[efi] Add NII / UNDI driver

Some UEFI network drivers provide a software UNDI interface which is
exposed via the Network Interface Identifier Protocol (NII), rather
than providing a Simple Network Protocol (SNP).

The UEFI platform firmware will usually include the SnpDxe driver,
which attaches to NII and provides an SNP interface.  The SNP
interface is usually provided on the same handle as the underlying NII
device.  This causes problems for our EFI driver model: when
efi_driver_connect() detaches existing drivers from the handle it will
cause the SNP interface to be uninstalled, and so our SNP driver will
not be able to attach to the handle.  The platform firmware will
eventually reattach the SnpDxe driver and may attach us to the SNP
handle, but we have no way to prevent other drivers from attaching
first.

Fix by providing a driver which can attach directly to the NII
protocol, using the software UNDI interface to drive the network
device.

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

1 files changed, 1134 insertions, 0 deletions

diff --git a/src/drivers/net/efi/nii.c b/src/drivers/net/efi/nii.c
new file mode 100644
index 00000000..5b1872ca
--- /dev/null
+++ b/src/drivers/net/efi/nii.c
@@ -0,0 +1,1134 @@
+/*
+ * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+#include <errno.h>
+#include <ipxe/netdevice.h>
+#include <ipxe/ethernet.h>
+#include <ipxe/umalloc.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/efi_driver.h>
+#include <ipxe/efi/efi_snp.h>
+#include <ipxe/efi/efi_pci.h>
+#include <ipxe/efi/efi_utils.h>
+#include <ipxe/efi/IndustryStandard/Acpi10.h>
+
+/** @file
+ *
+ * NII driver
+ *
+ */
+
+/* Error numbers generated by NII */
+#define EIO_INVALID_CDB __einfo_error ( EINFO_EIO_INVALID_CDB )
+#define EINFO_EIO_INVALID_CDB						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_INVALID_CDB,		      \
+			  "Invalid CDB" )
+#define EIO_INVALID_CPB __einfo_error ( EINFO_EIO_INVALID_CPB )
+#define EINFO_EIO_INVALID_CPB						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_INVALID_CPB,		      \
+			  "Invalid CPB" )
+#define EIO_BUSY __einfo_error ( EINFO_EIO_BUSY )
+#define EINFO_EIO_BUSY							      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_BUSY,			      \
+			  "Busy" )
+#define EIO_QUEUE_FULL __einfo_error ( EINFO_EIO_QUEUE_FULL )
+#define EINFO_EIO_QUEUE_FULL						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_QUEUE_FULL,		      \
+			  "Queue full" )
+#define EIO_ALREADY_STARTED __einfo_error ( EINFO_EIO_ALREADY_STARTED )
+#define EINFO_EIO_ALREADY_STARTED					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_ALREADY_STARTED,	      \
+			  "Already started" )
+#define EIO_NOT_STARTED __einfo_error ( EINFO_EIO_NOT_STARTED )
+#define EINFO_EIO_NOT_STARTED						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NOT_STARTED,		      \
+			  "Not started" )
+#define EIO_NOT_SHUTDOWN __einfo_error ( EINFO_EIO_NOT_SHUTDOWN )
+#define EINFO_EIO_NOT_SHUTDOWN						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NOT_SHUTDOWN,		      \
+			  "Not shutdown" )
+#define EIO_ALREADY_INITIALIZED __einfo_error ( EINFO_EIO_ALREADY_INITIALIZED )
+#define EINFO_EIO_ALREADY_INITIALIZED					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_ALREADY_INITIALIZED,	      \
+			  "Already initialized" )
+#define EIO_NOT_INITIALIZED __einfo_error ( EINFO_EIO_NOT_INITIALIZED )
+#define EINFO_EIO_NOT_INITIALIZED					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NOT_INITIALIZED,	      \
+			  "Not initialized" )
+#define EIO_DEVICE_FAILURE __einfo_error ( EINFO_EIO_DEVICE_FAILURE )
+#define EINFO_EIO_DEVICE_FAILURE					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_DEVICE_FAILURE,	      \
+			  "Device failure" )
+#define EIO_NVDATA_FAILURE __einfo_error ( EINFO_EIO_NVDATA_FAILURE )
+#define EINFO_EIO_NVDATA_FAILURE					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NVDATA_FAILURE,	      \
+			  "Non-volatile data failure" )
+#define EIO_UNSUPPORTED __einfo_error ( EINFO_EIO_UNSUPPORTED )
+#define EINFO_EIO_UNSUPPORTED						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_UNSUPPORTED,		      \
+			  "Unsupported" )
+#define EIO_BUFFER_FULL __einfo_error ( EINFO_EIO_BUFFER_FULL )
+#define EINFO_EIO_BUFFER_FULL						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_BUFFER_FULL,		      \
+			  "Buffer full" )
+#define EIO_INVALID_PARAMETER __einfo_error ( EINFO_EIO_INVALID_PARAMETER )
+#define EINFO_EIO_INVALID_PARAMETER					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_INVALID_PARAMETER,	      \
+			  "Invalid parameter" )
+#define EIO_INVALID_UNDI __einfo_error ( EINFO_EIO_INVALID_UNDI )
+#define EINFO_EIO_INVALID_UNDI						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_INVALID_UNDI,		      \
+			  "Invalid UNDI" )
+#define EIO_IPV4_NOT_SUPPORTED __einfo_error ( EINFO_EIO_IPV4_NOT_SUPPORTED )
+#define EINFO_EIO_IPV4_NOT_SUPPORTED					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_IPV4_NOT_SUPPORTED,	      \
+			  "IPv4 not supported" )
+#define EIO_IPV6_NOT_SUPPORTED __einfo_error ( EINFO_EIO_IPV6_NOT_SUPPORTED )
+#define EINFO_EIO_IPV6_NOT_SUPPORTED					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_IPV6_NOT_SUPPORTED,	      \
+			  "IPv6 not supported" )
+#define EIO_NOT_ENOUGH_MEMORY __einfo_error ( EINFO_EIO_NOT_ENOUGH_MEMORY )
+#define EINFO_EIO_NOT_ENOUGH_MEMORY					      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NOT_ENOUGH_MEMORY,	      \
+			  "Not enough memory" )
+#define EIO_NO_DATA __einfo_error ( EINFO_EIO_NO_DATA )
+#define EINFO_EIO_NO_DATA						      \
+	__einfo_uniqify ( EINFO_EIO, PXE_STATCODE_NO_DATA,		      \
+			  "No data" )
+#define EIO_STAT( stat )						      \
+	EUNIQ ( EINFO_EIO, -(stat), EIO_INVALID_CDB, EIO_INVALID_CPB,	      \
+		EIO_BUSY, EIO_QUEUE_FULL, EIO_ALREADY_STARTED,		      \
+		EIO_NOT_STARTED, EIO_NOT_SHUTDOWN, EIO_ALREADY_INITIALIZED,   \
+		EIO_NOT_INITIALIZED, EIO_DEVICE_FAILURE, EIO_NVDATA_FAILURE,  \
+		EIO_UNSUPPORTED, EIO_BUFFER_FULL, EIO_INVALID_PARAMETER,      \
+		EIO_INVALID_UNDI, EIO_IPV4_NOT_SUPPORTED,		      \
+		EIO_IPV6_NOT_SUPPORTED, EIO_NOT_ENOUGH_MEMORY, EIO_NO_DATA )
+
+/** Maximum PCI BAR
+ *
+ * This is defined in <ipxe/efi/IndustryStandard/Pci22.h>, but we
+ * can't #include that since it collides with <ipxe/pci.h>.
+ */
+#define PCI_MAX_BAR 6
+
+/** An NII NIC */
+struct nii_nic {
+	/** EFI device */
+	struct efi_device *efidev;
+	/** Network interface identifier protocol */
+	EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL *nii;
+	/** !PXE structure */
+	PXE_SW_UNDI *undi;
+	/** Entry point */
+	EFIAPI VOID ( * issue ) ( UINT64 cdb );
+	/** Generic device */
+	struct device dev;
+
+	/** PCI device */
+	EFI_HANDLE pci_device;
+	/** PCI I/O protocol */
+	EFI_PCI_IO_PROTOCOL *pci_io;
+	/** Memory BAR */
+	unsigned int mem_bar;
+	/** I/O BAR */
+	unsigned int io_bar;
+
+	/** Broadcast address */
+	PXE_MAC_ADDR broadcast;
+	/** Maximum packet length */
+	size_t mtu;
+
+	/** Hardware transmit/receive buffer */
+	userptr_t buffer;
+	/** Hardware transmit/receive buffer length */
+	size_t buffer_len;
+
+	/** Saved task priority level */
+	EFI_TPL saved_tpl;
+
+	/** Current transmit buffer */
+	struct io_buffer *txbuf;
+	/** Current receive buffer */
+	struct io_buffer *rxbuf;
+};
+
+/** Maximum number of received packets per poll */
+#define NII_RX_QUOTA 4
+
+/**
+ * Open PCI I/O protocol and identify BARs
+ *
+ * @v nii		NII NIC
+ * @ret rc		Return status code
+ */
+static int nii_pci_open ( struct nii_nic *nii ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	EFI_HANDLE device = nii->efidev->device;
+	EFI_HANDLE pci_device;
+	union {
+		EFI_PCI_IO_PROTOCOL *pci_io;
+		void *interface;
+	} pci_io;
+	union {
+		EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *acpi;
+		void *resource;
+	} desc;
+	unsigned int bar;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Locate PCI I/O protocol */
+	if ( ( rc = efi_locate_device ( device, &efi_pci_io_protocol_guid,
+					&pci_device ) ) != 0 ) {
+		DBGC ( nii, "NII %s could not locate PCI I/O protocol: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		goto err_locate;
+	}
+	nii->pci_device = pci_device;
+
+	/* Open PCI I/O protocol */
+	if ( ( efirc = bs->OpenProtocol ( pci_device, &efi_pci_io_protocol_guid,
+					  &pci_io.interface, efi_image_handle,
+					  device,
+					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( nii, "NII %s could not open PCI I/O protocol: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		goto err_open;
+	}
+	nii->pci_io = pci_io.pci_io;
+
+	/* Identify memory and I/O BARs */
+	nii->mem_bar = PCI_MAX_BAR;
+	nii->io_bar = PCI_MAX_BAR;
+	for ( bar = 0 ; bar < PCI_MAX_BAR ; bar++ ) {
+		efirc = nii->pci_io->GetBarAttributes ( nii->pci_io, bar, NULL,
+							&desc.resource );
+		if ( efirc == EFI_UNSUPPORTED ) {
+			/* BAR not present; ignore */
+			continue;
+		}
+		if ( efirc != 0 ) {
+			rc = -EEFI ( efirc );
+			DBGC ( nii, "NII %s could not get BAR %d attributes: "
+			       "%s\n", nii->dev.name, bar, strerror ( rc ) );
+			goto err_get_bar_attributes;
+		}
+		if ( desc.acpi->ResType == ACPI_ADDRESS_SPACE_TYPE_MEM ) {
+			nii->mem_bar = bar;
+		} else if ( desc.acpi->ResType == ACPI_ADDRESS_SPACE_TYPE_IO ) {
+			nii->io_bar = bar;
+		}
+		bs->FreePool ( desc.resource );
+	}
+	DBGC ( nii, "NII %s has ", nii->dev.name );
+	if ( nii->mem_bar < PCI_MAX_BAR ) {
+		DBGC ( nii, "memory BAR %d and ", nii->mem_bar );
+	} else {
+		DBGC ( nii, "no memory BAR and " );
+	}
+	if ( nii->io_bar < PCI_MAX_BAR ) {
+		DBGC ( nii, "I/O BAR %d\n", nii->io_bar );
+	} else {
+		DBGC ( nii, "no I/O BAR\n" );
+	}
+
+	return 0;
+
+ err_get_bar_attributes:
+	bs->CloseProtocol ( pci_device, &efi_pci_io_protocol_guid,
+			    efi_image_handle, device );
+ err_open:
+ err_locate:
+	return rc;
+}
+
+/**
+ * Close PCI I/O protocol
+ *
+ * @v nii		NII NIC
+ * @ret rc		Return status code
+ */
+static void nii_pci_close ( struct nii_nic *nii ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+
+	bs->CloseProtocol ( nii->pci_device, &efi_pci_io_protocol_guid,
+			    efi_image_handle, nii->efidev->device );
+}
+
+/**
+ * I/O callback
+ *
+ * @v unique_id		NII NIC
+ * @v op		Operations
+ * @v len		Length of data
+ * @v addr		Address
+ * @v data		Data buffer
+ */
+static EFIAPI VOID nii_io ( UINT64 unique_id, UINT8 op, UINT8 len, UINT64 addr,
+			    UINT64 data ) {
+	struct nii_nic *nii = ( ( void * ) ( intptr_t ) unique_id );
+	EFI_PCI_IO_PROTOCOL_ACCESS *access;
+	EFI_PCI_IO_PROTOCOL_IO_MEM io;
+	EFI_PCI_IO_PROTOCOL_WIDTH width;
+	unsigned int bar;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Determine accessor and BAR */
+	if ( op & ( PXE_MEM_READ | PXE_MEM_WRITE ) ) {
+		access = &nii->pci_io->Mem;
+		bar = nii->mem_bar;
+	} else {
+		access = &nii->pci_io->Io;
+		bar = nii->io_bar;
+	}
+
+	/* Determine operaton */
+	io = ( ( op & ( PXE_IO_WRITE | PXE_MEM_WRITE ) ) ?
+	       access->Write : access->Read );
+
+	/* Determine width */
+	width = ( fls ( len ) - 1 );
+
+	/* Issue operation */
+	if ( ( efirc = io ( nii->pci_io, width, bar, addr, 1,
+			    ( ( void * ) ( intptr_t ) data ) ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( nii, "NII %s I/O operation %#x failed: %s\n",
+		       nii->dev.name, op, strerror ( rc ) );
+		/* No way to report failure */
+		return;
+	}
+}
+
+/**
+ * Delay callback
+ *
+ * @v unique_id		NII NIC
+ * @v microseconds	Delay in microseconds
+ */
+static EFIAPI VOID nii_delay ( UINT64 unique_id __unused, UINTN microseconds ) {
+
+	udelay ( microseconds );
+}
+
+/**
+ * Block callback
+ *
+ * @v unique_id		NII NIC
+ * @v acquire		Acquire lock
+ */
+static EFIAPI VOID nii_block ( UINT64 unique_id, UINT32 acquire ) {
+	struct nii_nic *nii = ( ( void * ) ( intptr_t ) unique_id );
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+
+	/* This functionality (which is copied verbatim from the
+	 * SnpDxe implementation of this function) appears to be
+	 * totally brain-dead, since it produces no actual blocking
+	 * behaviour.
+	 */
+	if ( acquire ) {
+		nii->saved_tpl = bs->RaiseTPL ( TPL_NOTIFY );
+	} else {
+		bs->RestoreTPL ( nii->saved_tpl );
+	}
+}
+
+/**
+ * Construct operation from opcode and flags
+ *
+ * @v opcode		Opcode
+ * @v opflags		Flags
+ * @ret op		Operation
+ */
+#define NII_OP( opcode, opflags ) ( (opcode) | ( (opflags) << 16 ) )
+
+/**
+ * Extract opcode from operation
+ *
+ * @v op		Operation
+ * @ret opcode		Opcode
+ */
+#define NII_OPCODE( op ) ( (op) & 0xffff )
+
+/**
+ * Extract flags from operation
+ *
+ * @v op		Operation
+ * @ret opflags		Flags
+ */
+#define NII_OPFLAGS( op ) ( (op) >> 16 )
+
+/**
+ * Issue command with parameter block and data block
+ *
+ * @v nii		NII NIC
+ * @v op		Operation
+ * @v cpb		Command parameter block, or NULL
+ * @v cpb_len		Command parameter block length
+ * @v db		Data block, or NULL
+ * @v db_len		Data block length
+ * @ret stat		Status flags, or negative status code
+ */
+static int nii_issue_cpb_db ( struct nii_nic *nii, unsigned int op, void *cpb,
+			      size_t cpb_len, void *db, size_t db_len ) {
+	PXE_CDB cdb;
+
+	/* Prepare command descriptor block */
+	memset ( &cdb, 0, sizeof ( cdb ) );
+	cdb.OpCode = NII_OPCODE ( op );
+	cdb.OpFlags = NII_OPFLAGS ( op );
+	cdb.CPBaddr = ( ( intptr_t ) cpb );
+	cdb.CPBsize = cpb_len;
+	cdb.DBaddr = ( ( intptr_t ) db );
+	cdb.DBsize = db_len;
+	cdb.IFnum = nii->nii->IfNum;
+
+	/* Issue command */
+	nii->issue ( ( intptr_t ) &cdb );
+
+	/* Check completion status */
+	if ( cdb.StatCode != PXE_STATCODE_SUCCESS )
+		return -cdb.StatCode;
+
+	/* Return command-specific status flags */
+	return ( cdb.StatFlags & ~PXE_STATFLAGS_STATUS_MASK );
+}
+
+/**
+ * Issue command with parameter block
+ *
+ * @v nii		NII NIC
+ * @v op		Operation
+ * @v cpb		Command parameter block, or NULL
+ * @v cpb_len		Command parameter block length
+ * @ret stat		Status flags, or negative status code
+ */
+static int nii_issue_cpb ( struct nii_nic *nii, unsigned int op, void *cpb,
+			   size_t cpb_len ) {
+
+	return nii_issue_cpb_db ( nii, op, cpb, cpb_len, NULL, 0 );
+}
+
+/**
+ * Issue command with data block
+ *
+ * @v nii		NII NIC
+ * @v op		Operation
+ * @v db		Data block, or NULL
+ * @v db_len		Data block length
+ * @ret stat		Status flags, or negative status code
+ */
+static int nii_issue_db ( struct nii_nic *nii, unsigned int op, void *db,
+			  size_t db_len ) {
+
+	return nii_issue_cpb_db ( nii, op, NULL, 0, db, db_len );
+}
+
+/**
+ * Issue command
+ *
+ *
+ * @v nii		NII NIC
+ * @v op		Operation
+ * @ret stat		Status flags, or negative status code
+ */
+static int nii_issue ( struct nii_nic *nii, unsigned int op ) {
+
+	return nii_issue_cpb_db ( nii, op, NULL, 0, NULL, 0 );
+}
+
+/**
+ * Start UNDI
+ *
+ * @v nii		NII NIC
+ * @ret rc		Return status code
+ */
+static int nii_start_undi ( struct nii_nic *nii ) {
+	PXE_CPB_START_31 cpb;
+	int stat;
+	int rc;
+
+	/* Construct parameter block */
+	memset ( &cpb, 0, sizeof ( cpb ) );
+	cpb.Delay = ( ( intptr_t ) nii_delay );
+	cpb.Block = ( ( intptr_t ) nii_block );
+	cpb.Mem_IO = ( ( intptr_t ) nii_io );
+	cpb.Unique_ID = ( ( intptr_t ) nii );
+
+	/* Issue command */
+	if ( ( stat = nii_issue_cpb ( nii, PXE_OPCODE_START, &cpb,
+				      sizeof ( cpb ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not start: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Stop UNDI
+ *
+ * @v nii		NII NIC
+ */
+static void nii_stop_undi ( struct nii_nic *nii ) {
+	int stat;
+	int rc;
+
+	/* Issue command */
+	if ( ( stat = nii_issue ( nii, PXE_OPCODE_STOP ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not stop: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		/* Nothing we can do about it */
+		return;
+	}
+}
+
+/**
+ * Get initialisation information
+ *
+ * @v nii		NII NIC
+ * @v netdev		Network device to fill in
+ * @ret rc		Return status code
+ */
+static int nii_get_init_info ( struct nii_nic *nii,
+			       struct net_device *netdev ) {
+	PXE_DB_GET_INIT_INFO db;
+	int stat;
+	int rc;
+
+	/* Issue command */
+	if ( ( stat = nii_issue_db ( nii, PXE_OPCODE_GET_INIT_INFO, &db,
+				     sizeof ( db ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not get initialisation info: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return rc;
+	}
+
+	/* Determine link layer protocol */
+	switch ( db.IFtype ) {
+	case PXE_IFTYPE_ETHERNET :
+		netdev->ll_protocol = &ethernet_protocol;
+		break;
+	default:
+		DBGC ( nii, "NII %s unknown interface type %#02x\n",
+		       nii->dev.name, db.IFtype );
+		return -ENOTSUP;
+	}
+
+	/* Sanity checks */
+	assert ( db.MediaHeaderLen == netdev->ll_protocol->ll_header_len );
+	assert ( db.HWaddrLen == netdev->ll_protocol->hw_addr_len );
+	assert ( db.HWaddrLen == netdev->ll_protocol->ll_addr_len );
+
+	/* Extract parameters */
+	nii->buffer_len = db.MemoryRequired;
+	nii->mtu = ( db.FrameDataLen + db.MediaHeaderLen );
+	netdev->max_pkt_len = nii->mtu;
+
+	return 0;
+}
+
+/**
+ * Initialise UNDI
+ *
+ * @v nii		NII NIC
+ * @ret rc		Return status code
+ */
+static int nii_initialise ( struct nii_nic *nii ) {
+	PXE_CPB_INITIALIZE cpb;
+	unsigned int op;
+	int stat;
+	int rc;
+
+	/* Allocate memory buffer */
+	nii->buffer = umalloc ( nii->buffer_len );
+	if ( ! nii->buffer ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/* Construct parameter block */
+	memset ( &cpb, 0, sizeof ( cpb ) );
+	cpb.MemoryAddr = ( ( intptr_t ) nii->buffer );
+	cpb.MemoryLength = nii->buffer_len;
+
+	/* Issue command */
+	op = NII_OP ( PXE_OPCODE_INITIALIZE,
+		      PXE_OPFLAGS_INITIALIZE_DO_NOT_DETECT_CABLE );
+	if ( ( stat = nii_issue_cpb ( nii, op, &cpb, sizeof ( cpb ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not initialise: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		goto err_initialize;
+	}
+
+	return 0;
+
+ err_initialize:
+	ufree ( nii->buffer );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Shut down UNDI
+ *
+ * @v nii		NII NIC
+ */
+static void nii_shutdown ( struct nii_nic *nii ) {
+	int stat;
+	int rc;
+
+	/* Issue command */
+	if ( ( stat = nii_issue ( nii, PXE_OPCODE_SHUTDOWN ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not shut down: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		/* Leak memory to avoid corruption */
+		return;
+	}
+
+	/* Free buffer */
+	ufree ( nii->buffer );
+}
+
+/**
+ * Get station addresses
+ *
+ * @v nii		NII NIC
+ * @v netdev		Network device to fill in
+ * @ret rc		Return status code
+ */
+static int nii_get_station_address ( struct nii_nic *nii,
+				     struct net_device *netdev ) {
+	PXE_DB_STATION_ADDRESS db;
+	int stat;
+	int rc;
+
+	/* Initialise UNDI */
+	if ( ( rc = nii_initialise ( nii ) ) != 0 )
+		goto err_initialise;
+
+	/* Issue command */
+	if ( ( stat = nii_issue_db ( nii, PXE_OPCODE_STATION_ADDRESS, &db,
+				     sizeof ( db ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not get station address: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		goto err_station_address;
+	}
+
+	/* Copy MAC addresses */
+	memcpy ( netdev->ll_addr, db.StationAddr,
+		 netdev->ll_protocol->ll_addr_len );
+	memcpy ( netdev->hw_addr, db.PermanentAddr,
+		 netdev->ll_protocol->hw_addr_len );
+	memcpy ( nii->broadcast, db.BroadcastAddr,
+		 sizeof ( nii->broadcast ) );
+
+ err_station_address:
+	nii_shutdown ( nii );
+ err_initialise:
+	return rc;
+}
+
+/**
+ * Set station address
+ *
+ * @v nii		NII NIC
+ * @v netdev		Network device
+ * @ret rc		Return status code
+ */
+static int nii_set_station_address ( struct nii_nic *nii,
+				     struct net_device *netdev ) {
+	PXE_CPB_STATION_ADDRESS cpb;
+	int stat;
+	int rc;
+
+	/* Construct parameter block */
+	memset ( &cpb, 0, sizeof ( cpb ) );
+	memcpy ( cpb.StationAddr, netdev->ll_addr,
+		 netdev->ll_protocol->ll_addr_len );
+
+	/* Issue command */
+	if ( ( stat = nii_issue_cpb ( nii, PXE_OPCODE_STATION_ADDRESS,
+				      &cpb, sizeof ( cpb ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not set station address: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Set receive filters
+ *
+ * @v nii		NII NIC
+ * @ret rc		Return status code
+ */
+static int nii_set_rx_filters ( struct nii_nic *nii ) {
+	unsigned int op;
+	int stat;
+	int rc;
+
+	/* Issue command */
+	op = NII_OP ( PXE_OPCODE_RECEIVE_FILTERS,
+		      ( PXE_OPFLAGS_RECEIVE_FILTER_ENABLE |
+			PXE_OPFLAGS_RECEIVE_FILTER_UNICAST |
+			PXE_OPFLAGS_RECEIVE_FILTER_BROADCAST |
+			PXE_OPFLAGS_RECEIVE_FILTER_PROMISCUOUS |
+			PXE_OPFLAGS_RECEIVE_FILTER_ALL_MULTICAST ) );
+	if ( ( stat = nii_issue ( nii, op ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not set receive filters: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Transmit packet
+ *
+ * @v netdev		Network device
+ * @v iobuf		I/O buffer
+ * @ret rc		Return status code
+ */
+static int nii_transmit ( struct net_device *netdev,
+			  struct io_buffer *iobuf ) {
+	struct nii_nic *nii = netdev->priv;
+	PXE_CPB_TRANSMIT cpb;
+	int stat;
+	int rc;
+
+	/* Defer the packet if there is already a transmission in progress */
+	if ( nii->txbuf ) {
+		netdev_tx_defer ( netdev, iobuf );
+		return 0;
+	}
+
+	/* Construct parameter block */
+	memset ( &cpb, 0, sizeof ( cpb ) );
+	cpb.FrameAddr = virt_to_bus ( iobuf->data );
+	cpb.DataLen = iob_len ( iobuf );
+	cpb.MediaheaderLen = netdev->ll_protocol->ll_header_len;
+
+	/* Transmit packet */
+	if ( ( stat = nii_issue_cpb ( nii, PXE_OPCODE_TRANSMIT, &cpb,
+				      sizeof ( cpb ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not transmit: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return rc;
+	}
+	nii->txbuf = iobuf;
+
+	return 0;
+}
+
+/**
+ * Poll for completed packets
+ *
+ * @v netdev		Network device
+ * @v stat		Status flags
+ */
+static void nii_poll_tx ( struct net_device *netdev, unsigned int stat ) {
+	struct nii_nic *nii = netdev->priv;
+	struct io_buffer *iobuf;
+
+	/* Do nothing unless we have a completion */
+	if ( stat & PXE_STATFLAGS_GET_STATUS_NO_TXBUFS_WRITTEN )
+		return;
+
+	/* Sanity check */
+	if ( ! nii->txbuf ) {
+		DBGC ( nii, "NII %s reported spurious TX completion\n",
+		       nii->dev.name );
+		netdev_tx_err ( netdev, NULL, -EPIPE );
+		return;
+	}
+
+	/* Complete transmission */
+	iobuf = nii->txbuf;
+	nii->txbuf = NULL;
+	netdev_tx_complete ( netdev, iobuf );
+}
+
+/**
+ * Poll for received packets
+ *
+ * @v netdev		Network device
+ */
+static void nii_poll_rx ( struct net_device *netdev ) {
+	struct nii_nic *nii = netdev->priv;
+	PXE_CPB_RECEIVE cpb;
+	PXE_DB_RECEIVE db;
+	unsigned int quota;
+	int stat;
+	int rc;
+
+	/* Retrieve up to NII_RX_QUOTA packets */
+	for ( quota = NII_RX_QUOTA ; quota ; quota-- ) {
+
+		/* Allocate buffer, if required */
+		if ( ! nii->rxbuf ) {
+			nii->rxbuf = alloc_iob ( nii->mtu );
+			if ( ! nii->rxbuf ) {
+				/* Leave for next poll */
+				break;
+			}
+		}
+
+		/* Construct parameter block */
+		memset ( &cpb, 0, sizeof ( cpb ) );
+		cpb.BufferAddr = virt_to_bus ( nii->rxbuf->data );
+		cpb.BufferLen = iob_tailroom ( nii->rxbuf );
+
+		/* Issue command */
+		if ( ( stat = nii_issue_cpb_db ( nii, PXE_OPCODE_RECEIVE,
+						 &cpb, sizeof ( cpb ),
+						 &db, sizeof ( db ) ) ) < 0 ) {
+
+			/* PXE_STATCODE_NO_DATA is just the usual "no packet"
+			 * status indicator; ignore it.
+			 */
+			if ( stat == -PXE_STATCODE_NO_DATA )
+				break;
+
+			/* Anything else is an error */
+			rc = -EIO_STAT ( stat );
+			DBGC ( nii, "NII %s could not receive: %s\n",
+			       nii->dev.name, strerror ( rc ) );
+			netdev_rx_err ( netdev, NULL, rc );
+			break;
+		}
+
+		/* Hand off to network stack */
+		iob_put ( nii->rxbuf, db.FrameLen );
+		netdev_rx ( netdev, nii->rxbuf );
+		nii->rxbuf = NULL;
+	}
+}
+
+/**
+ * Check for link state changes
+ *
+ * @v netdev		Network device
+ * @v stat		Status flags
+ */
+static void nii_poll_link ( struct net_device *netdev, unsigned int stat ) {
+	int no_media = ( stat & PXE_STATFLAGS_GET_STATUS_NO_MEDIA );
+
+	if ( no_media && netdev_link_ok ( netdev ) ) {
+		netdev_link_down ( netdev );
+	} else if ( ( ! no_media ) && ( ! netdev_link_ok ( netdev ) ) ) {
+		netdev_link_up ( netdev );
+	}
+}
+
+/**
+ * Poll for completed packets
+ *
+ * @v netdev		Network device
+ */
+static void nii_poll ( struct net_device *netdev ) {
+	struct nii_nic *nii = netdev->priv;
+	PXE_DB_GET_STATUS db;
+	unsigned int op;
+	int stat;
+	int rc;
+
+	/* Get status */
+	op = NII_OP ( PXE_OPCODE_GET_STATUS,
+		      ( PXE_OPFLAGS_GET_INTERRUPT_STATUS |
+			PXE_OPFLAGS_GET_TRANSMITTED_BUFFERS |
+			PXE_OPFLAGS_GET_MEDIA_STATUS ) );
+	if ( ( stat = nii_issue_db ( nii, op, &db, sizeof ( db ) ) ) < 0 ) {
+		rc = -EIO_STAT ( stat );
+		DBGC ( nii, "NII %s could not get status: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		return;
+	}
+
+	/* Process any TX completions */
+	nii_poll_tx ( netdev, stat );
+
+	/* Process any RX completions */
+	nii_poll_rx ( netdev );
+
+	/* Check for link state changes */
+	nii_poll_link ( netdev, stat );
+}
+
+/**
+ * Open network device
+ *
+ * @v netdev		Network device
+ * @ret rc		Return status code
+ */
+static int nii_open ( struct net_device *netdev ) {
+	struct nii_nic *nii = netdev->priv;
+	int rc;
+
+	/* Initialise NIC */
+	if ( ( rc = nii_initialise ( nii ) ) != 0 )
+		goto err_initialise;
+
+	/* Attempt to set station address */
+	if ( ( rc = nii_set_station_address ( nii, netdev ) ) != 0 ) {
+		DBGC ( nii, "NII %s could not set station address: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		/* Treat as non-fatal */
+	}
+
+	/* Set receive filters */
+	if ( ( rc = nii_set_rx_filters ( nii ) ) != 0 )
+		goto err_set_rx_filters;
+
+	return 0;
+
+ err_set_rx_filters:
+	nii_shutdown ( nii );
+ err_initialise:
+	return rc;
+}
+
+/**
+ * Close network device
+ *
+ * @v netdev		Network device
+ */
+static void nii_close ( struct net_device *netdev ) {
+	struct nii_nic *nii = netdev->priv;
+
+	/* Shut down NIC */
+	nii_shutdown ( nii );
+
+	/* Discard transmit buffer, if applicable */
+	if ( nii->txbuf ) {
+		netdev_tx_complete_err ( netdev, nii->txbuf, -ECANCELED );
+		nii->txbuf = NULL;
+	}
+
+	/* Discard receive buffer, if applicable */
+	if ( nii->rxbuf ) {
+		free_iob ( nii->rxbuf );
+		nii->rxbuf = NULL;
+	}
+}
+
+/** NII network device operations */
+static struct net_device_operations nii_operations = {
+	.open = nii_open,
+	.close = nii_close,
+	.transmit = nii_transmit,
+	.poll = nii_poll,
+};
+
+/**
+ * Check to see if driver supports a device
+ *
+ * @v device		EFI device handle
+ * @ret rc		Return status code
+ */
+static int nii_supported ( EFI_HANDLE device ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	EFI_STATUS efirc;
+
+	/* Check that this is not a device we are providing ourselves */
+	if ( find_snpdev ( device ) != NULL ) {
+		DBGCP ( device, "NII %p %s is provided by this binary\n",
+			device, efi_handle_name ( device ) );
+		return -ENOTTY;
+	}
+
+	/* Test for presence of NII protocol */
+	if ( ( efirc = bs->OpenProtocol ( device,
+					  &efi_nii31_protocol_guid,
+					  NULL, efi_image_handle, device,
+					  EFI_OPEN_PROTOCOL_TEST_PROTOCOL))!=0){
+		DBGCP ( device, "NII %p %s is not an NII device\n",
+			device, efi_handle_name ( device ) );
+		return -EEFI ( efirc );
+	}
+	DBGC ( device, "NII %p %s is an NII device\n",
+	       device, efi_handle_name ( device ) );
+
+	return 0;
+}
+
+/**
+ * Attach driver to device
+ *
+ * @v efidev		EFI device
+ * @ret rc		Return status code
+ */
+static int nii_start ( struct efi_device *efidev ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	EFI_HANDLE device = efidev->device;
+	struct net_device *netdev;
+	struct nii_nic *nii;
+	void *interface;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Allocate and initialise structure */
+	netdev = alloc_netdev ( sizeof ( *nii ) );
+	if ( ! netdev ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	netdev_init ( netdev, &nii_operations );
+	nii = netdev->priv;
+	nii->efidev = efidev;
+	netdev->ll_broadcast = nii->broadcast;
+	efidev_set_drvdata ( efidev, netdev );
+
+	/* Populate underlying device information */
+	efi_device_info ( device, "NII", &nii->dev );
+	nii->dev.driver_name = "NII";
+	nii->dev.parent = &efidev->dev;
+	list_add ( &nii->dev.siblings, &efidev->dev.children );
+	INIT_LIST_HEAD ( &nii->dev.children );
+	netdev->dev = &nii->dev;
+
+	/* Open NII protocol */
+	if ( ( efirc = bs->OpenProtocol ( device, &efi_nii31_protocol_guid,
+					  &interface, efi_image_handle, device,
+					  ( EFI_OPEN_PROTOCOL_BY_DRIVER |
+					    EFI_OPEN_PROTOCOL_EXCLUSIVE )))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( nii, "NII %s cannot open NII protocol: %s\n",
+		       nii->dev.name, strerror ( rc ) );
+		DBGC_EFI_OPENERS ( device, device, &efi_nii31_protocol_guid );
+		goto err_open_protocol;
+	}
+	nii->nii = interface;
+
+	/* Locate UNDI and entry point */
+	nii->undi = ( ( void * ) ( intptr_t ) nii->nii->Id );
+	if ( nii->undi->Implementation & PXE_ROMID_IMP_HW_UNDI ) {
+		DBGC ( nii, "NII %s is a mythical hardware UNDI\n",
+		       nii->dev.name );
+		rc = -ENOTSUP;
+		goto err_hw_undi;
+	}
+	if ( nii->undi->Implementation & PXE_ROMID_IMP_SW_VIRT_ADDR ) {
+		nii->issue = ( ( void * ) ( intptr_t ) nii->undi->EntryPoint );
+	} else {
+		nii->issue = ( ( ( void * ) nii->undi ) +
+			       nii->undi->EntryPoint );
+	}
+	DBGC ( nii, "NII %s using UNDI v%x.%x at %p entry %p\n", nii->dev.name,
+	       nii->nii->MajorVer, nii->nii->MinorVer, nii->undi, nii->issue );
+
+	/* Open PCI I/O protocols and locate BARs */
+	if ( ( rc = nii_pci_open ( nii ) ) != 0 )
+		goto err_pci_open;
+
+	/* Start UNDI */
+	if ( ( rc = nii_start_undi ( nii ) ) != 0 )
+		goto err_start_undi;
+
+	/* Get initialisation information */
+	if ( ( rc = nii_get_init_info ( nii, netdev ) ) != 0 )
+		goto err_get_init_info;
+
+	/* Get MAC addresses */
+	if ( ( rc = nii_get_station_address ( nii, netdev ) ) != 0 )
+		goto err_get_station_address;
+
+	/* Register network device */
+	if ( ( rc = register_netdev ( netdev ) ) != 0 )
+		goto err_register_netdev;
+	DBGC ( nii, "NII %s registered as %s for %p %s\n", nii->dev.name,
+	       netdev->name, device, efi_handle_name ( device ) );
+
+	return 0;
+
+	unregister_netdev ( netdev );
+ err_register_netdev:
+ err_get_station_address:
+ err_get_init_info:
+	nii_stop_undi ( nii );
+ err_start_undi:
+	nii_pci_close ( nii );
+ err_pci_open:
+ err_hw_undi:
+	bs->CloseProtocol ( device, &efi_nii31_protocol_guid,
+			    efi_image_handle, device );
+ err_open_protocol:
+	list_del ( &nii->dev.siblings );
+	netdev_nullify ( netdev );
+	netdev_put ( netdev );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Detach driver from device
+ *
+ * @v efidev		EFI device
+ */
+static void nii_stop ( struct efi_device *efidev ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct net_device *netdev = efidev_get_drvdata ( efidev );
+	struct nii_nic *nii = netdev->priv;
+	EFI_HANDLE device = efidev->device;
+
+	/* Unregister network device */
+	unregister_netdev ( netdev );
+
+	/* Stop UNDI */
+	nii_stop_undi ( nii );
+
+	/* Close PCI I/O protocols */
+	nii_pci_close ( nii );
+
+	/* Close NII protocol */
+	bs->CloseProtocol ( device, &efi_nii31_protocol_guid,
+			    efi_image_handle, device );
+
+	/* Free network device */
+	list_del ( &nii->dev.siblings );
+	netdev_nullify ( netdev );
+	netdev_put ( netdev );
+}
+
+/** EFI NII driver */
+struct efi_driver nii_driver __efi_driver ( EFI_DRIVER_NORMAL ) = {
+	.name = "NII",
+	.supported = nii_supported,
+	.start = nii_start,
+	.stop = nii_stop,
+};