scsi: megaraid_sas: Add 32 bit atomic descriptor support to AERO adapters

Aero adapters provides Atomic Request Descriptor as an alternative method
for posting an entry onto a request queue. The posting of an Atomic Request
Descriptor is an atomic operation, providing a safe mechanism for multiple
processors on the host to post requests without synchronization. This
Atomic Request Descriptor format is identical to first 32 bits of Default
Request Descriptor and uses only 32 bits.

If Aero adapters support Atomic descriptor, driver should use it for
posting IOs and DCMDs to firmware.
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.h

@@ -1600,6 +1600,8 @@ enum FW_BOOT_CONTEXT {
 
 #define MR_CAN_HANDLE_SYNC_CACHE_OFFSET		0X01000000
 
+#define MR_ATOMIC_DESCRIPTOR_SUPPORT_OFFSET	(1 << 24)
+
 #define MR_CAN_HANDLE_64_BIT_DMA_OFFSET		(1 << 25)
 
 #define MEGASAS_WATCHDOG_THREAD_INTERVAL	1000
@@ -2395,6 +2397,7 @@ struct megasas_instance {
 	struct dentry *raidmap_dump;
 #endif
 	u8 enable_fw_dev_list;
+	bool atomic_desc_support;
 };
 struct MR_LD_VF_MAP {
 	u32 size;

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -277,21 +277,17 @@ inline void megasas_return_cmd_fusion(struct megasas_instance *instance,
 }
 
 /**
- * megasas_fire_cmd_fusion -	Sends command to the FW
- * @instance:			Adapter soft state
- * @req_desc:			64bit Request descriptor
- *
- * Perform PCI Write.
+ * megasas_write_64bit_req_desc -	PCI writes 64bit request descriptor
+ * @instance:				Adapter soft state
+ * @req_desc:				64bit Request descriptor
  */
-
 static void
-megasas_fire_cmd_fusion(struct megasas_instance *instance,
+megasas_write_64bit_req_desc(struct megasas_instance *instance,
 		union MEGASAS_REQUEST_DESCRIPTOR_UNION *req_desc)
 {
 #if defined(writeq) && defined(CONFIG_64BIT)
 	u64 req_data = (((u64)le32_to_cpu(req_desc->u.high) << 32) |
 		le32_to_cpu(req_desc->u.low));
-
 	writeq(req_data, &instance->reg_set->inbound_low_queue_port);
 #else
 	unsigned long flags;
@@ -304,6 +300,25 @@ megasas_fire_cmd_fusion(struct megasas_instance *instance,
 #endif
 }
 
+/**
+ * megasas_fire_cmd_fusion -	Sends command to the FW
+ * @instance:			Adapter soft state
+ * @req_desc:			32bit or 64bit Request descriptor
+ *
+ * Perform PCI Write. AERO SERIES supports 32 bit Descriptor.
+ * Prior to AERO_SERIES support 64 bit Descriptor.
+ */
+static void
+megasas_fire_cmd_fusion(struct megasas_instance *instance,
+		union MEGASAS_REQUEST_DESCRIPTOR_UNION *req_desc)
+{
+	if (instance->atomic_desc_support)
+		writel(le32_to_cpu(req_desc->u.low),
+			&instance->reg_set->inbound_single_queue_port);
+	else
+		megasas_write_64bit_req_desc(instance, req_desc);
+}
+
 /**
  * megasas_fusion_update_can_queue -	Do all Adapter Queue depth related calculations here
  * @instance:							Adapter soft state
@@ -1171,7 +1186,8 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
 			break;
 	}
 
-	megasas_fire_cmd_fusion(instance, &req_desc);
+	/* For AERO also, IOC_INIT requires 64 bit descriptor write */
+	megasas_write_64bit_req_desc(instance, &req_desc);
 
 	wait_and_poll(instance, cmd, MFI_IO_TIMEOUT_SECS);
 
@@ -1181,6 +1197,17 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
 		goto fail_fw_init;
 	}
 
+	if (instance->adapter_type >= AERO_SERIES) {
+		scratch_pad_1 = megasas_readl
+			(instance, &instance->reg_set->outbound_scratch_pad_1);
+
+		instance->atomic_desc_support =
+			(scratch_pad_1 & MR_ATOMIC_DESCRIPTOR_SUPPORT_OFFSET) ? 1 : 0;
+
+		dev_info(&instance->pdev->dev, "FW supports atomic descriptor\t: %s\n",
+			instance->atomic_desc_support ? "Yes" : "No");
+	}
+
 	return 0;
 
 fail_fw_init: