[PATCH net-next v6 05/10] enic: define MBOX message types and header structures

[Satish Kharat]

Define the mailbox protocol structures for PF-VF communication:
message header, generic reply, and per-message-type payloads for
capability negotiation, VF registration/unregistration, and link
state notification/acknowledgment.

Include linux/types.h and linux/bits.h for __le16/__le32/__le64
and BIT() used in the header.

Message types use an even=request / odd=reply convention.  The
header carries source and destination VNIC IDs, a monotonically
increasing message number, and the total message length.

Signed-off-by: Satish Kharat <satishkh@xxxxxxxxx>
---
 drivers/net/ethernet/cisco/enic/enic_mbox.h | 83 +++++++++++++++++++++++++++++
 1 file changed, 83 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..a52f1d25cb21
--- /dev/null
+++ b/drivers/net/ethernet/cisco/enic/enic_mbox.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright 2025 Cisco Systems, Inc.  All rights reserved. */
+
+#ifndef _ENIC_MBOX_H_
+#define _ENIC_MBOX_H_
+
+#include <linux/bits.h>
+#include <linux/types.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];
+};
+
+/* The embedded enic_mbox_generic_reply has 2-byte alignment, but the
+ * __le32 members give this struct 4-byte natural alignment.  Receive
+ * buffers come from kmalloc (>= 8-byte aligned), so there is no
+ * misaligned access risk when casting from the receive buffer.
+ */
+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