1 files changed, 52 insertions, 0 deletions
diff --git a/arch/x86/include/asm/acpi/cros_ec/keyboard_backlight.asl b/arch/x86/include/asm/acpi/cros_ec/keyboard_backlight.asl
new file mode 100644
index 0000000000..e6edd9680c
--- /dev/null
+++ b/arch/x86/include/asm/acpi/cros_ec/keyboard_backlight.asl
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015 Google Inc.
+ */
+
+Scope (\_SB)
+{
+	/*
+	 * Chrome EC Keyboard Backlight interface
+	 */
+	Device (KBLT)
+	{
+		Name (_HID, "GOOG0002")
+		Name (_UID, 1)
+
+		/* Ask EC if we even have a backlight
+		 * Return 0xf (present, enabled, show in UI, functioning) or 0
+		 *
+		 * With older EC codebases that don't support the Device
+		 * Features bitfield, this reports the keyboard backlight as
+		 * enabled since reads to undefined addresses in EC address
+		 * space return 0xff and so KBLE will be 1.
+		 */
+		Method (_STA, 0, NotSerialized)
+		{
+			/* If query is unsupported, but this code is compiled
+			 * in, assume the backlight exists physically.
+			 */
+			If (LEqual (1, \_SB.PCI0.LPCB.EC0.DFUD)) {
+				Return (0xf)
+			}
+			/* If EC reports that backlight exists, trust it */
+			If (LEqual (1, \_SB.PCI0.LPCB.EC0.KBLE)) {
+				Return (0xf)
+			}
+			/* Otherwise: no device -> disable */
+			Return (0)
+		}
+
+		/* Read current backlight value */
+		Method (KBQC, 0, NotSerialized)
+		{
+			Return (\_SB.PCI0.LPCB.EC0.KBLV)
+		}
+
+		/* Write new backlight value */
+		Method (KBCM, 1, NotSerialized)
+		{
+			Store (Arg0, \_SB.PCI0.LPCB.EC0.KBLV)
+		}
+	}
+}