scsi: aacraid: Auto detect INTx or MSIx mode during sync cmd processing

During sync command processing, if legacy INTx status indicates command
is not completed, sample the MSIx register and check if it indicates
command completion, set controller MSIx enabled flag.
Signed-off-by: Prasad B Munirathnam <prasad.munirathnam@microsemi.com>
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Reviewed-by: Dave Carroll <david.carroll@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aacraid/aacraid.h

@@ -1231,6 +1231,7 @@ struct src_registers {
 
 #define SRC_ODR_SHIFT		12
 #define SRC_IDR_SHIFT		9
+#define SRC_MSI_READ_MASK	0x1000
 
 typedef void (*fib_callback)(void *ctxt, struct fib *fibctx);
 

drivers/scsi/aacraid/src.c

@@ -1405,13 +1405,23 @@ void aac_src_access_devreg(struct aac_dev *dev, int mode)
 
 static int aac_src_get_sync_status(struct aac_dev *dev)
 {
+	int msix_val = 0;
+	int legacy_val = 0;
 
-	int val;
+	msix_val = src_readl(dev, MUnit.ODR_MSI) & SRC_MSI_READ_MASK ? 1 : 0;
 
-	if (dev->msi_enabled)
-		val = src_readl(dev, MUnit.ODR_MSI) & 0x1000 ? 1 : 0;
-	else
-		val = src_readl(dev, MUnit.ODR_R) >> SRC_ODR_SHIFT;
+	if (!dev->msi_enabled) {
+		/*
+		 * if Legacy int status indicates cmd is not complete
+		 * sample MSIx register to see if it indiactes cmd complete,
+		 * if yes set the controller in MSIx mode and consider cmd
+		 * completed
+		 */
+		legacy_val = src_readl(dev, MUnit.ODR_R) >> SRC_ODR_SHIFT;
+		if (!(legacy_val & 1) && msix_val)
+			dev->msi_enabled = 1;
+		return legacy_val;
+	}
 
-	return val;
+	return msix_val;
 }