scsi: mpt3sas: Introduce struct mpt3sas_nvme_cmd

Make _base_build_nvme_prp() easier to read by introducing a structure
to access NVMe command fields.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Sathya Prakash <sathya.prakash@broadcom.com>
Cc: Chaitra P B <chaitra.basappa@broadcom.com>
Cc: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.c

@@ -1864,6 +1864,8 @@ _base_build_nvme_prp(struct MPT3SAS_ADAPTER *ioc, u16 smid,
 	u32		offset, entry_len;
 	u32		page_mask_result, page_mask;
 	size_t		length;
+	struct mpt3sas_nvme_cmd *nvme_cmd =
+		(void *)nvme_encap_request->NVMe_Command;
 
 	/*
 	 * Not all commands require a data transfer. If no data, just return
@@ -1871,15 +1873,8 @@ _base_build_nvme_prp(struct MPT3SAS_ADAPTER *ioc, u16 smid,
 	 */
 	if (!data_in_sz && !data_out_sz)
 		return;
-	/*
-	 * Set pointers to PRP1 and PRP2, which are in the NVMe command.
-	 * PRP1 is located at a 24 byte offset from the start of the NVMe
-	 * command.  Then set the current PRP entry pointer to PRP1.
-	 */
-	prp1_entry = (__le64 *)(nvme_encap_request->NVMe_Command +
-	    NVME_CMD_PRP1_OFFSET);
-	prp2_entry = (__le64 *)(nvme_encap_request->NVMe_Command +
-	    NVME_CMD_PRP2_OFFSET);
+	prp1_entry = &nvme_cmd->prp1;
+	prp2_entry = &nvme_cmd->prp2;
 	prp_entry = prp1_entry;
 	/*
 	 * For the PRP entries, use the specially allocated buffer of

drivers/scsi/mpt3sas/mpt3sas_base.h

@@ -143,14 +143,17 @@
  * NVMe defines
  */
 #define	NVME_PRP_SIZE			8	/* PRP size */
-#define	NVME_CMD_PRP1_OFFSET		24	/* PRP1 offset in NVMe cmd */
-#define	NVME_CMD_PRP2_OFFSET		32	/* PRP2 offset in NVMe cmd */
 #define	NVME_ERROR_RESPONSE_SIZE	16	/* Max NVME Error Response */
 #define NVME_TASK_ABORT_MIN_TIMEOUT	6
 #define NVME_TASK_ABORT_MAX_TIMEOUT	60
 #define NVME_TASK_MNGT_CUSTOM_MASK	(0x0010)
 #define	NVME_PRP_PAGE_SIZE		4096	/* Page size */
 
+struct mpt3sas_nvme_cmd {
+	u8	rsvd[24];
+	__le64	prp1;
+	__le64	prp2;
+};
 
 /*
  * reset phases