mei: late_bind: add late binding component driver

Introduce a new MEI client driver to support Late Binding firmware
upload/update for Intel discrete graphics platforms.

Late Binding is a runtime firmware upload/update mechanism that allows
payloads, such as fan control and voltage regulator, to be securely
delivered and applied without requiring SPI flash updates or
system reboots. This driver enables the Xe graphics driver and other
user-space tools to push such firmware blobs to the authentication
firmware via the MEI interface.

The driver handles authentication, versioning, and communication
with the authentication firmware, which in turn coordinates with
the PUnit/PCODE to apply the payload.

This is a foundational component for enabling dynamic, secure,
and re-entrant configuration updates on platforms like Battlemage.

Cc: Badal Nilawar <[e-mail]>
Reviewed-by: Mika Westerberg <[e-mail]>
Signed-off-by: Badal Nilawar <[e-mail]>
Reviewed-by: Anshuman Gupta <[e-mail]>
Signed-off-by: Rodrigo Vivi <[e-mail]>
Signed-off-by: Alexander Usyskin <[e-mail]>
Reviewed-by: Lucas De Marchi <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lucas De Marchi <[e-mail]>

drivers/misc/mei/Kconfig

···
 	  This driver can also be built as a module. If so, the module
 	  will be called mei-vsc.
 
+config INTEL_MEI_LB
+	tristate "Intel Late Binding (LB) support on ME Interface"
+	depends on INTEL_MEI_ME
+	depends on DRM_XE
+	help
+	  Enable support for Intel Late Binding (LB) via the MEI interface.
+
+	  Late Binding is a method for applying firmware updates at runtime,
+	  allowing the Intel Xe driver to load firmware payloads such as
+	  fan controller or voltage regulator. These firmware updates are
+	  authenticated and versioned, and do not require firmware flashing
+	  or system reboot.
+
 source "drivers/misc/mei/hdcp/Kconfig"
 source "drivers/misc/mei/pxp/Kconfig"
 source "drivers/misc/mei/gsc_proxy/Kconfig"

drivers/misc/mei/Makefile

···
 obj-$(CONFIG_INTEL_MEI_HDCP) += hdcp/
 obj-$(CONFIG_INTEL_MEI_PXP) += pxp/
 obj-$(CONFIG_INTEL_MEI_GSC_PROXY) += gsc_proxy/
+obj-$(CONFIG_INTEL_MEI_LB) += mei_lb.o
 
 obj-$(CONFIG_INTEL_MEI_VSC_HW) += mei-vsc-hw.o
 mei-vsc-hw-y := vsc-tp.o

drivers/misc/mei/mei_lb.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+#include <linux/component.h>
+#include <linux/mei_cl_bus.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+
+#include <drm/intel/i915_component.h>
+#include <drm/intel/intel_lb_mei_interface.h>
+
+#include "mkhi.h"
+
+/**
+ * DOC: Late Binding Firmware Update/Upload
+ *
+ * Late Binding is a firmware update/upload mechanism that allows configuration
+ * payloads to be securely delivered and applied at runtime, rather than
+ * being embedded in the system firmware image (e.g., IFWI or SPI flash).
+ *
+ * This mechanism is used to update device-level configuration such as:
+ * - Fan controller
+ * - Voltage regulator (VR)
+ *
+ * Key Characteristics:
+ * ---------------------
+ * - Runtime Delivery:
+ *   Firmware blobs are loaded by the host driver (e.g., Xe KMD)
+ *   after the GPU or SoC has booted.
+ *
+ * - Secure and Authenticated:
+ *   All payloads are signed and verified by the authentication firmware.
+ *
+ * - No Firmware Flashing Required:
+ *   Updates are applied in volatile memory and do not require SPI flash
+ *   modification or system reboot.
+ *
+ * - Re-entrant:
+ *   Multiple updates of the same or different types can be applied
+ *   sequentially within a single boot session.
+ *
+ * - Version Controlled:
+ *   Each payload includes version and security version number (SVN)
+ *   metadata to support anti-rollback enforcement.
+ *
+ * Upload Flow:
+ * ------------
+ * 1. Host driver (KMD or user-space tool) loads the late binding firmware.
+ * 2. Firmware is passed to the MEI interface and forwarded to
+ *    authentication firmware.
+ * 3. Authentication firmware authenticates the payload and extracts
+ *    command and data arrays.
+ * 4. Authentication firmware delivers the configuration to PUnit/PCODE.
+ * 5. Status is returned back to the host via MEI.
+ */
+
+#define INTEL_LB_CMD	0x12
+#define INTEL_LB_RSP	(INTEL_LB_CMD | 0x80)
+
+#define INTEL_LB_SEND_TIMEOUT_MSEC 3000
+#define INTEL_LB_RECV_TIMEOUT_MSEC 3000
+
+/**
+ * struct mei_lb_req - Late Binding request structure
+ * @header: MKHI message header (see struct mkhi_msg_hdr)
+ * @type: Type of the Late Binding payload
+ * @flags: Flags to be passed to the authentication firmware (e.g. %INTEL_LB_FLAGS_IS_PERSISTENT)
+ * @reserved: Reserved for future use by authentication firmware, must be set to 0
+ * @payload_size: Size of the payload data in bytes
+ * @payload: Payload data to be sent to the authentication firmware
+ */
+struct mei_lb_req {
+	struct mkhi_msg_hdr header;
+	__le32 type;
+	__le32 flags;
+	__le32 reserved[2];
+	__le32 payload_size;
+	u8 payload[] __counted_by(payload_size);
+} __packed;
+
+/**
+ * struct mei_lb_rsp - Late Binding response structure
+ * @header: MKHI message header (see struct mkhi_msg_hdr)
+ * @type: Type of the Late Binding payload
+ * @reserved: Reserved for future use by authentication firmware, must be set to 0
+ * @status: Status returned by authentication firmware (see &enum intel_lb_status)
+ */
+struct mei_lb_rsp {
+	struct mkhi_msg_hdr header;
+	__le32 type;
+	__le32 reserved[2];
+	__le32 status;
+} __packed;
+
+static bool mei_lb_check_response(const struct device *dev, ssize_t bytes,
+				  struct mei_lb_rsp *rsp)
+{
+	/*
+	 * Received message size may be smaller than the full message size when
+	 * reply contains only MKHI header with result field set to the error code.
+	 * Check the header size and content first to output exact error, if needed,
+	 * and then process to the whole message.
+	 */
+	if (bytes < sizeof(rsp->header)) {
+		dev_err(dev, "Received less than header size from the firmware: %zd < %zu\n",
+			bytes, sizeof(rsp->header));
+		return false;
+	}
+	if (rsp->header.group_id != MKHI_GROUP_ID_GFX) {
+		dev_err(dev, "Mismatch group id: 0x%x instead of 0x%x\n",
+			rsp->header.group_id, MKHI_GROUP_ID_GFX);
+		return false;
+	}
+	if (rsp->header.command != INTEL_LB_RSP) {
+		dev_err(dev, "Mismatch command: 0x%x instead of 0x%x\n",
+			rsp->header.command, INTEL_LB_RSP);
+		return false;
+	}
+	if (rsp->header.result) {
+		dev_err(dev, "Error in result: 0x%x\n", rsp->header.result);
+		return false;
+	}
+	if (bytes < sizeof(*rsp)) {
+		dev_err(dev, "Received less than message size from the firmware: %zd < %zu\n",
+			bytes, sizeof(*rsp));
+		return false;
+	}
+
+	return true;
+}
+
+static int mei_lb_push_payload(struct device *dev,
+			       enum intel_lb_type type, u32 flags,
+			       const void *payload, size_t payload_size)
+{
+	struct mei_cl_device *cldev;
+	struct mei_lb_req *req = NULL;
+	struct mei_lb_rsp rsp;
+	size_t req_size;
+	ssize_t bytes;
+	int ret;
+
+	cldev = to_mei_cl_device(dev);
+
+	ret = mei_cldev_enable(cldev);
+	if (ret) {
+		dev_dbg(dev, "Failed to enable firmware client. %d\n", ret);
+		return ret;
+	}
+
+	req_size = struct_size(req, payload, payload_size);
+	if (req_size > mei_cldev_mtu(cldev)) {
+		dev_err(dev, "Payload is too big: %zu\n", payload_size);
+		ret = -EMSGSIZE;
+		goto end;
+	}
+
+	req = kmalloc(req_size, GFP_KERNEL);
+	if (!req) {
+		ret = -ENOMEM;
+		goto end;
+	}
+
+	req->header.group_id = MKHI_GROUP_ID_GFX;
+	req->header.command = INTEL_LB_CMD;
+	req->type = cpu_to_le32(type);
+	req->flags = cpu_to_le32(flags);
+	req->reserved[0] = 0;
+	req->reserved[1] = 0;
+	req->payload_size = cpu_to_le32(payload_size);
+	memcpy(req->payload, payload, payload_size);
+
+	bytes = mei_cldev_send_timeout(cldev, (u8 *)req, req_size,
+				       INTEL_LB_SEND_TIMEOUT_MSEC);
+	if (bytes < 0) {
+		dev_err(dev, "Failed to send late binding request to firmware. %zd\n", bytes);
+		ret = bytes;
+		goto end;
+	}
+
+	bytes = mei_cldev_recv_timeout(cldev, (u8 *)&rsp, sizeof(rsp),
+				       INTEL_LB_RECV_TIMEOUT_MSEC);
+	if (bytes < 0) {
+		dev_err(dev, "Failed to receive late binding reply from MEI firmware. %zd\n",
+			bytes);
+		ret = bytes;
+		goto end;
+	}
+	if (!mei_lb_check_response(dev, bytes, &rsp)) {
+		dev_err(dev, "Bad response from the firmware. header: %02x %02x %02x %02x\n",
+			rsp.header.group_id, rsp.header.command,
+			rsp.header.reserved, rsp.header.result);
+		ret = -EPROTO;
+		goto end;
+	}
+
+	dev_dbg(dev, "status = %u\n", le32_to_cpu(rsp.status));
+	ret = (int)le32_to_cpu(rsp.status);
+end:
+	mei_cldev_disable(cldev);
+	kfree(req);
+	return ret;
+}
+
+static const struct intel_lb_component_ops mei_lb_ops = {
+	.push_payload = mei_lb_push_payload,
+};
+
+static int mei_lb_component_master_bind(struct device *dev)
+{
+	return component_bind_all(dev, (void *)&mei_lb_ops);
+}
+
+static void mei_lb_component_master_unbind(struct device *dev)
+{
+	component_unbind_all(dev, (void *)&mei_lb_ops);
+}
+
+static const struct component_master_ops mei_lb_component_master_ops = {
+	.bind = mei_lb_component_master_bind,
+	.unbind = mei_lb_component_master_unbind,
+};
+
+static int mei_lb_component_match(struct device *dev, int subcomponent,
+				  void *data)
+{
+	/*
+	 * This function checks if requester is Intel %PCI_CLASS_DISPLAY_VGA or
+	 * %PCI_CLASS_DISPLAY_OTHER device, and checks if the requester is the
+	 * grand parent of mei_if i.e. late bind MEI device
+	 */
+	struct device *base = data;
+	struct pci_dev *pdev;
+
+	if (!dev)
+		return 0;
+
+	if (!dev_is_pci(dev))
+		return 0;
+
+	pdev = to_pci_dev(dev);
+
+	if (pdev->vendor != PCI_VENDOR_ID_INTEL)
+		return 0;
+
+	if (pdev->class != (PCI_CLASS_DISPLAY_VGA << 8) &&
+	    pdev->class != (PCI_CLASS_DISPLAY_OTHER << 8))
+		return 0;
+
+	if (subcomponent != INTEL_COMPONENT_LB)
+		return 0;
+
+	base = base->parent;
+	if (!base) /* mei device */
+		return 0;
+
+	base = base->parent; /* pci device */
+
+	return !!base && dev == base;
+}
+
+static int mei_lb_probe(struct mei_cl_device *cldev,
+			const struct mei_cl_device_id *id)
+{
+	struct component_match *master_match = NULL;
+	int ret;
+
+	component_match_add_typed(&cldev->dev, &master_match,
+				  mei_lb_component_match, &cldev->dev);
+	if (IS_ERR_OR_NULL(master_match))
+		return -ENOMEM;
+
+	ret = component_master_add_with_match(&cldev->dev,
+					      &mei_lb_component_master_ops,
+					      master_match);
+	if (ret < 0)
+		dev_err(&cldev->dev, "Failed to add late binding master component. %d\n", ret);
+
+	return ret;
+}
+
+static void mei_lb_remove(struct mei_cl_device *cldev)
+{
+	component_master_del(&cldev->dev, &mei_lb_component_master_ops);
+}
+
+#define MEI_GUID_MKHI UUID_LE(0xe2c2afa2, 0x3817, 0x4d19, \
+			      0x9d, 0x95, 0x6, 0xb1, 0x6b, 0x58, 0x8a, 0x5d)
+
+static const struct mei_cl_device_id mei_lb_tbl[] = {
+	{ .uuid = MEI_GUID_MKHI, .version = MEI_CL_VERSION_ANY },
+	{ }
+};
+MODULE_DEVICE_TABLE(mei, mei_lb_tbl);
+
+static struct mei_cl_driver mei_lb_driver = {
+	.id_table = mei_lb_tbl,
+	.name = "mei_lb",
+	.probe = mei_lb_probe,
+	.remove	= mei_lb_remove,
+};
+
+module_mei_cl_driver(mei_lb_driver);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MEI Late Binding Firmware Update/Upload");

include/drm/intel/i915_component.h

···
 	I915_COMPONENT_HDCP,
 	I915_COMPONENT_PXP,
 	I915_COMPONENT_GSC_PROXY,
+	INTEL_COMPONENT_LB,
 };
 
 /* MAX_PORT is the number of port

include/drm/intel/intel_lb_mei_interface.h

···
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright (c) 2025 Intel Corporation
+ */
+
+#ifndef _INTEL_LB_MEI_INTERFACE_H_
+#define _INTEL_LB_MEI_INTERFACE_H_
+
+#include <linux/types.h>
+
+struct device;
+
+/**
+ * define INTEL_LB_FLAG_IS_PERSISTENT - Mark the payload as persistent
+ *
+ * This flag indicates that the late binding payload should be stored
+ * persistently in flash across warm resets.
+ */
+#define INTEL_LB_FLAG_IS_PERSISTENT	BIT(0)
+
+/**
+ * enum intel_lb_type - enum to determine late binding payload type
+ * @INTEL_LB_TYPE_FAN_CONTROL: Fan controller configuration
+ */
+enum intel_lb_type {
+	INTEL_LB_TYPE_FAN_CONTROL = 1,
+};
+
+/**
+ * enum intel_lb_status - Status codes returned on late binding transmissions
+ * @INTEL_LB_STATUS_SUCCESS: Operation completed successfully
+ * @INTEL_LB_STATUS_4ID_MISMATCH: Mismatch in the expected 4ID (firmware identity/token)
+ * @INTEL_LB_STATUS_ARB_FAILURE: Arbitration failure (e.g. conflicting access or state)
+ * @INTEL_LB_STATUS_GENERAL_ERROR: General firmware error not covered by other codes
+ * @INTEL_LB_STATUS_INVALID_PARAMS: One or more input parameters are invalid
+ * @INTEL_LB_STATUS_INVALID_SIGNATURE: Payload has an invalid or untrusted signature
+ * @INTEL_LB_STATUS_INVALID_PAYLOAD: Payload contents are not accepted by firmware
+ * @INTEL_LB_STATUS_TIMEOUT: Operation timed out before completion
+ */
+enum intel_lb_status {
+	INTEL_LB_STATUS_SUCCESS           = 0,
+	INTEL_LB_STATUS_4ID_MISMATCH      = 1,
+	INTEL_LB_STATUS_ARB_FAILURE       = 2,
+	INTEL_LB_STATUS_GENERAL_ERROR     = 3,
+	INTEL_LB_STATUS_INVALID_PARAMS    = 4,
+	INTEL_LB_STATUS_INVALID_SIGNATURE = 5,
+	INTEL_LB_STATUS_INVALID_PAYLOAD   = 6,
+	INTEL_LB_STATUS_TIMEOUT           = 7,
+};
+
+/**
+ * struct intel_lb_component_ops - Ops for late binding services
+ */
+struct intel_lb_component_ops {
+	/**
+	 * push_payload - Sends a payload to the authentication firmware
+	 * @dev: Device struct corresponding to the mei device
+	 * @type: Payload type (see &enum intel_lb_type)
+	 * @flags: Payload flags bitmap (e.g. %INTEL_LB_FLAGS_IS_PERSISTENT)
+	 * @payload: Pointer to payload buffer
+	 * @payload_size: Payload buffer size in bytes
+	 *
+	 * Return: 0 success, negative errno value on transport failure,
+	 *         positive status returned by firmware
+	 */
+	int (*push_payload)(struct device *dev, u32 type, u32 flags,
+			    const void *payload, size_t payload_size);
+};
+
+#endif /* _INTEL_LB_MEI_INTERFACE_H_ */