[PATCH] platform/x86: thinkpad-acpi: Add X1 Fold keyboard attachment detection
From: Pit Henrich
Date: Sat Mar 14 2026 - 10:22:54 EST
ThinkPad X1 Fold 16 Gen 1 firmware reports whether the keyboard is magnetically
attached (on the screen) via EC register 0xc1 bit 7, but thinkpad-acpi does
not expose this to userspace.
Add a read-only keyboard_attached_on_screen sysfs attribute, gated by
a DMI match. The state is read directly from the EC.
Cache the state and emit a sysfs notification on
TP_HKEY_EV_TABLET_CHANGED (0x60c0) when it changes. Initialize the cache during
hotkey setup and refresh it before the resume notification to keep the state
consistent across suspend and resume.
Signed-off-by: Pit Henrich <pithenrich2d@xxxxxxxxx>
---
drivers/platform/x86/lenovo/thinkpad_acpi.c | 92 ++++++++++++++++++++-
1 file changed, 90 insertions(+), 2 deletions(-)
diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c
index 8982d92dfd97..5b255062ff51 100644
--- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
+++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
@@ -218,8 +218,9 @@ enum tpacpi_hkey_event_t {
TP_HKEY_EV_LID_OPEN = 0x5002, /* laptop lid opened */
TP_HKEY_EV_TABLET_TABLET = 0x5009, /* tablet swivel up */
TP_HKEY_EV_TABLET_NOTEBOOK = 0x500a, /* tablet swivel down */
- TP_HKEY_EV_TABLET_CHANGED = 0x60c0, /* X1 Yoga (2016):
- * enter/leave tablet mode
+ TP_HKEY_EV_TABLET_CHANGED = 0x60c0, /* posture change event:
+ * X1 Yoga (2016): enter/leave tablet mode
+ * X1 Fold 16 Gen 1: keyboard attachment state changed
*/
TP_HKEY_EV_PEN_INSERTED = 0x500b, /* tablet pen inserted */
TP_HKEY_EV_PEN_REMOVED = 0x500c, /* tablet pen removed */
@@ -375,6 +376,7 @@ static struct {
u32 has_adaptive_kbd:1;
u32 kbd_lang:1;
u32 trackpoint_doubletap:1;
+ u32 has_keyboard_attached_on_screen:1;
struct quirk_entry *quirks;
} tp_features;
@@ -2928,6 +2930,70 @@ static void hotkey_tablet_mode_notify_change(void)
"hotkey_tablet_mode");
}
+/*
+ * On the ThinkPad X1 Fold 16 Gen 1, EC register 0xc1 reports the keyboard
+ * attachment state in bit 7.
+ */
+#define TPACPI_X1_FOLD_KBD_EC_STATUS 0xc1
+#define TPACPI_X1_FOLD_KBD_ATTACHED BIT(7)
+
+static bool keyboard_attached_on_screen;
+static bool keyboard_attached_on_screen_initialized;
+
+static int x1_fold_keyboard_attached_on_screen_get(bool *attached)
+{
+ u8 status;
+
+ if (!tp_features.has_keyboard_attached_on_screen)
+ return -ENODEV;
+
+ if (!acpi_ec_read(TPACPI_X1_FOLD_KBD_EC_STATUS, &status))
+ return -EIO;
+
+ *attached = status & TPACPI_X1_FOLD_KBD_ATTACHED;
+ return 0;
+}
+
+static ssize_t keyboard_attached_on_screen_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ bool attached;
+ int res;
+
+ res = x1_fold_keyboard_attached_on_screen_get(&attached);
+ if (res)
+ return res;
+
+ return sysfs_emit(buf, "%d\n", attached);
+}
+
+static DEVICE_ATTR_RO(keyboard_attached_on_screen);
+
+static void keyboard_attached_on_screen_notify_change(void)
+{
+ if (tp_features.has_keyboard_attached_on_screen)
+ sysfs_notify(&tpacpi_pdev->dev.kobj, NULL,
+ "keyboard_attached_on_screen");
+}
+
+static bool keyboard_attached_on_screen_update(void)
+{
+ bool attached;
+
+ if (x1_fold_keyboard_attached_on_screen_get(&attached))
+ return false;
+
+ if (keyboard_attached_on_screen_initialized &&
+ keyboard_attached_on_screen == attached)
+ return false;
+
+ keyboard_attached_on_screen = attached;
+ keyboard_attached_on_screen_initialized = true;
+
+ return true;
+}
+
/* sysfs wakeup reason (pollable) -------------------------------------- */
static ssize_t hotkey_wakeup_reason_show(struct device *dev,
struct device_attribute *attr,
@@ -3032,6 +3098,7 @@ static struct attribute *hotkey_attributes[] = {
&dev_attr_hotkey_adaptive_all_mask.attr,
&dev_attr_hotkey_recommended_mask.attr,
&dev_attr_hotkey_tablet_mode.attr,
+ &dev_attr_keyboard_attached_on_screen.attr,
&dev_attr_hotkey_radio_sw.attr,
#ifdef CONFIG_THINKPAD_ACPI_HOTKEY_POLL
&dev_attr_hotkey_source_mask.attr,
@@ -3046,6 +3113,9 @@ static umode_t hotkey_attr_is_visible(struct kobject *kobj,
if (attr == &dev_attr_hotkey_tablet_mode.attr) {
if (!tp_features.hotkey_tablet)
return 0;
+ } else if (attr == &dev_attr_keyboard_attached_on_screen.attr) {
+ if (!tp_features.has_keyboard_attached_on_screen)
+ return 0;
} else if (attr == &dev_attr_hotkey_radio_sw.attr) {
if (!tp_features.hotkey_wlsw)
return 0;
@@ -3462,6 +3532,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
}
tabletsw_state = hotkey_init_tablet_mode();
+ keyboard_attached_on_screen_update();
/* Set up key map */
keymap_id = tpacpi_check_quirks(tpacpi_keymap_qtable,
@@ -3842,6 +3913,8 @@ static bool hotkey_notify_6xxx(const u32 hkey, bool *send_acpi_ev)
case TP_HKEY_EV_TABLET_CHANGED:
tpacpi_input_send_tabletsw();
hotkey_tablet_mode_notify_change();
+ if (keyboard_attached_on_screen_update())
+ keyboard_attached_on_screen_notify_change();
*send_acpi_ev = false;
return true;
@@ -3998,6 +4071,8 @@ static void hotkey_resume(void)
tpacpi_send_radiosw_update();
tpacpi_input_send_tabletsw();
hotkey_tablet_mode_notify_change();
+ keyboard_attached_on_screen_update();
+ keyboard_attached_on_screen_notify_change();
hotkey_wakeup_reason_notify_change();
hotkey_wakeup_hotunplug_complete_notify_change();
hotkey_poll_setup_safe(false);
@@ -4296,6 +4371,17 @@ static const struct dmi_system_id fwbug_list[] __initconst = {
{}
};
+static const struct dmi_system_id keyboard_attached_on_screen_list[] __initconst = {
+ {
+ .ident = "ThinkPad X1 Fold 16 Gen 1",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+ DMI_MATCH(DMI_PRODUCT_FAMILY, "ThinkPad X1 Fold 16 Gen 1"),
+ },
+ },
+ {}
+};
+
static const struct pci_device_id fwbug_cards_ids[] __initconst = {
{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x24F3) },
{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x24FD) },
@@ -12230,6 +12316,8 @@ static int __init thinkpad_acpi_module_init(void)
dmi_id = dmi_first_match(fwbug_list);
if (dmi_id)
tp_features.quirks = dmi_id->driver_data;
+ tp_features.has_keyboard_attached_on_screen =
+ dmi_check_system(keyboard_attached_on_screen_list);
/* Device initialization */
tpacpi_pdev = platform_device_register_simple(TPACPI_DRVR_NAME, PLATFORM_DEVID_NONE,
--
2.43.0