Re: [PATCH v13 2/2] platform/x86/lenovo: Add Yoga Book 9 keyboard dock detection driver

[Dave Carey <carvsdriver@gmail.com>]

Ugh ... let me check, was trying to do a few different things today at 
the same time.  Appreciate the patience.


-DC


On 7/22/26 10:42 AM, Ilpo Järvinen wrote:
> On Wed, 22 Jul 2026, Dave Carey wrote:
>
>> The Lenovo Yoga Book 9 14IAH10 ships with a detachable Bluetooth keyboard
>> that magnetically attaches to the bottom (secondary) screen in one of two
>> positions.  The Embedded Controller tracks the attachment state in a 2-bit
>> field called BKBD and signals changes via WMI event GUID
>> 806BD2A2-177B-481D-BFB5-3BA0BB4A2285 (notify ID 0xEB on the WM10 ACPI
>> device, _UID "GMZN").
>>
>> The device contains embedded BMOF data (WQDD, 20705 bytes) documenting
>> both WMI interfaces used by this driver:
>>
>>    LENOVO_BTKBD_EVENT (event GUID): WmiDataId(1) uint32 Status.
>>    The ACPI _WED(0xEB) method returns EC.BKBD directly as an integer,
>>    so the notify callback receives BKBD without a separate query.
>>
>>    LENOVO_FEATURE_STATUS_DATA (block GUID, WQAF method): returns an
>>    8-byte buffer {uint32 IDs=0x00060000, uint32 Status=BKBD}.
>>    Used for the initial state read on probe and after resume.
>>
>> BKBD encoding:
>>    0 = keyboard detached
>>    1 = keyboard docked on top half of bottom screen
>>    2 = keyboard docked on bottom half of bottom screen
>>    3 = reserved (not observed in practice)
>>
>> This driver registers two WMI drivers sharing a module-level
>> BLOCKING_NOTIFIER_HEAD:
>>
>>    - The event driver (LENOVO_BTKBD_EVENT) uses .notify_new() to receive
>>      a pre-parsed wmi_buffer and fires the notifier chain with the BKBD
>>      value extracted from the buffer.
>>
>>    - The block driver (LENOVO_FEATURE_STATUS_DATA) owns the input_dev in
>>      its per-device private struct.  At probe time it registers a
>>      notifier_block on the chain and reads the initial BKBD state via
>>      wmidev_query_block().  The WMI buffer is parsed as
>>      struct lenovo_feature_status { __le32 id; __le32 status; }, and the
>>      ID field is verified before the status is used.
>>
>>    - SW_TABLET_MODE=1 is reported when the keyboard is detached;
>>      SW_TABLET_MODE=0 when docked in either position (keyboard present).
>>
>>    - The raw BKBD value is exposed via read-only sysfs attribute
>>      "keyboard_position".
>>
>>    - BKBD state is re-read via wmidev_query_block() on resume from
>>      suspend or hibernation.
>>
>> Tested on: Lenovo Yoga Book 9 14IAH10 (model 83KJ), kernel 7.0.
>>
>> Acked-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
>> Reviewed-by: Armin Wolf <W_Armin@gmx.de>
>> Signed-off-by: Dave Carey <carvsdriver@gmail.com>
>> ---
>> v13:
>> - Resend of v12: patch was corrupted in transit.  git-send-email chose
>>    quoted-printable encoding (triggered by non-ASCII in the changelog)
>>    which encoded '=' as '=3D', corrupting the RST table separators in
>>    the ABI doc and breaking git-am.  No content changes from v12.
>>
>> v12:
>> - Add #include <linux/sysfs.h> (for sysfs_emit; Ilpo Järvinen)
>> - Add #include <linux/types.h> (for __le32 and __packed; Ilpo Järvinen)
>>
>> v11 (addressing Armin Wolf's v10 review):
>> - ABI doc: correct Date to "June 2027" and KernelVersion to "7.3"
>>
>> v10 (addressing Armin Wolf's v9 review):
>> - Update ABI doc: Date: June 2026, KernelVersion: 6.16
>> - Add #include <linux/compiler_attributes.h> and <linux/types.h>
>> - yb9_kbdock_query(): change return to pointer-out u32 *bkbd
>> - struct yb9_kbdock_data: add spinlock_t lock
>> - yb9_kbdock_report(): hold lock across input_report_switch + input_sync
>> - yb9_kbdock_sync(): return int, propagate query error to callers
>> - yb9_kbdock_resume(), yb9_kbdock_block_probe(): propagate sync error
>> - struct wmi_buffer out: remove zero-initializer
>> - yb9_kbdock_notify_new(): drop manual length check; use
>>    .min_event_size = sizeof(__le32) in struct wmi_driver instead
>>
>>   .../testing/sysfs-driver-lenovo-yb9-kbdock    |  19 ++
>>   MAINTAINERS                                   |   7 +
>>   drivers/platform/x86/lenovo/Kconfig           |  14 +
>>   drivers/platform/x86/lenovo/Makefile          |   1 +
>>   drivers/platform/x86/lenovo/yb9-kbdock.c      | 312 ++++++++++++++++++
>>   5 files changed, 353 insertions(+)
>>   create mode 100644 Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock
>>   create mode 100644 drivers/platform/x86/lenovo/yb9-kbdock.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock b/Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock
>> new file mode 100644
>> index 0000000..ebe713a
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock
>> @@ -0,0 +1,19 @@
>> +What:		/sys/bus/wmi/drivers/lenovo-yb9-kbdock/<guid>/keyboard_position
>> +Date:		June 2027
>> +KernelVersion:	7.3
>> +Contact:	Dave Carey <carvsdriver@gmail.com>
>> +Description:
>> +		Read-only attribute reporting the current keyboard dock position
>> +		as reported by the Embedded Controller on the Lenovo Yoga Book 9
>> +		14IAH10.
>> +
>> +		Possible values:
>> +
>> +		==  =============================================================
>> +		0   keyboard is not docked to any screen (detached)
>> +		1   keyboard docked on the top half of the bottom screen
>> +		2   keyboard docked on the bottom half of the bottom screen
>> +		==  =============================================================
>> +
>> +		SW_TABLET_MODE input events are also emitted: 0 when the keyboard
>> +		is docked (either position), 1 when detached.
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index d1cc0e1..00e8275 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -14479,6 +14479,13 @@ L:	platform-driver-x86@vger.kernel.org
>>   S:	Maintained
>>   F:	drivers/platform/x86/lenovo/wmi-hotkey-utilities.c
>>   
>> +LENOVO YOGA BOOK 9 KEYBOARD DOCK DRIVER
>> +M:	Dave Carey <carvsdriver@gmail.com>
>> +L:	platform-driver-x86@vger.kernel.org
>> +S:	Maintained
>> +F:	Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock
>> +F:	drivers/platform/x86/lenovo/yb9-kbdock.c
>> +
>>   LETSKETCH HID TABLET DRIVER
>>   M:	Hans de Goede <hansg@kernel.org>
>>   L:	linux-input@vger.kernel.org
>> diff --git a/drivers/platform/x86/lenovo/Kconfig b/drivers/platform/x86/lenovo/Kconfig
>> index 9c48487..938b361 100644
>> --- a/drivers/platform/x86/lenovo/Kconfig
>> +++ b/drivers/platform/x86/lenovo/Kconfig
>> @@ -43,6 +43,20 @@ config LENOVO_WMI_CAMERA
>>   	  To compile this driver as a module, choose M here: the module
>>   	  will be called lenovo-wmi-camera.
>>   
>> +config LENOVO_YB9_KBDOCK
>> +	tristate "Lenovo Yoga Book 9 keyboard dock detection"
>> +	depends on ACPI_WMI
>> +	depends on DMI
>> +	depends on INPUT
>> +	help
>> +	  Say Y here to enable keyboard dock detection on the Lenovo Yoga Book 9
>> +	  14IAH10.  The detachable Bluetooth keyboard magnetically attaches to
>> +	  either screen; this driver reports SW_TABLET_MODE input events based
>> +	  on the attachment state and exposes the raw position in sysfs.
>> +
>> +	  To compile this driver as a module, choose M here: the module will be
>> +	  called lenovo-yb9-kbdock.
>> +
>>   config LENOVO_YMC
>>   	tristate "Lenovo Yoga Tablet Mode Control"
>>   	depends on ACPI_WMI
>> diff --git a/drivers/platform/x86/lenovo/Makefile b/drivers/platform/x86/lenovo/Makefile
>> index 7b2128e..2842d7d 100644
>> --- a/drivers/platform/x86/lenovo/Makefile
>> +++ b/drivers/platform/x86/lenovo/Makefile
>> @@ -8,6 +8,7 @@ obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
>>   obj-$(CONFIG_THINKPAD_ACPI)	+= thinkpad_acpi.o
>>   
>>   lenovo-target-$(CONFIG_LENOVO_WMI_HOTKEY_UTILITIES)	+= wmi-hotkey-utilities.o
>> +lenovo-target-$(CONFIG_LENOVO_YB9_KBDOCK)	+= yb9-kbdock.o
>>   lenovo-target-$(CONFIG_LENOVO_YMC)	+= ymc.o
>>   lenovo-target-$(CONFIG_YOGABOOK)	+= yogabook.o
>>   lenovo-target-$(CONFIG_YT2_1380)	+= yoga-tab2-pro-1380-fastcharger.o
>> diff --git a/drivers/platform/x86/lenovo/yb9-kbdock.c b/drivers/platform/x86/lenovo/yb9-kbdock.c
>> new file mode 100644
>> index 0000000..69c68a0
>> --- /dev/null
>> +++ b/drivers/platform/x86/lenovo/yb9-kbdock.c
>> @@ -0,0 +1,312 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Lenovo Yoga Book 9 keyboard-dock detection
>> + *
>> + * The Yoga Book 9 ships with a detachable Bluetooth keyboard that magnetically
>> + * attaches to the bottom screen in one of two positions.  The EC tracks
>> + * attachment state in a 2-bit field called BKBD and signals changes via WMI
>> + * event 0xEB on the WM10 ACPI device (_UID "GMZN").
>> + *
>> + * BKBD values:
>> + *   0 = keyboard detached
>> + *   1 = keyboard docked on the top half of the bottom screen
>> + *   2 = keyboard docked on the bottom half of the bottom screen
>> + *   3 = reserved / not observed
>> + *
>> + * Two WMI interfaces are used (documented in embedded BMOF, WQDD, 20705 bytes):
>> + *
>> + *   LENOVO_BTKBD_EVENT (event GUID, 806BD2A2-...)
>> + *     WmiDataId(1) uint32 Status — _WED(0xEB) returns EC.BKBD directly.
>> + *     The notify callback receives BKBD as an integer; no separate query needed.
>> + *
>> + *   LENOVO_FEATURE_STATUS_DATA (block GUID, E7F300FA-...)
>> + *     WmiDataId(1) uint32 IDs   = 0x00060000 (feature selector)
>> + *     WmiDataId(2) uint32 Status = BKBD value
>> + *     Used on probe and resume to read initial state.
>> + *
>> + * The event driver (LENOVO_BTKBD_EVENT) fires a notifier chain on each WMI
>> + * event.  The block driver (LENOVO_FEATURE_STATUS_DATA) owns the input_dev
>> + * and registers a notifier_block to receive those events, eliminating the
>> + * need for shared global state or a mutex.
>> + *
>> + * SW_TABLET_MODE=1 is reported when the keyboard is detached;
>> + * SW_TABLET_MODE=0 when docked in either position (keyboard present).
>> + * The raw BKBD value is exposed via the sysfs attribute "keyboard_position".
>> + *
>> + * Copyright (C) 2026 Dave Carey <carvsdriver@gmail.com>
>> + */
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/cleanup.h>
>> +#include <linux/dev_printk.h>
>> +#include <linux/dmi.h>
>> +#include <linux/input.h>
>> +#include <linux/module.h>
>> +#include <linux/notifier.h>
>> +#include <linux/pm.h>
>> +#include <linux/slab.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/types.h>
>> +#include <linux/wmi.h>
> Hi,
>
> Are you sure you sent the latest version, AFAICT, v12 had this:
>
> +#include <linux/acpi.h>
> +#include <linux/cleanup.h>
> +#include <linux/compiler_attributes.h>
> +#include <linux/dev_printk.h>
> ...
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +#include <linux/wmi.h>
>
> ?
>