Some systems implement a system MAC address object in the ACPI table, using either \\_SB.AMAC or \\MACA object names. This system MAC address, when enabled, is intended to override the permanent MAC address of the any network controller attached via a docking station. The purpose is to allow the host PC retain its network identity in a corporate environment, regardless of the specific docking station it is connected to. The expectation is that only one docking station is attached at a time, or that only a single network controller is plugged in at a time.
Implement seamless passthrough of the system MAC address to the I225/I226 network controller, by looking up the relevant ACPI object names and using them to initialize the MAC address. Limit the lookup only to controllers that are Thunderbolt-attached, as these are the only docking stations that can pass through an I225/I226 controller to the host. On systems where the feature is disabled or unsupported, the ACPI objects do not exist or do not contain a valid Ethernet MAC, the default MAC address of the device is used. Assisted-by: GitHub-Copilot:claude-opus-4.7 Signed-off-by: Dima Ruinskiy <[email protected]> --- Change log v3->v4: use pci_is_thunderbolt_attached instead of device id check explicitly save permanent address when using passthrough mac v2->v3: fix typo that introduced check reversal v1->v2: limit scope to dock device ids --- drivers/net/ethernet/intel/igc/igc_main.c | 70 +++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index f6d1ee75627d..d51e9bcdfc3e 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1,6 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2018 Intel Corporation */ +#include <linux/acpi.h> +#include <linux/hex.h> #include <linux/module.h> #include <linux/types.h> #include <linux/if_vlan.h> @@ -7134,6 +7136,58 @@ static enum hrtimer_restart igc_qbv_scheduling_timer(struct hrtimer *timer) return HRTIMER_NORESTART; } +static bool igc_get_acpi_mac_passthru(u8 *mac) +{ + static const struct { + const char *name; + acpi_object_type type; + u32 length; + } sources[] = { + { "\\_SB.AMAC", ACPI_TYPE_BUFFER, 23 }, + { "\\MACA", ACPI_TYPE_STRING, 22 }, + }; + struct acpi_buffer buffer; + union acpi_object *obj; + bool mac_found = false; + acpi_status status; + u8 buf[ETH_ALEN]; + int i; + + if (!IS_ENABLED(CONFIG_ACPI)) + return false; + + for (i = 0; i < ARRAY_SIZE(sources) && !mac_found; i++) { + buffer.length = ACPI_ALLOCATE_BUFFER; + buffer.pointer = NULL; + + status = acpi_evaluate_object(NULL, (char *)sources[i].name, + NULL, &buffer); + if (ACPI_FAILURE(status)) + continue; + + obj = buffer.pointer; + if (!obj || obj->type != sources[i].type || + obj->string.length != sources[i].length || + !obj->string.pointer) + goto free_obj; + + if (strncmp(obj->string.pointer, "_AUXMAC_#", 9) || + obj->string.pointer[21] != '#') + goto free_obj; + + if (hex2bin(buf, obj->string.pointer + 9, ETH_ALEN) || + !is_valid_ether_addr(buf)) + goto free_obj; + + ether_addr_copy(mac, buf); + mac_found = true; +free_obj: + ACPI_FREE(obj); + } + + return mac_found; +} + /** * igc_probe - Device Initialization Routine * @pdev: PCI device information struct @@ -7300,6 +7354,22 @@ static int igc_probe(struct pci_dev *pdev, /* copy the MAC address out of the NVM */ if (hw->mac.ops.read_mac_addr(hw)) dev_err(&pdev->dev, "NVM Read Error\n"); + + /* For devices behind a Thunderbolt/USB4 dock, look for a + * system-provided MAC in the ACPI table + */ + if (pci_is_thunderbolt_attached(pdev) && + igc_get_acpi_mac_passthru(hw->mac.addr)) { + /* Set the permanent MAC address. Leave blank if invalid to + * reflect there is something wrong with the NVM MAC. + */ + if (is_valid_ether_addr(hw->mac.perm_addr)) + ether_addr_copy(netdev->perm_addr, hw->mac.perm_addr); + netdev->addr_assign_type = NET_ADDR_STOLEN; + dev_info(&pdev->dev, + "Using ACPI pass-thru MAC addr %pM\n", + hw->mac.addr); + } } eth_hw_addr_set(netdev, hw->mac.addr); -- 2.55.0
