[dma] Record DMA device as part of DMA mapping if needed

Allow for dma_unmap() to be called by code other than the DMA device
driver itself.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

6 files changed, 150 insertions, 129 deletions

diff --git a/src/core/dma.c b/src/core/dma.c
index 3bf6957..561aec1 100644
--- a/src/core/dma.c
+++ b/src/core/dma.c
@@ -59,66 +59,65 @@ PROVIDE_DMAAPI_INLINE ( flat, dma_phys );
  * Map buffer for DMA
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v addr		Buffer address
  * @v len		Length of buffer
  * @v flags		Mapping flags
- * @v map		DMA mapping to fill in
  * @ret rc		Return status code
  */
-static int dma_op_map ( struct dma_device *dma, physaddr_t addr, size_t len,
-			int flags, struct dma_mapping *map ) {
+static int dma_op_map ( struct dma_device *dma, struct dma_mapping *map,
+			physaddr_t addr, size_t len, int flags ) {
 	struct dma_operations *op = dma->op;
 
 	if ( ! op )
 		return -ENODEV;
-	return op->map ( dma, addr, len, flags, map );
+	return op->map ( dma, map, addr, len, flags );
 }
 
 /**
  * Unmap buffer
  *
- * @v dma		DMA device
  * @v map		DMA mapping
  */
-static void dma_op_unmap ( struct dma_device *dma, struct dma_mapping *map ) {
-	struct dma_operations *op = dma->op;
+static void dma_op_unmap ( struct dma_mapping *map ) {
+	struct dma_device *dma = map->dma;
 
-	assert ( op != NULL );
-	op->unmap ( dma, map );
+	assert ( dma != NULL );
+	assert ( dma->op != NULL );
+	dma->op->unmap ( dma, map );
 }
 
 /**
  * Allocate and map DMA-coherent buffer
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v len		Length of buffer
  * @v align		Physical alignment
- * @v map		DMA mapping to fill in
  * @ret addr		Buffer address, or NULL on error
  */
-static void * dma_op_alloc ( struct dma_device *dma, size_t len, size_t align,
-			     struct dma_mapping *map ) {
+static void * dma_op_alloc ( struct dma_device *dma, struct dma_mapping *map,
+			     size_t len, size_t align ) {
 	struct dma_operations *op = dma->op;
 
 	if ( ! op )
 		return NULL;
-	return op->alloc ( dma, len, align, map );
+	return op->alloc ( dma, map, len, align );
 }
 
 /**
  * Unmap and free DMA-coherent buffer
  *
- * @v dma		DMA device
+ * @v map		DMA mapping
  * @v addr		Buffer address
  * @v len		Length of buffer
- * @v map		DMA mapping
  */
-static void dma_op_free ( struct dma_device *dma, void *addr, size_t len,
-			  struct dma_mapping *map ) {
-	struct dma_operations *op = dma->op;
+static void dma_op_free ( struct dma_mapping *map, void *addr, size_t len ) {
+	struct dma_device *dma = map->dma;
 
-	assert ( op != NULL );
-	op->free ( dma, addr, len, map );
+	assert ( dma != NULL );
+	assert ( dma->op != NULL );
+	dma->op->free ( dma, map, addr, len );
 }
 
 /**
@@ -152,12 +151,13 @@ PROVIDE_DMAAPI_INLINE ( op, dma_phys );
  * Allocate and map I/O buffer for receiving data from device
  *
  * @v dma		DMA device
- * @v len		Length of I/O buffer
  * @v map		DMA mapping to fill in
+ * @v len		Length of I/O buffer
  * @ret iobuf		I/O buffer, or NULL on error
  */
-struct io_buffer * dma_alloc_rx_iob ( struct dma_device *dma, size_t len,
-				      struct dma_mapping *map ) {
+struct io_buffer * dma_alloc_rx_iob ( struct dma_device *dma,
+				      struct dma_mapping *map,
+				      size_t len ) {
 	struct io_buffer *iobuf;
 	int rc;
 
@@ -167,13 +167,13 @@ struct io_buffer * dma_alloc_rx_iob ( struct dma_device *dma, size_t len,
 		goto err_alloc;
 
 	/* Map I/O buffer */
-	if ( ( rc = dma_map ( dma, virt_to_phys ( iobuf->data ), len,
-			      DMA_RX, map ) ) != 0 )
+	if ( ( rc = dma_map ( dma, map, virt_to_phys ( iobuf->data ),
+			      len, DMA_RX ) ) != 0 )
 		goto err_map;
 
 	return iobuf;
 
-	dma_unmap ( dma, map );
+	dma_unmap ( map );
  err_map:
 	free_iob ( iobuf );
  err_alloc:
diff --git a/src/drivers/net/intel.c b/src/drivers/net/intel.c
index 5c6dc21..93c5fd1 100644
--- a/src/drivers/net/intel.c
+++ b/src/drivers/net/intel.c
@@ -504,8 +504,8 @@ int intel_create_ring ( struct intel_nic *intel, struct intel_ring *ring ) {
 	 * prevent any possible page-crossing errors due to hardware
 	 * errata.
 	 */
-	ring->desc = dma_alloc ( intel->dma, ring->len, ring->len,
-				 &ring->map );
+	ring->desc = dma_alloc ( intel->dma, &ring->map, ring->len,
+				 ring->len );
 	if ( ! ring->desc )
 		return -ENOMEM;
 
@@ -554,7 +554,7 @@ void intel_destroy_ring ( struct intel_nic *intel, struct intel_ring *ring ) {
 	intel_reset_ring ( intel, ring->reg );
 
 	/* Free descriptor ring */
-	dma_free ( intel->dma, ring->desc, ring->len, &ring->map );
+	dma_free ( &ring->map, ring->desc, ring->len );
 	ring->desc = NULL;
 	ring->prod = 0;
 	ring->cons = 0;
@@ -584,7 +584,7 @@ void intel_refill_rx ( struct intel_nic *intel ) {
 		assert ( intel->rx.iobuf[rx_idx] == NULL );
 
 		/* Allocate I/O buffer */
-		iobuf = dma_alloc_rx_iob ( intel->dma, INTEL_RX_MAX_LEN, map );
+		iobuf = dma_alloc_rx_iob ( intel->dma, map, INTEL_RX_MAX_LEN );
 		if ( ! iobuf ) {
 			/* Wait for next refill */
 			break;
@@ -630,7 +630,7 @@ void intel_flush ( struct intel_nic *intel ) {
 	/* Discard unused receive buffers */
 	for ( i = 0 ; i < INTEL_NUM_RX_DESC ; i++ ) {
 		if ( intel->rx.iobuf[i] ) {
-			dma_unmap ( intel->dma, &intel->rx.map[i] );
+			dma_unmap ( &intel->rx.map[i] );
 			free_iob ( intel->rx.iobuf[i] );
 		}
 		intel->rx.iobuf[i] = NULL;
@@ -639,7 +639,7 @@ void intel_flush ( struct intel_nic *intel ) {
 	/* Unmap incomplete transmit buffers */
 	for ( i = intel->tx.ring.cons ; i != intel->tx.ring.prod ; i++ ) {
 		tx_idx = ( i % INTEL_NUM_TX_DESC );
-		dma_unmap ( intel->dma, &intel->tx.map[tx_idx] );
+		dma_unmap ( &intel->tx.map[tx_idx] );
 	}
 }
 
@@ -773,7 +773,7 @@ int intel_transmit ( struct net_device *netdev, struct io_buffer *iobuf ) {
 	map = &intel->tx.map[tx_idx];
 
 	/* Map I/O buffer */
-	if ( ( rc = dma_map_tx_iob ( intel->dma, iobuf, map ) ) != 0 )
+	if ( ( rc = dma_map_tx_iob ( intel->dma, map, iobuf ) ) != 0 )
 		return rc;
 
 	/* Update producer index */
@@ -822,7 +822,7 @@ void intel_poll_tx ( struct net_device *netdev ) {
 		DBGC2 ( intel, "INTEL %p TX %d complete\n", intel, tx_idx );
 
 		/* Unmap I/O buffer */
-		dma_unmap ( intel->dma, &intel->tx.map[tx_idx] );
+		dma_unmap ( &intel->tx.map[tx_idx] );
 
 		/* Complete TX descriptor */
 		netdev_tx_complete_next ( netdev );
@@ -854,7 +854,7 @@ void intel_poll_rx ( struct net_device *netdev ) {
 			return;
 
 		/* Unmap I/O buffer */
-		dma_unmap ( intel->dma, &intel->rx.map[rx_idx] );
+		dma_unmap ( &intel->rx.map[rx_idx] );
 
 		/* Populate I/O buffer */
 		iobuf = intel->rx.iobuf[rx_idx];
diff --git a/src/drivers/net/intelxl.c b/src/drivers/net/intelxl.c
index 0808c78..5de432a 100644
--- a/src/drivers/net/intelxl.c
+++ b/src/drivers/net/intelxl.c
@@ -136,9 +136,9 @@ int intelxl_msix_enable ( struct intelxl_nic *intelxl,
 	int rc;
 
 	/* Map dummy target location */
-	if ( ( rc = dma_map ( intelxl->dma, virt_to_phys ( &intelxl->msix.msg ),
-			      sizeof ( intelxl->msix.msg ), DMA_RX,
-			      &intelxl->msix.map ) ) != 0 ) {
+	if ( ( rc = dma_map ( intelxl->dma, &intelxl->msix.map,
+			      virt_to_phys ( &intelxl->msix.msg ),
+			      sizeof ( intelxl->msix.msg ), DMA_RX ) ) != 0 ) {
 		DBGC ( intelxl, "INTELXL %p could not map MSI-X target: %s\n",
 		       intelxl, strerror ( rc ) );
 		goto err_map;
@@ -162,7 +162,7 @@ int intelxl_msix_enable ( struct intelxl_nic *intelxl,
 
 	pci_msix_disable ( pci, &intelxl->msix.cap );
  err_enable:
-	dma_unmap ( intelxl->dma, &intelxl->msix.map );
+	dma_unmap ( &intelxl->msix.map );
  err_map:
 	return rc;
 }
@@ -183,7 +183,7 @@ void intelxl_msix_disable ( struct intelxl_nic *intelxl,
 	pci_msix_disable ( pci, &intelxl->msix.cap );
 
 	/* Unmap dummy target location */
-	dma_unmap ( intelxl->dma, &intelxl->msix.map );
+	dma_unmap ( &intelxl->msix.map );
 }
 
 /******************************************************************************
@@ -215,8 +215,8 @@ static int intelxl_alloc_admin ( struct intelxl_nic *intelxl,
 	size_t len = ( sizeof ( admin->desc[0] ) * INTELXL_ADMIN_NUM_DESC );
 
 	/* Allocate admin queue */
-	admin->buf = dma_alloc ( intelxl->dma, ( buf_len + len ),
-				 INTELXL_ALIGN, &admin->map );
+	admin->buf = dma_alloc ( intelxl->dma, &admin->map, ( buf_len + len ),
+				 INTELXL_ALIGN );
 	if ( ! admin->buf )
 		return -ENOMEM;
 	admin->desc = ( ( ( void * ) admin->buf ) + buf_len );
@@ -291,13 +291,13 @@ static void intelxl_disable_admin ( struct intelxl_nic *intelxl,
  * @v intelxl		Intel device
  * @v admin		Admin queue
  */
-static void intelxl_free_admin ( struct intelxl_nic *intelxl,
+static void intelxl_free_admin ( struct intelxl_nic *intelxl __unused,
 				 struct intelxl_admin *admin ) {
 	size_t buf_len = ( sizeof ( admin->buf[0] ) * INTELXL_ADMIN_NUM_DESC );
 	size_t len = ( sizeof ( admin->desc[0] ) * INTELXL_ADMIN_NUM_DESC );
 
 	/* Free queue */
-	dma_free ( intelxl->dma, admin->buf, ( buf_len + len ), &admin->map );
+	dma_free ( &admin->map, admin->buf, ( buf_len + len ) );
 }
 
 /**
@@ -945,8 +945,8 @@ int intelxl_alloc_ring ( struct intelxl_nic *intelxl,
 	int rc;
 
 	/* Allocate descriptor ring */
-	ring->desc.raw = dma_alloc ( intelxl->dma, ring->len, INTELXL_ALIGN,
-				     &ring->map );
+	ring->desc.raw = dma_alloc ( intelxl->dma, &ring->map, ring->len,
+				     INTELXL_ALIGN );
 	if ( ! ring->desc.raw ) {
 		rc = -ENOMEM;
 		goto err_alloc;
@@ -969,7 +969,7 @@ int intelxl_alloc_ring ( struct intelxl_nic *intelxl,
 
 	return 0;
 
-	dma_free ( intelxl->dma, ring->desc.raw, ring->len, &ring->map );
+	dma_free ( &ring->map, ring->desc.raw, ring->len );
  err_alloc:
 	return rc;
 }
@@ -980,11 +980,11 @@ int intelxl_alloc_ring ( struct intelxl_nic *intelxl,
  * @v intelxl		Intel device
  * @v ring		Descriptor ring
  */
-void intelxl_free_ring ( struct intelxl_nic *intelxl,
+void intelxl_free_ring ( struct intelxl_nic *intelxl __unused,
 			 struct intelxl_ring *ring ) {
 
 	/* Free descriptor ring */
-	dma_free ( intelxl->dma, ring->desc.raw, ring->len, &ring->map );
+	dma_free ( &ring->map, ring->desc.raw, ring->len );
 	ring->desc.raw = NULL;
 }
 
@@ -1322,7 +1322,7 @@ static void intelxl_refill_rx ( struct intelxl_nic *intelxl ) {
 		assert ( intelxl->rx.iobuf[rx_idx] == NULL );
 
 		/* Allocate I/O buffer */
-		iobuf = dma_alloc_rx_iob ( intelxl->dma, intelxl->mfs, map );
+		iobuf = dma_alloc_rx_iob ( intelxl->dma, map, intelxl->mfs );
 		if ( ! iobuf ) {
 			/* Wait for next refill */
 			break;
@@ -1365,7 +1365,7 @@ void intelxl_flush ( struct intelxl_nic *intelxl ) {
 	/* Discard any unused receive buffers */
 	for ( i = 0 ; i < INTELXL_RX_NUM_DESC ; i++ ) {
 		if ( intelxl->rx.iobuf[i] ) {
-			dma_unmap ( intelxl->dma, &intelxl->rx.map[i] );
+			dma_unmap ( &intelxl->rx.map[i] );
 			free_iob ( intelxl->rx.iobuf[i] );
 		}
 		intelxl->rx.iobuf[i] = NULL;
@@ -1374,7 +1374,7 @@ void intelxl_flush ( struct intelxl_nic *intelxl ) {
 	/* Unmap incomplete transmit buffers */
 	for ( i = intelxl->tx.ring.cons ; i != intelxl->tx.ring.prod ; i++ ) {
 		tx_idx = ( i % INTELXL_TX_NUM_DESC );
-		dma_unmap ( intelxl->dma, &intelxl->tx.map[tx_idx] );
+		dma_unmap ( &intelxl->tx.map[tx_idx] );
 	}
 }
 
@@ -1516,7 +1516,7 @@ int intelxl_transmit ( struct net_device *netdev, struct io_buffer *iobuf ) {
 	map = &intelxl->tx.map[tx_idx];
 
 	/* Map I/O buffer */
-	if ( ( rc = dma_map_tx_iob ( intelxl->dma, iobuf, map ) ) != 0 )
+	if ( ( rc = dma_map_tx_iob ( intelxl->dma, map, iobuf ) ) != 0 )
 		return rc;
 
 	/* Update producer index */
@@ -1564,7 +1564,7 @@ static void intelxl_poll_tx ( struct net_device *netdev ) {
 			intelxl, tx_idx );
 
 		/* Unmap I/O buffer */
-		dma_unmap ( intelxl->dma, &intelxl->tx.map[tx_idx] );
+		dma_unmap ( &intelxl->tx.map[tx_idx] );
 
 		/* Complete TX descriptor */
 		netdev_tx_complete_next ( netdev );
@@ -1597,7 +1597,7 @@ static void intelxl_poll_rx ( struct net_device *netdev ) {
 			return;
 
 		/* Unmap I/O buffer */
-		dma_unmap ( intelxl->dma, &intelxl->rx.map[rx_idx] );
+		dma_unmap ( &intelxl->rx.map[rx_idx] );
 
 		/* Populate I/O buffer */
 		iobuf = intelxl->rx.iobuf[rx_idx];
diff --git a/src/drivers/net/realtek.c b/src/drivers/net/realtek.c
index bca5226..47d435f 100644
--- a/src/drivers/net/realtek.c
+++ b/src/drivers/net/realtek.c
@@ -514,7 +514,8 @@ static int realtek_create_buffer ( struct realtek_nic *rtl ) {
 		return 0;
 
 	/* Allocate buffer */
-	rxbuf->data = dma_alloc ( rtl->dma, len, RTL_RXBUF_ALIGN, &rxbuf->map );
+	rxbuf->data = dma_alloc ( rtl->dma, &rxbuf->map, len,
+				  RTL_RXBUF_ALIGN );
 	if ( ! rxbuf->data )
 		return -ENOMEM;
 
@@ -545,7 +546,7 @@ static void realtek_destroy_buffer ( struct realtek_nic *rtl ) {
 	writel ( 0, rtl->regs + RTL_RBSTART );
 
 	/* Free buffer */
-	dma_free ( rtl->dma, rxbuf->data, len, &rxbuf->map );
+	dma_free ( &rxbuf->map, rxbuf->data, len );
 	rxbuf->data = NULL;
 	rxbuf->offset = 0;
 }
@@ -566,8 +567,8 @@ static int realtek_create_ring ( struct realtek_nic *rtl,
 		return 0;
 
 	/* Allocate descriptor ring */
-	ring->desc = dma_alloc ( rtl->dma, ring->len, RTL_RING_ALIGN,
-				 &ring->map );
+	ring->desc = dma_alloc ( rtl->dma, &ring->map, ring->len,
+				 RTL_RING_ALIGN );
 	if ( ! ring->desc )
 		return -ENOMEM;
 
@@ -608,7 +609,7 @@ static void realtek_destroy_ring ( struct realtek_nic *rtl,
 	writel ( 0, rtl->regs + ring->reg + 4 );
 
 	/* Free descriptor ring */
-	dma_free ( rtl->dma, ring->desc, ring->len, &ring->map );
+	dma_free ( &ring->map, ring->desc, ring->len );
 	ring->desc = NULL;
 }
 
@@ -638,7 +639,7 @@ static void realtek_refill_rx ( struct realtek_nic *rtl ) {
 		assert ( rtl->rx.iobuf[rx_idx] == NULL );
 
 		/* Allocate I/O buffer */
-		iobuf = dma_alloc_rx_iob ( rtl->dma, RTL_RX_MAX_LEN, map );
+		iobuf = dma_alloc_rx_iob ( rtl->dma, map, RTL_RX_MAX_LEN );
 		if ( ! iobuf ) {
 			/* Wait for next refill */
 			return;
@@ -748,7 +749,7 @@ static void realtek_close ( struct net_device *netdev ) {
 	/* Discard any unused receive buffers */
 	for ( i = 0 ; i < RTL_NUM_RX_DESC ; i++ ) {
 		if ( rtl->rx.iobuf[i] ) {
-			dma_unmap ( rtl->dma, &rtl->rx.map[i] );
+			dma_unmap ( &rtl->rx.map[i] );
 			free_iob ( rtl->rx.iobuf[i] );
 		}
 		rtl->rx.iobuf[i] = NULL;
@@ -756,7 +757,7 @@ static void realtek_close ( struct net_device *netdev ) {
 
 	/* Unmap any incomplete transmit buffers */
 	for ( i = rtl->tx.ring.cons ; i != rtl->tx.ring.prod ; i++ )
-		dma_unmap ( rtl->dma, &rtl->tx.map[ i % RTL_NUM_TX_DESC ] );
+		dma_unmap ( &rtl->tx.map[ i % RTL_NUM_TX_DESC ] );
 
 	/* Destroy transmit descriptor ring */
 	realtek_destroy_ring ( rtl, &rtl->tx.ring );
@@ -796,7 +797,7 @@ static int realtek_transmit ( struct net_device *netdev,
 		iob_pad ( iobuf, ETH_ZLEN );
 
 	/* Map I/O buffer */
-	if ( ( rc = dma_map_tx_iob ( rtl->dma, iobuf, map ) ) != 0 )
+	if ( ( rc = dma_map_tx_iob ( rtl->dma, map, iobuf ) ) != 0 )
 		return rc;
 	address = dma ( map, iobuf->data );
 
@@ -870,7 +871,7 @@ static void realtek_poll_tx ( struct net_device *netdev ) {
 		DBGC2 ( rtl, "REALTEK %p TX %d complete\n", rtl, tx_idx );
 
 		/* Unmap I/O buffer */
-		dma_unmap ( rtl->dma, &rtl->tx.map[tx_idx] );
+		dma_unmap ( &rtl->tx.map[tx_idx] );
 
 		/* Complete TX descriptor */
 		rtl->tx.ring.cons++;
@@ -964,7 +965,7 @@ static void realtek_poll_rx ( struct net_device *netdev ) {
 			return;
 
 		/* Unmap buffer */
-		dma_unmap ( rtl->dma, &rtl->rx.map[rx_idx] );
+		dma_unmap ( &rtl->rx.map[rx_idx] );
 
 		/* Populate I/O buffer */
 		iobuf = rtl->rx.iobuf[rx_idx];
diff --git a/src/include/ipxe/dma.h b/src/include/ipxe/dma.h
index 0577493..842c9d6 100644
--- a/src/include/ipxe/dma.h
+++ b/src/include/ipxe/dma.h
@@ -37,6 +37,8 @@ struct dma_mapping {
 	 * device-side DMA address.
 	 */
 	physaddr_t offset;
+	/** DMA device (if unmapping is required) */
+	struct dma_device *dma;
 	/** Platform mapping token */
 	void *token;
 };
@@ -59,14 +61,14 @@ struct dma_operations {
 	 * Map buffer for DMA
 	 *
 	 * @v dma		DMA device
+	 * @v map		DMA mapping to fill in
 	 * @v addr		Buffer address
 	 * @v len		Length of buffer
 	 * @v flags		Mapping flags
-	 * @v map		DMA mapping to fill in
 	 * @ret rc		Return status code
 	 */
-	int ( * map ) ( struct dma_device *dma, physaddr_t addr, size_t len,
-			int flags, struct dma_mapping *map );
+	int ( * map ) ( struct dma_device *dma, struct dma_mapping *map,
+			physaddr_t addr, size_t len, int flags );
 	/**
 	 * Unmap buffer
 	 *
@@ -78,23 +80,23 @@ struct dma_operations {
 	 * Allocate and map DMA-coherent buffer
 	 *
 	 * @v dma		DMA device
+	 * @v map		DMA mapping to fill in
 	 * @v len		Length of buffer
 	 * @v align		Physical alignment
-	 * @v map		DMA mapping to fill in
 	 * @ret addr		Buffer address, or NULL on error
 	 */
-	void * ( * alloc ) ( struct dma_device *dma, size_t len, size_t align,
-			     struct dma_mapping *map );
+	void * ( * alloc ) ( struct dma_device *dma, struct dma_mapping *map,
+			     size_t len, size_t align );
 	/**
 	 * Unmap and free DMA-coherent buffer
 	 *
 	 * @v dma		DMA device
+	 * @v map		DMA mapping
 	 * @v addr		Buffer address
 	 * @v len		Length of buffer
-	 * @v map		DMA mapping
 	 */
-	void ( * free ) ( struct dma_device *dma, void *addr, size_t len,
-			  struct dma_mapping *map );
+	void ( * free ) ( struct dma_device *dma, struct dma_mapping *map,
+			  void *addr, size_t len );
 	/**
 	 * Set addressable space mask
 	 *
@@ -146,21 +148,23 @@ struct dma_operations {
  * Map buffer for DMA
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v addr		Buffer address
  * @v len		Length of buffer
  * @v flags		Mapping flags
- * @v map		DMA mapping to fill in
  * @ret rc		Return status code
  */
 static inline __always_inline int
 DMAAPI_INLINE ( flat, dma_map ) ( struct dma_device *dma,
+				  struct dma_mapping *map,
 				  physaddr_t addr __unused,
-				  size_t len __unused, int flags __unused,
-				  struct dma_mapping *map __unused ) {
+				  size_t len __unused, int flags __unused ) {
 
 	/* Increment mapping count (for debugging) */
-	if ( DBG_LOG )
+	if ( DBG_LOG ) {
+		map->dma = dma;
 		dma->mapped++;
+	}
 
 	return 0;
 }
@@ -168,39 +172,42 @@ DMAAPI_INLINE ( flat, dma_map ) ( struct dma_device *dma,
 /**
  * Unmap buffer
  *
- * @v dma		DMA device
  * @v map		DMA mapping
  */
 static inline __always_inline void
-DMAAPI_INLINE ( flat, dma_unmap ) ( struct dma_device *dma,
-				    struct dma_mapping *map __unused ) {
+DMAAPI_INLINE ( flat, dma_unmap ) ( struct dma_mapping *map ) {
 
 	/* Decrement mapping count (for debugging) */
-	if ( DBG_LOG )
-		dma->mapped--;
+	if ( DBG_LOG ) {
+		assert ( map->dma != NULL );
+		map->dma->mapped--;
+		map->dma = NULL;
+	}
 }
 
 /**
  * Allocate and map DMA-coherent buffer
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v len		Length of buffer
  * @v align		Physical alignment
- * @v map		DMA mapping to fill in
  * @ret addr		Buffer address, or NULL on error
  */
 static inline __always_inline void *
 DMAAPI_INLINE ( flat, dma_alloc ) ( struct dma_device *dma,
-				    size_t len, size_t align,
-				    struct dma_mapping *map __unused ) {
+				    struct dma_mapping *map,
+				    size_t len, size_t align ) {
 	void *addr;
 
 	/* Allocate buffer */
 	addr = malloc_phys ( len, align );
 
-	/* Increment allocation count (for debugging) */
-	if ( DBG_LOG && addr )
-		dma->allocated++;
+	/* Increment mapping count (for debugging) */
+	if ( DBG_LOG && addr ) {
+		map->dma = dma;
+		dma->mapped++;
+	}
 
 	return addr;
 }
@@ -208,22 +215,23 @@ DMAAPI_INLINE ( flat, dma_alloc ) ( struct dma_device *dma,
 /**
  * Unmap and free DMA-coherent buffer
  *
- * @v dma		DMA device
+ * @v map		DMA mapping
  * @v addr		Buffer address
  * @v len		Length of buffer
- * @v map		DMA mapping
  */
 static inline __always_inline void
-DMAAPI_INLINE ( flat, dma_free ) ( struct dma_device *dma,
-				   void *addr, size_t len,
-				   struct dma_mapping *map __unused ) {
+DMAAPI_INLINE ( flat, dma_free ) ( struct dma_mapping *map,
+				   void *addr, size_t len ) {
 
 	/* Free buffer */
 	free_phys ( addr, len );
 
-	/* Decrement allocation count (for debugging) */
-	if ( DBG_LOG )
-		dma->allocated--;
+	/* Decrement mapping count (for debugging) */
+	if ( DBG_LOG ) {
+		assert ( map->dma != NULL );
+		map->dma->mapped--;
+		map->dma = NULL;
+	}
 }
 
 /**
@@ -272,45 +280,42 @@ DMAAPI_INLINE ( op, dma_phys ) ( struct dma_mapping *map, physaddr_t addr ) {
  * Map buffer for DMA
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v addr		Buffer address
  * @v len		Length of buffer
  * @v flags		Mapping flags
- * @v map		DMA mapping to fill in
  * @ret rc		Return status code
  */
-int dma_map ( struct dma_device *dma, physaddr_t addr, size_t len,
-	      int flags, struct dma_mapping *map );
+int dma_map ( struct dma_device *dma, struct dma_mapping *map,
+	      physaddr_t addr, size_t len, int flags );
 
 /**
  * Unmap buffer
  *
- * @v dma		DMA device
  * @v map		DMA mapping
  */
-void dma_unmap ( struct dma_device *dma, struct dma_mapping *map );
+void dma_unmap ( struct dma_mapping *map );
 
 /**
  * Allocate and map DMA-coherent buffer
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v len		Length of buffer
  * @v align		Physical alignment
- * @v map		DMA mapping to fill in
  * @ret addr		Buffer address, or NULL on error
  */
-void * dma_alloc ( struct dma_device *dma, size_t len, size_t align,
-		   struct dma_mapping *map );
+void * dma_alloc ( struct dma_device *dma, struct dma_mapping *map,
+		   size_t len, size_t align );
 
 /**
  * Unmap and free DMA-coherent buffer
  *
- * @v dma		DMA device
+ * @v map		DMA mapping
  * @v addr		Buffer address
  * @v len		Length of buffer
- * @v map		DMA mapping
  */
-void dma_free ( struct dma_device *dma, void *addr, size_t len,
-		struct dma_mapping *map );
+void dma_free ( struct dma_mapping *map, void *addr, size_t len );
 
 /**
  * Set addressable space mask
@@ -339,10 +344,23 @@ physaddr_t dma_phys ( struct dma_mapping *map, physaddr_t addr );
 static inline __always_inline physaddr_t dma ( struct dma_mapping *map,
 					       void *addr ) {
 
+	/* Get DMA address from corresponding physical address */
 	return dma_phys ( map, virt_to_phys ( addr ) );
 }
 
 /**
+ * Check if DMA unmapping is required
+ *
+ * @v map		DMA mapping
+ * @v unmap		Unmapping is required
+ */
+static inline __always_inline int dma_mapped ( struct dma_mapping *map ) {
+
+	/* Unmapping is required if a DMA device was recorded */
+	return ( map->dma != NULL );
+}
+
+/**
  * Initialise DMA device
  *
  * @v dma		DMA device
@@ -371,20 +389,21 @@ dma_set_mask_64bit ( struct dma_device *dma ) {
  * Map I/O buffer for transmitting data to device
  *
  * @v dma		DMA device
- * @v iobuf		I/O buffer
  * @v map		DMA mapping to fill in
+ * @v iobuf		I/O buffer
  * @ret rc		Return status code
  */
 static inline __always_inline int
-dma_map_tx_iob ( struct dma_device *dma, struct io_buffer *iobuf,
-		 struct dma_mapping *map ) {
+dma_map_tx_iob ( struct dma_device *dma, struct dma_mapping *map,
+		 struct io_buffer *iobuf ) {
 
 	/* Map I/O buffer */
-	return dma_map ( dma, virt_to_phys ( iobuf->data ), iob_len ( iobuf ),
-			 DMA_TX, map );
+	return dma_map ( dma, map, virt_to_phys ( iobuf->data ),
+			 iob_len ( iobuf ), DMA_TX );
 }
 
-extern struct io_buffer * dma_alloc_rx_iob ( struct dma_device *dma, size_t len,
-					     struct dma_mapping *map );
+extern struct io_buffer * dma_alloc_rx_iob ( struct dma_device *dma,
+					     struct dma_mapping *map,
+					     size_t len );
 
 #endif /* _IPXE_DMA_H */
diff --git a/src/interface/efi/efi_pci.c b/src/interface/efi/efi_pci.c
index e33a898..7687ffb 100644
--- a/src/interface/efi/efi_pci.c
+++ b/src/interface/efi/efi_pci.c
@@ -315,14 +315,14 @@ PROVIDE_PCIAPI ( efi, pci_ioremap, efipci_ioremap );
  * Map buffer for DMA
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v addr		Buffer address
  * @v len		Length of buffer
  * @v flags		Mapping flags
- * @v map		DMA mapping to fill in
  * @ret rc		Return status code
  */
-static int efipci_dma_map ( struct dma_device *dma, physaddr_t addr, size_t len,
-			    int flags, struct dma_mapping *map ) {
+static int efipci_dma_map ( struct dma_device *dma, struct dma_mapping *map,
+			    physaddr_t addr, size_t len, int flags ) {
 	struct efi_pci_device *efipci =
 		container_of ( dma, struct efi_pci_device, pci.dma );
 	struct pci_device *pci = &efipci->pci;
@@ -374,6 +374,7 @@ static int efipci_dma_map ( struct dma_device *dma, physaddr_t addr, size_t len,
 	}
 
 	/* Populate mapping */
+	map->dma = dma;
 	map->offset = ( bus - addr );
 	map->token = mapping;
 
@@ -420,14 +421,14 @@ static void efipci_dma_unmap ( struct dma_device *dma,
  * Allocate and map DMA-coherent buffer
  *
  * @v dma		DMA device
+ * @v map		DMA mapping to fill in
  * @v len		Length of buffer
  * @v align		Physical alignment
- * @v map		DMA mapping to fill in
  * @ret addr		Buffer address, or NULL on error
  */
-static void * efipci_dma_alloc ( struct dma_device *dma, size_t len,
-				 size_t align __unused,
-				 struct dma_mapping *map ) {
+static void * efipci_dma_alloc ( struct dma_device *dma,
+				 struct dma_mapping *map,
+				 size_t len, size_t align __unused ) {
 	struct efi_pci_device *efipci =
 		container_of ( dma, struct efi_pci_device, pci.dma );
 	struct pci_device *pci = &efipci->pci;
@@ -451,8 +452,8 @@ static void * efipci_dma_alloc ( struct dma_device *dma, size_t len,
 	}
 
 	/* Map buffer */
-	if ( ( rc = efipci_dma_map ( dma, virt_to_phys ( addr ), len, DMA_BI,
-				     map ) ) != 0 )
+	if ( ( rc = efipci_dma_map ( dma, map, virt_to_phys ( addr ),
+				     len, DMA_BI ) ) != 0 )
 		goto err_map;
 
 	/* Increment allocation count (for debugging) */
@@ -472,12 +473,12 @@ static void * efipci_dma_alloc ( struct dma_device *dma, size_t len,
  * Unmap and free DMA-coherent buffer
  *
  * @v dma		DMA device
+ * @v map		DMA mapping
  * @v addr		Buffer address
  * @v len		Length of buffer
- * @v map		DMA mapping
  */
-static void efipci_dma_free ( struct dma_device *dma, void *addr, size_t len,
-			      struct dma_mapping *map ) {
+static void efipci_dma_free ( struct dma_device *dma, struct dma_mapping *map,
+			      void *addr, size_t len ) {
 	struct efi_pci_device *efipci =
 		container_of ( dma, struct efi_pci_device, pci.dma );
 	EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;