsung-galaxybook/SAM*
> +
> +Most shells should support using wildcard expansion to directly read and write
> +these attributes using the above pattern. Example: ::
> +
> +  # read value of start_on_lid_open
> +  cat /sys/bus/platform/drivers/samsung-galaxybook/SAM*/start_on_lid_open
> +
> +  # turn on start_on_lid_open
> +  echo true | sudo tee /sys/bus/platform/drivers/samsung-galaxybook/SAM*/start_on_lid_open
> +
> +It is also possible to use a udev rule to create a fixed-path symlink to your
> +device under ``/dev`` (e.g. ``/dev/samsung-galaxybook``), no matter the device
> +ID, to further simplify reading and writing these attributes in the userspace.
> +
> +Allow recording (allow_recording)
> +---------------------------------
> +
> +``/sys/bus/platform/drivers/samsung-galaxybook/SAM*/allow_recording``
> +
> +Controlled by parameter: ``allow_recording``
> +
> +Controls the "Allow recording" setting, which allows or blocks usage of the
> +built-in camera and microphone (boolean).
> +
> +Start on lid open (start_on_lid_open)
> +-------------------------------------
> +
> +``/sys/bus/platform/drivers/samsung-galaxybook/SAM*/start_on_lid_open``
> +
> +Controls the "Start on lid open" setting, which sets the device to power on
> +automatically when the lid is opened (boolean).
> +
> +USB charge (usb_charge)
> +-----------------------
> +
> +``/sys/bus/platform/drivers/samsung-galaxybook/SAM*/usb_charge``
> +
> +Controls the "USB charge" setting, which allows USB ports to provide power even
> +when the device is turned off (boolean).
> +
> +.. note::
> +  For most devices, this setting seems to only apply to the USB-C ports.
> +
> +
> +.. _keyboard-hotkey-actions:
> +
> +Keyboard hotkey actions (i8042 filter)
> +======================================
> +
> +Controlled by parameter: ``i8042_filter``
> +
> +The i8042 filter will swallow the keyboard events for the Fn+F9 hotkey (Multi-
> +level keyboard backlight toggle) and Fn+F10 hotkey (Allow/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 "Allow recording" setting.
> +
> +
> +ACPI notifications and ACPI hotkey actions
> +==========================================
> +
> +There is a new "Samsung Galaxy Book extra buttons" input device created which
> +will send input events for the following notifications from the ACPI device:
> +
> +- Notification when the battery charge control end threshold has been reached
> +  and the "battery saver" feature has stopped the battery from charging
> +- Notification when the device has been placed on a table (not available on all
> +  models)
> +- Notification when the device has been lifted from a table (not available on
> +  all models)
> +
> +The Fn+F11 Performance mode hotkey is received as an ACPI notification. It will
> +be handled in a similar way as the Fn+F9 and Fn+F10 hotkeys; namely, that the
> +keypress will be swallowed by the driver and each press will cycle to the next
> +available platform profile.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3809931b9..21b4fc504 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20733,6 +20733,12 @@ L:	linux-fbdev@xxxxxxxxxxxxxxx
>  S:	Maintained
>  F:	drivers/video/fbdev/s3c-fb.c
>  
> +SAMSUNG GALAXY BOOK EXTRAS DRIVER
> +M:	Joshua Grisham <josh@xxxxxxxxxxxxxxxxx>
> +L:	platform-driver-x86@xxxxxxxxxxxxxxx
> +S:	Maintained
> +F:	drivers/platform/x86/samsung-galaxybook.c
> +
>  SAMSUNG INTERCONNECT DRIVERS
>  M:	Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
>  M:	Artur Świgoń <a.swigon@xxxxxxxxxxx>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 0258dd879..b6d28b6a4 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -778,6 +778,25 @@ config BARCO_P50_GPIO
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called barco-p50-gpio.
>  
> +config SAMSUNG_GALAXYBOOK
> +	tristate "Samsung Galaxy Book extras driver"
> +	depends on ACPI
> +	depends on ACPI_BATTERY
> +	depends on INPUT
> +	depends on SERIO_I8042
> +	depends on HWMON || HWMON = n
> +	select ACPI_PLATFORM_PROFILE
> +	select INPUT_SPARSEKMAP
> +	select NEW_LEDS
> +	select LEDS_CLASS
> +	help
> +	  This is a driver for Samsung Galaxy Book series notebooks. It adds
> +	  support for the keyboard backlight control, performance mode control, fan
> +	  speed reporting, function keys, and various other device controls.
> +
> +	  For more information about this driver, see
> +	  <file:Documentation/admin-guide/laptops/samsung-galaxybook.rst>.
> +
>  config SAMSUNG_LAPTOP
>  	tristate "Samsung Laptop driver"
>  	depends on RFKILL || RFKILL = n
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index e1b142947..32ec4cb9d 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -95,8 +95,9 @@ obj-$(CONFIG_PCENGINES_APU2)	+= pcengines-apuv2.o
>  obj-$(CONFIG_BARCO_P50_GPIO)	+= barco-p50-gpio.o
>  
>  # Samsung
> -obj-$(CONFIG_SAMSUNG_LAPTOP)	+= samsung-laptop.o
> -obj-$(CONFIG_SAMSUNG_Q10)	+= samsung-q10.o
> +obj-$(CONFIG_SAMSUNG_GALAXYBOOK)	+= samsung-galaxybook.o
> +obj-$(CONFIG_SAMSUNG_LAPTOP)		+= samsung-laptop.o
> +obj-$(CONFIG_SAMSUNG_Q10)		+= samsung-q10.o
>  
>  # Toshiba
>  obj-$(CONFIG_TOSHIBA_BT_RFKILL)	+= toshiba_bluetooth.o
> diff --git a/drivers/platform/x86/samsung-galaxybook.c b/drivers/platform/x86/samsung-galaxybook.c
> new file mode 100644
> index 000000000..ce8b76d91
> --- /dev/null
> +++ b/drivers/platform/x86/samsung-galaxybook.c
> @@ -0,0 +1,1972 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Samsung Galaxy Book series extras driver
> + *
> + * Copyright (c) 2024 Joshua Grisham <josh@xxxxxxxxxxxxxxxxx>
> + *
> + * With contributions to the SCAI ACPI device interface:
> + * Copyright (c) 2024 Giulio Girardi <giulio.girardi@xxxxxxxxxxxxxxx>
> + *
> + * Implementation inspired by existing x86 platform drivers.
> + * Thank you to the authors!
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/dmi.h>
> +#include <linux/hwmon.h>
> +#include <linux/i8042.h>
> +#include <linux/init.h>
> +#include <linux/input.h>
> +#include <linux/input/sparse-keymap.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/nls.h>
> +#include <linux/platform_device.h>
> +#include <linux/platform_profile.h>
> +#include <linux/serio.h>
> +#include <linux/workqueue.h>
> +#include <acpi/battery.h>
> +
> +#define SAMSUNG_GALAXYBOOK_CLASS  "samsung-galaxybook"
> +#define SAMSUNG_GALAXYBOOK_NAME   "Samsung Galaxy Book Extras"
> +
> +/*
> + * Module parameters
> + */
> +
> +static bool kbd_backlight = true;
> +static bool battery_threshold = true;
> +static bool performance_mode = true;
> +static bool allow_recording = true;
> +static bool fan_speed = true;
> +static bool i8042_filter = true;
> +
> +module_param(kbd_backlight, bool, 0644);
> +MODULE_PARM_DESC(kbd_backlight, "Enable Keyboard Backlight control (default on)");
> +module_param(battery_threshold, bool, 0644);
> +MODULE_PARM_DESC(battery_threshold, "Enable battery charge threshold control (default on)");
> +module_param(performance_mode, bool, 0644);
> +MODULE_PARM_DESC(performance_mode, "Enable Performance Mode control (default on)");
> +module_param(allow_recording, bool, 0644);
> +MODULE_PARM_DESC(allow_recording,
> +		 "Enable control to allow or block access to camera and microphone (default on)");
> +module_param(fan_speed, bool, 0644);
> +MODULE_PARM_DESC(fan_speed, "Enable fan speed (default on)");
> +module_param(i8042_filter, bool, 0644);
> +MODULE_PARM_DESC(i8042_filter, "Enable capturing keyboard hotkey events (default on)");
> +
> +/*
> + * Device definitions and matching
> + */
> +
> +static const struct acpi_device_id galaxybook_device_ids[] = {
> +	{ "SAM0427" },
> +	{ "SAM0428" },
> +	{ "SAM0429" },
> +	{ "SAM0430" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(acpi, galaxybook_device_ids);
> +
> +static const struct dmi_system_id galaxybook_dmi_ids[] = {
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
> +			DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /* Notebook */
> +		},
> +	},
> +	{}
> +};
> +
> +struct galaxybook_fan {
> +	struct acpi_device fan;
> +	char *description;
> +	bool supports_fst;
> +	unsigned int *fan_speeds;
> +	int fan_speeds_count;
> +	struct dev_ext_attribute fan_speed_rpm_ext_attr;
> +};
> +
> +#define MAX_FAN_COUNT 5
> +
> +struct samsung_galaxybook {
> +	struct platform_device *platform;
> +	struct acpi_device *acpi;
> +
> +	struct led_classdev kbd_backlight;
> +	struct work_struct kbd_backlight_hotkey_work;
> +
> +	struct input_dev *input;
> +	struct key_entry *keymap;
> +
> +	u8 *profile_performance_modes;
> +	struct platform_profile_handler profile_handler;
> +	struct work_struct performance_mode_hotkey_work;
> +
> +	struct work_struct allow_recording_hotkey_work;
> +
> +	struct galaxybook_fan fans[MAX_FAN_COUNT];
> +	int fans_count;
> +
> +#if IS_ENABLED(CONFIG_HWMON)
> +	struct device *hwmon;
> +#endif
> +};
> +static struct samsung_galaxybook *galaxybook_ptr;
> +
> +struct sawb {
> +	u16 safn;
> +	u16 sasb;
> +	u8 rflg;
> +	union {
> +		struct {
> +			u8 gunm;
> +			u8 guds[250];
> +		};
> +		struct {
> +			u8 caid[16];
> +			u8 fncn;
> +			u8 subn;
> +			u8 iob0;
> +			u8 iob1;
> +			u8 iob2;
> +			u8 iob3;
> +			u8 iob4;
> +			u8 iob5;
> +			u8 iob6;
> +			u8 iob7;
> +			u8 iob8;
> +			u8 iob9;
> +		};
> +		struct {
> +			u8 iob_prefix[18];
> +			u8 iob_values[10];
> +		};
> +	};
> +};
> +
> +#define SAWB_LEN_SETTINGS         0x15
> +#define SAWB_LEN_PERFORMANCE_MODE 0x100
> +
> +#define SAFN  0x5843
> +
> +#define SASB_KBD_BACKLIGHT     0x78
> +#define SASB_POWER_MANAGEMENT  0x7a
> +#define SASB_USB_CHARGE_GET    0x67
> +#define SASB_USB_CHARGE_SET    0x68
> +#define SASB_NOTIFICATIONS     0x86
> +#define SASB_ALLOW_RECORDING   0x8a
> +#define SASB_PERFORMANCE_MODE  0x91
> +
> +#define SAWB_RFLG_POS  4
> +#define SAWB_GUNM_POS  5
> +
> +#define RFLG_SUCCESS  0xaa
> +#define GUNM_FAIL     0xff
> +
> +#define GUNM_FEATURE_ENABLE          0xbb
> +#define GUNM_FEATURE_ENABLE_SUCCESS  0xdd
> +#define GUDS_FEATURE_ENABLE          0xaa
> +#define GUDS_FEATURE_ENABLE_SUCCESS  0xcc
> +
> +#define GUNM_GET  0x81
> +#define GUNM_SET  0x82
> +
> +#define GUNM_POWER_MANAGEMENT  0x82
> +
> +#define GUNM_USB_CHARGE_GET              0x80
> +#define GUNM_USB_CHARGE_ON               0x81
> +#define GUNM_USB_CHARGE_OFF              0x80
> +#define GUDS_START_ON_LID_OPEN           0xa3
> +#define GUDS_START_ON_LID_OPEN_GET       0x81
> +#define GUDS_START_ON_LID_OPEN_SET       0x80
> +#define GUDS_BATTERY_CHARGE_CONTROL      0xe9
> +#define GUDS_BATTERY_CHARGE_CONTROL_GET  0x91
> +#define GUDS_BATTERY_CHARGE_CONTROL_SET  0x90
> +#define GUNM_ACPI_NOTIFY_ENABLE          0x80
> +#define GUDS_ACPI_NOTIFY_ENABLE          0x02
> +
> +#define FNCN_PERFORMANCE_MODE       0x51
> +#define SUBN_PERFORMANCE_MODE_LIST  0x01
> +#define SUBN_PERFORMANCE_MODE_GET   0x02
> +#define SUBN_PERFORMANCE_MODE_SET   0x03
> +
> +/* guid 8246028d-8bca-4a55-ba0f-6f1e6b921b8f */
> +static const guid_t performance_mode_guid_value =
> +	GUID_INIT(0x8246028d, 0x8bca, 0x4a55, 0xba, 0x0f, 0x6f, 0x1e, 0x6b, 0x92, 0x1b, 0x8f);
> +#define PERFORMANCE_MODE_GUID performance_mode_guid_value
> +
> +#define PERFORMANCE_MODE_ULTRA               0x16
> +#define PERFORMANCE_MODE_PERFORMANCE         0x15
> +#define PERFORMANCE_MODE_SILENT              0xb
> +#define PERFORMANCE_MODE_QUIET               0xa
> +#define PERFORMANCE_MODE_OPTIMIZED           0x2
> +#define PERFORMANCE_MODE_PERFORMANCE_LEGACY  0x1
> +#define PERFORMANCE_MODE_OPTIMIZED_LEGACY    0x0
> +#define PERFORMANCE_MODE_UNKNOWN             0xff
> +
> +#define DEFAULT_PLATFORM_PROFILE PLATFORM_PROFILE_BALANCED
> +
> +#define ACPI_METHOD_ENABLE           "SDLS"
> +#define ACPI_METHOD_ENABLE_ON        1
> +#define ACPI_METHOD_ENABLE_OFF       0
> +#define ACPI_METHOD_SETTINGS         "CSFI"
> +#define ACPI_METHOD_PERFORMANCE_MODE "CSXI"
> +
> +#define ACPI_FAN_DEVICE_ID    "PNP0C0B"
> +#define ACPI_FAN_SPEED_LIST   "FANT"
> +#define ACPI_FAN_SPEED_VALUE  "\\_SB.PC00.LPCB.H_EC.FANS"
> +
> +#define KBD_BACKLIGHT_MAX_BRIGHTNESS  3
> +
> +#define ACPI_NOTIFY_BATTERY_STATE_CHANGED    0x61
> +#define ACPI_NOTIFY_DEVICE_ON_TABLE          0x6c
> +#define ACPI_NOTIFY_DEVICE_OFF_TABLE         0x6d
> +#define ACPI_NOTIFY_HOTKEY_PERFORMANCE_MODE  0x70
> +
> +#define GB_KEY_KBD_BACKLIGHT_KEYDOWN    0x2c
> +#define GB_KEY_KBD_BACKLIGHT_KEYUP      0xac
> +#define GB_KEY_ALLOW_RECORDING_KEYDOWN  0x1f
> +#define GB_KEY_ALLOW_RECORDING_KEYUP    0x9f
> +
> +static const struct key_entry galaxybook_acpi_keymap[] = {
> +	{ KE_KEY, ACPI_NOTIFY_BATTERY_STATE_CHANGED,   { KEY_BATTERY } },
> +	{ KE_KEY, ACPI_NOTIFY_DEVICE_ON_TABLE,         { KEY_F14 } },
> +	{ KE_KEY, ACPI_NOTIFY_DEVICE_OFF_TABLE,        { KEY_F15 } },
> +	{ KE_KEY, ACPI_NOTIFY_HOTKEY_PERFORMANCE_MODE, { KEY_UNKNOWN } },
> +	{ KE_END, 0 },
> +};
> +
> +/*
> + * ACPI method handling
> + */
> +
> +#define pr_debug_prefixed(...) pr_debug("[DEBUG] " __VA_ARGS__)
> +
> +#define print_acpi_object_buffer_debug(header_str, buf_ptr, buf_len)	\
> +	do {								\
> +		pr_debug_prefixed("%s\n", header_str);			\
> +		print_hex_dump_debug("samsung_galaxybook: [DEBUG]   ",	\

You can use pr_fmt() wrapping here so you don't need to hardcode the 
prefix.

> +				     DUMP_PREFIX_NONE, 16, 1, buf_ptr,	\
> +				     buf_len, false);			\
> +	} while (0)
> +
> +static char *get_acpi_device_description(struct acpi_device *acpi_dev)
> +{
> +	struct acpi_buffer str_buf = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *str_obj;
> +	struct acpi_buffer name_buf = { ACPI_ALLOCATE_BUFFER, NULL };

Reverse xmas tree order is preferred (unless there's a good reason to 
break it due to dependency).

> +	acpi_status status;
> +	int result;
> +
> +	/* first try to get value of _STR (and also convert it to utf8)  */
> +	if (!acpi_has_method(acpi_dev->handle, "_STR"))
> +		goto use_name;
> +	status = acpi_evaluate_object_typed(acpi_dev->handle, "_STR", NULL,
> +					   &str_buf, ACPI_TYPE_BUFFER);
> +	if (ACPI_SUCCESS(status) && str_buf.length > 0) {
> +		str_obj = str_buf.pointer;
> +		char *buf = kzalloc(sizeof(*buf) * str_obj->buffer.length, GFP_KERNEL);

Don't mix variable declarations with, always put them first in the 
block/function and leave blank line in between. There's only one exception 
and that is using cleanup.h when ordering of the declarations matter but 
that's the only exception (it's the reason why it's allowed at all).

> +		result = utf16s_to_utf8s((wchar_t *)str_obj->buffer.pointer,
> +					 str_obj->buffer.length,
> +					 UTF16_LITTLE_ENDIAN, buf,
> +					 PAGE_SIZE - 1);
> +		kfree(str_obj);
> +		if (result > 0)
> +			return buf;
> +		/* if no result then free buf */
> +		kfree(buf);
> +	}
> +
> +	kfree(str_buf.pointer);
> +
> +use_name:
> +	/* if _STR is missing then just use the device name */
> +	status = acpi_get_name(acpi_dev->handle, ACPI_SINGLE_NAME, &name_buf);
> +	if (ACPI_SUCCESS(status) && name_buf.length > 0)
> +		return name_buf.pointer;
> +
> +	kfree(name_buf.pointer);
> +
> +	return NULL;
> +}
> +
> +static int galaxybook_acpi_method(struct samsung_galaxybook *galaxybook, acpi_string method,
> +				  struct sawb *buf, u32 len, const char *purpose_str,
> +				  struct sawb *ret)
> +{
> +	union acpi_object in_obj, *out_obj;
> +	struct acpi_object_list input;
> +	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
> +	acpi_status status;
> +
> +	in_obj.type = ACPI_TYPE_BUFFER;
> +	in_obj.buffer.length = len;
> +	in_obj.buffer.pointer = (u8 *)buf;
> +
> +	input.count = 1;
> +	input.pointer = &in_obj;
> +
> +	print_acpi_object_buffer_debug(purpose_str, in_obj.buffer.pointer, in_obj.buffer.length);
> +
> +	status = acpi_evaluate_object(galaxybook->acpi->handle, method, &input, &output);
> +
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("failed %s with ACPI method %s; got %s\n", purpose_str, method,
> +		       acpi_format_exception(status));

Use dev_err()

> +		return status;
> +	}
> +
> +	out_obj = output.pointer;
> +
> +	if (out_obj->type != ACPI_TYPE_BUFFER) {
> +		pr_err("failed %s with ACPI method %s; response was not a buffer\n",
> +			purpose_str, method);
> +		status = -EIO;
> +		goto out_free;
> +	}
> +
> +	print_acpi_object_buffer_debug("response was: ", out_obj->buffer.pointer,
> +				       out_obj->buffer.length);
> +
> +	if (out_obj->buffer.length != len) {
> +		pr_err("failed %s with ACPI method %s; response length mismatch\n",
> +		       purpose_str, method);
> +		status = -EIO;
> +		goto out_free;
> +	}
> +	if (out_obj->buffer.length < SAWB_GUNM_POS + 1) {
> +		pr_err("failed %s with ACPI method %s; response from device was too short\n",
> +		       purpose_str, method);
> +		status = -EIO;
> +		goto out_free;
> +	}
> +	if (out_obj->buffer.pointer[SAWB_RFLG_POS] != RFLG_SUCCESS) {
> +		pr_err("failed %s with ACPI method %s; "
> +		       "device did not respond with success code 0x%x\n",
> +		       purpose_str, method, RFLG_SUCCESS);
> +		status = -EIO;
> +		goto out_free;
> +	}
> +	if (out_obj->buffer.pointer[SAWB_GUNM_POS] == GUNM_FAIL) {
> +		pr_err("failed %s with ACPI method %s; device responded with failure code 0x%x\n",
> +		       purpose_str, method, GUNM_FAIL);
> +		status = -EIO;
> +		goto out_free;
> +	}
> +
> +	memcpy(ret, out_obj->buffer.pointer, len);

In kernel, ret is typically int so I suggest you pick some other name for 
the variable (Yes, I went back to find out what the type is in this case).

> +
> +out_free:
> +	kfree(output.pointer);
> +	return status;
> +}
> +
> +static int galaxybook_enable_acpi_feature(struct samsung_galaxybook *galaxybook, const u16 sasb)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = sasb;
> +	buf.gunm = GUNM_FEATURE_ENABLE;
> +	buf.guds[0] = GUDS_FEATURE_ENABLE;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "enabling ACPI feature", &buf);
> +	if (err)
> +		return err;
> +
> +	if (buf.gunm != GUNM_FEATURE_ENABLE_SUCCESS && buf.guds[0] != GUDS_FEATURE_ENABLE_SUCCESS)
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +/*
> + * Keyboard Backlight
> + */
> +
> +static int kbd_backlight_acpi_set(struct samsung_galaxybook *galaxybook,
> +				  const enum led_brightness brightness)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_KBD_BACKLIGHT;
> +	buf.gunm = GUNM_SET;
> +
> +	buf.guds[0] = brightness;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "setting kbd_backlight brightness", &buf);
> +	if (err)
> +		return err;
> +
> +	galaxybook->kbd_backlight.brightness = brightness;
> +
> +	pr_debug_prefixed("set kbd_backlight brightness to %d\n", brightness);

Use dev_dbg() directly.

> +
> +	return 0;
> +}
> +
> +static int kbd_backlight_acpi_get(struct samsung_galaxybook *galaxybook,
> +				  enum led_brightness *brightness)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_KBD_BACKLIGHT;
> +	buf.gunm = GUNM_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "getting kbd_backlight brightness", &buf);
> +	if (err)
> +		return err;
> +
> +	*brightness = buf.gunm;
> +	galaxybook->kbd_backlight.brightness = buf.gunm;
> +
> +	pr_debug_prefixed("current kbd_backlight brightness is %d\n", buf.gunm);
> +
> +	return 0;
> +}
> +
> +static int kbd_backlight_store(struct led_classdev *led,
> +			       const enum led_brightness brightness)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(led, struct samsung_galaxybook, kbd_backlight);
> +	int err;
> +
> +	err = kbd_backlight_acpi_set(galaxybook, brightness);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static enum led_brightness kbd_backlight_show(struct led_classdev *led)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(led, struct samsung_galaxybook, kbd_backlight);
> +	enum led_brightness brightness;
> +	int err;
> +
> +	err = kbd_backlight_acpi_get(galaxybook, &brightness);
> +	if (err)
> +		return err;
> +
> +	return brightness;
> +}
> +
> +static int galaxybook_kbd_backlight_init(struct samsung_galaxybook *galaxybook)
> +{
> +	enum led_brightness brightness;
> +	struct led_init_data init_data = {};
> +	int err;
> +
> +	err = galaxybook_enable_acpi_feature(galaxybook, SASB_KBD_BACKLIGHT);
> +	if (err)
> +		return err;
> +
> +	/* verify we can read the value, otherwise init should stop and fail */
> +	err = kbd_backlight_acpi_get(galaxybook, &brightness);
> +	if (err)
> +		return err;
> +
> +	init_data.devicename = SAMSUNG_GALAXYBOOK_CLASS;
> +	init_data.default_label = ":kbd_backlight";
> +	init_data.devname_mandatory = true;
> +
> +	galaxybook->kbd_backlight = (struct led_classdev){
> +		.brightness_get = kbd_backlight_show,
> +		.brightness_set_blocking = kbd_backlight_store,
> +		.flags = LED_BRIGHT_HW_CHANGED,
> +		.max_brightness = KBD_BACKLIGHT_MAX_BRIGHTNESS,
> +	};
> +
> +	pr_info("registering LED class using default name of %s:%s\n",
> +		init_data.devicename, init_data.default_label);
> +
> +	return led_classdev_register_ext(&galaxybook->platform->dev, &galaxybook->kbd_backlight,
> +					 &init_data);
> +}
> +
> +static void galaxybook_kbd_backlight_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	led_classdev_unregister(&galaxybook->kbd_backlight);
> +}
> +
> +/*
> + * Platform device attributes (configuration properties which can be controlled via userspace)
> + */
> +
> +/* Start on lid open (device should power on when lid is opened) */
> +
> +static int start_on_lid_open_acpi_set(struct samsung_galaxybook *galaxybook, const bool value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_POWER_MANAGEMENT;
> +	buf.gunm = GUNM_POWER_MANAGEMENT;
> +	buf.guds[0] = GUDS_START_ON_LID_OPEN;
> +	buf.guds[1] = GUDS_START_ON_LID_OPEN_SET;
> +	buf.guds[2] = value;

This relies on bool -> u8 implicit conversion. While it probably works as 
is, I'd prefer to make the conversion explicit with e.g. ?: operator (and 
let the compiler optimize it if it wants to).

> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "setting start_on_lid_open", &buf);
> +	if (err)
> +		return err;
> +
> +	pr_debug_prefixed("turned start_on_lid_open %s\n", value ? "on (1)" : "off (0)");

Use a helper from linux/string_choices.h.

I'd change it to:
	dev_dbg(..., "start_on_lid_open %s\n", str_enabled_disabled(value));

> +
> +	return 0;
> +}
> +
> +static int start_on_lid_open_acpi_get(struct samsung_galaxybook *galaxybook, bool *value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_POWER_MANAGEMENT;
> +	buf.gunm = GUNM_POWER_MANAGEMENT;
> +	buf.guds[0] = GUDS_START_ON_LID_OPEN;
> +	buf.guds[1] = GUDS_START_ON_LID_OPEN_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "getting start_on_lid_open", &buf);
> +	if (err)
> +		return err;
> +
> +	*value = buf.guds[1];
> +
> +	pr_debug_prefixed("start_on_lid_open is currently %s\n",
> +			  (buf.guds[1] ? "on (1)" : "off (0)"));

I suspect a debug print like this is not going to be very useful. You get 
the result right out of the sysfs anyway so why bother printing at all and
it's anyway not the raw value but synthetized on/off string.

> +
> +	return 0;
> +}
> +
> +static ssize_t start_on_lid_open_store(struct device *dev, struct device_attribute *attr,
> +				       const char *buffer, size_t count)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	if (!count || kstrtobool(buffer, &value))
> +		return -EINVAL;
> +
> +	err = start_on_lid_open_acpi_set(galaxybook, value);
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +
> +static ssize_t start_on_lid_open_show(struct device *dev, struct device_attribute *attr,
> +				      char *buffer)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	err = start_on_lid_open_acpi_get(galaxybook, &value);
> +	if (err)
> +		return err;
> +
> +	return sysfs_emit(buffer, "%u\n", value);
> +}
> +
> +static DEVICE_ATTR_RW(start_on_lid_open);
> +
> +/* USB Charge (USB ports can charge other devices even when device is powered off) */
> +
> +static int usb_charge_acpi_set(struct samsung_galaxybook *galaxybook, const bool value)

Don't leave empty line in between.

> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_USB_CHARGE_SET;
> +	buf.gunm = value ? GUNM_USB_CHARGE_ON : GUNM_USB_CHARGE_OFF;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "setting usb_charge", &buf);
> +	if (err)
> +		return err;
> +
> +	pr_debug_prefixed("turned usb_charge %s\n", value ? "on (1)" : "off (0)");
> +
> +	return 0;
> +}
> +
> +static int usb_charge_acpi_get(struct samsung_galaxybook *galaxybook, bool *value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_USB_CHARGE_GET;
> +	buf.gunm = GUNM_USB_CHARGE_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "getting usb_charge", &buf);
> +	if (err)
> +		return err;
> +
> +	*value = buf.gunm;
> +
> +	pr_debug_prefixed("usb_charge is currently %s\n", (buf.gunm ? "on (1)" : "off (0)"));
> +
> +	return 0;
> +}
> +
> +static ssize_t usb_charge_store(struct device *dev, struct device_attribute *attr,
> +				const char *buffer, size_t count)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	if (!count || kstrtobool(buffer, &value))
> +		return -EINVAL;
> +
> +	err = usb_charge_acpi_set(galaxybook, value);
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +
> +static ssize_t usb_charge_show(struct device *dev, struct device_attribute *attr, char *buffer)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	err = usb_charge_acpi_get(galaxybook, &value);
> +	if (err)
> +		return err;
> +
> +	return sysfs_emit(buffer, "%u\n", value);
> +}
> +
> +static DEVICE_ATTR_RW(usb_charge);
> +
> +/* Allow recording (allows or blocks access to camera and microphone) */
> +
> +static int allow_recording_acpi_set(struct samsung_galaxybook *galaxybook, const bool value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_ALLOW_RECORDING;
> +	buf.gunm = GUNM_SET;
> +	buf.guds[0] = value;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "setting allow_recording", &buf);
> +	if (err)
> +		return err;
> +
> +	pr_debug_prefixed("turned allow_recording %s\n", value ? "on (1)" : "off (0)");
> +
> +	return 0;
> +}
> +
> +static int allow_recording_acpi_get(struct samsung_galaxybook *galaxybook, bool *value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_ALLOW_RECORDING;
> +	buf.gunm = GUNM_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "getting allow_recording", &buf);
> +	if (err)
> +		return err;
> +
> +	*value = buf.gunm;
> +
> +	pr_debug_prefixed("allow_recording is currently %s\n", (buf.gunm ? "on (1)" : "off (0)"));

For some reason parenthesis are used in this while the others have been 
w/o them (but use string_choices.h helpers anyway so that probably makes 
the comment moot).

> +
> +	return 0;
> +}
> +
> +static ssize_t allow_recording_store(struct device *dev, struct device_attribute *attr,
> +				     const char *buffer, size_t count)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	if (!count || kstrtobool(buffer, &value))
> +		return -EINVAL;
> +
> +	err = allow_recording_acpi_set(galaxybook, value);
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +
> +static ssize_t allow_recording_show(struct device *dev, struct device_attribute *attr, char *buffer)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(dev);
> +	bool value;
> +	int err;
> +
> +	err = allow_recording_acpi_get(galaxybook, &value);
> +	if (err)
> +		return err;
> +
> +	return sysfs_emit(buffer, "%u\n", value);
> +}
> +
> +static DEVICE_ATTR_RW(allow_recording);
> +
> +/*
> + * Battery Extension (adds charge_control_end_threshold to the battery device)
> + */
> +
> +static int charge_control_end_threshold_acpi_set(struct samsung_galaxybook *galaxybook,
> +						 const u8 value)

While certainly not forbidden, using const on plain integer types is not 
extremely useful. In fact, if it wouldn't be const, you could do the 100 
-> 0 mapping for it separately and not do it twice below.

> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	if (value > 100)
> +		return -EINVAL;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_POWER_MANAGEMENT;
> +	buf.gunm = GUNM_POWER_MANAGEMENT;
> +	buf.guds[0] = GUDS_BATTERY_CHARGE_CONTROL;
> +	buf.guds[1] = GUDS_BATTERY_CHARGE_CONTROL_SET;
> +
> +	buf.guds[2] = (value == 100 ? 0 : value); /* if setting to 100, should be set to 0 (off) */

Put comment on line before it so it's easier to read.

"off" -> "no threshold" ?

> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "setting battery charge_control_end_threshold", &buf);
> +	if (err)
> +		return err;
> +
> +	pr_debug_prefixed("set battery charge_control_end_threshold to %d\n",
> +			  (value == 100 ? 0 : value));

Do you want to differentiate 0 from 0? Should this function actually 
return -EINVAL if somebody attempts to set 0 threshold?

> +	return 0;
> +}
> +
> +static int charge_control_end_threshold_acpi_get(struct samsung_galaxybook *galaxybook, u8 *value)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_POWER_MANAGEMENT;
> +	buf.gunm = GUNM_POWER_MANAGEMENT;
> +	buf.guds[0] = GUDS_BATTERY_CHARGE_CONTROL;
> +	buf.guds[1] = GUDS_BATTERY_CHARGE_CONTROL_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				     "getting battery charge_control_end_threshold", &buf);
> +	if (err)
> +		return err;
> +
> +	*value = buf.guds[1];
> +
> +	pr_debug_prefixed("battery charge control is currently %s; "
> +			  "battery charge_control_end_threshold is %d\n",
> +			  (buf.guds[1] > 0 ? "on" : "off"), buf.guds[1]);
> +
> +	return 0;
> +}
> +
> +static ssize_t charge_control_end_threshold_store(struct device *dev, struct device_attribute *attr,
> +						  const char *buffer, size_t count)
> +{
> +	u8 value;
> +	int err;
> +
> +	if (!count || kstrtou8(buffer, 0, &value))
> +		return -EINVAL;
> +
> +	err = charge_control_end_threshold_acpi_set(galaxybook_ptr, value);
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +
> +static ssize_t charge_control_end_threshold_show(struct device *dev, struct device_attribute *attr,
> +						 char *buffer)
> +{
> +	u8 value;
> +	int err;
> +
> +	err = charge_control_end_threshold_acpi_get(galaxybook_ptr, &value);
> +	if (err)
> +		return err;
> +
> +	return sysfs_emit(buffer, "%d\n", value);
> +}
> +
> +static DEVICE_ATTR_RW(charge_control_end_threshold);
> +
> +static int galaxybook_battery_add(struct power_supply *battery, struct acpi_battery_hook *hook)
> +{
> +	if (device_create_file(&battery->dev, &dev_attr_charge_control_end_threshold))
> +		return -ENODEV;
> +	return 0;
> +}
> +
> +static int galaxybook_battery_remove(struct power_supply *battery, struct acpi_battery_hook *hook)
> +{
> +	device_remove_file(&battery->dev, &dev_attr_charge_control_end_threshold);
> +	return 0;
> +}
> +
> +static struct acpi_battery_hook galaxybook_battery_hook = {
> +	.add_battery = galaxybook_battery_add,
> +	.remove_battery = galaxybook_battery_remove,
> +	.name = "Samsung Galaxy Book Battery Extension",
> +};
> +
> +static int galaxybook_battery_threshold_init(struct samsung_galaxybook *galaxybook)
> +{
> +	u8 value;
> +	int err;
> +
> +	err = charge_control_end_threshold_acpi_get(galaxybook, &value);
> +	if (err)
> +		return err;
> +
> +	battery_hook_register(&galaxybook_battery_hook);
> +	return 0;
> +}
> +
> +static void galaxybook_battery_threshold_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	battery_hook_unregister(&galaxybook_battery_hook);
> +}
> +
> +/*
> + * Fan speed
> + */
> +
> +static int fan_speed_get_fst(struct galaxybook_fan *fan, unsigned int *speed)
> +{
> +	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *response_obj = NULL;
> +	acpi_status status;
> +	int ret = 0;
> +
> +	status = acpi_evaluate_object(fan->fan.handle, "_FST", NULL, &response);
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("Get fan state failed\n");
> +		return -ENODEV;
> +	}
> +
> +	response_obj = response.pointer;
> +	if (!response_obj || response_obj->type != ACPI_TYPE_PACKAGE ||
> +	    response_obj->package.count != 3 ||
> +	    response_obj->package.elements[2].type != ACPI_TYPE_INTEGER) {
> +		pr_err("Invalid _FST data\n");
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	*speed = response_obj->package.elements[2].integer.value;
> +
> +	pr_debug_prefixed("fan device %s (%s) reporting fan speed of %d\n",
> +			  dev_name(&fan->fan.dev), fan->description, *speed);
> +
> +out_free:
> +	ACPI_FREE(response.pointer);
> +	return ret;

You're mixing err and ret within a file as the error/return code variable. 
It would be nice to be consistent within a file.

> +}
> +
> +static int fan_speed_get_fans(struct galaxybook_fan *fan, unsigned int *speed)
> +{
> +	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *response_obj = NULL;
> +	acpi_status status;
> +	int ret = 0;
> +	int speed_level = -1;
> +
> +	status = acpi_evaluate_object(NULL, ACPI_FAN_SPEED_VALUE, NULL, &response);
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("Get fan state failed\n");
> +		return -ENODEV;
> +	}
> +
> +	response_obj = response.pointer;
> +	if (!response_obj || response_obj->type != ACPI_TYPE_INTEGER ||
> +	    response_obj->integer.value > INT_MAX ||

I don't know what's the logic behind doing bound check here but not in the 
previous function.

> +	    (int)response_obj->integer.value > fan->fan_speeds_count) {
> +		pr_err("invalid fan speed data\n");
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	speed_level = (int)response_obj->integer.value;
> +	*speed = fan->fan_speeds[speed_level];
> +
> +	pr_debug_prefixed("fan device %s (%s) reporting fan speed of %d (level %d)\n",
> +			  dev_name(&fan->fan.dev), fan->description, *speed, speed_level);
> +
> +out_free:
> +	ACPI_FREE(response.pointer);
> +	return ret;
> +}
> +
> +static int fan_speed_get(struct galaxybook_fan *fan, unsigned int *speed)
> +{
> +	if (!fan)
> +		return -ENODEV;
> +	if (fan->supports_fst)
> +		return fan_speed_get_fst(fan, speed);
> +	else
> +		return fan_speed_get_fans(fan, speed);
> +}
> +
> +static ssize_t fan_speed_rpm_show(struct device *dev, struct device_attribute *attr, char *buffer)
> +{
> +	struct dev_ext_attribute *ea = container_of(attr, struct dev_ext_attribute, attr);
> +	struct galaxybook_fan *fan = ea->var;
> +	unsigned int speed;
> +	int ret = 0;

Unnecessary init.

> +
> +	if (!fan)
> +		return -ENODEV;
> +
> +	ret = fan_speed_get(fan, &speed);
> +	if (ret)
> +		return ret;
> +
> +	return sysfs_emit(buffer, "%u\n", speed);
> +}
> +
> +static int __init fan_speed_list_init(acpi_handle handle, struct galaxybook_fan *fan)
> +{
> +	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *response_obj = NULL;
> +	acpi_status status;
> +	unsigned int speed;
> +	int i;
> +
> +	status = acpi_evaluate_object(handle, ACPI_FAN_SPEED_LIST, NULL, &response);
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("failed to read fan speed list\n");
> +		return -ENODEV;
> +	}
> +
> +	response_obj = response.pointer;
> +	if (!response_obj || response_obj->type != ACPI_TYPE_PACKAGE ||
> +	    response_obj->package.count == 0) {
> +		pr_err("invalid fan speed list data\n");
> +		status = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	/*
> +	 * fan_speeds[] starts with a hard-coded 0 (fan is off), then has some "funny" logic:
> +	 *  - fetch the speed level values read in from FANT and add 0x0a to each value
> +	 *  - _FST method in the DSDT seems to indicate that level 3 and 4 should have same value,
> +	 *    however real-life observation suggests that the speed actually does change
> +	 *  - _FST says that level 5 should give the 4th value from FANT but it seems significantly
> +	 *    louder -- we will just "guess" it is 1000 RPM faster than the highest value from FANT?
> +	 */
> +
> +	fan->fan_speeds = kzalloc(sizeof(unsigned int) * (response_obj->package.count + 2),

kcalloc()

> +				  GFP_KERNEL);
> +	if (!fan->fan_speeds)
> +		return -ENOMEM;
> +
> +	/* hard-coded "off" value (0) */
> +	fan->fan_speeds[0] = 0;

Name with a define and drop the comment?

> +	fan->fan_speeds_count = 1;
> +
> +	/* fetch and assign the next values from FANT response */
> +	i = 0;

Does nothing.

> +	for (i = 1; i <= response_obj->package.count; i++) {
> +		if (response_obj->package.elements[i - 1].type != ACPI_TYPE_INTEGER) {
> +			pr_err("invalid fan speed list value at position %d; "
> +			       "expected type %d, got type %d\n",
> +			       i - 1, ACPI_TYPE_INTEGER,
> +			       response_obj->package.elements[i - 1].type);
> +			status = -EINVAL;
> +			goto err_fan_speeds_free;
> +		}
> +		fan->fan_speeds[i] = response_obj->package.elements[i - 1].integer.value + 0x0a;

Add a local variable to avoid repeating response_obj->package.elements[i - 1] ?

> +		fan->fan_speeds_count++;
> +	}
> +
> +	/* add the missing final level where we "guess" 1000 RPM faster than highest from FANT */

Fold comments at 80 chars.

> +	if (fan->fan_speeds_count > 1) {
> +		fan->fan_speeds[i] = fan->fan_speeds[i - 1] + 1000;
> +		fan->fan_speeds_count++;
> +	}
> +
> +	/* test that it actually works to read the speed, otherwise the init should fail */
> +	status = fan_speed_get_fans(fan, &speed);
> +	if (ACPI_FAILURE(status)) {
> +		pr_err("failed to read fan speed level from FANS\n");
> +		goto err_fan_speeds_free;
> +	}
> +
> +	pr_info("initialized fan speed reporting for device %s (%s) with the following levels:\n",
> +		dev_name(&fan->fan.dev), fan->description);
> +	for (i = 0; i < fan->fan_speeds_count; i++)
> +		pr_info("  %s (%s) fan speed level %d = %d\n",
> +			dev_name(&fan->fan.dev), fan->description, i, fan->fan_speeds[i]);

On successful probe, the driver should not print anything.

> +
> +out_free:
> +	ACPI_FREE(response.pointer);
> +	return status;
> +
> +err_fan_speeds_free:
> +	kfree(fan->fan_speeds);
> +	goto out_free;
> +}
> +
> +static acpi_status galaxybook_add_fan(acpi_handle handle, u32 level, void *context,
> +				      void **return_value)
> +{
> +	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
> +	struct samsung_galaxybook *galaxybook = context;
> +	struct galaxybook_fan *fan;
> +	int speed = -1;
> +
> +	pr_info("found fan device %s\n", dev_name(&adev->dev));
> +
> +	/* if fan meets acpi4 fan device requirements, assume it is added already under ACPI */
> +	if (acpi_has_method(handle, "_FIF") &&
> +	    acpi_has_method(handle, "_FPS") &&
> +	    acpi_has_method(handle, "_FSL") &&
> +	    acpi_has_method(handle, "_FST")) {
> +		pr_info("fan device %s should already be available as an ACPI fan; skipping\n",
> +			dev_name(&adev->dev));
> +		return 0;
> +	}
> +
> +	if (galaxybook->fans_count >= MAX_FAN_COUNT) {
> +		pr_err("maximum number of %d fans has already been reached\n", MAX_FAN_COUNT);
> +		return 0;
> +	}
> +
> +	fan = &galaxybook->fans[galaxybook->fans_count];
> +	fan->fan = *adev;
> +	fan->description = get_acpi_device_description(&fan->fan);
> +
> +	/* try to get speed from _FST */
> +	if (ACPI_FAILURE(fan_speed_get_fst(fan, &speed))) {
> +		pr_debug_prefixed("_FST is present but failed on fan device %s (%s); "
> +				  "will attempt to add fan speed support using FANT and FANS\n",
> +				  dev_name(&fan->fan.dev), fan->description);
> +		fan->supports_fst = false;
> +	}
> +	/* if speed was 0 and FANT and FANS exist, they should be used anyway due to bugs in ACPI */
> +	else if (speed <= 0 &&
> +		 acpi_has_method(handle, ACPI_FAN_SPEED_LIST) &&
> +		 acpi_has_method(NULL, ACPI_FAN_SPEED_VALUE)) {
> +		pr_debug_prefixed("_FST is present on fan device %s (%s) but returned value of 0; "
> +				  "will attempt to add fan speed support using FANT and FANS\n",
> +				  dev_name(&fan->fan.dev), fan->description);
> +		fan->supports_fst = false;
> +	} else {
> +		fan->supports_fst = true;
> +	}
> +
> +	if (!fan->supports_fst) {
> +		/* since FANS is a field on the EC, it does not make sense to use more than once */
> +		for (int i = 0; i < galaxybook->fans_count; i++) {
> +			if (!galaxybook->fans[i].supports_fst) {
> +				pr_err("more than one fan using FANS is not supported\n");
> +				return 0;
> +			}
> +		}
> +		if (ACPI_FAILURE(fan_speed_list_init(handle, fan))) {
> +			pr_err("unable to initialize fan speeds for fan device %s (%s)\n",
> +			       dev_name(&fan->fan.dev), fan->description);
> +			return 0;
> +		}
> +	} else {
> +		pr_info("initialized fan speed reporting for device %s (%s) using method _FST\n",
> +			dev_name(&fan->fan.dev), fan->description);
> +	}
> +
> +	/* set up RO dev_ext_attribute */
> +	fan->fan_speed_rpm_ext_attr.attr.attr.name = "fan_speed_rpm";
> +	fan->fan_speed_rpm_ext_attr.attr.attr.mode = 0444;
> +	fan->fan_speed_rpm_ext_attr.attr.show = fan_speed_rpm_show;
> +	/* extended attribute var points to this galaxybook_fan so it can used in the show method */
> +	fan->fan_speed_rpm_ext_attr.var = fan;
> +
> +	if (sysfs_create_file(&adev->dev.kobj, &fan->fan_speed_rpm_ext_attr.attr.attr))
> +		pr_err("unable to create fan_speed_rpm attribute for fan device %s (%s)\n",
> +		       dev_name(&fan->fan.dev), fan->description);

You can use is_visible function to decide which sysfs files are shown so 
you don't need to do the manual sysfs handling like this per fan.

But why you need this whole dev_ext_attribute thing in the first place?

> +	galaxybook->fans_count++;
> +
> +	return 0;
> +}
> +
> +static int __init galaxybook_fan_speed_init(struct samsung_galaxybook *galaxybook)
> +{
> +	acpi_status status;
> +
> +	/* get and set up all fans matching ACPI_FAN_DEVICE_ID */
> +	status = acpi_get_devices(ACPI_FAN_DEVICE_ID, galaxybook_add_fan, galaxybook, NULL);
> +
> +	if (galaxybook->fans_count == 0)
> +		return -ENODEV;
> +
> +	return status;
> +}
> +
> +static void galaxybook_fan_speed_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	for (int i = 0; i < galaxybook->fans_count; i++)
> +		sysfs_remove_file(&galaxybook->fans[i].fan.dev.kobj,
> +				  &galaxybook->fans[i].fan_speed_rpm_ext_attr.attr.attr);
> +}
> +
> +/*
> + * Hwmon device
> + */
> +
> +#if IS_ENABLED(CONFIG_HWMON)
> +static umode_t galaxybook_hwmon_is_visible(const void *drvdata, enum hwmon_sensor_types type,
> +					   u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_fan:
> +		if (channel < galaxybook_ptr->fans_count &&
> +		    (attr == hwmon_fan_input || attr == hwmon_fan_label))
> +			return 0444;
> +		return 0;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static int galaxybook_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +				 u32 attr, int channel, long *val)
> +{
> +	unsigned int speed;
> +
> +	switch (type) {
> +	case hwmon_fan:
> +		if (channel < galaxybook_ptr->fans_count && attr == hwmon_fan_input) {
> +			if (fan_speed_get(&galaxybook_ptr->fans[channel], &speed))
> +				return -EIO;
> +			*val = speed;
> +			return 0;
> +		}
> +		return -EOPNOTSUPP;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int galaxybook_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
> +					u32 attr, int channel, const char **str)
> +{
> +	switch (type) {
> +	case hwmon_fan:
> +		if (channel < galaxybook_ptr->fans_count && attr == hwmon_fan_label) {
> +			*str = galaxybook_ptr->fans[channel].description;
> +			return 0;
> +		}
> +		return -EOPNOTSUPP;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static const struct hwmon_ops galaxybook_hwmon_ops = {
> +	.is_visible = galaxybook_hwmon_is_visible,
> +	.read = galaxybook_hwmon_read,
> +	.read_string = galaxybook_hwmon_read_string,
> +};
> +
> +static const struct hwmon_channel_info *const galaxybook_hwmon_info[] = {
> +	/* note: number of max possible fan channel entries here should match MAX_FAN_COUNT */
> +	HWMON_CHANNEL_INFO(fan,
> +			   HWMON_F_INPUT | HWMON_F_LABEL,
> +			   HWMON_F_INPUT | HWMON_F_LABEL,
> +			   HWMON_F_INPUT | HWMON_F_LABEL,
> +			   HWMON_F_INPUT | HWMON_F_LABEL,
> +			   HWMON_F_INPUT | HWMON_F_LABEL),
> +	NULL
> +};
> +
> +static const struct hwmon_chip_info galaxybook_hwmon_chip_info = {
> +	.ops = &galaxybook_hwmon_ops,
> +	.info = galaxybook_hwmon_info,
> +};
> +
> +static int galaxybook_hwmon_init(struct samsung_galaxybook *galaxybook)
> +{
> +	int ret = 0;
> +

No empty lines in between variable declarations.

> +	char *hwmon_device_name = devm_hwmon_sanitize_name(&galaxybook->platform->dev,
> +							   SAMSUNG_GALAXYBOOK_CLASS);

Declare variable separately since you have to split the line.

> +	galaxybook->hwmon = devm_hwmon_device_register_with_info(
> +		&galaxybook->platform->dev, hwmon_device_name, NULL,
> +		&galaxybook_hwmon_chip_info, NULL);
> +	if (PTR_ERR_OR_ZERO(galaxybook->hwmon)) {
> +		ret = PTR_ERR(galaxybook->hwmon);
> +		galaxybook->hwmon = NULL;
> +	}
> +
> +	return ret;
> +}
> +
> +static void galaxybook_hwmon_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	if (galaxybook->hwmon)
> +		hwmon_device_unregister(galaxybook->hwmon);
> +}
> +#endif
> +
> +/*
> + * Platform Profile / Performance mode
> + */
> +
> +static int performance_mode_acpi_set(struct samsung_galaxybook *galaxybook,
> +				     const u8 performance_mode)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_PERFORMANCE_MODE;
> +	export_guid(buf.caid, &PERFORMANCE_MODE_GUID);
> +	buf.fncn = FNCN_PERFORMANCE_MODE;
> +	buf.subn = SUBN_PERFORMANCE_MODE_SET;
> +	buf.iob0 = performance_mode;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_PERFORMANCE_MODE, &buf,
> +				     SAWB_LEN_PERFORMANCE_MODE, "setting performance_mode", &buf);
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +static int performance_mode_acpi_get(struct samsung_galaxybook *galaxybook, u8 *performance_mode)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_PERFORMANCE_MODE;
> +	export_guid(buf.caid, &PERFORMANCE_MODE_GUID);

Add linux/uuid.h

> +	buf.fncn = FNCN_PERFORMANCE_MODE;
> +	buf.subn = SUBN_PERFORMANCE_MODE_GET;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_PERFORMANCE_MODE, &buf,
> +				     SAWB_LEN_PERFORMANCE_MODE, "getting performance_mode", &buf);
> +	if (err)
> +		return err;
> +
> +	*performance_mode = buf.iob0;
> +
> +	return 0;
> +}
> +
> +static enum platform_profile_option
> +profile_performance_mode(struct samsung_galaxybook *galaxybook, const u8 performance_mode)
> +{
> +	for (int i = 0; i < PLATFORM_PROFILE_LAST; i++)
> +		if (galaxybook->profile_performance_modes[i] == performance_mode)
> +			return i;
> +	return -1;

Returning value that is not part of enum looks a bit hacky.

> +}
> +
> +/* copied from platform_profile.c; better if this could be fetched from a public function, maybe? */

You are allowed to propose patches in the patch series for things you 
need. :-)

> +static const char *const profile_names[] = {
> +	[PLATFORM_PROFILE_LOW_POWER] = "low-power",
> +	[PLATFORM_PROFILE_COOL] = "cool",
> +	[PLATFORM_PROFILE_QUIET] = "quiet",
> +	[PLATFORM_PROFILE_BALANCED] = "balanced",
> +	[PLATFORM_PROFILE_BALANCED_PERFORMANCE] = "balanced-performance",
> +	[PLATFORM_PROFILE_PERFORMANCE] = "performance",
> +};
> +static_assert(ARRAY_SIZE(profile_names) == PLATFORM_PROFILE_LAST);

Is this assert compatible with the custom platform profile series that is 
practically ready to be merged?

> +static int galaxybook_platform_profile_set(struct platform_profile_handler *pprof,
> +					   enum platform_profile_option profile)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(pprof, struct samsung_galaxybook, profile_handler);
> +	int err;
> +
> +	err = performance_mode_acpi_set(galaxybook, galaxybook->profile_performance_modes[profile]);
> +	if (err)
> +		return err;
> +
> +	pr_debug_prefixed("set platform profile to '%s' (performance mode 0x%x)\n",
> +			  profile_names[profile], galaxybook->profile_performance_modes[profile]);
> +	return 0;
> +}
> +
> +static int galaxybook_platform_profile_get(struct platform_profile_handler *pprof,
> +					   enum platform_profile_option *profile)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(pprof, struct samsung_galaxybook, profile_handler);
> +	u8 performance_mode;
> +	int err;
> +
> +	err = performance_mode_acpi_get(galaxybook, &performance_mode);
> +	if (err)
> +		return err;
> +
> +	*profile = profile_performance_mode(galaxybook, performance_mode);
> +	if (*profile == -1)
> +		return -EINVAL;
> +
> +	pr_debug_prefixed("platform profile is currently '%s' (performance mode 0x%x)\n",
> +			  profile_names[*profile], performance_mode);
> +
> +	return 0;
> +}
> +
> +#define IGNORE_PERFORMANCE_MODE_MAPPING  -1
> +
> +static int galaxybook_profile_init(struct samsung_galaxybook *galaxybook)
> +{
> +	struct sawb buf = { 0 };
> +	int mode_profile, err;
> +	u8 current_performance_mode;
> +
> +	galaxybook->profile_handler.profile_get = galaxybook_platform_profile_get;
> +	galaxybook->profile_handler.profile_set = galaxybook_platform_profile_set;
> +
> +	/* fetch supported performance mode values from ACPI method */
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_PERFORMANCE_MODE;
> +	export_guid(buf.caid, &PERFORMANCE_MODE_GUID);
> +	buf.fncn = FNCN_PERFORMANCE_MODE;
> +	buf.subn = SUBN_PERFORMANCE_MODE_LIST;
> +
> +	err = galaxybook_acpi_method(galaxybook, ACPI_METHOD_PERFORMANCE_MODE,
> +				     &buf, SAWB_LEN_PERFORMANCE_MODE,
> +				     "get supported performance modes", &buf);
> +	if (err)
> +		return err;
> +
> +	/* set up profile_performance_modes with "unknown" as init value */
> +	galaxybook->profile_performance_modes =
> +		kzalloc(sizeof(u8) * PLATFORM_PROFILE_LAST, GFP_KERNEL);

kcalloc() ?

> +	if (!galaxybook->profile_performance_modes)
> +		return -ENOMEM;
> +	for (int i = 0; i < PLATFORM_PROFILE_LAST; i++)
> +		galaxybook->profile_performance_modes[i] = PERFORMANCE_MODE_UNKNOWN;
> +
> +	/*
> +	 * Value returned in iob0 will have the number of supported performance modes.
> +	 * The performance mode values will then be given as a list after this (iob1-iobX).
> +	 * Loop backwards from last value to first value (to handle fallback cases which come with
> +	 * smaller values) and map each supported value to its correct platform_profile_option.
> +	 */
> +	err = -ENODEV; /* set err to "no device" to signal that we have not yet mapped profiles */
> +	for (int i = buf.iob0; i > 0; i--) {
> +		/*
> +		 * Prefer mapping to at least performance, balanced, and low-power profiles, as they
> +		 * are the profiles which are typically supported by userspace tools
> +		 * (power-profiles-daemon, etc).
> +		 * - performance = "ultra", otherwise "performance"
> +		 * - balanced    = "optimized", otherwise "performance" when "ultra" is supported
> +		 * - low-power   = "silent", otherwise "quiet"
> +		 * Different models support different modes. Additional supported modes will be
> +		 * mapped to profiles that fall in between these 3.
> +		 */
> +		switch (buf.iob_values[i]) {
> +
> +		case PERFORMANCE_MODE_ULTRA:
> +			/* ultra always maps to performance */
> +			mode_profile = PLATFORM_PROFILE_PERFORMANCE;
> +			break;
> +
> +		case PERFORMANCE_MODE_PERFORMANCE:
> +			/* if ultra exists, map performance to balanced-performance */
> +			if (galaxybook->profile_performance_modes[PLATFORM_PROFILE_PERFORMANCE] !=
> +			    PERFORMANCE_MODE_UNKNOWN)
> +				mode_profile = PLATFORM_PROFILE_BALANCED_PERFORMANCE;
> +			else /* otherwise map it to performance instead */
> +				mode_profile = PLATFORM_PROFILE_PERFORMANCE;
> +			break;
> +
> +		case PERFORMANCE_MODE_SILENT:
> +			/* silent always maps to low-power */
> +			mode_profile = PLATFORM_PROFILE_LOW_POWER;
> +			break;
> +
> +		case PERFORMANCE_MODE_QUIET:
> +			/* if silent exists, map quiet to quiet */
> +			if (galaxybook->profile_performance_modes[PLATFORM_PROFILE_LOW_POWER] !=
> +			    PERFORMANCE_MODE_UNKNOWN)
> +				mode_profile = PLATFORM_PROFILE_QUIET;
> +			else /* otherwise map it to low-power for better userspace tool support */
> +				mode_profile = PLATFORM_PROFILE_LOW_POWER;
> +			break;
> +
> +		case PERFORMANCE_MODE_OPTIMIZED:
> +			/* optimized always maps to balanced */
> +			mode_profile = PLATFORM_PROFILE_BALANCED;
> +			break;
> +
> +		case PERFORMANCE_MODE_PERFORMANCE_LEGACY:
> +			/* map to performance if performance is not already supported */
> +			if (galaxybook->profile_performance_modes[PLATFORM_PROFILE_PERFORMANCE] ==
> +			    PERFORMANCE_MODE_UNKNOWN)
> +				mode_profile = PLATFORM_PROFILE_PERFORMANCE;
> +			else /* otherwise, ignore */
> +				mode_profile = IGNORE_PERFORMANCE_MODE_MAPPING;
> +			break;
> +
> +		case PERFORMANCE_MODE_OPTIMIZED_LEGACY:
> +			/* map to balanced if balanced is not already supported */
> +			if (galaxybook->profile_performance_modes[PLATFORM_PROFILE_BALANCED] ==
> +			    PERFORMANCE_MODE_UNKNOWN)
> +				mode_profile = PLATFORM_PROFILE_BALANCED;
> +			else /* otherwise, ignore */
> +				mode_profile = IGNORE_PERFORMANCE_MODE_MAPPING;
> +			break;
> +
> +		default: /* any other value is not supported */
> +			mode_profile = IGNORE_PERFORMANCE_MODE_MAPPING;
> +			break;
> +		}
> +
> +		/* if current mode value mapped to a supported platform_profile_option, set it up */
> +		if (mode_profile > IGNORE_PERFORMANCE_MODE_MAPPING) {
> +			err = 0; /* clear err to signal that at least one profile is now mapped */
> +			galaxybook->profile_performance_modes[mode_profile] = buf.iob_values[i];
> +			set_bit(mode_profile, galaxybook->profile_handler.choices);
> +			pr_info("will support platform profile '%s' (performance mode 0x%x)\n",
> +				profile_names[mode_profile], buf.iob_values[i]);
> +		} else {
> +			pr_debug_prefixed("unmapped performance mode 0x%x will be ignored\n",
> +					  buf.iob_values[i]);
> +		}
> +	}
> +
> +	/* if no performance modes were mapped (err is still -ENODEV) then stop and fail here */
> +	if (err)
> +		return err;

It would be much more obvious to count number of mapped modes with a 
variable and not play with err variable like this. You needed lots of 
comment to explain which all could be dropped and this could just return 
-ENODEV directly.

I'll stop here as I'm out of time.

-- 
 i.

> +	err = platform_profile_register(&galaxybook->profile_handler);
> +	if (err)
> +		return err;
> +
> +	/* now check currently set performance mode; if not supported then set default profile */
> +	err = performance_mode_acpi_get(galaxybook, &current_performance_mode);
> +	if (err)
> +		pr_warn("failed with code %d when fetching initial performance mode\n", err);
> +	if (profile_performance_mode(galaxybook, current_performance_mode) == -1) {
> +		pr_debug_prefixed("initial performance mode value is not supported by device; "
> +				  "setting to default\n");
> +		err = galaxybook_platform_profile_set(&galaxybook->profile_handler,
> +						      DEFAULT_PLATFORM_PROFILE);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static void galaxybook_profile_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	platform_profile_remove();
> +}
> +
> +/*
> + * Hotkey work and filters
> + */
> +
> +static void galaxybook_performance_mode_hotkey_work(struct work_struct *work)
> +{
> +	platform_profile_cycle();
> +}
> +
> +static void galaxybook_kbd_backlight_hotkey_work(struct work_struct *work)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(work, struct samsung_galaxybook, kbd_backlight_hotkey_work);
> +
> +	if (galaxybook->kbd_backlight.brightness < galaxybook->kbd_backlight.max_brightness)
> +		kbd_backlight_acpi_set(galaxybook, galaxybook->kbd_backlight.brightness + 1);
> +	else
> +		kbd_backlight_acpi_set(galaxybook, 0);
> +
> +	led_classdev_notify_brightness_hw_changed(
> +		&galaxybook->kbd_backlight,
> +		galaxybook->kbd_backlight.brightness);
> +}
> +
> +static void galaxybook_allow_recording_hotkey_work(struct work_struct *work)
> +{
> +	struct samsung_galaxybook *galaxybook =
> +		container_of(work, struct samsung_galaxybook, allow_recording_hotkey_work);
> +	bool value;
> +
> +	allow_recording_acpi_get(galaxybook, &value);
> +	allow_recording_acpi_set(galaxybook, !value);
> +}
> +
> +static bool galaxybook_i8042_filter(unsigned char data, unsigned char str, struct serio *port)
> +{
> +	static bool extended;
> +
> +	if (str & I8042_STR_AUXDATA)
> +		return false;
> +
> +	if (unlikely(data == 0xe0)) {
> +		extended = true;
> +		return true;
> +	} else if (unlikely(extended)) {
> +		extended = false;
> +		switch (data) {
> +
> +		case GB_KEY_KBD_BACKLIGHT_KEYDOWN:
> +			return true;
> +		case GB_KEY_KBD_BACKLIGHT_KEYUP:
> +			if (kbd_backlight)
> +				schedule_work(&galaxybook_ptr->kbd_backlight_hotkey_work);
> +			return true;
> +
> +		case GB_KEY_ALLOW_RECORDING_KEYDOWN:
> +			return true;
> +		case GB_KEY_ALLOW_RECORDING_KEYUP:
> +			if (allow_recording)
> +				schedule_work(&galaxybook_ptr->allow_recording_hotkey_work);
> +			return true;
> +
> +		default:
> +			/*
> +			 * Report the previously filtered e0 before continuing
> +			 * with the next non-filtered byte.
> +			 */
> +			serio_interrupt(port, 0xe0, 0);
> +			return false;
> +		}
> +	}
> +
> +	return false;
> +}
> +
> +/*
> + * Input device (hotkeys and notifications)
> + */
> +
> +static void galaxybook_input_notify(struct samsung_galaxybook *galaxybook, int event)
> +{
> +	if (!galaxybook->input)
> +		return;
> +	pr_debug_prefixed("input notification event: 0x%x\n", event);
> +	if (!sparse_keymap_report_event(galaxybook->input, event, 1, true))
> +		pr_warn("unknown input notification event: 0x%x\n", event);
> +}
> +
> +static int galaxybook_input_init(struct samsung_galaxybook *galaxybook)
> +{
> +	struct input_dev *input;
> +	int error;
> +
> +	input = input_allocate_device();
> +	if (!input)
> +		return -ENOMEM;
> +
> +	input->name = "Samsung Galaxy Book Extra Buttons";
> +	input->phys = SAMSUNG_GALAXYBOOK_CLASS "/input0";
> +	input->id.bustype = BUS_HOST;
> +	input->dev.parent = &galaxybook->platform->dev;
> +
> +	error = sparse_keymap_setup(input, galaxybook_acpi_keymap, NULL);
> +	if (error) {
> +		pr_err("Unable to setup input device keymap\n");
> +		goto err_free_dev;
> +	}
> +	error = input_register_device(input);
> +	if (error) {
> +		pr_err("Unable to register input device\n");
> +		goto err_free_dev;
> +	}
> +
> +	galaxybook->input = input;
> +	return 0;
> +
> +err_free_dev:
> +	input_free_device(input);
> +	return error;
> +}
> +
> +static void galaxybook_input_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	if (galaxybook->input)
> +		input_unregister_device(galaxybook->input);
> +	galaxybook->input = NULL;
> +}
> +
> +/*
> + * Platform device attributes
> + */
> +
> +/* galaxybook_attrs can include start_on_lid_open, usb_charge, and/or allow_recording */
> +#define MAX_NUM_DEVICE_ATTRIBUTES 3
> +
> +static struct attribute *galaxybook_attrs[MAX_NUM_DEVICE_ATTRIBUTES + 1] = { NULL };
> +static const struct attribute_group galaxybook_attrs_group = {
> +	.attrs = galaxybook_attrs,
> +};
> +
> +static int galaxybook_device_attrs_init(struct samsung_galaxybook *galaxybook)
> +{
> +	bool value;
> +	int err;
> +	int i = 0;
> +
> +	/* attempt to get each attribute's value and add them if the get does not fail */
> +
> +	err = start_on_lid_open_acpi_get(galaxybook, &value);
> +	if (err)
> +		pr_debug_prefixed("failed to get start_on_lid_open value; "
> +				  "this feature will not be enabled\n");
> +	else
> +		galaxybook_attrs[i++] = &dev_attr_start_on_lid_open.attr;
> +
> +	err = usb_charge_acpi_get(galaxybook, &value);
> +	if (err)
> +		pr_debug_prefixed("failed to get usb_charge value; "
> +				  "this feature will not be enabled\n");
> +	else
> +		galaxybook_attrs[i++] = &dev_attr_usb_charge.attr;
> +
> +	if (allow_recording) {
> +		pr_debug_prefixed("initializing ACPI allow_recording feature\n");
> +		err = galaxybook_enable_acpi_feature(galaxybook, SASB_ALLOW_RECORDING);
> +		if (err) {
> +			pr_debug_prefixed("failed to initialize ACPI allow_recording feature\n");
> +			allow_recording = false;
> +			return 0;
> +		}
> +
> +		err = allow_recording_acpi_get(galaxybook, &value);
> +		if (err) {
> +			pr_debug_prefixed("failed to get allow_recording value; "
> +					  "this feature will not be enabled\n");
> +			allow_recording = false;
> +		} else {
> +			galaxybook_attrs[i++] = &dev_attr_allow_recording.attr;
> +		}
> +	}
> +
> +	return device_add_group(&galaxybook->platform->dev, &galaxybook_attrs_group);
> +};
> +
> +static void galaxybook_device_attrs_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	device_remove_group(&galaxybook->platform->dev, &galaxybook_attrs_group);
> +}
> +
> +/*
> + * ACPI device setup
> + */
> +
> +static void galaxybook_acpi_notify(acpi_handle handle, u32 event, void *data)
> +{
> +	struct samsung_galaxybook *galaxybook = data;
> +
> +	if (event == ACPI_NOTIFY_HOTKEY_PERFORMANCE_MODE) {
> +		pr_debug_prefixed("hotkey: performance_mode keydown\n");
> +		if (performance_mode) {
> +			schedule_work(&galaxybook->performance_mode_hotkey_work);
> +			return;
> +		}
> +	}
> +
> +	galaxybook_input_notify(galaxybook, event);
> +}
> +
> +static int galaxybook_enable_acpi_notify(struct samsung_galaxybook *galaxybook)
> +{
> +	struct sawb buf = { 0 };
> +	int err;
> +
> +	err = galaxybook_enable_acpi_feature(galaxybook, SASB_NOTIFICATIONS);
> +	if (err)
> +		return err;
> +
> +	buf.safn = SAFN;
> +	buf.sasb = SASB_NOTIFICATIONS;
> +	buf.gunm = GUNM_ACPI_NOTIFY_ENABLE;
> +	buf.guds[0] = GUDS_ACPI_NOTIFY_ENABLE;
> +
> +	return galaxybook_acpi_method(galaxybook, ACPI_METHOD_SETTINGS, &buf, SAWB_LEN_SETTINGS,
> +				      "activate ACPI notifications", &buf);
> +}
> +
> +static int galaxybook_acpi_init(struct samsung_galaxybook *galaxybook)
> +{
> +	return acpi_execute_simple_method(galaxybook->acpi->handle,
> +					  ACPI_METHOD_ENABLE, ACPI_METHOD_ENABLE_ON);
> +}
> +
> +static void galaxybook_acpi_exit(struct samsung_galaxybook *galaxybook)
> +{
> +	acpi_execute_simple_method(galaxybook->acpi->handle,
> +				   ACPI_METHOD_ENABLE, ACPI_METHOD_ENABLE_OFF);
> +}
> +
> +/*
> + * Platform driver
> + */
> +
> +static int galaxybook_probe(struct platform_device *pdev)
> +{
> +	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
> +	struct samsung_galaxybook *galaxybook;
> +	acpi_status status;
> +	int err;
> +
> +	dmi_check_system(galaxybook_dmi_ids);
> +
> +	pr_info("found matched device %s; loading driver\n", dev_name(&adev->dev));
> +
> +	galaxybook = kzalloc(sizeof(struct samsung_galaxybook), GFP_KERNEL);
> +	if (!galaxybook)
> +		return -ENOMEM;
> +	/* set static pointer here so it can be used in various methods for hotkeys, hwmon, etc */
> +	galaxybook_ptr = galaxybook;
> +
> +	galaxybook->platform = pdev;
> +	galaxybook->acpi = adev;
> +
> +	dev_set_drvdata(&galaxybook->platform->dev, galaxybook);
> +
> +	pr_debug_prefixed("initializing ACPI device\n");
> +	err = galaxybook_acpi_init(galaxybook);
> +	if (err) {
> +		pr_err("failed to initialize the ACPI device\n");
> +		goto err_free;
> +	}
> +
> +	pr_debug_prefixed("initializing ACPI power management features\n");
> +	err = galaxybook_enable_acpi_feature(galaxybook, SASB_POWER_MANAGEMENT);
> +	if (err) {
> +		pr_warn("failed to initialize ACPI power management features; "
> +			"many features of this driver will not be available\n");
> +		performance_mode = false;
> +		battery_threshold = false;
> +	}
> +
> +	if (performance_mode) {
> +		pr_debug_prefixed("initializing performance mode and platform profile\n");
> +		err = galaxybook_profile_init(galaxybook);
> +		if (err) {
> +			pr_debug_prefixed(
> +				"failed to initialize performance mode and platform profile\n");
> +			performance_mode = false;
> +		}
> +	} else {
> +		pr_debug_prefixed("performance_mode is disabled\n");
> +	}
> +
> +	if (battery_threshold) {
> +		pr_debug_prefixed("initializing battery charge threshold control\n");
> +		err = galaxybook_battery_threshold_init(galaxybook);
> +		if (err) {
> +			pr_debug_prefixed(
> +				"failed to initialize battery charge threshold control\n");
> +			battery_threshold = false;
> +		}
> +	} else {
> +		pr_debug_prefixed("battery_threshold is disabled\n");
> +	}
> +
> +	pr_debug_prefixed("adding platform device attributes\n");
> +	err = galaxybook_device_attrs_init(galaxybook);
> +	if (err)
> +		pr_err("failed to add platform device attributes\n");
> +
> +	if (kbd_backlight) {
> +		pr_debug_prefixed("initializing kbd_backlight\n");
> +		err = galaxybook_kbd_backlight_init(galaxybook);
> +		if (err) {
> +			pr_debug_prefixed("failed to initialize kbd_backlight\n");
> +			kbd_backlight = false;
> +		}
> +	} else {
> +		pr_debug_prefixed("kbd_backlight is disabled\n");
> +	}
> +
> +	if (fan_speed) {
> +		pr_debug_prefixed("initializing fan speed\n");
> +		err = galaxybook_fan_speed_init(galaxybook);
> +		if (err) {
> +			pr_debug_prefixed("failed to initialize fan speed\n");
> +			fan_speed = false;
> +		} else {
> +#if IS_ENABLED(CONFIG_HWMON)
> +			pr_debug_prefixed("initializing hwmon device\n");
> +			err = galaxybook_hwmon_init(galaxybook);
> +			if (err)
> +				pr_warn("failed to initialize hwmon device\n");
> +#endif
> +		}
> +	} else {
> +		pr_debug_prefixed("fan_speed is disabled\n");
> +	}
> +
> +	/* i8042_filter should be disabled if kbd_backlight and allow_recording are disabled */
> +	if (!kbd_backlight && !allow_recording)
> +		i8042_filter = false;
> +
> +	if (i8042_filter) {
> +		pr_debug_prefixed("installing i8402 key filter to capture hotkey input\n");
> +
> +		/* initialize hotkey work queues */
> +		if (kbd_backlight)
> +			INIT_WORK(&galaxybook->kbd_backlight_hotkey_work,
> +				  galaxybook_kbd_backlight_hotkey_work);
> +		if (allow_recording)
> +			INIT_WORK(&galaxybook->allow_recording_hotkey_work,
> +				  galaxybook_allow_recording_hotkey_work);
> +
> +		err = i8042_install_filter(galaxybook_i8042_filter);
> +		if (err) {
> +			pr_err("failed to install i8402 key filter\n");
> +			cancel_work_sync(&galaxybook->kbd_backlight_hotkey_work);
> +			cancel_work_sync(&galaxybook->allow_recording_hotkey_work);
> +			i8042_filter = false;
> +		}
> +	} else {
> +		pr_debug_prefixed("i8042_filter is disabled\n");
> +	}
> +
> +	pr_debug_prefixed("installing ACPI notify handler\n");
> +	status = acpi_install_notify_handler(galaxybook->acpi->handle, ACPI_ALL_NOTIFY,
> +					     galaxybook_acpi_notify, galaxybook);
> +	if (ACPI_SUCCESS(status)) {
> +		pr_debug_prefixed("enabling ACPI notifications\n");
> +		err = galaxybook_enable_acpi_notify(galaxybook);
> +		if (err) {
> +			pr_warn("failed to enable ACPI notifications; "
> +				"some hotkeys will not be supported\n");
> +		} else {
> +			/* initialize ACPI hotkey work queues */
> +			INIT_WORK(&galaxybook->performance_mode_hotkey_work,
> +				  galaxybook_performance_mode_hotkey_work);
> +
> +			pr_debug_prefixed("initializing input device\n");
> +			err = galaxybook_input_init(galaxybook);
> +			if (err) {
> +				pr_err("failed to initialize input device\n");
> +				cancel_work_sync(&galaxybook->performance_mode_hotkey_work);
> +				galaxybook_input_exit(galaxybook);
> +			}
> +		}
> +	} else {
> +		pr_debug_prefixed("failed to install ACPI notify handler\n");
> +	}
> +
> +	pr_info("driver successfully loaded\n");
> +
> +	return 0;
> +
> +err_free:
> +	kfree(galaxybook);
> +	return err;
> +}
> +
> +static void galaxybook_remove(struct platform_device *pdev)
> +{
> +	struct samsung_galaxybook *galaxybook = dev_get_drvdata(&pdev->dev);
> +
> +	pr_info("removing driver\n");
> +
> +	galaxybook_device_attrs_exit(galaxybook);
> +
> +	galaxybook_input_exit(galaxybook);
> +	cancel_work_sync(&galaxybook->performance_mode_hotkey_work);
> +
> +	if (i8042_filter) {
> +		i8042_remove_filter(galaxybook_i8042_filter);
> +		cancel_work_sync(&galaxybook->kbd_backlight_hotkey_work);
> +		cancel_work_sync(&galaxybook->allow_recording_hotkey_work);
> +	}
> +
> +	acpi_remove_notify_handler(galaxybook->acpi->handle, ACPI_ALL_NOTIFY,
> +				   galaxybook_acpi_notify);
> +
> +	if (fan_speed) {
> +		galaxybook_fan_speed_exit(galaxybook);
> +#if IS_ENABLED(CONFIG_HWMON)
> +		galaxybook_hwmon_exit(galaxybook);
> +#endif
> +	}
> +
> +	if (kbd_backlight)
> +		galaxybook_kbd_backlight_exit(galaxybook);
> +
> +	if (battery_threshold)
> +		galaxybook_battery_threshold_exit(galaxybook);
> +
> +	if (performance_mode)
> +		galaxybook_profile_exit(galaxybook);
> +
> +	galaxybook_acpi_exit(galaxybook);
> +
> +	if (galaxybook_ptr)
> +		galaxybook_ptr = NULL;
> +
> +	kfree(galaxybook);
> +
> +	pr_info("driver successfully removed\n");
> +}
> +
> +static struct platform_driver galaxybook_platform_driver = {
> +	.driver = {
> +		.name = SAMSUNG_GALAXYBOOK_CLASS,
> +		.acpi_match_table = galaxybook_device_ids,
> +	},
> +	.probe = galaxybook_probe,
> +	.remove = galaxybook_remove,
> +};
> +
> +static int __init samsung_galaxybook_init(void)
> +{
> +	return platform_driver_register(&galaxybook_platform_driver);
> +}
> +
> +static void __exit samsung_galaxybook_exit(void)
> +{
> +	platform_driver_unregister(&galaxybook_platform_driver);
> +}
> +
> +module_init(samsung_galaxybook_init);
> +module_exit(samsung_galaxybook_exit);
> +
> +MODULE_AUTHOR("Joshua Grisham <josh@xxxxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION(SAMSUNG_GALAXYBOOK_NAME);
> +MODULE_LICENSE("GPL");
>