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Thu, 21 May 2026 07:40:40 -0700 (PDT) Received: from fedora ([2600:382:9e2f:545e:1025:cba1:a424:4218]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8cc781b37a8sm6387266d6.24.2026.05.21.07.40.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2026 07:40:40 -0700 (PDT) From: Dave Carey To: platform-driver-x86@vger.kernel.org Cc: ilpo.jarvinen@linux.intel.com, carvsdriver@gmail.com Subject: [PATCH v4] platform/x86/lenovo: Add Yoga Book 9 keyboard dock detection driver Date: Thu, 21 May 2026 10:40:34 -0400 Message-ID: <20260521144034.282419-1-carvsdriver@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260519000239.29446-1-carvsdriver@gmail.com> References: <20260519000239.29446-1-carvsdriver@gmail.com> Precedence: bulk X-Mailing-List: platform-driver-x86@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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). The current BKBD state is read via WMI query GUID E7F300FA-21CD-4003-ADAC-2696135982E6 (WQAF method), which returns an 8-byte buffer: bytes [0..3] hold the LFID constant 0x00060000 and bytes [4..7] hold the BKBD value. 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 as a WMI driver on the event GUID. - Queries BKBD state on probe and on each WMI notification. - Reports SW_TABLET_MODE=1 when detached, SW_TABLET_MODE=0 when docked in either position (a physical keyboard is present in both cases). - Exposes the raw BKBD value via a read-only sysfs attribute "keyboard_position" for use by userspace (e.g. to distinguish between the two docked positions for different UI layouts). Tested on: Lenovo Yoga Book 9 14IAH10 (model 83KJ), kernel 6.19. Signed-off-by: Dave Carey --- .../testing/sysfs-driver-lenovo-yb9-kbdock | 21 ++ MAINTAINERS | 7 + drivers/platform/x86/lenovo/Kconfig | 14 ++ drivers/platform/x86/lenovo/Makefile | 1 + drivers/platform/x86/lenovo/yb9-kbdock.c | 216 ++++++++++++++++++ 5 files changed, 259 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..bb57690 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-lenovo-yb9-kbdock @@ -0,0 +1,21 @@ +What: /sys/bus/wmi/drivers/lenovo-yb9-kbdock//keyboard_position +Date: April 2026 +KernelVersion: 6.10 +Contact: Dave Carey +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 detached — keyboard is not docked to any screen + 1 top-half — keyboard docked on the top half of the bottom screen + 2 bottom-half — keyboard docked on the bottom half of the bottom screen + == ============================================================ + + The value is formatted as " ()\n", e.g. "1 (top-half)\n". + + 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 +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 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..693e287 --- /dev/null +++ b/drivers/platform/x86/lenovo/yb9-kbdock.c @@ -0,0 +1,216 @@ +// 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. + * + * 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 + * + * This driver registers for the WMI event GUID, queries BKBD on probe and on + * each event, reports SW_TABLET_MODE=0 when the keyboard is docked (either + * position) and SW_TABLET_MODE=1 when detached, and exposes the raw BKBD + * value in sysfs as "keyboard_position". + * + * Copyright (C) 2026 Dave Carey + */ + +#include +#include +#include +#include +#include + +/* + * WM10 ACPI device (_UID "GMZN"): + * Event GUID — notify ID 0xEB fires on keyboard attachment change. + * Query GUID — object "AF", maps to WQAF(); returns 8-byte buffer + * {LFID=0x00060000, BKBD[31:0]}. + */ +#define YB9_KBDOCK_EVENT_GUID "806BD2A2-177B-481D-BFB5-3BA0BB4A2285" +#define YB9_KBDOCK_QUERY_GUID "E7F300FA-21CD-4003-ADAC-2696135982E6" + +#define YB9_KBDOCK_QUERY_INSTANCE 0 + +/* BKBD encoding — keyboard always docks on the bottom screen */ +#define BKBD_DETACHED 0 +#define BKBD_TOP_HALF 1 /* docked on top half of bottom screen */ +#define BKBD_BOTTOM_HALF 2 /* docked on bottom half of bottom screen */ + +static const struct dmi_system_id yb9_kbdock_dmi_table[] = { + { + /* Lenovo Yoga Book 9 14IAH10 */ + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"), + DMI_MATCH(DMI_PRODUCT_NAME, "83KJ"), + }, + }, + { } +}; + +struct yb9_kbdock_priv { + struct input_dev *input_dev; + unsigned int bkbd; /* last read BKBD value (0-3) */ +}; + +/* Read current BKBD state via WQAF. Returns 0-3 or -errno. */ +static int yb9_kbdock_query(struct wmi_device *wdev) +{ + struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL }; + union acpi_object *obj; + acpi_status status; + u32 bkbd; + + status = wmi_query_block(YB9_KBDOCK_QUERY_GUID, + YB9_KBDOCK_QUERY_INSTANCE, &out); + if (ACPI_FAILURE(status)) { + dev_warn(&wdev->dev, "WQAF query failed: %s\n", + acpi_format_exception(status)); + return -EIO; + } + + obj = out.pointer; + if (!obj) { + dev_warn(&wdev->dev, "WQAF returned NULL\n"); + return -EIO; + } + + /* + * WQAF returns an 8-byte buffer: bytes [0..3] = LFID (0x00060000), + * bytes [4..7] = BKBD value. Guard against short buffers. + */ + if (obj->type == ACPI_TYPE_BUFFER && obj->buffer.length >= 8) { + memcpy(&bkbd, obj->buffer.pointer + 4, sizeof(bkbd)); + bkbd &= 0x3; + } else if (obj->type == ACPI_TYPE_INTEGER) { + bkbd = obj->integer.value & 0x3; + } else { + dev_warn(&wdev->dev, + "WQAF: unexpected result type %d len %u\n", + obj->type, + obj->type == ACPI_TYPE_BUFFER + ? obj->buffer.length : 0); + kfree(obj); + return -EIO; + } + + kfree(obj); + return (int)bkbd; +} + +static void yb9_kbdock_update(struct wmi_device *wdev) +{ + struct yb9_kbdock_priv *priv = dev_get_drvdata(&wdev->dev); + int bkbd; + int tablet_mode; + + bkbd = yb9_kbdock_query(wdev); + if (bkbd < 0) + return; + + priv->bkbd = bkbd; + + /* + * Report tablet mode only when the keyboard is fully detached. + * Both docked positions (top-half and bottom-half of the bottom screen) + * indicate a physical keyboard is present — report laptop mode. + */ + tablet_mode = (bkbd == BKBD_DETACHED) ? 1 : 0; + + input_report_switch(priv->input_dev, SW_TABLET_MODE, tablet_mode); + input_sync(priv->input_dev); + + dev_dbg(&wdev->dev, "BKBD=%u tablet_mode=%d\n", bkbd, tablet_mode); +} + +static void yb9_kbdock_notify(struct wmi_device *wdev, union acpi_object *data) +{ + yb9_kbdock_update(wdev); +} + +/* sysfs: keyboard_position — exposes raw BKBD value */ +static ssize_t keyboard_position_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct yb9_kbdock_priv *priv = dev_get_drvdata(dev); + static const char * const names[] = { + "detached", "top-half", "bottom-half", "unknown" + }; + unsigned int bkbd = priv->bkbd; + + if (bkbd > 3) + bkbd = 3; + return sysfs_emit(buf, "%u (%s)\n", bkbd, names[bkbd]); +} +static DEVICE_ATTR_RO(keyboard_position); + +static struct attribute *yb9_kbdock_attrs[] = { + &dev_attr_keyboard_position.attr, + NULL, +}; +ATTRIBUTE_GROUPS(yb9_kbdock); + +static int yb9_kbdock_probe(struct wmi_device *wdev, const void *ctx) +{ + struct yb9_kbdock_priv *priv; + struct input_dev *input_dev; + int err; + + if (!dmi_check_system(yb9_kbdock_dmi_table)) { + dev_dbg(&wdev->dev, "not a Yoga Book 9, skipping\n"); + return -ENODEV; + } + + priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + input_dev = devm_input_allocate_device(&wdev->dev); + if (!input_dev) + return -ENOMEM; + + input_dev->name = "Lenovo Yoga Book 9 keyboard dock switch"; + input_dev->phys = YB9_KBDOCK_EVENT_GUID "/input0"; + input_dev->id.bustype = BUS_HOST; + input_set_capability(input_dev, EV_SW, SW_TABLET_MODE); + + err = input_register_device(input_dev); + if (err) { + dev_err(&wdev->dev, "failed to register input device: %d\n", err); + return err; + } + + priv->input_dev = input_dev; + dev_set_drvdata(&wdev->dev, priv); + + /* Report initial state */ + yb9_kbdock_update(wdev); + return 0; +} + +static const struct wmi_device_id yb9_kbdock_wmi_id_table[] = { + { .guid_string = YB9_KBDOCK_EVENT_GUID }, + { } +}; +MODULE_DEVICE_TABLE(wmi, yb9_kbdock_wmi_id_table); + +static struct wmi_driver yb9_kbdock_driver = { + .driver = { + .name = "lenovo-yb9-kbdock", + .dev_groups = yb9_kbdock_groups, + }, + .id_table = yb9_kbdock_wmi_id_table, + .probe = yb9_kbdock_probe, + .notify = yb9_kbdock_notify, +}; +module_wmi_driver(yb9_kbdock_driver); + +MODULE_AUTHOR("Dave Carey "); +MODULE_DESCRIPTION("Lenovo Yoga Book 9 keyboard dock detection"); +MODULE_LICENSE("GPL"); -- 2.54.0