platform/chrome: cros_ec_lpc: Only check for events on MKBP notifies

Only check EC for MKBP events when the ACPI notify value indicates the
notify is due to an MKBP host event. This reduces unnecessary queries to
the EC.

Notify value 0x80 is reserved for devices specific notifies. It is used
by many devices to indicate various events. It's only used by cros_ec
for MKBP events.

Signed-off-by: Rob Barnes <robbarnes@google.com>
Link: https://lore.kernel.org/r/20241218015759.3558830-1-robbarnes@google.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Author: rbbrns

drivers/platform/chrome/cros_ec_lpc.c

@@ -419,7 +419,7 @@ static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
 		return;
 	}
 
-	if (ec_dev->mkbp_event_supported)
+	if (value == ACPI_NOTIFY_CROS_EC_MKBP && ec_dev->mkbp_event_supported)
 		do {
 			ret = cros_ec_get_next_event(ec_dev, NULL,
 						     &ec_has_more_events);

include/linux/platform_data/cros_ec_proto.h

@@ -41,6 +41,11 @@
 #define EC_MAX_REQUEST_OVERHEAD		1
 #define EC_MAX_RESPONSE_OVERHEAD	32
 
+/*
+ * ACPI notify value for MKBP host event.
+ */
+#define ACPI_NOTIFY_CROS_EC_MKBP 0x80
+
 /*
  * EC panic is not covered by the standard (0-F) ACPI notify values.
  * Arbitrarily choosing B0 to notify ec panic, which is in the 84-BF