scsi: megaraid_sas: Offload Aero RAID5/6 division calculations to driver

For RAID5/RAID6 volumes configured behind Aero, driver will be doing 64bit
division operations on behalf of firmware as controller's ARM CPU is very
slow in this division. Later, driver calculates Q-ARM, P-ARM and Log-ARM and
passes those values to firmware by writing these values to RAID_CONTEXT.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -5777,8 +5777,16 @@ static int megasas_init_fw(struct megasas_instance *instance)
 			MR_MAX_RAID_MAP_SIZE_MASK);
 	}
 
-	if (instance->adapter_type == VENTURA_SERIES)
+	switch (instance->adapter_type) {
+	case VENTURA_SERIES:
 		fusion->pcie_bw_limitation = true;
+		break;
+	case AERO_SERIES:
+		fusion->r56_div_offload = true;
+		break;
+	default:
+		break;
+	}
 
 	/* Check if MSI-X is supported while in ready state */
 	msix_enable = (instance->instancet->read_fw_status_reg(instance) &

drivers/scsi/megaraid/megaraid_sas_fp.c

@@ -901,6 +901,77 @@ u8 MR_GetPhyParams(struct megasas_instance *instance, u32 ld, u64 stripRow,
 	return retval;
 }
 
+/*
+ * mr_get_phy_params_r56_rmw -  Calculate parameters for R56 CTIO write operation
+ * @instance:			Adapter soft state
+ * @ld:				LD index
+ * @stripNo:			Strip Number
+ * @io_info:			IO info structure pointer
+ * pRAID_Context:		RAID context pointer
+ * map:				RAID map pointer
+ *
+ * This routine calculates the logical arm, data Arm, row number and parity arm
+ * for R56 CTIO write operation.
+ */
+static void mr_get_phy_params_r56_rmw(struct megasas_instance *instance,
+			    u32 ld, u64 stripNo,
+			    struct IO_REQUEST_INFO *io_info,
+			    struct RAID_CONTEXT_G35 *pRAID_Context,
+			    struct MR_DRV_RAID_MAP_ALL *map)
+{
+	struct MR_LD_RAID  *raid = MR_LdRaidGet(ld, map);
+	u8          span, dataArms, arms, dataArm, logArm;
+	s8          rightmostParityArm, PParityArm;
+	u64         rowNum;
+	u64 *pdBlock = &io_info->pdBlock;
+
+	dataArms = raid->rowDataSize;
+	arms = raid->rowSize;
+
+	rowNum =  mega_div64_32(stripNo, dataArms);
+	/* parity disk arm, first arm is 0 */
+	rightmostParityArm = (arms - 1) - mega_mod64(rowNum, arms);
+
+	/* logical arm within row */
+	logArm =  mega_mod64(stripNo, dataArms);
+	/* physical arm for data */
+	dataArm = mega_mod64((rightmostParityArm + 1 + logArm), arms);
+
+	if (raid->spanDepth == 1) {
+		span = 0;
+	} else {
+		span = (u8)MR_GetSpanBlock(ld, rowNum, pdBlock, map);
+		if (span == SPAN_INVALID)
+			return;
+	}
+
+	if (raid->level == 6) {
+		/* P Parity arm, note this can go negative adjust if negative */
+		PParityArm = (arms - 2) - mega_mod64(rowNum, arms);
+
+		if (PParityArm < 0)
+			PParityArm += arms;
+
+		/* rightmostParityArm is P-Parity for RAID 5 and Q-Parity for RAID */
+		pRAID_Context->flow_specific.r56_arm_map = rightmostParityArm;
+		pRAID_Context->flow_specific.r56_arm_map |=
+				    (u16)(PParityArm << RAID_CTX_R56_P_ARM_SHIFT);
+	} else {
+		pRAID_Context->flow_specific.r56_arm_map |=
+				    (u16)(rightmostParityArm << RAID_CTX_R56_P_ARM_SHIFT);
+	}
+
+	pRAID_Context->reg_lock_row_lba = cpu_to_le64(rowNum);
+	pRAID_Context->flow_specific.r56_arm_map |=
+				   (u16)(logArm << RAID_CTX_R56_LOG_ARM_SHIFT);
+	cpu_to_le16s(&pRAID_Context->flow_specific.r56_arm_map);
+	pRAID_Context->span_arm = (span << RAID_CTX_SPANARM_SPAN_SHIFT) | dataArm;
+	pRAID_Context->raid_flags = (MR_RAID_FLAGS_IO_SUB_TYPE_R56_DIV_OFFLOAD <<
+				    MR_RAID_CTX_RAID_FLAGS_IO_SUB_TYPE_SHIFT);
+
+	return;
+}
+
 /*
 ******************************************************************************
 *
@@ -1108,6 +1179,13 @@ MR_BuildRaidContext(struct megasas_instance *instance,
 	/* save pointer to raid->LUN array */
 	*raidLUN = raid->LUN;
 
+	/* Aero R5/6 Division Offload for WRITE */
+	if (fusion->r56_div_offload && (raid->level >= 5) && !isRead) {
+		mr_get_phy_params_r56_rmw(instance, ld, start_strip, io_info,
+				       (struct RAID_CONTEXT_G35 *)pRAID_Context,
+				       map);
+		return true;
+	}
 
 	/*Get Phy Params only if FP capable, or else leave it to MR firmware
 	  to do the calculation.*/

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -3324,9 +3324,9 @@ void megasas_prepare_secondRaid1_IO(struct megasas_instance *instance,
 	r1_cmd->request_desc->SCSIIO.DevHandle = cmd->r1_alt_dev_handle;
 	r1_cmd->io_request->DevHandle = cmd->r1_alt_dev_handle;
 	r1_cmd->r1_alt_dev_handle = cmd->io_request->DevHandle;
-	cmd->io_request->RaidContext.raid_context_g35.smid.peer_smid =
+	cmd->io_request->RaidContext.raid_context_g35.flow_specific.peer_smid =
 			cpu_to_le16(r1_cmd->index);
-	r1_cmd->io_request->RaidContext.raid_context_g35.smid.peer_smid =
+	r1_cmd->io_request->RaidContext.raid_context_g35.flow_specific.peer_smid =
 			cpu_to_le16(cmd->index);
 	/*MSIxIndex of both commands request descriptors should be same*/
 	r1_cmd->request_desc->SCSIIO.MSIxIndex =
@@ -3444,7 +3444,7 @@ megasas_complete_r1_command(struct megasas_instance *instance,
 
 	rctx_g35 = &cmd->io_request->RaidContext.raid_context_g35;
 	fusion = instance->ctrl_context;
-	peer_smid = le16_to_cpu(rctx_g35->smid.peer_smid);
+	peer_smid = le16_to_cpu(rctx_g35->flow_specific.peer_smid);
 
 	r1_cmd = fusion->cmd_list[peer_smid - 1];
 	scmd_local = cmd->scmd;

drivers/scsi/megaraid/megaraid_sas_fusion.h

@@ -87,7 +87,8 @@ enum MR_RAID_FLAGS_IO_SUB_TYPE {
 	MR_RAID_FLAGS_IO_SUB_TYPE_RMW_P        = 3,
 	MR_RAID_FLAGS_IO_SUB_TYPE_RMW_Q        = 4,
 	MR_RAID_FLAGS_IO_SUB_TYPE_CACHE_BYPASS = 6,
-	MR_RAID_FLAGS_IO_SUB_TYPE_LDIO_BW_LIMIT = 7
+	MR_RAID_FLAGS_IO_SUB_TYPE_LDIO_BW_LIMIT = 7,
+	MR_RAID_FLAGS_IO_SUB_TYPE_R56_DIV_OFFLOAD = 8
 };
 
 /*
@@ -151,12 +152,15 @@ struct RAID_CONTEXT_G35 {
 	u16 timeout_value; /* 0x02 -0x03 */
 	u16		routing_flags;	// 0x04 -0x05 routing flags
 	u16 virtual_disk_tgt_id;   /* 0x06 -0x07 */
-	u64 reg_lock_row_lba;      /* 0x08 - 0x0F */
+	__le64 reg_lock_row_lba;      /* 0x08 - 0x0F */
 	u32 reg_lock_length;      /* 0x10 - 0x13 */
-	union {
-		u16 next_lmid; /* 0x14 - 0x15 */
-		u16	peer_smid;	/* used for the raid 1/10 fp writes */
-	} smid;
+	union {                     // flow specific
+		u16 rmw_op_index;   /* 0x14 - 0x15, R5/6 RMW: rmw operation index*/
+		u16 peer_smid;      /* 0x14 - 0x15, R1 Write: peer smid*/
+		u16 r56_arm_map;    /* 0x14 - 0x15, Unused [15], LogArm[14:10], P-Arm[9:5], Q-Arm[4:0] */
+
+	} flow_specific;
+
 	u8 ex_status;       /* 0x16 : OUT */
 	u8 status;          /* 0x17 status */
 	u8 raid_flags;		/* 0x18 resvd[7:6], ioSubType[5:4],
@@ -247,6 +251,13 @@ union RAID_CONTEXT_UNION {
 #define RAID_CTX_SPANARM_SPAN_SHIFT	(5)
 #define RAID_CTX_SPANARM_SPAN_MASK	(0xE0)
 
+/* LogArm[14:10], P-Arm[9:5], Q-Arm[4:0] */
+#define RAID_CTX_R56_Q_ARM_MASK		(0x1F)
+#define RAID_CTX_R56_P_ARM_SHIFT	(5)
+#define RAID_CTX_R56_P_ARM_MASK		(0x3E0)
+#define RAID_CTX_R56_LOG_ARM_SHIFT	(10)
+#define RAID_CTX_R56_LOG_ARM_MASK	(0x7C00)
+
 /* number of bits per index in U32 TrackStream */
 #define BITS_PER_INDEX_STREAM		4
 #define INVALID_STREAM_NUM              16
@@ -1336,6 +1347,7 @@ struct fusion_context {
 	struct MPI2_IOC_INIT_REQUEST *ioc_init_request;
 	struct megasas_cmd *ioc_init_cmd;
 	bool pcie_bw_limitation;
+	bool r56_div_offload;
 };
 
 union desc_value {