dmaengine: ioatdma: adding shutdown support

The ioatdma needs to be queisced and block all additional op submission
during reboots. When NET_DMA was used, this caused issue as ops were still
being sent to ioatdma during reboots even though PCI BME has been turned
off. Even though NET_DMA has been deprecated, we need to prevent similar
situations. The shutdown handler should address that.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index 1bc08498..8f4e607 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -82,8 +82,9 @@
 	struct dma_pool *sed_hw_pool[MAX_SED_POOLS];
 	struct dma_device dma_dev;
 	u8 version;
-	struct msix_entry msix_entries[4];
-	struct ioatdma_chan *idx[4];
+#define IOAT_MAX_CHANS 4
+	struct msix_entry msix_entries[IOAT_MAX_CHANS];
+	struct ioatdma_chan *idx[IOAT_MAX_CHANS];
 	struct dca_provider *dca;
 	enum ioat_irq_mode irq_mode;
 	u32 cap;
@@ -95,6 +96,7 @@
 	dma_addr_t last_completion;
 	spinlock_t cleanup_lock;
 	unsigned long state;
+	#define IOAT_CHAN_DOWN 0
 	#define IOAT_COMPLETION_ACK 1
 	#define IOAT_RESET_PENDING 2
 	#define IOAT_KOBJ_INIT_FAIL 3