fm10k: Implement PF <-> SM mailbox operations

This patch adds support for the mailbox that connects the PF to the Switch
Management entity.  This mailbox will pass TLV formatted messages between
the two entities by using a pair of shared ring buffers.

The primary use of the mailbox is to configure L2 forwarding addresses,
VLANs, and general resource allocation from the switch.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

3 files changed, 1355 insertions, 1 deletions

diff --git a/drivers/net/ethernet/intel/fm10k/Makefile b/drivers/net/ethernet/intel/fm10k/Makefile
index 10528085545d..6642611c234d 100644
--- a/drivers/net/ethernet/intel/fm10k/Makefile
+++ b/drivers/net/ethernet/intel/fm10k/Makefile
@@ -28,4 +28,4 @@
 obj-$(CONFIG_FM10K) += fm10k.o
 
 fm10k-objs := fm10k_main.o fm10k_pci.o \
-	      fm10k_tlv.o
+	      fm10k_mbx.o fm10k_tlv.o
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_mbx.c b/drivers/net/ethernet/intel/fm10k/fm10k_mbx.c
new file mode 100644
index 000000000000..2609847bbdea
--- /dev/null
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_mbx.c
@@ -0,0 +1,1351 @@
+/* Intel Ethernet Switch Host Interface Driver
+ * Copyright(c) 2013 - 2014 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Contact Information:
+ * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
+ * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
+ */
+
+#include "fm10k_common.h"
+
+/**
+ *  fm10k_fifo_init - Initialize a message FIFO
+ *  @fifo: pointer to FIFO
+ *  @buffer: pointer to memory to be used to store FIFO
+ *  @size: maximum message size to store in FIFO, must be 2^n - 1
+ **/
+static void fm10k_fifo_init(struct fm10k_mbx_fifo *fifo, u32 *buffer, u16 size)
+{
+	fifo->buffer = buffer;
+	fifo->size = size;
+	fifo->head = 0;
+	fifo->tail = 0;
+}
+
+/**
+ *  fm10k_fifo_used - Retrieve used space in FIFO
+ *  @fifo: pointer to FIFO
+ *
+ *  This function returns the number of DWORDs used in the FIFO
+ **/
+static u16 fm10k_fifo_used(struct fm10k_mbx_fifo *fifo)
+{
+	return fifo->tail - fifo->head;
+}
+
+/**
+ *  fm10k_fifo_unused - Retrieve unused space in FIFO
+ *  @fifo: pointer to FIFO
+ *
+ *  This function returns the number of unused DWORDs in the FIFO
+ **/
+static u16 fm10k_fifo_unused(struct fm10k_mbx_fifo *fifo)
+{
+	return fifo->size + fifo->head - fifo->tail;
+}
+
+/**
+ *  fm10k_fifo_empty - Test to verify if fifo is empty
+ *  @fifo: pointer to FIFO
+ *
+ *  This function returns true if the FIFO is empty, else false
+ **/
+static bool fm10k_fifo_empty(struct fm10k_mbx_fifo *fifo)
+{
+	return fifo->head == fifo->tail;
+}
+
+/**
+ *  fm10k_fifo_head_offset - returns indices of head with given offset
+ *  @fifo: pointer to FIFO
+ *  @offset: offset to add to head
+ *
+ *  This function returns the indicies into the fifo based on head + offset
+ **/
+static u16 fm10k_fifo_head_offset(struct fm10k_mbx_fifo *fifo, u16 offset)
+{
+	return (fifo->head + offset) & (fifo->size - 1);
+}
+
+/**
+ *  fm10k_fifo_tail_offset - returns indices of tail with given offset
+ *  @fifo: pointer to FIFO
+ *  @offset: offset to add to tail
+ *
+ *  This function returns the indicies into the fifo based on tail + offset
+ **/
+static u16 fm10k_fifo_tail_offset(struct fm10k_mbx_fifo *fifo, u16 offset)
+{
+	return (fifo->tail + offset) & (fifo->size - 1);
+}
+
+/**
+ *  fm10k_fifo_head_len - Retrieve length of first message in FIFO
+ *  @fifo: pointer to FIFO
+ *
+ *  This function returns the size of the first message in the FIFO
+ **/
+static u16 fm10k_fifo_head_len(struct fm10k_mbx_fifo *fifo)
+{
+	u32 *head = fifo->buffer + fm10k_fifo_head_offset(fifo, 0);
+
+	/* verify there is at least 1 DWORD in the fifo so *head is valid */
+	if (fm10k_fifo_empty(fifo))
+		return 0;
+
+	/* retieve the message length */
+	return FM10K_TLV_DWORD_LEN(*head);
+}
+
+/**
+ *  fm10k_fifo_head_drop - Drop the first message in FIFO
+ *  @fifo: pointer to FIFO
+ *
+ *  This function returns the size of the message dropped from the FIFO
+ **/
+static u16 fm10k_fifo_head_drop(struct fm10k_mbx_fifo *fifo)
+{
+	u16 len = fm10k_fifo_head_len(fifo);
+
+	/* update head so it is at the start of next frame */
+	fifo->head += len;
+
+	return len;
+}
+
+/**
+ *  fm10k_mbx_index_len - Convert a head/tail index into a length value
+ *  @mbx: pointer to mailbox
+ *  @head: head index
+ *  @tail: head index
+ *
+ *  This function takes the head and tail index and determines the length
+ *  of the data indicated by this pair.
+ **/
+static u16 fm10k_mbx_index_len(struct fm10k_mbx_info *mbx, u16 head, u16 tail)
+{
+	u16 len = tail - head;
+
+	/* we wrapped so subtract 2, one for index 0, one for all 1s index */
+	if (len > tail)
+		len -= 2;
+
+	return len & ((mbx->mbmem_len << 1) - 1);
+}
+
+/**
+ *  fm10k_mbx_tail_add - Determine new tail value with added offset
+ *  @mbx: pointer to mailbox
+ *  @offset: length to add to head offset
+ *
+ *  This function takes the local tail index and recomputes it for
+ *  a given length added as an offset.
+ **/
+static u16 fm10k_mbx_tail_add(struct fm10k_mbx_info *mbx, u16 offset)
+{
+	u16 tail = (mbx->tail + offset + 1) & ((mbx->mbmem_len << 1) - 1);
+
+	/* add/sub 1 because we cannot have offset 0 or all 1s */
+	return (tail > mbx->tail) ? --tail : ++tail;
+}
+
+/**
+ *  fm10k_mbx_tail_sub - Determine new tail value with subtracted offset
+ *  @mbx: pointer to mailbox
+ *  @offset: length to add to head offset
+ *
+ *  This function takes the local tail index and recomputes it for
+ *  a given length added as an offset.
+ **/
+static u16 fm10k_mbx_tail_sub(struct fm10k_mbx_info *mbx, u16 offset)
+{
+	u16 tail = (mbx->tail - offset - 1) & ((mbx->mbmem_len << 1) - 1);
+
+	/* sub/add 1 because we cannot have offset 0 or all 1s */
+	return (tail < mbx->tail) ? ++tail : --tail;
+}
+
+/**
+ *  fm10k_mbx_head_add - Determine new head value with added offset
+ *  @mbx: pointer to mailbox
+ *  @offset: length to add to head offset
+ *
+ *  This function takes the local head index and recomputes it for
+ *  a given length added as an offset.
+ **/
+static u16 fm10k_mbx_head_add(struct fm10k_mbx_info *mbx, u16 offset)
+{
+	u16 head = (mbx->head + offset + 1) & ((mbx->mbmem_len << 1) - 1);
+
+	/* add/sub 1 because we cannot have offset 0 or all 1s */
+	return (head > mbx->head) ? --head : ++head;
+}
+
+/**
+ *  fm10k_mbx_head_sub - Determine new head value with subtracted offset
+ *  @mbx: pointer to mailbox
+ *  @offset: length to add to head offset
+ *
+ *  This function takes the local head index and recomputes it for
+ *  a given length added as an offset.
+ **/
+static u16 fm10k_mbx_head_sub(struct fm10k_mbx_info *mbx, u16 offset)
+{
+	u16 head = (mbx->head - offset - 1) & ((mbx->mbmem_len << 1) - 1);
+
+	/* sub/add 1 because we cannot have offset 0 or all 1s */
+	return (head < mbx->head) ? ++head : --head;
+}
+
+/**
+ *  fm10k_mbx_pushed_tail_len - Retrieve the length of message being pushed
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will return the length of the message currently being
+ *  pushed onto the tail of the Rx queue.
+ **/
+static u16 fm10k_mbx_pushed_tail_len(struct fm10k_mbx_info *mbx)
+{
+	u32 *tail = mbx->rx.buffer + fm10k_fifo_tail_offset(&mbx->rx, 0);
+
+	/* pushed tail is only valid if pushed is set */
+	if (!mbx->pushed)
+		return 0;
+
+	return FM10K_TLV_DWORD_LEN(*tail);
+}
+
+/**
+ *  fm10k_fifo_write_copy - pulls data off of msg and places it in fifo
+ *  @fifo: pointer to FIFO
+ *  @msg: message array to populate
+ *  @tail_offset: additional offset to add to tail pointer
+ *  @len: length of FIFO to copy into message header
+ *
+ *  This function will take a message and copy it into a section of the
+ *  FIFO.  In order to get something into a location other than just
+ *  the tail you can use tail_offset to adjust the pointer.
+ **/
+static void fm10k_fifo_write_copy(struct fm10k_mbx_fifo *fifo,
+				  const u32 *msg, u16 tail_offset, u16 len)
+{
+	u16 end = fm10k_fifo_tail_offset(fifo, tail_offset);
+	u32 *tail = fifo->buffer + end;
+
+	/* track when we should cross the end of the FIFO */
+	end = fifo->size - end;
+
+	/* copy end of message before start of message */
+	if (end < len)
+		memcpy(fifo->buffer, msg + end, (len - end) << 2);
+	else
+		end = len;
+
+	/* Copy remaining message into Tx FIFO */
+	memcpy(tail, msg, end << 2);
+}
+
+/**
+ *  fm10k_fifo_enqueue - Enqueues the message to the tail of the FIFO
+ *  @fifo: pointer to FIFO
+ *  @msg: message array to read
+ *
+ *  This function enqueues a message up to the size specified by the length
+ *  contained in the first DWORD of the message and will place at the tail
+ *  of the FIFO.  It will return 0 on success, or a negative value on error.
+ **/
+static s32 fm10k_fifo_enqueue(struct fm10k_mbx_fifo *fifo, const u32 *msg)
+{
+	u16 len = FM10K_TLV_DWORD_LEN(*msg);
+
+	/* verify parameters */
+	if (len > fifo->size)
+		return FM10K_MBX_ERR_SIZE;
+
+	/* verify there is room for the message */
+	if (len > fm10k_fifo_unused(fifo))
+		return FM10K_MBX_ERR_NO_SPACE;
+
+	/* Copy message into FIFO */
+	fm10k_fifo_write_copy(fifo, msg, 0, len);
+
+	/* memory barrier to guarantee FIFO is written before tail update */
+	wmb();
+
+	/* Update Tx FIFO tail */
+	fifo->tail += len;
+
+	return 0;
+}
+
+/**
+ *  fm10k_mbx_validate_msg_size - Validate incoming message based on size
+ *  @mbx: pointer to mailbox
+ *  @len: length of data pushed onto buffer
+ *
+ *  This function analyzes the frame and will return a non-zero value when
+ *  the start of a message larger than the mailbox is detected.
+ **/
+static u16 fm10k_mbx_validate_msg_size(struct fm10k_mbx_info *mbx, u16 len)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->rx;
+	u16 total_len = 0, msg_len;
+	u32 *msg;
+
+	/* length should include previous amounts pushed */
+	len += mbx->pushed;
+
+	/* offset in message is based off of current message size */
+	do {
+		msg = fifo->buffer + fm10k_fifo_tail_offset(fifo, total_len);
+		msg_len = FM10K_TLV_DWORD_LEN(*msg);
+		total_len += msg_len;
+	} while (total_len < len);
+
+	/* message extends out of pushed section, but fits in FIFO */
+	if ((len < total_len) && (msg_len <= mbx->rx.size))
+		return 0;
+
+	/* return length of invalid section */
+	return (len < total_len) ? len : (len - total_len);
+}
+
+/**
+ *  fm10k_mbx_write_copy - pulls data off of Tx FIFO and places it in mbmem
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will take a seciton of the Rx FIFO and copy it into the
+		mbx->tail--;
+ *  mailbox memory.  The offset in mbmem is based on the lower bits of the
+ *  tail and len determines the length to copy.
+ **/
+static void fm10k_mbx_write_copy(struct fm10k_hw *hw,
+				 struct fm10k_mbx_info *mbx)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->tx;
+	u32 mbmem = mbx->mbmem_reg;
+	u32 *head = fifo->buffer;
+	u16 end, len, tail, mask;
+
+	if (!mbx->tail_len)
+		return;
+
+	/* determine data length and mbmem tail index */
+	mask = mbx->mbmem_len - 1;
+	len = mbx->tail_len;
+	tail = fm10k_mbx_tail_sub(mbx, len);
+	if (tail > mask)
+		tail++;
+
+	/* determine offset in the ring */
+	end = fm10k_fifo_head_offset(fifo, mbx->pulled);
+	head += end;
+
+	/* memory barrier to guarantee data is ready to be read */
+	rmb();
+
+	/* Copy message from Tx FIFO */
+	for (end = fifo->size - end; len; head = fifo->buffer) {
+		do {
+			/* adjust tail to match offset for FIFO */
+			tail &= mask;
+			if (!tail)
+				tail++;
+
+			/* write message to hardware FIFO */
+			fm10k_write_reg(hw, mbmem + tail++, *(head++));
+		} while (--len && --end);
+	}
+}
+
+/**
+ *  fm10k_mbx_pull_head - Pulls data off of head of Tx FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *  @head: acknowledgement number last received
+ *
+ *  This function will push the tail index forward based on the remote
+ *  head index.  It will then pull up to mbmem_len DWORDs off of the
+ *  head of the FIFO and will place it in the MBMEM registers
+ *  associated with the mailbox.
+ **/
+static void fm10k_mbx_pull_head(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx, u16 head)
+{
+	u16 mbmem_len, len, ack = fm10k_mbx_index_len(mbx, head, mbx->tail);
+	struct fm10k_mbx_fifo *fifo = &mbx->tx;
+
+	/* update number of bytes pulled and update bytes in transit */
+	mbx->pulled += mbx->tail_len - ack;
+
+	/* determine length of data to pull, reserve space for mbmem header */
+	mbmem_len = mbx->mbmem_len - 1;
+	len = fm10k_fifo_used(fifo) - mbx->pulled;
+	if (len > mbmem_len)
+		len = mbmem_len;
+
+	/* update tail and record number of bytes in transit */
+	mbx->tail = fm10k_mbx_tail_add(mbx, len - ack);
+	mbx->tail_len = len;
+
+	/* drop pulled messages from the FIFO */
+	for (len = fm10k_fifo_head_len(fifo);
+	     len && (mbx->pulled >= len);
+	     len = fm10k_fifo_head_len(fifo)) {
+		mbx->pulled -= fm10k_fifo_head_drop(fifo);
+		mbx->tx_messages++;
+		mbx->tx_dwords += len;
+	}
+
+	/* Copy message out from the Tx FIFO */
+	fm10k_mbx_write_copy(hw, mbx);
+}
+
+/**
+ *  fm10k_mbx_read_copy - pulls data off of mbmem and places it in Rx FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will take a seciton of the mailbox memory and copy it
+ *  into the Rx FIFO.  The offset is based on the lower bits of the
+ *  head and len determines the length to copy.
+ **/
+static void fm10k_mbx_read_copy(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->rx;
+	u32 mbmem = mbx->mbmem_reg ^ mbx->mbmem_len;
+	u32 *tail = fifo->buffer;
+	u16 end, len, head;
+
+	/* determine data length and mbmem head index */
+	len = mbx->head_len;
+	head = fm10k_mbx_head_sub(mbx, len);
+	if (head >= mbx->mbmem_len)
+		head++;
+
+	/* determine offset in the ring */
+	end = fm10k_fifo_tail_offset(fifo, mbx->pushed);
+	tail += end;
+
+	/* Copy message into Rx FIFO */
+	for (end = fifo->size - end; len; tail = fifo->buffer) {
+		do {
+			/* adjust head to match offset for FIFO */
+			head &= mbx->mbmem_len - 1;
+			if (!head)
+				head++;
+
+			/* read message from hardware FIFO */
+			*(tail++) = fm10k_read_reg(hw, mbmem + head++);
+		} while (--len && --end);
+	}
+
+	/* memory barrier to guarantee FIFO is written before tail update */
+	wmb();
+}
+
+/**
+ *  fm10k_mbx_push_tail - Pushes up to 15 DWORDs on to tail of FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *  @tail: tail index of message
+ *
+ *  This function will first validate the tail index and size for the
+ *  incoming message.  It then updates the acknowlegment number and
+ *  copies the data into the FIFO.  It will return the number of messages
+ *  dequeued on success and a negative value on error.
+ **/
+static s32 fm10k_mbx_push_tail(struct fm10k_hw *hw,
+			       struct fm10k_mbx_info *mbx,
+			       u16 tail)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->rx;
+	u16 len, seq = fm10k_mbx_index_len(mbx, mbx->head, tail);
+
+	/* determine length of data to push */
+	len = fm10k_fifo_unused(fifo) - mbx->pushed;
+	if (len > seq)
+		len = seq;
+
+	/* update head and record bytes received */
+	mbx->head = fm10k_mbx_head_add(mbx, len);
+	mbx->head_len = len;
+
+	/* nothing to do if there is no data */
+	if (!len)
+		return 0;
+
+	/* Copy msg into Rx FIFO */
+	fm10k_mbx_read_copy(hw, mbx);
+
+	/* determine if there are any invalid lengths in message */
+	if (fm10k_mbx_validate_msg_size(mbx, len))
+		return FM10K_MBX_ERR_SIZE;
+
+	/* Update pushed */
+	mbx->pushed += len;
+
+	/* flush any completed messages */
+	for (len = fm10k_mbx_pushed_tail_len(mbx);
+	     len && (mbx->pushed >= len);
+	     len = fm10k_mbx_pushed_tail_len(mbx)) {
+		fifo->tail += len;
+		mbx->pushed -= len;
+		mbx->rx_messages++;
+		mbx->rx_dwords += len;
+	}
+
+	return 0;
+}
+
+/**
+ *  fm10k_mbx_rx_ready - Indicates that a message is ready in the Rx FIFO
+ *  @mbx: pointer to mailbox
+ *
+ *  This function returns true if there is a message in the Rx FIFO to dequeue.
+ **/
+static bool fm10k_mbx_rx_ready(struct fm10k_mbx_info *mbx)
+{
+	u16 msg_size = fm10k_fifo_head_len(&mbx->rx);
+
+	return msg_size && (fm10k_fifo_used(&mbx->rx) >= msg_size);
+}
+
+/**
+ *  fm10k_mbx_tx_ready - Indicates that the mailbox is in state ready for Tx
+ *  @mbx: pointer to mailbox
+ *  @len: verify free space is >= this value
+ *
+ *  This function returns true if the mailbox is in a state ready to transmit.
+ **/
+static bool fm10k_mbx_tx_ready(struct fm10k_mbx_info *mbx, u16 len)
+{
+	u16 fifo_unused = fm10k_fifo_unused(&mbx->tx);
+
+	return (mbx->state == FM10K_STATE_OPEN) && (fifo_unused >= len);
+}
+
+/**
+ *  fm10k_mbx_tx_complete - Indicates that the Tx FIFO has been emptied
+ *  @mbx: pointer to mailbox
+ *
+ *  This function returns true if the Tx FIFO is empty.
+ **/
+static bool fm10k_mbx_tx_complete(struct fm10k_mbx_info *mbx)
+{
+	return fm10k_fifo_empty(&mbx->tx);
+}
+
+/**
+ *  fm10k_mbx_deqeueue_rx - Dequeues the message from the head in the Rx FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function dequeues messages and hands them off to the tlv parser.
+ *  It will return the number of messages processed when called.
+ **/
+static u16 fm10k_mbx_dequeue_rx(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->rx;
+	s32 err;
+	u16 cnt;
+
+	/* parse Rx messages out of the Rx FIFO to empty it */
+	for (cnt = 0; !fm10k_fifo_empty(fifo); cnt++) {
+		err = fm10k_tlv_msg_parse(hw, fifo->buffer + fifo->head,
+					  mbx, mbx->msg_data);
+		if (err < 0)
+			mbx->rx_parse_err++;
+
+		fm10k_fifo_head_drop(fifo);
+	}
+
+	/* shift remaining bytes back to start of FIFO */
+	memmove(fifo->buffer, fifo->buffer + fifo->tail, mbx->pushed << 2);
+
+	/* shift head and tail based on the memory we moved */
+	fifo->tail -= fifo->head;
+	fifo->head = 0;
+
+	return cnt;
+}
+
+/**
+ *  fm10k_mbx_enqueue_tx - Enqueues the message to the tail of the Tx FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *  @msg: message array to read
+ *
+ *  This function enqueues a message up to the size specified by the length
+ *  contained in the first DWORD of the message and will place at the tail
+ *  of the FIFO.  It will return 0 on success, or a negative value on error.
+ **/
+static s32 fm10k_mbx_enqueue_tx(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx, const u32 *msg)
+{
+	u32 countdown = mbx->timeout;
+	s32 err;
+
+	switch (mbx->state) {
+	case FM10K_STATE_CLOSED:
+	case FM10K_STATE_DISCONNECT:
+		return FM10K_MBX_ERR_NO_MBX;
+	default:
+		break;
+	}
+
+	/* enqueue the message on the Tx FIFO */
+	err = fm10k_fifo_enqueue(&mbx->tx, msg);
+
+	/* if it failed give the FIFO a chance to drain */
+	while (err && countdown) {
+		countdown--;
+		udelay(mbx->udelay);
+		mbx->ops.process(hw, mbx);
+		err = fm10k_fifo_enqueue(&mbx->tx, msg);
+	}
+
+	/* if we failed trhead the error */
+	if (err) {
+		mbx->timeout = 0;
+		mbx->tx_busy++;
+	}
+
+	/* begin processing message, ignore errors as this is just meant
+	 * to start the mailbox flow so we are not concerned if there
+	 * is a bad error, or the mailbox is already busy with a request
+	 */
+	if (!mbx->tail_len)
+		mbx->ops.process(hw, mbx);
+
+	return 0;
+}
+
+/**
+ *  fm10k_mbx_read - Copies the mbmem to local message buffer
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function copies the message from the mbmem to the message array
+ **/
+static s32 fm10k_mbx_read(struct fm10k_hw *hw, struct fm10k_mbx_info *mbx)
+{
+	/* only allow one reader in here at a time */
+	if (mbx->mbx_hdr)
+		return FM10K_MBX_ERR_BUSY;
+
+	/* read to capture initial interrupt bits */
+	if (fm10k_read_reg(hw, mbx->mbx_reg) & FM10K_MBX_REQ_INTERRUPT)
+		mbx->mbx_lock = FM10K_MBX_ACK;
+
+	/* write back interrupt bits to clear */
+	fm10k_write_reg(hw, mbx->mbx_reg,
+			FM10K_MBX_REQ_INTERRUPT | FM10K_MBX_ACK_INTERRUPT);
+
+	/* read remote header */
+	mbx->mbx_hdr = fm10k_read_reg(hw, mbx->mbmem_reg ^ mbx->mbmem_len);
+
+	return 0;
+}
+
+/**
+ *  fm10k_mbx_write - Copies the local message buffer to mbmem
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function copies the message from the the message array to mbmem
+ **/
+static void fm10k_mbx_write(struct fm10k_hw *hw, struct fm10k_mbx_info *mbx)
+{
+	u32 mbmem = mbx->mbmem_reg;
+
+	/* write new msg header to notify recepient of change */
+	fm10k_write_reg(hw, mbmem, mbx->mbx_hdr);
+
+	/* write mailbox to sent interrupt */
+	if (mbx->mbx_lock)
+		fm10k_write_reg(hw, mbx->mbx_reg, mbx->mbx_lock);
+
+	/* we no longer are using the header so free it */
+	mbx->mbx_hdr = 0;
+	mbx->mbx_lock = 0;
+}
+
+/**
+ *  fm10k_mbx_reset_work- Reset internal pointers for any pending work
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will reset all internal pointers so any work in progress
+ *  is dropped.  This call should occur every time we transition from the
+ *  open state to the connect state.
+ **/
+static void fm10k_mbx_reset_work(struct fm10k_mbx_info *mbx)
+{
+	/* reset our outgoing max size back to Rx limits */
+	mbx->max_size = mbx->rx.size - 1;
+
+	/* just do a quick resysnc to start of message */
+	mbx->pushed = 0;
+	mbx->pulled = 0;
+	mbx->tail_len = 0;
+	mbx->head_len = 0;
+	mbx->rx.tail = 0;
+	mbx->rx.head = 0;
+}
+
+/**
+ *  fm10k_mbx_update_max_size - Update the max_size and drop any large messages
+ *  @mbx: pointer to mailbox
+ *  @size: new value for max_size
+ *
+ *  This function will update the max_size value and drop any outgoing messages
+ *  from the head of the Tx FIFO that are larger than max_size.
+ **/
+static void fm10k_mbx_update_max_size(struct fm10k_mbx_info *mbx, u16 size)
+{
+	u16 len;
+
+	mbx->max_size = size;
+
+	/* flush any oversized messages from the queue */
+	for (len = fm10k_fifo_head_len(&mbx->tx);
+	     len > size;
+	     len = fm10k_fifo_head_len(&mbx->tx)) {
+		fm10k_fifo_head_drop(&mbx->tx);
+		mbx->tx_dropped++;
+	}
+}
+
+/**
+ *  fm10k_mbx_validate_handlers - Validate layout of message parsing data
+ *  @msg_data: handlers for mailbox events
+ *
+ *  This function validates the layout of the message parsing data.  This
+ *  should be mostly static, but it is important to catch any errors that
+ *  are made when constructing the parsers.
+ **/
+static s32 fm10k_mbx_validate_handlers(const struct fm10k_msg_data *msg_data)
+{
+	const struct fm10k_tlv_attr *attr;
+	unsigned int id;
+
+	/* Allow NULL mailboxes that transmit but don't receive */
+	if (!msg_data)
+		return 0;
+
+	while (msg_data->id != FM10K_TLV_ERROR) {
+		/* all messages should have a function handler */
+		if (!msg_data->func)
+			return FM10K_ERR_PARAM;
+
+		/* parser is optional */
+		attr = msg_data->attr;
+		if (attr) {
+			while (attr->id != FM10K_TLV_ERROR) {
+				id = attr->id;
+				attr++;
+				/* ID should always be increasing */
+				if (id >= attr->id)
+					return FM10K_ERR_PARAM;
+				/* ID should fit in results array */
+				if (id >= FM10K_TLV_RESULTS_MAX)
+					return FM10K_ERR_PARAM;
+			}
+
+			/* verify terminator is in the list */
+			if (attr->id != FM10K_TLV_ERROR)
+				return FM10K_ERR_PARAM;
+		}
+
+		id = msg_data->id;
+		msg_data++;
+		/* ID should always be increasing */
+		if (id >= msg_data->id)
+			return FM10K_ERR_PARAM;
+	}
+
+	/* verify terminator is in the list */
+	if ((msg_data->id != FM10K_TLV_ERROR) || !msg_data->func)
+		return FM10K_ERR_PARAM;
+
+	return 0;
+}
+
+/**
+ *  fm10k_mbx_register_handlers - Register a set of handler ops for mailbox
+ *  @mbx: pointer to mailbox
+ *  @msg_data: handlers for mailbox events
+ *
+ *  This function associates a set of message handling ops with a mailbox.
+ **/
+static s32 fm10k_mbx_register_handlers(struct fm10k_mbx_info *mbx,
+				       const struct fm10k_msg_data *msg_data)
+{
+	/* validate layout of handlers before assigning them */
+	if (fm10k_mbx_validate_handlers(msg_data))
+		return FM10K_ERR_PARAM;
+
+	/* initialize the message handlers */
+	mbx->msg_data = msg_data;
+
+	return 0;
+}
+
+/**
+ *  fm10k_sm_mbx_create_data_hdr - Generate a mailbox header for local FIFO
+ *  @mbx: pointer to mailbox
+ *
+ *  This function returns a connection mailbox header
+ **/
+static void fm10k_sm_mbx_create_data_hdr(struct fm10k_mbx_info *mbx)
+{
+	if (mbx->tail_len)
+		mbx->mbx_lock |= FM10K_MBX_REQ;
+
+	mbx->mbx_hdr = FM10K_MSG_HDR_FIELD_SET(mbx->tail, SM_TAIL) |
+		       FM10K_MSG_HDR_FIELD_SET(mbx->remote, SM_VER) |
+		       FM10K_MSG_HDR_FIELD_SET(mbx->head, SM_HEAD);
+}
+
+/**
+ *  fm10k_sm_mbx_create_connect_hdr - Generate a mailbox header for local FIFO
+ *  @mbx: pointer to mailbox
+ *  @err: error flags to report if any
+ *
+ *  This function returns a connection mailbox header
+ **/
+static void fm10k_sm_mbx_create_connect_hdr(struct fm10k_mbx_info *mbx, u8 err)
+{
+	if (mbx->local)
+		mbx->mbx_lock |= FM10K_MBX_REQ;
+
+	mbx->mbx_hdr = FM10K_MSG_HDR_FIELD_SET(mbx->tail, SM_TAIL) |
+		       FM10K_MSG_HDR_FIELD_SET(mbx->remote, SM_VER) |
+		       FM10K_MSG_HDR_FIELD_SET(mbx->head, SM_HEAD) |
+		       FM10K_MSG_HDR_FIELD_SET(err, SM_ERR);
+}
+
+/**
+ *  fm10k_sm_mbx_connect_reset - Reset following request for reset
+ *  @mbx: pointer to mailbox
+ *
+ *  This function resets the mailbox to a just connected state
+ **/
+static void fm10k_sm_mbx_connect_reset(struct fm10k_mbx_info *mbx)
+{
+	/* flush any uncompleted work */
+	fm10k_mbx_reset_work(mbx);
+
+	/* set local version to max and remote version to 0 */
+	mbx->local = FM10K_SM_MBX_VERSION;
+	mbx->remote = 0;
+
+	/* initalize tail and head */
+	mbx->tail = 1;
+	mbx->head = 1;
+
+	/* reset state back to connect */
+	mbx->state = FM10K_STATE_CONNECT;
+}
+
+/**
+ *  fm10k_sm_mbx_connect - Start switch manager mailbox connection
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will initiate a mailbox connection with the switch
+ *  manager.  To do this it will first disconnect the mailbox, and then
+ *  reconnect it in order to complete a reset of the mailbox.
+ *
+ *  This function will return an error if the mailbox has not been initiated
+ *  or is currently in use.
+ **/
+static s32 fm10k_sm_mbx_connect(struct fm10k_hw *hw, struct fm10k_mbx_info *mbx)
+{
+	/* we cannot connect an uninitialized mailbox */
+	if (!mbx->rx.buffer)
+		return FM10K_MBX_ERR_NO_SPACE;
+
+	/* we cannot connect an already connected mailbox */
+	if (mbx->state != FM10K_STATE_CLOSED)
+		return FM10K_MBX_ERR_BUSY;
+
+	/* mailbox timeout can now become active */
+	mbx->timeout = FM10K_MBX_INIT_TIMEOUT;
+
+	/* Place mbx in ready to connect state */
+	mbx->state = FM10K_STATE_CONNECT;
+	mbx->max_size = FM10K_MBX_MSG_MAX_SIZE;
+
+	/* reset interface back to connect */
+	fm10k_sm_mbx_connect_reset(mbx);
+
+	/* enable interrupt and notify other party of new message */
+	mbx->mbx_lock = FM10K_MBX_REQ_INTERRUPT | FM10K_MBX_ACK_INTERRUPT |
+			FM10K_MBX_INTERRUPT_ENABLE;
+
+	/* generate and load connect header into mailbox */
+	fm10k_sm_mbx_create_connect_hdr(mbx, 0);
+	fm10k_mbx_write(hw, mbx);
+
+	/* enable interrupt and notify other party of new message */
+
+	return 0;
+}
+
+/**
+ *  fm10k_sm_mbx_disconnect - Shutdown mailbox connection
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will shut down the mailbox.  It places the mailbox first
+ *  in the disconnect state, it then allows up to a predefined timeout for
+ *  the mailbox to transition to close on its own.  If this does not occur
+ *  then the mailbox will be forced into the closed state.
+ *
+ *  Any mailbox transactions not completed before calling this function
+ *  are not guaranteed to complete and may be dropped.
+ **/
+static void fm10k_sm_mbx_disconnect(struct fm10k_hw *hw,
+				    struct fm10k_mbx_info *mbx)
+{
+	int timeout = mbx->timeout ? FM10K_MBX_DISCONNECT_TIMEOUT : 0;
+
+	/* Place mbx in ready to disconnect state */
+	mbx->state = FM10K_STATE_DISCONNECT;
+
+	/* trigger interrupt to start shutdown process */
+	fm10k_write_reg(hw, mbx->mbx_reg, FM10K_MBX_REQ |
+					  FM10K_MBX_INTERRUPT_DISABLE);
+	do {
+		udelay(FM10K_MBX_POLL_DELAY);
+		mbx->ops.process(hw, mbx);
+		timeout -= FM10K_MBX_POLL_DELAY;
+	} while ((timeout > 0) && (mbx->state != FM10K_STATE_CLOSED));
+
+	/* in case we didn't close just force the mailbox into shutdown */
+	mbx->state = FM10K_STATE_CLOSED;
+	mbx->remote = 0;
+	fm10k_mbx_reset_work(mbx);
+	fm10k_mbx_update_max_size(mbx, 0);
+
+	fm10k_write_reg(hw, mbx->mbmem_reg, 0);
+}
+
+/**
+ *  fm10k_mbx_validate_fifo_hdr - Validate fields in the remote FIFO header
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will parse up the fields in the mailbox header and return
+ *  an error if the header contains any of a number of invalid configurations
+ *  including unrecognized offsets or version numbers.
+ **/
+static s32 fm10k_sm_mbx_validate_fifo_hdr(struct fm10k_mbx_info *mbx)
+{
+	const u32 *hdr = &mbx->mbx_hdr;
+	u16 tail, head, ver;
+
+	tail = FM10K_MSG_HDR_FIELD_GET(*hdr, SM_TAIL);
+	ver = FM10K_MSG_HDR_FIELD_GET(*hdr, SM_VER);
+	head = FM10K_MSG_HDR_FIELD_GET(*hdr, SM_HEAD);
+
+	switch (ver) {
+	case 0:
+		break;
+	case FM10K_SM_MBX_VERSION:
+		if (!head || head > FM10K_SM_MBX_FIFO_LEN)
+			return FM10K_MBX_ERR_HEAD;
+		if (!tail || tail > FM10K_SM_MBX_FIFO_LEN)
+			return FM10K_MBX_ERR_TAIL;
+		if (mbx->tail < head)
+			head += mbx->mbmem_len - 1;
+		if (tail < mbx->head)
+			tail += mbx->mbmem_len - 1;
+		if (fm10k_mbx_index_len(mbx, head, mbx->tail) > mbx->tail_len)
+			return FM10K_MBX_ERR_HEAD;
+		if (fm10k_mbx_index_len(mbx, mbx->head, tail) < mbx->mbmem_len)
+			break;
+		return FM10K_MBX_ERR_TAIL;
+	default:
+		return FM10K_MBX_ERR_SRC;
+	}
+
+	return 0;
+}
+
+/**
+ *  fm10k_sm_mbx_process_error - Process header with error flag set
+ *  @mbx: pointer to mailbox
+ *
+ *  This function is meant to respond to a request where the error flag
+ *  is set.  As a result we will terminate a connection if one is present
+ *  and fall back into the reset state with a connection header of version
+ *  0 (RESET).
+ **/
+static void fm10k_sm_mbx_process_error(struct fm10k_mbx_info *mbx)
+{
+	const enum fm10k_mbx_state state = mbx->state;
+
+	switch (state) {
+	case FM10K_STATE_DISCONNECT:
+		/* if there is an error just disconnect */
+		mbx->remote = 0;
+		break;
+	case FM10K_STATE_OPEN:
+		/* flush any uncompleted work */
+		fm10k_sm_mbx_connect_reset(mbx);
+		break;
+	case FM10K_STATE_CONNECT:
+		/* try connnecting at lower version */
+		if (mbx->remote) {
+			while (mbx->local > 1)
+				mbx->local--;
+			mbx->remote = 0;
+		}
+		break;
+	default:
+		break;
+	}
+
+	fm10k_sm_mbx_create_connect_hdr(mbx, 0);
+}
+
+/**
+ *  fm10k_sm_mbx_create_error_message - Process an error in FIFO hdr
+ *  @mbx: pointer to mailbox
+ *  @err: local error encountered
+ *
+ *  This function will interpret the error provided by err, and based on
+ *  that it may set the error bit in the local message header
+ **/
+static void fm10k_sm_mbx_create_error_msg(struct fm10k_mbx_info *mbx, s32 err)
+{
+	/* only generate an error message for these types */
+	switch (err) {
+	case FM10K_MBX_ERR_TAIL:
+	case FM10K_MBX_ERR_HEAD:
+	case FM10K_MBX_ERR_SRC:
+	case FM10K_MBX_ERR_SIZE:
+	case FM10K_MBX_ERR_RSVD0:
+		break;
+	default:
+		return;
+	}
+
+	/* process it as though we received an error, and send error reply */
+	fm10k_sm_mbx_process_error(mbx);
+	fm10k_sm_mbx_create_connect_hdr(mbx, 1);
+}
+
+/**
+ *  fm10k_sm_mbx_receive - Take message from Rx mailbox FIFO and put it in Rx
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will dequeue one message from the Rx switch manager mailbox
+ *  FIFO and place it in the Rx mailbox FIFO for processing by software.
+ **/
+static s32 fm10k_sm_mbx_receive(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx,
+				u16 tail)
+{
+	/* reduce length by 1 to convert to a mask */
+	u16 mbmem_len = mbx->mbmem_len - 1;
+	s32 err;
+
+	/* push tail in front of head */
+	if (tail < mbx->head)
+		tail += mbmem_len;
+
+	/* copy data to the Rx FIFO */
+	err = fm10k_mbx_push_tail(hw, mbx, tail);
+	if (err < 0)
+		return err;
+
+	/* process messages if we have received any */
+	fm10k_mbx_dequeue_rx(hw, mbx);
+
+	/* guarantee head aligns with the end of the last message */
+	mbx->head = fm10k_mbx_head_sub(mbx, mbx->pushed);
+	mbx->pushed = 0;
+
+	/* clear any extra bits left over since index adds 1 extra bit */
+	if (mbx->head > mbmem_len)
+		mbx->head -= mbmem_len;
+
+	return err;
+}
+
+/**
+ *  fm10k_sm_mbx_transmit - Take message from Tx and put it in Tx mailbox FIFO
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will dequeue one message from the Tx mailbox FIFO and place
+ *  it in the Tx switch manager mailbox FIFO for processing by hardware.
+ **/
+static void fm10k_sm_mbx_transmit(struct fm10k_hw *hw,
+				  struct fm10k_mbx_info *mbx, u16 head)
+{
+	struct fm10k_mbx_fifo *fifo = &mbx->tx;
+	/* reduce length by 1 to convert to a mask */
+	u16 mbmem_len = mbx->mbmem_len - 1;
+	u16 tail_len, len = 0;
+	u32 *msg;
+
+	/* push head behind tail */
+	if (mbx->tail < head)
+		head += mbmem_len;
+
+	fm10k_mbx_pull_head(hw, mbx, head);
+
+	/* determine msg aligned offset for end of buffer */
+	do {
+		msg = fifo->buffer + fm10k_fifo_head_offset(fifo, len);
+		tail_len = len;
+		len += FM10K_TLV_DWORD_LEN(*msg);
+	} while ((len <= mbx->tail_len) && (len < mbmem_len));
+
+	/* guarantee we stop on a message boundary */
+	if (mbx->tail_len > tail_len) {
+		mbx->tail = fm10k_mbx_tail_sub(mbx, mbx->tail_len - tail_len);
+		mbx->tail_len = tail_len;
+	}
+
+	/* clear any extra bits left over since index adds 1 extra bit */
+	if (mbx->tail > mbmem_len)
+		mbx->tail -= mbmem_len;
+}
+
+/**
+ *  fm10k_sm_mbx_create_reply - Generate reply based on state and remote head
+ *  @mbx: pointer to mailbox
+ *  @head: acknowledgement number
+ *
+ *  This function will generate an outgoing message based on the current
+ *  mailbox state and the remote fifo head.  It will return the length
+ *  of the outgoing message excluding header on success, and a negative value
+ *  on error.
+ **/
+static void fm10k_sm_mbx_create_reply(struct fm10k_hw *hw,
+				      struct fm10k_mbx_info *mbx, u16 head)
+{
+	switch (mbx->state) {
+	case FM10K_STATE_OPEN:
+	case FM10K_STATE_DISCONNECT:
+		/* flush out Tx data */
+		fm10k_sm_mbx_transmit(hw, mbx, head);
+
+		/* generate new header based on data */
+		if (mbx->tail_len || (mbx->state == FM10K_STATE_OPEN)) {
+			fm10k_sm_mbx_create_data_hdr(mbx);
+		} else {
+			mbx->remote = 0;
+			fm10k_sm_mbx_create_connect_hdr(mbx, 0);
+		}
+		break;
+	case FM10K_STATE_CONNECT:
+	case FM10K_STATE_CLOSED:
+		fm10k_sm_mbx_create_connect_hdr(mbx, 0);
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ *  fm10k_sm_mbx_process_reset - Process header with version == 0 (RESET)
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function is meant to respond to a request where the version data
+ *  is set to 0.  As such we will either terminate the connection or go
+ *  into the connect state in order to re-establish the connection.  This
+ *  function can also be used to respond to an error as the connection
+ *  resetting would also be a means of dealing with errors.
+ **/
+static void fm10k_sm_mbx_process_reset(struct fm10k_hw *hw,
+				       struct fm10k_mbx_info *mbx)
+{
+	const enum fm10k_mbx_state state = mbx->state;
+
+	switch (state) {
+	case FM10K_STATE_DISCONNECT:
+		/* drop remote connections and disconnect */
+		mbx->state = FM10K_STATE_CLOSED;
+		mbx->remote = 0;
+		mbx->local = 0;
+		break;
+	case FM10K_STATE_OPEN:
+		/* flush any incomplete work */
+		fm10k_sm_mbx_connect_reset(mbx);
+		break;
+	case FM10K_STATE_CONNECT:
+		/* Update remote value to match local value */
+		mbx->remote = mbx->local;
+	default:
+		break;
+	}
+
+	fm10k_sm_mbx_create_reply(hw, mbx, mbx->tail);
+}
+
+/**
+ *  fm10k_sm_mbx_process_version_1 - Process header with version == 1
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function is meant to process messages received when the remote
+ *  mailbox is active.
+ **/
+static s32 fm10k_sm_mbx_process_version_1(struct fm10k_hw *hw,
+					  struct fm10k_mbx_info *mbx)
+{
+	const u32 *hdr = &mbx->mbx_hdr;
+	u16 head, tail;
+	s32 len;
+
+	/* pull all fields needed for verification */
+	tail = FM10K_MSG_HDR_FIELD_GET(*hdr, SM_TAIL);
+	head = FM10K_MSG_HDR_FIELD_GET(*hdr, SM_HEAD);
+
+	/* if we are in connect and wanting version 1 then start up and go */
+	if (mbx->state == FM10K_STATE_CONNECT) {
+		if (!mbx->remote)
+			goto send_reply;
+		if (mbx->remote != 1)
+			return FM10K_MBX_ERR_SRC;
+
+		mbx->state = FM10K_STATE_OPEN;
+	}
+
+	do {
+		/* abort on message size errors */
+		len = fm10k_sm_mbx_receive(hw, mbx, tail);
+		if (len < 0)
+			return len;
+
+		/* continue until we have flushed the Rx FIFO */
+	} while (len);
+
+send_reply:
+	fm10k_sm_mbx_create_reply(hw, mbx, head);
+
+	return 0;
+}
+
+/**
+ *  fm10k_sm_mbx_process - Process mailbox switch mailbox interrupt
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *
+ *  This function will process incoming mailbox events and generate mailbox
+ *  replies.  It will return a value indicating the number of DWORDs
+ *  transmitted excluding header on success or a negative value on error.
+ **/
+static s32 fm10k_sm_mbx_process(struct fm10k_hw *hw,
+				struct fm10k_mbx_info *mbx)
+{
+	s32 err;
+
+	/* we do not read mailbox if closed */
+	if (mbx->state == FM10K_STATE_CLOSED)
+		return 0;
+
+	/* retrieve data from switch manager */
+	err = fm10k_mbx_read(hw, mbx);
+	if (err)
+		return err;
+
+	err = fm10k_sm_mbx_validate_fifo_hdr(mbx);
+	if (err < 0)
+		goto fifo_err;
+
+	if (FM10K_MSG_HDR_FIELD_GET(mbx->mbx_hdr, SM_ERR)) {
+		fm10k_sm_mbx_process_error(mbx);
+		goto fifo_err;
+	}
+
+	switch (FM10K_MSG_HDR_FIELD_GET(mbx->mbx_hdr, SM_VER)) {
+	case 0:
+		fm10k_sm_mbx_process_reset(hw, mbx);
+		break;
+	case FM10K_SM_MBX_VERSION:
+		err = fm10k_sm_mbx_process_version_1(hw, mbx);
+		break;
+	}
+
+fifo_err:
+	if (err < 0)
+		fm10k_sm_mbx_create_error_msg(mbx, err);
+
+	/* report data to switch manager */
+	fm10k_mbx_write(hw, mbx);
+
+	return err;
+}
+
+/**
+ *  fm10k_sm_mbx_init - Initialize mailbox memory for PF/SM mailbox
+ *  @hw: pointer to hardware structure
+ *  @mbx: pointer to mailbox
+ *  @msg_data: handlers for mailbox events
+ *
+ *  This function for now is used to stub out the PF/SM mailbox
+ **/
+s32 fm10k_sm_mbx_init(struct fm10k_hw *hw, struct fm10k_mbx_info *mbx,
+		      const struct fm10k_msg_data *msg_data)
+{
+	mbx->mbx_reg = FM10K_GMBX;
+	mbx->mbmem_reg = FM10K_MBMEM_PF(0);
+	/* start out in closed state */
+	mbx->state = FM10K_STATE_CLOSED;
+
+	/* validate layout of handlers before assigning them */
+	if (fm10k_mbx_validate_handlers(msg_data))
+		return FM10K_ERR_PARAM;
+
+	/* initialize the message handlers */
+	mbx->msg_data = msg_data;
+
+	/* start mailbox as timed out and let the reset_hw call
+	 * set the timeout value to begin communications
+	 */
+	mbx->timeout = 0;
+	mbx->udelay = FM10K_MBX_INIT_DELAY;
+
+	/* Split buffer for use by Tx/Rx FIFOs */
+	mbx->max_size = FM10K_MBX_MSG_MAX_SIZE;
+	mbx->mbmem_len = FM10K_MBMEM_PF_XOR;
+
+	/* initialize the FIFOs, sizes are in 4 byte increments */
+	fm10k_fifo_init(&mbx->tx, mbx->buffer, FM10K_MBX_TX_BUFFER_SIZE);
+	fm10k_fifo_init(&mbx->rx, &mbx->buffer[FM10K_MBX_TX_BUFFER_SIZE],
+			FM10K_MBX_RX_BUFFER_SIZE);
+
+	/* initialize function pointers */
+	mbx->ops.connect = fm10k_sm_mbx_connect;
+	mbx->ops.disconnect = fm10k_sm_mbx_disconnect;
+	mbx->ops.rx_ready = fm10k_mbx_rx_ready;
+	mbx->ops.tx_ready = fm10k_mbx_tx_ready;
+	mbx->ops.tx_complete = fm10k_mbx_tx_complete;
+	mbx->ops.enqueue_tx = fm10k_mbx_enqueue_tx;
+	mbx->ops.process = fm10k_sm_mbx_process;
+	mbx->ops.register_handlers = fm10k_mbx_register_handlers;
+
+	return 0;
+}
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_mbx.h b/drivers/net/ethernet/intel/fm10k/fm10k_mbx.h
index cb7aa4af9437..f5ba86f0f725 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_mbx.h
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_mbx.h
@@ -237,4 +237,7 @@ struct fm10k_mbx_info {
 	u32 buffer[FM10K_MBX_BUFFER_SIZE];
 };
 
+s32 fm10k_sm_mbx_init(struct fm10k_hw *, struct fm10k_mbx_info *,
+		      const struct fm10k_msg_data *);
+
 #endif /* _FM10K_MBX_H_ */