aacraid: Fix for KDUMP driver hang

When KDUMP is triggered the driver first talks to the firmware in INTX
mode, but the adapter firmware is still in MSIX mode. Therefore the first
driver command hangs since the driver is waiting for an INTX response and
firmware gives a MSIX response. If when the OS is installed on a RAID
drive created by the adapter KDUMP will hang since the driver does not
receive a response in sync mode.

Fixed by: Change the firmware to INTX mode if it is in MSIX mode before
sending the first sync command.

Cc: stable@vger.kernel.org
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aacraid/aacraid.h

@@ -29,6 +29,7 @@ enum {
 #define AAC_INT_MODE_MSI		(1<<1)
 #define AAC_INT_MODE_AIF		(1<<2)
 #define AAC_INT_MODE_SYNC		(1<<3)
+#define AAC_INT_MODE_MSIX		(1<<16)
 
 #define AAC_INT_ENABLE_TYPE1_INTX	0xfffffffb
 #define AAC_INT_ENABLE_TYPE1_MSIX	0xfffffffa

drivers/scsi/aacraid/comminit.c

@@ -37,6 +37,7 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
+#include <linux/delay.h>
 #include <linux/completion.h>
 #include <linux/mm.h>
 #include <scsi/scsi_host.h>
@@ -47,6 +48,20 @@ struct aac_common aac_config = {
 	.irq_mod = 1
 };
 
+static inline int aac_is_msix_mode(struct aac_dev *dev)
+{
+	u32 status;
+
+	status = src_readl(dev, MUnit.OMR);
+	return (status & AAC_INT_MODE_MSIX);
+}
+
+static inline void aac_change_to_intx(struct aac_dev *dev)
+{
+	aac_src_access_devreg(dev, AAC_DISABLE_MSIX);
+	aac_src_access_devreg(dev, AAC_ENABLE_INTX);
+}
+
 static int aac_alloc_comm(struct aac_dev *dev, void **commaddr, unsigned long commsize, unsigned long commalign)
 {
 	unsigned char *base;
@@ -414,6 +429,15 @@ struct aac_dev *aac_init_adapter(struct aac_dev *dev)
 	dev->comm_interface = AAC_COMM_PRODUCER;
 	dev->raw_io_interface = dev->raw_io_64 = 0;
 
+
+	/*
+	 * Enable INTX mode, if not done already Enabled
+	 */
+	if (aac_is_msix_mode(dev)) {
+		aac_change_to_intx(dev);
+		dev_info(&dev->pdev->dev, "Changed firmware to INTX mode");
+	}
+
 	if ((!aac_adapter_sync_cmd(dev, GET_ADAPTER_PROPERTIES,
 		0, 0, 0, 0, 0, 0,
 		status+0, status+1, status+2, status+3, NULL)) &&