mb/google/brya/crota: Enable MAC address passthru support

Enable the support for providing a MAC address
for a dock to use based on the VPD values set in the platform.

BUG=b:235045188
TEST=tested on Brya by setting VPD values and observing the string
returned by the AMAC() method:

> vpd -i RO_VPD -s "dock_mac"="BB:BB:BB:BB:BB:BB"

> echo 1 > /sys/module/acpi/parameters/aml_debug_output
[acpi.aml_debug_output=1]
ACPI Debug: "Found VPD KEY dock_mac = BB:BB:BB:BB:BB:BB"
ACPI Debug: "MAC address returned from VPD: BB:BB:BB:BB:BB:BB"
ACPI Debug: "AMAC = _AUXMAC_#BBBBBBBBBBBB#"

Signed-off-by: Franklin Lin <franklin_lin@wistron.corp-partner.google.com>
Change-Id: I61b2a5e18bc17abeea0846f17e9be343e852c2b3
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65603
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 58 insertions, 0 deletions

diff --git a/src/mainboard/google/brya/Kconfig.name b/src/mainboard/google/brya/Kconfig.name
index e5091e6a4c..f2f3082657 100644
--- a/src/mainboard/google/brya/Kconfig.name
+++ b/src/mainboard/google/brya/Kconfig.name
@@ -206,6 +206,7 @@ config BOARD_GOOGLE_CROTA
 	select CHROMEOS_WIFI_SAR if CHROMEOS
 	select DRIVERS_GENESYSLOGIC_GL9750
 	select DRIVERS_I2C_CS42L42
+	select VPD
 
 config BOARD_GOOGLE_MOLI
 	bool "->  Moli"
diff --git a/src/mainboard/google/brya/variants/crota/variant.c b/src/mainboard/google/brya/variants/crota/variant.c
index e8c62ebdc2..cb4935b1df 100644
--- a/src/mainboard/google/brya/variants/crota/variant.c
+++ b/src/mainboard/google/brya/variants/crota/variant.c
@@ -4,12 +4,23 @@
 #include <chip.h>
 #include <fw_config.h>
 #include <baseboard/variants.h>
+#include <acpi/acpi.h>
+#include <acpi/acpigen.h>
+#include <drivers/vpd/vpd.h>
+#include <stdio.h>
 
 const char *get_wifi_sar_cbfs_filename(void)
 {
 	return "wifi_sar_0.hex";
 }
 
+static const char *get_dock_mac_from_vpd(char *buf, int size)
+{
+	/* Support MAC address pass-through */
+	/* Read value of 'dock_mac' from RO VPD */
+	return vpd_gets("dock_mac", buf, size, VPD_RO);
+}
+
 void variant_update_soc_chip_config(struct soc_intel_alderlake_config *config)
 {
 	if (fw_config_probe(FW_CONFIG(DB_LTE, LTE_USB))) {
@@ -26,3 +37,49 @@ void variant_update_soc_chip_config(struct soc_intel_alderlake_config *config)
 		config->ext_fivr_settings.vnn_sx_voltage_mv = 1250;
 	}
 }
+
+void variant_fill_ssdt(const struct device *unused)
+{
+	/* Write MAC address to SSDT for Linux kernel r8152 driver */
+	/* enable pass-through support */
+	/* and read ACPI object name: "\_SB.AMAC" */
+
+	/* ASL code like this */
+	//     Scope (\_SB)
+	// {
+	//     Method (AMAC, 0, Serialized)
+	//     {
+	//         Return (ToBuffer (STRING))
+	//     }
+	// }
+
+	char buf[32], acpi_buf[32];
+	if (get_dock_mac_from_vpd(buf, sizeof(buf)) != NULL) {
+		printk(BIOS_INFO, "RO_VPD, dock_mac=%s\n", buf);
+
+		/* remove ':' from mac address string */
+		size_t len = strlen(buf);
+		int i, j;
+		for (i = 0; i < len; i++) {
+			if (buf[i] == ':') {
+				for (j = i; j < len; j++)
+					buf[j] = buf[j+1];
+				len--;
+				i--;
+			}
+		}
+		buf[len] = '\0';
+
+		/* Format expected by the Linux kernel r8152 driver */
+		/* "_AUXMAC_#XXXXXXXXXXXX#" */
+		int acpi_buf_len = snprintf(acpi_buf, sizeof(acpi_buf), "_AUXMAC_#%s#", buf);
+
+		acpigen_write_scope("\\_SB");
+		acpigen_write_method_serialized("AMAC", 0);
+
+		acpigen_write_return_byte_buffer((uint8_t *)acpi_buf, acpi_buf_len);
+
+		acpigen_write_method_end();
+		acpigen_write_scope_end();
+	}
+}