[PATCH 05/10] enic: define MBOX message types and header structures

[Satish Kharat via B4 Relay]

From: Satish Kharat <satishkh@xxxxxxxxx>

Define the mailbox protocol used for PF-VF communication over the
admin channel. The protocol uses request/reply pairs where even
message types are requests and odd are replies.

Initial message types cover the core SR-IOV handshake:
  - VF_CAPABILITY: version negotiation
  - VF_REGISTER/UNREGISTER: VF lifecycle management
  - PF_LINK_STATE_NOTIF: PF-initiated link state changes

Each message carries a common header (src/dst vnic ID, type,
length, sequence number) followed by a type-specific payload.

Signed-off-by: Satish Kharat <satishkh@xxxxxxxxx>
---
 drivers/net/ethernet/cisco/enic/enic_mbox.h | 75 +++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/drivers/net/ethernet/cisco/enic/enic_mbox.h b/drivers/net/ethernet/cisco/enic/enic_mbox.h
new file mode 100644
index 000000000000..84cb6bbc1ead
--- /dev/null
+++ b/drivers/net/ethernet/cisco/enic/enic_mbox.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright 2025 Cisco Systems, Inc.  All rights reserved. */
+
+#ifndef _ENIC_MBOX_H_
+#define _ENIC_MBOX_H_
+
+/*
+ * Mailbox protocol for PF-VF communication over the admin channel.
+ *
+ * Even numbers are requests, odd numbers are replies/acks.
+ * The prefix indicates the initiator: VF_ = VF-initiated, PF_ = PF-initiated.
+ */
+enum enic_mbox_msg_type {
+	ENIC_MBOX_VF_CAPABILITY_REQUEST		= 0,
+	ENIC_MBOX_VF_CAPABILITY_REPLY		= 1,
+	ENIC_MBOX_VF_REGISTER_REQUEST		= 2,
+	ENIC_MBOX_VF_REGISTER_REPLY		= 3,
+	ENIC_MBOX_VF_UNREGISTER_REQUEST		= 4,
+	ENIC_MBOX_VF_UNREGISTER_REPLY		= 5,
+	ENIC_MBOX_PF_LINK_STATE_NOTIF		= 6,
+	ENIC_MBOX_PF_LINK_STATE_ACK		= 7,
+	ENIC_MBOX_MAX
+};
+
+struct enic_mbox_hdr {
+	__le16 src_vnic_id;
+	__le16 dst_vnic_id;
+	u8 msg_type;
+	u8 flags;
+	__le16 msg_len;
+	__le64 msg_num;
+};
+
+struct enic_mbox_generic_reply {
+	__le16 ret_major;
+	__le16 ret_minor;
+};
+
+#define ENIC_MBOX_ERR_GENERIC		BIT(0)
+#define ENIC_MBOX_ERR_VF_NOT_REGISTERED	BIT(1)
+#define ENIC_MBOX_ERR_MSG_NOT_SUPPORTED	BIT(2)
+
+/* ENIC_MBOX_VF_CAPABILITY_REQUEST / _REPLY */
+#define ENIC_MBOX_CAP_VERSION_0		0
+#define ENIC_MBOX_CAP_VERSION_1		1
+
+struct enic_mbox_vf_capability_msg {
+	__le32 version;
+	__le32 reserved[32];
+};
+
+struct enic_mbox_vf_capability_reply_msg {
+	struct enic_mbox_generic_reply reply;
+	__le32 version;
+	__le32 reserved[32];
+};
+
+/* ENIC_MBOX_VF_REGISTER / _UNREGISTER */
+struct enic_mbox_vf_register_reply_msg {
+	struct enic_mbox_generic_reply reply;
+};
+
+/* ENIC_MBOX_PF_LINK_STATE_NOTIF / _ACK */
+#define ENIC_MBOX_LINK_STATE_DISABLE	0
+#define ENIC_MBOX_LINK_STATE_ENABLE	1
+
+struct enic_mbox_pf_link_state_notif_msg {
+	__le32 link_state;
+};
+
+struct enic_mbox_pf_link_state_ack_msg {
+	struct enic_mbox_generic_reply ack;
+};
+
+#endif /* _ENIC_MBOX_H_ */

-- 
2.43.0