[PATCH] platform/x86: ideapad-laptop: do not poke keyboard controller

On Ideapad Z570 the driver tries to disable and re-enable data coming
from the touchpad by poking directly into 8042 keyboard controller.
This may coincide with the controller resuming and leads to spews in
dmesg and potentially other instabilities.

Instead of using i8042_command() to control the touchpad state create
an input handler that serves as a filter and drop events coming from
the touchpad when it is supposed to be off.

Signed-off-by: Dmitry Torokhov <[email protected]>
---

Spring^WFall patch queue cleaning. The concept of this patch was
discussed in August 2024 but I neglected to send the final version
of the patch:

https://lore.kernel.org/r/[email protected]/

 drivers/platform/x86/lenovo/ideapad-laptop.c | 171 ++++++++++++++++++-
 1 file changed, 168 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c
index 4fbc904f1fc3..384faa511120 100644
--- a/drivers/platform/x86/lenovo/ideapad-laptop.c
+++ b/drivers/platform/x86/lenovo/ideapad-laptop.c
@@ -18,7 +18,6 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/dmi.h>
-#include <linux/i8042.h>
 #include <linux/init.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
@@ -210,6 +209,13 @@ struct ideapad_private {
 		struct led_classdev led;
 		unsigned int last_brightness;
 	} fn_lock;
+	struct {
+		bool initialized;
+		bool active;
+		struct input_handler handler;
+		struct input_dev *tp_dev;
+		spinlock_t lock;
+	} tp_switch;
 };
 
 static bool no_bt_rfkill;
@@ -1462,6 +1468,158 @@ static void ideapad_check_special_buttons(struct ideapad_private *priv)
 	}
 }
 
+struct ideapad_tpswitch_handle {
+	struct input_handle handle;
+	struct ideapad_private *priv;
+};
+
+#define to_tpswitch_handle(h) \
+	container_of(h, struct ideapad_tpswitch_handle, handle);
+
+static int ideapad_tpswitch_connect(struct input_handler *handler,
+				    struct input_dev *dev,
+				    const struct input_device_id *id)
+{
+	struct ideapad_private *priv =
+		container_of(handler, struct ideapad_private, tp_switch.handler);
+	struct ideapad_tpswitch_handle *h;
+	int error;
+
+	h = kzalloc_obj(*h);
+	if (!h)
+		return -ENOMEM;
+
+	h->priv = priv;
+	h->handle.dev = dev;
+	h->handle.handler = handler;
+	h->handle.name = "ideapad-tpswitch";
+
+	error = input_register_handle(&h->handle);
+	if (error)
+		goto err_free_handle;
+
+	/*
+	 * FIXME: ideally we do not want to open the input device here
+	 * if there are no other users. We need a notion of "observer"
+	 * handlers in the input core.
+	 */
+	error = input_open_device(&h->handle);
+	if (error)
+		goto err_unregister_handle;
+
+	scoped_guard(spinlock_irq, &priv->tp_switch.lock)
+		priv->tp_switch.tp_dev = dev;
+
+	return 0;
+
+err_unregister_handle:
+	input_unregister_handle(&h->handle);
+err_free_handle:
+	kfree(h);
+	return error;
+}
+
+static void ideapad_tpswitch_disconnect(struct input_handle *handle)
+{
+	struct ideapad_tpswitch_handle *h = to_tpswitch_handle(handle);
+	struct ideapad_private *priv = h->priv;
+
+	scoped_guard(spinlock_irq, &priv->tp_switch.lock)
+		priv->tp_switch.tp_dev = NULL;
+
+	input_close_device(handle);
+	input_unregister_handle(handle);
+	kfree(h);
+}
+
+static bool ideapad_tpswitch_filter(struct input_handle *handle,
+				    unsigned int type, unsigned int code,
+				    int value)
+{
+	struct ideapad_tpswitch_handle *h = to_tpswitch_handle(handle);
+	struct ideapad_private *priv = h->priv;
+
+	if (!priv->tp_switch.active)
+		return false;
+
+	/* Allow passing button release events, drop everything else */
+	return !(type == EV_KEY && value == 0) &&
+	       !(type == EV_SYN && code == SYN_REPORT);
+
+}
+
+static const struct input_device_id ideapad_tpswitch_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
+				INPUT_DEVICE_ID_MATCH_KEYBIT |
+				INPUT_DEVICE_ID_MATCH_ABSBIT,
+		.bustype = BUS_I8042,
+		.vendor = 0x0002,
+		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) },
+		.keybit = { [BIT_WORD(BTN_TOOL_FINGER)] =
+				BIT_MASK(BTN_TOOL_FINGER) },
+		.absbit = { BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) |
+				BIT_MASK(ABS_PRESSURE) |
+				BIT_MASK(ABS_TOOL_WIDTH) },
+	},
+	{ }
+};
+
+static int ideapad_tpswitch_init(struct ideapad_private *priv)
+{
+	int error;
+
+	if (!priv->features.ctrl_ps2_aux_port)
+		return 0;
+
+	spin_lock_init(&priv->tp_switch.lock);
+
+	priv->tp_switch.handler.name = "ideapad-tpswitch";
+	priv->tp_switch.handler.id_table = ideapad_tpswitch_ids;
+	priv->tp_switch.handler.filter = ideapad_tpswitch_filter;
+	priv->tp_switch.handler.connect = ideapad_tpswitch_connect;
+	priv->tp_switch.handler.disconnect = ideapad_tpswitch_disconnect;
+
+	error = input_register_handler(&priv->tp_switch.handler);
+	if (error) {
+		dev_err(&priv->platform_device->dev,
+			"failed to register touchpad switch handler: %d",
+			error);
+		return error;
+	}
+
+	priv->tp_switch.initialized = true;
+	return 0;
+}
+
+static void ideapad_tpswitch_exit(struct ideapad_private *priv)
+{
+	if (priv->tp_switch.initialized) {
+		input_unregister_handler(&priv->tp_switch.handler);
+		priv->tp_switch.initialized = false;
+	}
+}
+
+static void ideapad_tpswitch_toggle(struct ideapad_private *priv, bool on)
+{
+	guard(spinlock_irq)(&priv->tp_switch.lock);
+
+	priv->tp_switch.active = on;
+	if (on) {
+		struct input_dev *tp_dev = priv->tp_switch.tp_dev;
+		if (tp_dev) {
+			input_report_key(tp_dev, BTN_TOUCH, 0);
+			input_report_key(tp_dev, BTN_TOOL_FINGER, 0);
+			input_report_key(tp_dev, BTN_TOOL_DOUBLETAP, 0);
+			input_report_key(tp_dev, BTN_TOOL_TRIPLETAP, 0);
+			input_report_key(tp_dev, BTN_LEFT, 0);
+			input_report_key(tp_dev, BTN_RIGHT, 0);
+			input_report_key(tp_dev, BTN_MIDDLE, 0);
+			input_sync(tp_dev);
+		}
+	}
+}
+
 /*
  * backlight
  */
@@ -1799,7 +1957,6 @@ static void ideapad_fn_lock_led_exit(struct ideapad_private *priv)
 static void ideapad_sync_touchpad_state(struct ideapad_private *priv, bool send_events)
 {
 	unsigned long value;
-	unsigned char param;
 	int ret;
 
 	/* Without reading from EC touchpad LED doesn't switch state */
@@ -1815,7 +1972,7 @@ static void ideapad_sync_touchpad_state(struct ideapad_private *priv, bool send_
 	 * KEY_TOUCHPAD_ON to not to get out of sync with LED
 	 */
 	if (priv->features.ctrl_ps2_aux_port)
-		i8042_command(&param, value ? I8042_CMD_AUX_ENABLE : I8042_CMD_AUX_DISABLE);
+		ideapad_tpswitch_toggle(priv, value);
 
 	/*
 	 * On older models the EC controls the touchpad and toggles it on/off
@@ -2402,6 +2559,10 @@ static int ideapad_acpi_add(struct platform_device *pdev)
 	if (err)
 		goto input_failed;
 
+	err = ideapad_tpswitch_init(priv);
+	if (err)
+		goto tpswitch_failed;
+
 	err = ideapad_kbd_bl_init(priv);
 	if (err) {
 		if (err != -ENODEV)
@@ -2478,6 +2639,9 @@ static int ideapad_acpi_add(struct platform_device *pdev)
 
 	ideapad_fn_lock_led_exit(priv);
 	ideapad_kbd_bl_exit(priv);
+	ideapad_tpswitch_exit(priv);
+
+tpswitch_failed:
 	ideapad_input_exit(priv);
 
 input_failed:
@@ -2507,6 +2671,7 @@ static void ideapad_acpi_remove(struct platform_device *pdev)
 
 	ideapad_fn_lock_led_exit(priv);
 	ideapad_kbd_bl_exit(priv);
+	ideapad_tpswitch_exit(priv);
 	ideapad_input_exit(priv);
 	ideapad_debugfs_exit(priv);
 }
-- 
2.55.0.571.g244d577d93-goog


-- 
Dmitry