[dma] Move I/O buffer DMA operations to iobuf.h

Include a potential DMA mapping within the definition of an I/O
buffer, and move all I/O buffer DMA mapping functions from dma.h to
iobuf.h.  This avoids the need for drivers to maintain a separate list
of DMA mappings for each I/O buffer that they may handle.

Network device drivers typically do not keep track of transmit I/O
buffers, since the network device core already maintains a transmit
queue.  Drivers will typically call netdev_tx_complete_next() to
complete a transmission without first obtaining the relevant I/O
buffer pointer (and will rely on the network device core automatically
cancelling any pending transmissions when the device is closed).

To allow this driver design approach to be retained, update the
netdev_tx_complete() family of functions to automatically perform the
DMA unmapping operation if required.  For symmetry, also update the
netdev_rx() family of functions to behave the same way.

As a further convenience for drivers, allow the network device core to
automatically perform DMA mapping on the transmit datapath before
calling the driver's transmit() method.  This avoids the need to
introduce a mapping error handling code path into the typically
error-free transmit methods.

With these changes, the modifications required to update a typical
network device driver to use the new DMA API are fairly minimal:

- Allocate and free descriptor rings and similar coherent structures
  using dma_alloc()/dma_free() rather than malloc_phys()/free_phys()

- Allocate and free receive buffers using alloc_rx_iob()/free_rx_iob()
  rather than alloc_iob()/free_iob()

- Calculate DMA addresses using dma() or iob_dma() rather than
  virt_to_bus()

- Set a 64-bit DMA mask if needed using dma_set_mask_64bit() and
  thereafter eliminate checks on DMA address ranges

- Either record the DMA device in netdev->dma, or call iob_map_tx() as
  part of the transmit() method

- Ensure that debug messages use virt_to_phys() when displaying
  "hardware" addresses

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

1 files changed, 44 insertions, 76 deletions

diff --git a/src/drivers/net/intel.c b/src/drivers/net/intel.c
index 93c5fd1f6..83492961f 100644
--- a/src/drivers/net/intel.c
+++ b/src/drivers/net/intel.c
@@ -568,34 +568,30 @@ void intel_destroy_ring ( struct intel_nic *intel, struct intel_ring *ring ) {
 void intel_refill_rx ( struct intel_nic *intel ) {
 	struct intel_descriptor *rx;
 	struct io_buffer *iobuf;
-	struct dma_mapping *map;
 	unsigned int rx_idx;
 	unsigned int rx_tail;
 	unsigned int refilled = 0;
 
 	/* Refill ring */
-	while ( ( intel->rx.ring.prod -
-		  intel->rx.ring.cons ) < INTEL_RX_FILL ) {
-
-		/* Get next receive descriptor */
-		rx_idx = ( intel->rx.ring.prod % INTEL_NUM_RX_DESC );
-		rx = &intel->rx.ring.desc[rx_idx];
-		map = &intel->rx.map[rx_idx];
-		assert ( intel->rx.iobuf[rx_idx] == NULL );
+	while ( ( intel->rx.prod - intel->rx.cons ) < INTEL_RX_FILL ) {
 
 		/* Allocate I/O buffer */
-		iobuf = dma_alloc_rx_iob ( intel->dma, map, INTEL_RX_MAX_LEN );
+		iobuf = alloc_rx_iob ( INTEL_RX_MAX_LEN, intel->dma );
 		if ( ! iobuf ) {
 			/* Wait for next refill */
 			break;
 		}
-		intel->rx.iobuf[rx_idx] = iobuf;
 
-		/* Update producer index */
-		intel->rx.ring.prod++;
+		/* Get next receive descriptor */
+		rx_idx = ( intel->rx.prod++ % INTEL_NUM_RX_DESC );
+		rx = &intel->rx.desc[rx_idx];
 
 		/* Populate receive descriptor */
-		intel->rx.ring.describe ( rx, dma ( map, iobuf->data ), 0 );
+		intel->rx.describe ( rx, iob_dma ( iobuf ), 0 );
+
+		/* Record I/O buffer */
+		assert ( intel->rx_iobuf[rx_idx] == NULL );
+		intel->rx_iobuf[rx_idx] = iobuf;
 
 		DBGC2 ( intel, "INTEL %p RX %d is [%lx,%lx)\n",
 			intel, rx_idx, virt_to_phys ( iobuf->data ),
@@ -606,40 +602,27 @@ void intel_refill_rx ( struct intel_nic *intel ) {
 	/* Push descriptors to card, if applicable */
 	if ( refilled ) {
 		wmb();
-		rx_tail = ( intel->rx.ring.prod % INTEL_NUM_RX_DESC );
+		rx_tail = ( intel->rx.prod % INTEL_NUM_RX_DESC );
 		profile_start ( &intel_vm_refill_profiler );
-		writel ( rx_tail,
-			 intel->regs + intel->rx.ring.reg + INTEL_xDT );
+		writel ( rx_tail, intel->regs + intel->rx.reg + INTEL_xDT );
 		profile_stop ( &intel_vm_refill_profiler );
 		profile_exclude ( &intel_vm_refill_profiler );
 	}
 }
 
 /**
- * Flush unused I/O buffers
+ * Discard unused receive I/O buffers
  *
  * @v intel		Intel device
- *
- * Discard any unused receive I/O buffers and unmap any incomplete
- * transmit I/O buffers.
  */
-void intel_flush ( struct intel_nic *intel ) {
+void intel_empty_rx ( struct intel_nic *intel ) {
 	unsigned int i;
-	unsigned int tx_idx;
 
 	/* Discard unused receive buffers */
 	for ( i = 0 ; i < INTEL_NUM_RX_DESC ; i++ ) {
-		if ( intel->rx.iobuf[i] ) {
-			dma_unmap ( &intel->rx.map[i] );
-			free_iob ( intel->rx.iobuf[i] );
-		}
-		intel->rx.iobuf[i] = NULL;
-	}
-
-	/* 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->tx.map[tx_idx] );
+		if ( intel->rx_iobuf[i] )
+			free_rx_iob ( intel->rx_iobuf[i] );
+		intel->rx_iobuf[i] = NULL;
 	}
 }
 
@@ -670,11 +653,11 @@ static int intel_open ( struct net_device *netdev ) {
 	}
 
 	/* Create transmit descriptor ring */
-	if ( ( rc = intel_create_ring ( intel, &intel->tx.ring ) ) != 0 )
+	if ( ( rc = intel_create_ring ( intel, &intel->tx ) ) != 0 )
 		goto err_create_tx;
 
 	/* Create receive descriptor ring */
-	if ( ( rc = intel_create_ring ( intel, &intel->rx.ring ) ) != 0 )
+	if ( ( rc = intel_create_ring ( intel, &intel->rx ) ) != 0 )
 		goto err_create_rx;
 
 	/* Program MAC address */
@@ -713,9 +696,9 @@ static int intel_open ( struct net_device *netdev ) {
 
 	return 0;
 
-	intel_destroy_ring ( intel, &intel->rx.ring );
+	intel_destroy_ring ( intel, &intel->rx );
  err_create_rx:
-	intel_destroy_ring ( intel, &intel->tx.ring );
+	intel_destroy_ring ( intel, &intel->tx );
  err_create_tx:
 	return rc;
 }
@@ -735,13 +718,13 @@ static void intel_close ( struct net_device *netdev ) {
 	writel ( 0, intel->regs + INTEL_TCTL );
 
 	/* Destroy receive descriptor ring */
-	intel_destroy_ring ( intel, &intel->rx.ring );
+	intel_destroy_ring ( intel, &intel->rx );
 
-	/* Flush unused buffers */
-	intel_flush ( intel );
+	/* Discard any unused receive buffers */
+	intel_empty_rx ( intel );
 
 	/* Destroy transmit descriptor ring */
-	intel_destroy_ring ( intel, &intel->tx.ring );
+	intel_destroy_ring ( intel, &intel->tx );
 
 	/* Reset the NIC, to flush the transmit and receive FIFOs */
 	intel_reset ( intel );
@@ -757,37 +740,27 @@ static void intel_close ( struct net_device *netdev ) {
 int intel_transmit ( struct net_device *netdev, struct io_buffer *iobuf ) {
 	struct intel_nic *intel = netdev->priv;
 	struct intel_descriptor *tx;
-	struct dma_mapping *map;
 	unsigned int tx_idx;
 	unsigned int tx_tail;
 	size_t len;
-	int rc;
 
 	/* Get next transmit descriptor */
-	if ( ( intel->tx.ring.prod - intel->tx.ring.cons ) >= INTEL_TX_FILL ) {
+	if ( ( intel->tx.prod - intel->tx.cons ) >= INTEL_TX_FILL ) {
 		DBGC ( intel, "INTEL %p out of transmit descriptors\n", intel );
 		return -ENOBUFS;
 	}
-	tx_idx = ( intel->tx.ring.prod % INTEL_NUM_TX_DESC );
-	tx = &intel->tx.ring.desc[tx_idx];
-	map = &intel->tx.map[tx_idx];
-
-	/* Map I/O buffer */
-	if ( ( rc = dma_map_tx_iob ( intel->dma, map, iobuf ) ) != 0 )
-		return rc;
-
-	/* Update producer index */
-	intel->tx.ring.prod++;
+	tx_idx = ( intel->tx.prod++ % INTEL_NUM_TX_DESC );
+	tx_tail = ( intel->tx.prod % INTEL_NUM_TX_DESC );
+	tx = &intel->tx.desc[tx_idx];
 
 	/* Populate transmit descriptor */
 	len = iob_len ( iobuf );
-	intel->tx.ring.describe ( tx, dma ( map, iobuf->data ), len );
+	intel->tx.describe ( tx, iob_dma ( iobuf ), len );
 	wmb();
 
 	/* Notify card that there are packets ready to transmit */
 	profile_start ( &intel_vm_tx_profiler );
-	tx_tail = ( intel->tx.ring.prod % INTEL_NUM_TX_DESC );
-	writel ( tx_tail, intel->regs + intel->tx.ring.reg + INTEL_xDT );
+	writel ( tx_tail, intel->regs + intel->tx.reg + INTEL_xDT );
 	profile_stop ( &intel_vm_tx_profiler );
 	profile_exclude ( &intel_vm_tx_profiler );
 
@@ -809,11 +782,11 @@ void intel_poll_tx ( struct net_device *netdev ) {
 	unsigned int tx_idx;
 
 	/* Check for completed packets */
-	while ( intel->tx.ring.cons != intel->tx.ring.prod ) {
+	while ( intel->tx.cons != intel->tx.prod ) {
 
 		/* Get next transmit descriptor */
-		tx_idx = ( intel->tx.ring.cons % INTEL_NUM_TX_DESC );
-		tx = &intel->tx.ring.desc[tx_idx];
+		tx_idx = ( intel->tx.cons % INTEL_NUM_TX_DESC );
+		tx = &intel->tx.desc[tx_idx];
 
 		/* Stop if descriptor is still in use */
 		if ( ! ( tx->status & cpu_to_le32 ( INTEL_DESC_STATUS_DD ) ) )
@@ -821,12 +794,9 @@ 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->tx.map[tx_idx] );
-
 		/* Complete TX descriptor */
 		netdev_tx_complete_next ( netdev );
-		intel->tx.ring.cons++;
+		intel->tx.cons++;
 	}
 }
 
@@ -843,22 +813,19 @@ void intel_poll_rx ( struct net_device *netdev ) {
 	size_t len;
 
 	/* Check for received packets */
-	while ( intel->rx.ring.cons != intel->rx.ring.prod ) {
+	while ( intel->rx.cons != intel->rx.prod ) {
 
 		/* Get next receive descriptor */
-		rx_idx = ( intel->rx.ring.cons % INTEL_NUM_RX_DESC );
-		rx = &intel->rx.ring.desc[rx_idx];
+		rx_idx = ( intel->rx.cons % INTEL_NUM_RX_DESC );
+		rx = &intel->rx.desc[rx_idx];
 
 		/* Stop if descriptor is still in use */
 		if ( ! ( rx->status & cpu_to_le32 ( INTEL_DESC_STATUS_DD ) ) )
 			return;
 
-		/* Unmap I/O buffer */
-		dma_unmap ( &intel->rx.map[rx_idx] );
-
 		/* Populate I/O buffer */
-		iobuf = intel->rx.iobuf[rx_idx];
-		intel->rx.iobuf[rx_idx] = NULL;
+		iobuf = intel->rx_iobuf[rx_idx];
+		intel->rx_iobuf[rx_idx] = NULL;
 		len = le16_to_cpu ( rx->length );
 		iob_put ( iobuf, len );
 
@@ -873,7 +840,7 @@ void intel_poll_rx ( struct net_device *netdev ) {
 				intel, rx_idx, len );
 			netdev_rx ( netdev, iobuf );
 		}
-		intel->rx.ring.cons++;
+		intel->rx.cons++;
 	}
 }
 
@@ -981,9 +948,9 @@ static int intel_probe ( struct pci_device *pci ) {
 	memset ( intel, 0, sizeof ( *intel ) );
 	intel->port = PCI_FUNC ( pci->busdevfn );
 	intel->flags = pci->id->driver_data;
-	intel_init_ring ( &intel->tx.ring, INTEL_NUM_TX_DESC, INTEL_TD,
+	intel_init_ring ( &intel->tx, INTEL_NUM_TX_DESC, INTEL_TD,
 			  intel_describe_tx );
-	intel_init_ring ( &intel->rx.ring, INTEL_NUM_RX_DESC, INTEL_RD,
+	intel_init_ring ( &intel->rx, INTEL_NUM_RX_DESC, INTEL_RD,
 			  intel_describe_rx );
 
 	/* Fix up PCI device */
@@ -999,6 +966,7 @@ static int intel_probe ( struct pci_device *pci ) {
 	/* Configure DMA */
 	intel->dma = &pci->dma;
 	dma_set_mask_64bit ( intel->dma );
+	netdev->dma = intel->dma;
 
 	/* Reset the NIC */
 	if ( ( rc = intel_reset ( intel ) ) != 0 )