diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index 8a708b7..3dfb28a 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -337,7 +337,7 @@
 	return idx_to_prio[index];
 }
 
-u16 b43_dmacontroller_base(int dma64bit, int controller_idx)
+static u16 b43_dmacontroller_base(enum b43_dmatype type, int controller_idx)
 {
 	static const u16 map64[] = {
 		B43_MMIO_DMA64_BASE0,
@@ -356,7 +356,7 @@
 		B43_MMIO_DMA32_BASE5,
 	};
 
-	if (dma64bit) {
+	if (type == B43_DMA_64BIT) {
 		B43_WARN_ON(!(controller_idx >= 0 &&
 			      controller_idx < ARRAY_SIZE(map64)));
 		return map64[controller_idx];
@@ -437,7 +437,7 @@
 	 * 02, which uses 64-bit DMA, needs the ring buffer in very low memory,
 	 * which accounts for the GFP_DMA flag below.
 	 */
-	if (ring->dma64)
+	if (ring->type == B43_DMA_64BIT)
 		flags |= GFP_DMA;
 	ring->descbase = dma_alloc_coherent(dev, B43_DMA_RINGMEMSIZE,
 					    &(ring->dmabase), flags);
@@ -459,7 +459,8 @@
 }
 
 /* Reset the RX DMA channel */
-int b43_dmacontroller_rx_reset(struct b43_wldev *dev, u16 mmio_base, int dma64)
+static int b43_dmacontroller_rx_reset(struct b43_wldev *dev, u16 mmio_base,
+				      enum b43_dmatype type)
 {
 	int i;
 	u32 value;
@@ -467,12 +468,13 @@
 
 	might_sleep();
 
-	offset = dma64 ? B43_DMA64_RXCTL : B43_DMA32_RXCTL;
+	offset = (type == B43_DMA_64BIT) ? B43_DMA64_RXCTL : B43_DMA32_RXCTL;
 	b43_write32(dev, mmio_base + offset, 0);
 	for (i = 0; i < 10; i++) {
-		offset = dma64 ? B43_DMA64_RXSTATUS : B43_DMA32_RXSTATUS;
+		offset = (type == B43_DMA_64BIT) ? B43_DMA64_RXSTATUS :
+						   B43_DMA32_RXSTATUS;
 		value = b43_read32(dev, mmio_base + offset);
-		if (dma64) {
+		if (type == B43_DMA_64BIT) {
 			value &= B43_DMA64_RXSTAT;
 			if (value == B43_DMA64_RXSTAT_DISABLED) {
 				i = -1;
@@ -496,7 +498,8 @@
 }
 
 /* Reset the TX DMA channel */
-int b43_dmacontroller_tx_reset(struct b43_wldev *dev, u16 mmio_base, int dma64)
+static int b43_dmacontroller_tx_reset(struct b43_wldev *dev, u16 mmio_base,
+				      enum b43_dmatype type)
 {
 	int i;
 	u32 value;
@@ -505,9 +508,10 @@
 	might_sleep();
 
 	for (i = 0; i < 10; i++) {
-		offset = dma64 ? B43_DMA64_TXSTATUS : B43_DMA32_TXSTATUS;
+		offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXSTATUS :
+						   B43_DMA32_TXSTATUS;
 		value = b43_read32(dev, mmio_base + offset);
-		if (dma64) {
+		if (type == B43_DMA_64BIT) {
 			value &= B43_DMA64_TXSTAT;
 			if (value == B43_DMA64_TXSTAT_DISABLED ||
 			    value == B43_DMA64_TXSTAT_IDLEWAIT ||
@@ -522,12 +526,13 @@
 		}
 		msleep(1);
 	}
-	offset = dma64 ? B43_DMA64_TXCTL : B43_DMA32_TXCTL;
+	offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXCTL : B43_DMA32_TXCTL;
 	b43_write32(dev, mmio_base + offset, 0);
 	for (i = 0; i < 10; i++) {
-		offset = dma64 ? B43_DMA64_TXSTATUS : B43_DMA32_TXSTATUS;
+		offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXSTATUS :
+						   B43_DMA32_TXSTATUS;
 		value = b43_read32(dev, mmio_base + offset);
-		if (dma64) {
+		if (type == B43_DMA_64BIT) {
 			value &= B43_DMA64_TXSTAT;
 			if (value == B43_DMA64_TXSTAT_DISABLED) {
 				i = -1;
@@ -552,6 +557,33 @@
 	return 0;
 }
 
+/* Check if a DMA mapping address is invalid. */
+static bool b43_dma_mapping_error(struct b43_dmaring *ring,
+				  dma_addr_t addr,
+				  size_t buffersize)
+{
+	if (unlikely(dma_mapping_error(addr)))
+		return 1;
+
+	switch (ring->type) {
+	case B43_DMA_30BIT:
+		if ((u64)addr + buffersize > (1ULL << 30))
+			return 1;
+		break;
+	case B43_DMA_32BIT:
+		if ((u64)addr + buffersize > (1ULL << 32))
+			return 1;
+		break;
+	case B43_DMA_64BIT:
+		/* Currently we can't have addresses beyond
+		 * 64bit in the kernel. */
+		break;
+	}
+
+	/* The address is OK. */
+	return 0;
+}
+
 static int setup_rx_descbuffer(struct b43_dmaring *ring,
 			       struct b43_dmadesc_generic *desc,
 			       struct b43_dmadesc_meta *meta, gfp_t gfp_flags)
@@ -567,7 +599,7 @@
 	if (unlikely(!skb))
 		return -ENOMEM;
 	dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0);
-	if (dma_mapping_error(dmaaddr)) {
+	if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize)) {
 		/* ugh. try to realloc in zone_dma */
 		gfp_flags |= GFP_DMA;
 
@@ -580,7 +612,7 @@
 					 ring->rx_buffersize, 0);
 	}
 
-	if (dma_mapping_error(dmaaddr)) {
+	if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize)) {
 		dev_kfree_skb_any(skb);
 		return -EIO;
 	}
@@ -645,7 +677,7 @@
 	u32 trans = ssb_dma_translation(ring->dev->dev);
 
 	if (ring->tx) {
-		if (ring->dma64) {
+		if (ring->type == B43_DMA_64BIT) {
 			u64 ringbase = (u64) (ring->dmabase);
 
 			addrext = ((ringbase >> 32) & SSB_DMA_TRANSLATION_MASK)
@@ -677,7 +709,7 @@
 		err = alloc_initial_descbuffers(ring);
 		if (err)
 			goto out;
-		if (ring->dma64) {
+		if (ring->type == B43_DMA_64BIT) {
 			u64 ringbase = (u64) (ring->dmabase);
 
 			addrext = ((ringbase >> 32) & SSB_DMA_TRANSLATION_MASK)
@@ -722,16 +754,16 @@
 {
 	if (ring->tx) {
 		b43_dmacontroller_tx_reset(ring->dev, ring->mmio_base,
-					   ring->dma64);
-		if (ring->dma64) {
+					   ring->type);
+		if (ring->type == B43_DMA_64BIT) {
 			b43_dma_write(ring, B43_DMA64_TXRINGLO, 0);
 			b43_dma_write(ring, B43_DMA64_TXRINGHI, 0);
 		} else
 			b43_dma_write(ring, B43_DMA32_TXRING, 0);
 	} else {
 		b43_dmacontroller_rx_reset(ring->dev, ring->mmio_base,
-					   ring->dma64);
-		if (ring->dma64) {
+					   ring->type);
+		if (ring->type == B43_DMA_64BIT) {
 			b43_dma_write(ring, B43_DMA64_RXRINGLO, 0);
 			b43_dma_write(ring, B43_DMA64_RXRINGHI, 0);
 		} else
@@ -786,7 +818,8 @@
 static
 struct b43_dmaring *b43_setup_dmaring(struct b43_wldev *dev,
 				      int controller_index,
-				      int for_tx, int dma64)
+				      int for_tx,
+				      enum b43_dmatype type)
 {
 	struct b43_dmaring *ring;
 	int err;
@@ -796,6 +829,7 @@
 	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
 	if (!ring)
 		goto out;
+	ring->type = type;
 
 	nr_slots = B43_RXRING_SLOTS;
 	if (for_tx)
@@ -818,7 +852,7 @@
 					  b43_txhdr_size(dev),
 					  DMA_TO_DEVICE);
 
-		if (dma_mapping_error(dma_test)) {
+		if (b43_dma_mapping_error(ring, dma_test, b43_txhdr_size(dev))) {
 			/* ugh realloc */
 			kfree(ring->txhdr_cache);
 			ring->txhdr_cache = kcalloc(nr_slots,
@@ -832,7 +866,8 @@
 						  b43_txhdr_size(dev),
 						  DMA_TO_DEVICE);
 
-			if (dma_mapping_error(dma_test))
+			if (b43_dma_mapping_error(ring, dma_test,
+						  b43_txhdr_size(dev)))
 				goto err_kfree_txhdr_cache;
 		}
 
@@ -843,10 +878,9 @@
 
 	ring->dev = dev;
 	ring->nr_slots = nr_slots;
-	ring->mmio_base = b43_dmacontroller_base(dma64, controller_index);
+	ring->mmio_base = b43_dmacontroller_base(type, controller_index);
 	ring->index = controller_index;
-	ring->dma64 = !!dma64;
-	if (dma64)
+	if (type == B43_DMA_64BIT)
 		ring->ops = &dma64_ops;
 	else
 		ring->ops = &dma32_ops;
@@ -896,8 +930,8 @@
 	if (!ring)
 		return;
 
-	b43dbg(ring->dev->wl, "DMA-%s 0x%04X (%s) max used slots: %d/%d\n",
-	       (ring->dma64) ? "64" : "32",
+	b43dbg(ring->dev->wl, "DMA-%u 0x%04X (%s) max used slots: %d/%d\n",
+	       (unsigned int)(ring->type),
 	       ring->mmio_base,
 	       (ring->tx) ? "TX" : "RX", ring->max_used_slots, ring->nr_slots);
 	/* Device IRQs are disabled prior entering this function,
@@ -941,12 +975,22 @@
 	struct b43_dmaring *ring;
 	int err;
 	u64 dmamask;
-	int dma64 = 0;
+	enum b43_dmatype type;
 
 	dmamask = supported_dma_mask(dev);
-	if (dmamask == DMA_64BIT_MASK)
-		dma64 = 1;
-
+	switch (dmamask) {
+	default:
+		B43_WARN_ON(1);
+	case DMA_30BIT_MASK:
+		type = B43_DMA_30BIT;
+		break;
+	case DMA_32BIT_MASK:
+		type = B43_DMA_32BIT;
+		break;
+	case DMA_64BIT_MASK:
+		type = B43_DMA_64BIT;
+		break;
+	}
 	err = ssb_dma_set_mask(dev->dev, dmamask);
 	if (err) {
 		b43err(dev->wl, "The machine/kernel does not support "
@@ -958,52 +1002,51 @@
 
 	err = -ENOMEM;
 	/* setup TX DMA channels. */
-	ring = b43_setup_dmaring(dev, 0, 1, dma64);
+	ring = b43_setup_dmaring(dev, 0, 1, type);
 	if (!ring)
 		goto out;
 	dma->tx_ring0 = ring;
 
-	ring = b43_setup_dmaring(dev, 1, 1, dma64);
+	ring = b43_setup_dmaring(dev, 1, 1, type);
 	if (!ring)
 		goto err_destroy_tx0;
 	dma->tx_ring1 = ring;
 
-	ring = b43_setup_dmaring(dev, 2, 1, dma64);
+	ring = b43_setup_dmaring(dev, 2, 1, type);
 	if (!ring)
 		goto err_destroy_tx1;
 	dma->tx_ring2 = ring;
 
-	ring = b43_setup_dmaring(dev, 3, 1, dma64);
+	ring = b43_setup_dmaring(dev, 3, 1, type);
 	if (!ring)
 		goto err_destroy_tx2;
 	dma->tx_ring3 = ring;
 
-	ring = b43_setup_dmaring(dev, 4, 1, dma64);
+	ring = b43_setup_dmaring(dev, 4, 1, type);
 	if (!ring)
 		goto err_destroy_tx3;
 	dma->tx_ring4 = ring;
 
-	ring = b43_setup_dmaring(dev, 5, 1, dma64);
+	ring = b43_setup_dmaring(dev, 5, 1, type);
 	if (!ring)
 		goto err_destroy_tx4;
 	dma->tx_ring5 = ring;
 
 	/* setup RX DMA channels. */
-	ring = b43_setup_dmaring(dev, 0, 0, dma64);
+	ring = b43_setup_dmaring(dev, 0, 0, type);
 	if (!ring)
 		goto err_destroy_tx5;
 	dma->rx_ring0 = ring;
 
 	if (dev->dev->id.revision < 5) {
-		ring = b43_setup_dmaring(dev, 3, 0, dma64);
+		ring = b43_setup_dmaring(dev, 3, 0, type);
 		if (!ring)
 			goto err_destroy_rx0;
 		dma->rx_ring3 = ring;
 	}
 
-	b43dbg(dev->wl, "%d-bit DMA initialized\n",
-	       (dmamask == DMA_64BIT_MASK) ? 64 :
-	       (dmamask == DMA_32BIT_MASK) ? 32 : 30);
+	b43dbg(dev->wl, "%u-bit DMA initialized\n",
+	       (unsigned int)type);
 	err = 0;
       out:
 	return err;
@@ -1146,7 +1189,7 @@
 
 	meta_hdr->dmaaddr = map_descbuffer(ring, (unsigned char *)header,
 					   hdrsize, 1);
-	if (dma_mapping_error(meta_hdr->dmaaddr)) {
+	if (b43_dma_mapping_error(ring, meta_hdr->dmaaddr, hdrsize)) {
 		ring->current_slot = old_top_slot;
 		ring->used_slots = old_used_slots;
 		return -EIO;
@@ -1165,7 +1208,7 @@
 
 	meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
 	/* create a bounce buffer in zone_dma on mapping failure. */
-	if (dma_mapping_error(meta->dmaaddr)) {
+	if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len)) {
 		bounce_skb = __dev_alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
 		if (!bounce_skb) {
 			ring->current_slot = old_top_slot;
@@ -1179,7 +1222,7 @@
 		skb = bounce_skb;
 		meta->skb = skb;
 		meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
-		if (dma_mapping_error(meta->dmaaddr)) {
+		if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len)) {
 			ring->current_slot = old_top_slot;
 			ring->used_slots = old_used_slots;
 			err = -EIO;
diff --git a/drivers/net/wireless/b43/dma.h b/drivers/net/wireless/b43/dma.h
index 58db03a..c0d6b69 100644
--- a/drivers/net/wireless/b43/dma.h
+++ b/drivers/net/wireless/b43/dma.h
@@ -203,6 +203,12 @@
 	void (*set_current_rxslot) (struct b43_dmaring * ring, int slot);
 };
 
+enum b43_dmatype {
+	B43_DMA_30BIT	= 30,
+	B43_DMA_32BIT	= 32,
+	B43_DMA_64BIT	= 64,
+};
+
 struct b43_dmaring {
 	/* Lowlevel DMA ops. */
 	const struct b43_dma_ops *ops;
@@ -235,8 +241,8 @@
 	int index;
 	/* Boolean. Is this a TX ring? */
 	bool tx;
-	/* Boolean. 64bit DMA if true, 32bit DMA otherwise. */
-	bool dma64;
+	/* The type of DMA engine used. */
+	enum b43_dmatype type;
 	/* Boolean. Is this ring stopped at ieee80211 level? */
 	bool stopped;
 	/* Lock, only used for TX. */
@@ -255,8 +261,7 @@
 	return b43_read32(ring->dev, ring->mmio_base + offset);
 }
 
-static inline
-    void b43_dma_write(struct b43_dmaring *ring, u16 offset, u32 value)
+static inline void b43_dma_write(struct b43_dmaring *ring, u16 offset, u32 value)
 {
 	b43_write32(ring->dev, ring->mmio_base + offset, value);
 }
@@ -264,13 +269,6 @@
 int b43_dma_init(struct b43_wldev *dev);
 void b43_dma_free(struct b43_wldev *dev);
 
-int b43_dmacontroller_rx_reset(struct b43_wldev *dev,
-			       u16 dmacontroller_mmio_base, int dma64);
-int b43_dmacontroller_tx_reset(struct b43_wldev *dev,
-			       u16 dmacontroller_mmio_base, int dma64);
-
-u16 b43_dmacontroller_base(int dma64bit, int dmacontroller_idx);
-
 void b43_dma_tx_suspend(struct b43_wldev *dev);
 void b43_dma_tx_resume(struct b43_wldev *dev);