1 files changed, 85 insertions, 0 deletions
diff --git a/src/vendorcode/google/chromeos/acpi/amac.asl b/src/vendorcode/google/chromeos/acpi/amac.asl
new file mode 100644
index 0000000000..838506abcb
--- /dev/null
+++ b/src/vendorcode/google/chromeos/acpi/amac.asl
@@ -0,0 +1,85 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * The Realtek r8152 driver in the Linux kernel supports a MAC address
+ * passthru feature which can result in the dock ethernet port using the
+ * same MAC address that is assigned to the internal NIC.  This is done
+ * by calling an ACPI method at \_SB.AMAC() which returns a formatted
+ * string containing the MAC address for the dock to use.
+ *
+ * The Linux kernel implementation can be found at
+ * drivers/net/usb/r8152.c:vendor_mac_passthru_addr_read()
+ *
+ * For Chrome OS, the policy which controls where the dock MAC address
+ * comes from is written into RW_VPD property "dock_passthru":
+ *
+ *   "dock_mac" or empty: Use MAC address from RO_VPD value "dock_mac"
+ *   "ethernet_mac0": Use MAC address from RO_VPD value "ethernet_mac0"
+ *   "builtin": existing dock MAC address (return nothing)
+ */
+
+Scope (\_SB)
+{
+	Method (AMAC, 0, Serialized)
+	{
+		/* Format expected by the Linux kernel r8152 driver */
+		Name (MACA, "_AUXMAC_#XXXXXXXXXXXX#")
+
+		/* Get "dock_passthru" value from RW_VPD */
+		Local0 = \VPD.VPDF ("RW", "dock_passthru")
+
+		Switch (ToString (Local0))
+		{
+			Case ("ethernet_mac0") {
+				Local1 = \VPD.VPDF ("RO", "ethernet_mac0")
+			}
+			Case ("builtin") {
+				Return (Zero)
+			}
+			/* "dock_mac" or policy not found. */
+			Default {
+				Local1 = \VPD.VPDF ("RO", "dock_mac")
+			}
+		}
+		If (!Local1) {
+			Return (Zero)
+		}
+		Printf ("MAC address returned from VPD: %o", Local1)
+
+		/* Verify MAC address format is AA:BB:CC:DD:EE:FF */
+		For (Local3 = 2, Local3 < 17, Local3 += 3) {
+			If (ToString (DerefOf (Local1[Local3])) != ":") {
+				Printf ("Invalid MAC address byte %o", Local3)
+				Return (Zero)
+			}
+		}
+
+		/* Convert MAC address into format specified by MACA */
+		Local2 = ToBuffer (MACA)
+		Local4 = 0 /* First MAC address byte in input buffer */
+		Local5 = 9 /* First MAC address byte in output buffer */
+		For (Local3 = 0, Local3 < 6, Local3++) {
+			Local2[Local5] = DerefOf (Local1[Local4])
+			Local2[Local5 + 1] = DerefOf (Local1[Local4 + 1])
+			Local5 += 2
+			Local4 += 3 /* Skip ":" in address from VPD */
+		}
+
+		Printf ("AMAC = %o", ToString (Local2))
+		Return (ToString (Local2))
+	}
+}