qed: Wait for ready indication before rereading the shmem

The MFW might be reset and re-update its shared memory.
Upon the detection of such a reset the driver rereads this memory, but it
has to wait till the data is valid.
This patch adds the missing wait for a data ready indication.
Signed-off-by: NTomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: NAriel Elior <Ariel.Elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_mcp.c

@@ -183,18 +183,57 @@ int qed_mcp_free(struct qed_hwfn *p_hwfn)
 	return 0;
 }
 
+/* Maximum of 1 sec to wait for the SHMEM ready indication */
+#define QED_MCP_SHMEM_RDY_MAX_RETRIES	20
+#define QED_MCP_SHMEM_RDY_ITER_MS	50
+
 static int qed_load_mcp_offsets(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt)
 {
 	struct qed_mcp_info *p_info = p_hwfn->mcp_info;
+	u8 cnt = QED_MCP_SHMEM_RDY_MAX_RETRIES;
+	u8 msec = QED_MCP_SHMEM_RDY_ITER_MS;
 	u32 drv_mb_offsize, mfw_mb_offsize;
 	u32 mcp_pf_id = MCP_PF_ID(p_hwfn);
 
 	p_info->public_base = qed_rd(p_hwfn, p_ptt, MISC_REG_SHARED_MEM_ADDR);
-	if (!p_info->public_base)
-		return 0;
+	if (!p_info->public_base) {
+		DP_NOTICE(p_hwfn,
+			  "The address of the MCP scratch-pad is not configured\n");
+		return -EINVAL;
+	}
 
 	p_info->public_base |= GRCBASE_MCP;
 
+	/* Get the MFW MB address and number of supported messages */
+	mfw_mb_offsize = qed_rd(p_hwfn, p_ptt,
+				SECTION_OFFSIZE_ADDR(p_info->public_base,
+						     PUBLIC_MFW_MB));
+	p_info->mfw_mb_addr = SECTION_ADDR(mfw_mb_offsize, mcp_pf_id);
+	p_info->mfw_mb_length = (u16)qed_rd(p_hwfn, p_ptt,
+					    p_info->mfw_mb_addr +
+					    offsetof(struct public_mfw_mb,
+						     sup_msgs));
+
+	/* The driver can notify that there was an MCP reset, and might read the
+	 * SHMEM values before the MFW has completed initializing them.
+	 * To avoid this, the "sup_msgs" field in the MFW mailbox is used as a
+	 * data ready indication.
+	 */
+	while (!p_info->mfw_mb_length && --cnt) {
+		msleep(msec);
+		p_info->mfw_mb_length =
+			(u16)qed_rd(p_hwfn, p_ptt,
+				    p_info->mfw_mb_addr +
+				    offsetof(struct public_mfw_mb, sup_msgs));
+	}
+
+	if (!cnt) {
+		DP_NOTICE(p_hwfn,
+			  "Failed to get the SHMEM ready notification after %d msec\n",
+			  QED_MCP_SHMEM_RDY_MAX_RETRIES * msec);
+		return -EBUSY;
+	}
+
 	/* Calculate the driver and MFW mailbox address */
 	drv_mb_offsize = qed_rd(p_hwfn, p_ptt,
 				SECTION_OFFSIZE_ADDR(p_info->public_base,
@@ -204,13 +243,6 @@ static int qed_load_mcp_offsets(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt)
 		   "drv_mb_offsiz = 0x%x, drv_mb_addr = 0x%x mcp_pf_id = 0x%x\n",
 		   drv_mb_offsize, p_info->drv_mb_addr, mcp_pf_id);
 
-	/* Set the MFW MB address */
-	mfw_mb_offsize = qed_rd(p_hwfn, p_ptt,
-				SECTION_OFFSIZE_ADDR(p_info->public_base,
-						     PUBLIC_MFW_MB));
-	p_info->mfw_mb_addr = SECTION_ADDR(mfw_mb_offsize, mcp_pf_id);
-	p_info->mfw_mb_length =	(u16)qed_rd(p_hwfn, p_ptt, p_info->mfw_mb_addr);
-
 	/* Get the current driver mailbox sequence before sending
 	 * the first command
 	 */