platform/x86: ideapad-laptop: Send KEY_TOUCHPAD_TOGGLE on some models

On recent Ideapad models the EC does not control the touchpad at all,
so instead of sending KEY_TOUCHPAD_ON/ _OFF on touchpad toggle hotkey
events, ideapad-laptop should send KEY_TOUCHPAD_TOGGLE and let userspace
handle the toggling.

Check for this by checking if the value read from VPCCMD_R_TOUCHPAD
actually changes when receiving a touchpad-toggle hotkey event; and
if it does not change send KEY_TOUCHPAD_TOGGLE to userspace to let
userspace enable/disable the touchpad in software.

Note this also drops the priv->features.touchpad_ctrl_via_ec check from
ideapad_sync_touchpad_state() so that KEY_TOUCHPAD_TOGGLE will be send
on laptops where this is not set too. This can be safely dropped now
because the i8042_command(I8042_CMD_AUX_ENABLE/_DISABLE) call is now
guarded by its own feature flag.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Tested-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Tested-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Link: https://lore.kernel.org/r/20221117110244.67811-5-hdegoede@redhat.com

drivers/platform/x86/ideapad-laptop.c

@@ -134,6 +134,7 @@ struct ideapad_private {
 	struct ideapad_dytc_priv *dytc;
 	struct dentry *debug;
 	unsigned long cfg;
+	unsigned long r_touchpad_val;
 	struct {
 		bool conservation_mode    : 1;
 		bool dytc                 : 1;
@@ -650,6 +651,8 @@ static ssize_t touchpad_show(struct device *dev,
 	if (err)
 		return err;
 
+	priv->r_touchpad_val = result;
+
 	return sysfs_emit(buf, "%d\n", !!result);
 }
 
@@ -669,6 +672,8 @@ static ssize_t touchpad_store(struct device *dev,
 	if (err)
 		return err;
 
+	priv->r_touchpad_val = state;
+
 	return count;
 }
 
@@ -1159,6 +1164,7 @@ static const struct key_entry ideapad_keymap[] = {
 	{ KE_KEY,  65, { KEY_PROG4 } },
 	{ KE_KEY,  66, { KEY_TOUCHPAD_OFF } },
 	{ KE_KEY,  67, { KEY_TOUCHPAD_ON } },
+	{ KE_KEY,  68, { KEY_TOUCHPAD_TOGGLE } },
 	{ KE_KEY, 128, { KEY_ESC } },
 
 	/*
@@ -1500,9 +1506,6 @@ static void ideapad_sync_touchpad_state(struct ideapad_private *priv, bool send_
 	unsigned char param;
 	int ret;
 
-	if (!priv->features.touchpad_ctrl_via_ec)
-		return;
-
 	/* Without reading from EC touchpad LED doesn't switch state */
 	ret = read_ec_data(priv->adev->handle, VPCCMD_R_TOUCHPAD, &value);
 	if (ret)
@@ -1518,9 +1521,20 @@ static void ideapad_sync_touchpad_state(struct ideapad_private *priv, bool send_
 		i8042_command(&param, value ? I8042_CMD_AUX_ENABLE : I8042_CMD_AUX_DISABLE);
 
 	if (send_events) {
-		ideapad_input_report(priv, value ? 67 : 66);
-		sysfs_notify(&priv->platform_device->dev.kobj, NULL, "touchpad");
+		/*
+		 * On older models the EC controls the touchpad and toggles it
+		 * on/off itself, in this case we report KEY_TOUCHPAD_ON/_OFF.
+		 * If the EC did not toggle, report KEY_TOUCHPAD_TOGGLE.
+		 */
+		if (value != priv->r_touchpad_val) {
+			ideapad_input_report(priv, value ? 67 : 66);
+			sysfs_notify(&priv->platform_device->dev.kobj, NULL, "touchpad");
+		} else {
+			ideapad_input_report(priv, 68);
+		}
 	}
+
+	priv->r_touchpad_val = value;
 }
 
 static void ideapad_acpi_notify(acpi_handle handle, u32 event, void *data)