/*
 * Copyright (C) 2008 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <gpxe/netdevice.h>
#include <gpxe/iobuf.h>
#include <gpxe/in.h>
#include <gpxe/pci.h>
#include <gpxe/efi/efi.h>
#include <gpxe/efi/Protocol/DriverBinding.h>
#include <gpxe/efi/Protocol/PciIo.h>
#include <gpxe/efi/Protocol/SimpleNetwork.h>
#include <gpxe/efi/Protocol/ComponentName2.h>
#include <gpxe/efi/Protocol/NetworkInterfaceIdentifier.h>
#include <config/general.h>

/** @file
 *
 * gPXE EFI SNP interface
 *
 */

/** An SNP device */
struct efi_snp_device {
        /** The underlying gPXE network device */
        struct net_device *netdev;
        /** EFI device handle */
        EFI_HANDLE handle;
        /** The SNP structure itself */
        EFI_SIMPLE_NETWORK_PROTOCOL snp;
        /** The SNP "mode" (parameters) */
        EFI_SIMPLE_NETWORK_MODE mode;
        /** Outstanding TX packet count (via "interrupt status")
         *
         * Used in order to generate TX completions.
         */
        unsigned int tx_count_interrupts;
        /** Outstanding TX packet count (via "recycled tx buffers")
         *
         * Used in order to generate TX completions.
         */
        unsigned int tx_count_txbufs;
        /** Outstanding RX packet count (via "interrupt status") */
        unsigned int rx_count_interrupts;
        /** Outstanding RX packet count (via WaitForPacket event) */
        unsigned int rx_count_events;
        /** The network interface identifier */
        EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL nii;
        /** Device name */
        wchar_t name[ sizeof ( ( ( struct net_device * ) NULL )->name ) ];
        /** The device path
         *
         * This field is variable in size and must appear at the end
         * of the structure.
         */
        EFI_DEVICE_PATH_PROTOCOL path;
};

/** EFI simple network protocol GUID */
static EFI_GUID efi_simple_network_protocol_guid
        = EFI_SIMPLE_NETWORK_PROTOCOL_GUID;

/** EFI driver binding protocol GUID */
static EFI_GUID efi_driver_binding_protocol_guid
        = EFI_DRIVER_BINDING_PROTOCOL_GUID;

/** EFI component name protocol GUID */
static EFI_GUID efi_component_name2_protocol_guid
        = EFI_COMPONENT_NAME2_PROTOCOL_GUID;

/** EFI device path protocol GUID */
static EFI_GUID efi_device_path_protocol_guid
        = EFI_DEVICE_PATH_PROTOCOL_GUID;

/** EFI network interface identifier GUID */
static EFI_GUID efi_nii_protocol_guid
        = EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL_GUID;

/** EFI network interface identifier GUID (extra special version) */
static EFI_GUID efi_nii31_protocol_guid = {
        /* At some point, it seems that someone decided to change the
         * GUID.  Current EFI builds ignore the older GUID, older EFI
         * builds ignore the newer GUID, so we have to expose both.
         */
        0x1ACED566, 0x76ED, 0x4218,
        { 0xBC, 0x81, 0x76, 0x7F, 0x1F, 0x97, 0x7A, 0x89 }
};

/** EFI PCI I/O protocol GUID */
static EFI_GUID efi_pci_io_protocol_guid
        = EFI_PCI_IO_PROTOCOL_GUID;

/**
 * Set EFI SNP mode based on gPXE net device parameters
 *
 * @v snp               SNP interface
 */
static void efi_snp_set_mode ( struct efi_snp_device *snpdev ) {
        struct net_device *netdev = snpdev->netdev;
        EFI_SIMPLE_NETWORK_MODE *mode = &snpdev->mode;
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
        unsigned int ll_addr_len = ll_protocol->ll_addr_len;

        mode->HwAddressSize = ll_addr_len;
        mode->MediaHeaderSize = ll_protocol->ll_header_len;
        mode->MaxPacketSize = netdev->max_pkt_len;
        mode->ReceiveFilterMask = ( EFI_SIMPLE_NETWORK_RECEIVE_UNICAST |
                                    EFI_SIMPLE_NETWORK_RECEIVE_MULTICAST |
                                    EFI_SIMPLE_NETWORK_RECEIVE_BROADCAST );
        assert ( ll_addr_len <= sizeof ( mode->CurrentAddress ) );
        memcpy ( &mode->CurrentAddress, netdev->ll_addr, ll_addr_len );
        memcpy ( &mode->BroadcastAddress, netdev->ll_broadcast, ll_addr_len );
        ll_protocol->init_addr ( netdev->hw_addr, &mode->PermanentAddress );
        mode->IfType = ntohs ( ll_protocol->ll_proto );
        mode->MacAddressChangeable = TRUE;
        mode->MediaPresentSupported = TRUE;
        mode->MediaPresent = ( netdev_link_ok ( netdev ) ? TRUE : FALSE );
}

/**
 * Poll net device and count received packets
 *
 * @v snpdev            SNP device
 */
static void efi_snp_poll ( struct efi_snp_device *snpdev ) {
        struct io_buffer *iobuf;
        unsigned int before = 0;
        unsigned int after = 0;
        unsigned int arrived;

        /* We have to report packet arrivals, and this is the easiest
         * way to fake it.
         */
        list_for_each_entry ( iobuf, &snpdev->netdev->rx_queue, list )
                before++;
        netdev_poll ( snpdev->netdev );
        list_for_each_entry ( iobuf, &snpdev->netdev->rx_queue, list )
                after++;
        arrived = ( after - before );

        snpdev->rx_count_interrupts += arrived;
        snpdev->rx_count_events += arrived;
}

/**
 * Change SNP state from "stopped" to "started"
 *
 * @v snp               SNP interface
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_start ( EFI_SIMPLE_NETWORK_PROTOCOL *snp ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );

        DBGC2 ( snpdev, "SNPDEV %p START\n", snpdev );

        snpdev->mode.State = EfiSimpleNetworkStarted;
        return 0;
}

/**
 * Change SNP state from "started" to "stopped"
 *
 * @v snp               SNP interface
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_stop ( EFI_SIMPLE_NETWORK_PROTOCOL *snp ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );

        DBGC2 ( snpdev, "SNPDEV %p STOP\n", snpdev );

        snpdev->mode.State = EfiSimpleNetworkStopped;
        return 0;
}

/**
 * Open the network device
 *
 * @v snp               SNP interface
 * @v extra_rx_bufsize  Extra RX buffer size, in bytes
 * @v extra_tx_bufsize  Extra TX buffer size, in bytes
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_initialize ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
                     UINTN extra_rx_bufsize, UINTN extra_tx_bufsize ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        int rc;

        DBGC2 ( snpdev, "SNPDEV %p INITIALIZE (%ld extra RX, %ld extra TX)\n",
                snpdev, ( ( unsigned long ) extra_rx_bufsize ),
                ( ( unsigned long ) extra_tx_bufsize ) );

        if ( ( rc = netdev_open ( snpdev->netdev ) ) != 0 ) {
                DBGC ( snpdev, "SNPDEV %p could not open %s: %s\n",
                       snpdev, snpdev->netdev->name, strerror ( rc ) );
                return RC_TO_EFIRC ( rc );
        }

        snpdev->mode.State = EfiSimpleNetworkInitialized;
        return 0;
}

/**
 * Reset the network device
 *
 * @v snp               SNP interface
 * @v ext_verify        Extended verification required
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_reset ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, BOOLEAN ext_verify ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        int rc;

        DBGC2 ( snpdev, "SNPDEV %p RESET (%s extended verification)\n",
                snpdev, ( ext_verify ? "with" : "without" ) );

        netdev_close ( snpdev->netdev );
        snpdev->mode.State = EfiSimpleNetworkStarted;

        if ( ( rc = netdev_open ( snpdev->netdev ) ) != 0 ) {
                DBGC ( snpdev, "SNPDEV %p could not reopen %s: %s\n",
                       snpdev, snpdev->netdev->name, strerror ( rc ) );
                return RC_TO_EFIRC ( rc );
        }

        snpdev->mode.State = EfiSimpleNetworkInitialized;
        return 0;
}

/**
 * Shut down the network device
 *
 * @v snp               SNP interface
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_shutdown ( EFI_SIMPLE_NETWORK_PROTOCOL *snp ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );

        DBGC2 ( snpdev, "SNPDEV %p SHUTDOWN\n", snpdev );

        netdev_close ( snpdev->netdev );
        snpdev->mode.State = EfiSimpleNetworkStarted;
        return 0;
}

/**
 * Manage receive filters
 *
 * @v snp               SNP interface
 * @v enable            Receive filters to enable
 * @v disable           Receive filters to disable
 * @v mcast_reset       Reset multicast filters
 * @v mcast_count       Number of multicast filters
 * @v mcast             Multicast filters
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_receive_filters ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, UINT32 enable,
                          UINT32 disable, BOOLEAN mcast_reset,
                          UINTN mcast_count, EFI_MAC_ADDRESS *mcast ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        unsigned int i;

        DBGC2 ( snpdev, "SNPDEV %p RECEIVE_FILTERS %08x&~%08x%s %ld mcast\n",
                snpdev, enable, disable, ( mcast_reset ? " reset" : "" ),
                ( ( unsigned long ) mcast_count ) );
        for ( i = 0 ; i < mcast_count ; i++ ) {
                DBGC2_HDA ( snpdev, i, &mcast[i],
                            snpdev->netdev->ll_protocol->ll_addr_len );
        }

        /* Lie through our teeth, otherwise MNP refuses to accept us */
        return 0;
}

/**
 * Set station address
 *
 * @v snp               SNP interface
 * @v reset             Reset to permanent address
 * @v new               New station address
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_station_address ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, BOOLEAN reset,
                          EFI_MAC_ADDRESS *new ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        struct ll_protocol *ll_protocol = snpdev->netdev->ll_protocol;

        DBGC2 ( snpdev, "SNPDEV %p STATION_ADDRESS %s\n", snpdev,
                ( reset ? "reset" : ll_protocol->ntoa ( new ) ) );

        /* Set the MAC address */
        if ( reset )
                new = &snpdev->mode.PermanentAddress;
        memcpy ( snpdev->netdev->ll_addr, new, ll_protocol->ll_addr_len );

        /* MAC address changes take effect only on netdev_open() */
        if ( snpdev->netdev->state & NETDEV_OPEN ) {
                DBGC ( snpdev, "SNPDEV %p MAC address changed while net "
                       "devive open\n", snpdev );
        }

        return 0;
}

/**
 * Get (or reset) statistics
 *
 * @v snp               SNP interface
 * @v reset             Reset statistics
 * @v stats_len         Size of statistics table
 * @v stats             Statistics table
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_statistics ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, BOOLEAN reset,
                     UINTN *stats_len, EFI_NETWORK_STATISTICS *stats ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        EFI_NETWORK_STATISTICS stats_buf;

        DBGC2 ( snpdev, "SNPDEV %p STATISTICS%s", snpdev,
                ( reset ? " reset" : "" ) );

        /* Gather statistics */
        memset ( &stats_buf, 0, sizeof ( stats_buf ) );
        stats_buf.TxGoodFrames = snpdev->netdev->tx_stats.good;
        stats_buf.TxDroppedFrames = snpdev->netdev->tx_stats.bad;
        stats_buf.TxTotalFrames = ( snpdev->netdev->tx_stats.good +
                                    snpdev->netdev->tx_stats.bad );
        stats_buf.RxGoodFrames = snpdev->netdev->rx_stats.good;
        stats_buf.RxDroppedFrames = snpdev->netdev->rx_stats.bad;
        stats_buf.RxTotalFrames = ( snpdev->netdev->rx_stats.good +
                                    snpdev->netdev->rx_stats.bad );
        if ( *stats_len > sizeof ( stats_buf ) )
                *stats_len = sizeof ( stats_buf );
        if ( stats )
                memcpy ( stats, &stats_buf, *stats_len );

        /* Reset statistics if requested to do so */
        if ( reset ) {
                memset ( &snpdev->netdev->tx_stats, 0,
                         sizeof ( snpdev->netdev->tx_stats ) );
                memset ( &snpdev->netdev->rx_stats, 0,
                         sizeof ( snpdev->netdev->rx_stats ) );
        }

        return 0;
}

/**
 * Convert multicast IP address to MAC address
 *
 * @v snp               SNP interface
 * @v ipv6              Address is IPv6
 * @v ip                IP address
 * @v mac               MAC address
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_mcast_ip_to_mac ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, BOOLEAN ipv6,
                          EFI_IP_ADDRESS *ip, EFI_MAC_ADDRESS *mac ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        struct ll_protocol *ll_protocol = snpdev->netdev->ll_protocol;
        const char *ip_str;
        int rc;

        ip_str = ( ipv6 ? "(IPv6)" /* FIXME when we have inet6_ntoa() */ :
                   inet_ntoa ( *( ( struct in_addr * ) ip ) ) );
        DBGC2 ( snpdev, "SNPDEV %p MCAST_IP_TO_MAC %s\n", snpdev, ip_str );

        /* Try to hash the address */
        if ( ( rc = ll_protocol->mc_hash ( ( ipv6 ? AF_INET6 : AF_INET ),
                                           ip, mac ) ) != 0 ) {
                DBGC ( snpdev, "SNPDEV %p could not hash %s: %s\n",
                       snpdev, ip_str, strerror ( rc ) );
                return RC_TO_EFIRC ( rc );
        }

        return 0;
}

/**
 * Read or write non-volatile storage
 *
 * @v snp               SNP interface
 * @v read              Operation is a read
 * @v offset            Starting offset within NVRAM
 * @v len               Length of data buffer
 * @v data              Data buffer
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_nvdata ( EFI_SIMPLE_NETWORK_PROTOCOL *snp, BOOLEAN read,
                 UINTN offset, UINTN len, VOID *data ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );

        DBGC2 ( snpdev, "SNPDEV %p NVDATA %s %lx+%lx\n", snpdev,
                ( read ? "read" : "write" ), ( ( unsigned long ) offset ),
                ( ( unsigned long ) len ) );
        if ( ! read )
                DBGC2_HDA ( snpdev, offset, data, len );

        return EFI_UNSUPPORTED;
}

/**
 * Read interrupt status and TX recycled buffer status
 *
 * @v snp               SNP interface
 * @v interrupts        Interrupt status, or NULL
 * @v txbufs            Recycled transmit buffer address, or NULL
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_get_status ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
                     UINT32 *interrupts, VOID **txbufs ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );

        DBGC2 ( snpdev, "SNPDEV %p GET_STATUS", snpdev );

        /* Poll the network device */
        efi_snp_poll ( snpdev );

        /* Interrupt status.  In practice, this seems to be used only
         * to detect TX completions.
         */
        if ( interrupts ) {
                *interrupts = 0;
                /* Report TX completions once queue is empty; this
                 * avoids having to add hooks in the net device layer.
                 */
                if ( snpdev->tx_count_interrupts &&
                     list_empty ( &snpdev->netdev->tx_queue ) ) {
                        *interrupts |= EFI_SIMPLE_NETWORK_TRANSMIT_INTERRUPT;
                        snpdev->tx_count_interrupts--;
                }
                /* Report RX */
                if ( snpdev->rx_count_interrupts ) {
                        *interrupts |= EFI_SIMPLE_NETWORK_RECEIVE_INTERRUPT;
                        snpdev->rx_count_interrupts--;
                }
                DBGC2 ( snpdev, " INTS:%02x", *interrupts );
        }

        /* TX completions.  It would be possible to design a more
         * idiotic scheme for this, but it would be a challenge.
         * According to the UEFI header file, txbufs will be filled in
         * with a list of "recycled transmit buffers" (i.e. completed
         * TX buffers).  Observant readers may care to note that
         * *txbufs is a void pointer.  Precisely how a list of
         * completed transmit buffers is meant to be represented as an
         * array of voids is left as an exercise for the reader.
         *
         * The only users of this interface (MnpDxe/MnpIo.c and
         * PxeBcDxe/Bc.c within the EFI dev kit) both just poll until
         * seeing a non-NULL result return in txbufs.  This is valid
         * provided that they do not ever attempt to transmit more
         * than one packet concurrently (and that TX never times out).
         */
        if ( txbufs ) {
                if ( snpdev->tx_count_txbufs &&
                     list_empty ( &snpdev->netdev->tx_queue ) ) {
                        *txbufs = "Which idiot designed this API?";
                        snpdev->tx_count_txbufs--;
                } else {
                        *txbufs = NULL;
                }
                DBGC2 ( snpdev, " TX:%s", ( *txbufs ? "some" : "none" ) );
        }

        DBGC2 ( snpdev, "\n" );
        return 0;
}

/**
 * Start packet transmission
 *
 * @v snp               SNP interface
 * @v ll_header_len     Link-layer header length, if to be filled in
 * @v len               Length of data buffer
 * @v data              Data buffer
 * @v ll_src            Link-layer source address, if specified
 * @v ll_dest           Link-layer destination address, if specified
 * @v net_proto         Network-layer protocol (in host order)
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_transmit ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
                   UINTN ll_header_len, UINTN len, VOID *data,
                   EFI_MAC_ADDRESS *ll_src, EFI_MAC_ADDRESS *ll_dest,
                   UINT16 *net_proto ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        struct ll_protocol *ll_protocol = snpdev->netdev->ll_protocol;
        struct io_buffer *iobuf;
        int rc;
        EFI_STATUS efirc;

        DBGC2 ( snpdev, "SNPDEV %p TRANSMIT %p+%lx", snpdev, data,
                ( ( unsigned long ) len ) );
        if ( ll_header_len ) {
                if ( ll_src ) {
                        DBGC2 ( snpdev, " src %s",
                                ll_protocol->ntoa ( ll_src ) );
                }
                if ( ll_dest ) {
                        DBGC2 ( snpdev, " dest %s",
                                ll_protocol->ntoa ( ll_dest ) );
                }
                if ( net_proto ) {
                        DBGC2 ( snpdev, " proto %04x", *net_proto );
                }
        }
        DBGC2 ( snpdev, "\n" );

        /* Sanity checks */
        if ( ll_header_len ) {
                if ( ll_header_len != ll_protocol->ll_header_len ) {
                        DBGC ( snpdev, "SNPDEV %p TX invalid header length "
                               "%ld\n", snpdev,
                               ( ( unsigned long ) ll_header_len ) );
                        efirc = EFI_INVALID_PARAMETER;
                        goto err_sanity;
                }
                if ( len < ll_header_len ) {
                        DBGC ( snpdev, "SNPDEV %p invalid packet length %ld\n",
                               snpdev, ( ( unsigned long ) len ) );
                        efirc = EFI_BUFFER_TOO_SMALL;
                        goto err_sanity;
                }
                if ( ! ll_dest ) {
                        DBGC ( snpdev, "SNPDEV %p TX missing destination "
                               "address\n", snpdev );
                        efirc = EFI_INVALID_PARAMETER;
                        goto err_sanity;
                }
                if ( ! net_proto ) {
                        DBGC ( snpdev, "SNPDEV %p TX missing network "
                               "protocol\n", snpdev );
                        efirc = EFI_INVALID_PARAMETER;
                        goto err_sanity;
                }
                if ( ! ll_src )
                        ll_src = &snpdev->mode.CurrentAddress;
        }

        /* Allocate buffer */
        iobuf = alloc_iob ( len );
        if ( ! iobuf ) {
                DBGC ( snpdev, "SNPDEV %p TX could not allocate %ld-byte "
                       "buffer\n", snpdev, ( ( unsigned long ) len ) );
                efirc = EFI_DEVICE_ERROR;
                goto err_alloc_iob;
        }
        memcpy ( iob_put ( iobuf, len ), data, len );

        /* Create link-layer header, if specified */
        if ( ll_header_len ) {
                iob_pull ( iobuf, ll_header_len );
                if ( ( rc = ll_protocol->push ( snpdev->netdev,
                                                iobuf, ll_dest, ll_src,
                                                htons ( *net_proto ) )) != 0 ){
                        DBGC ( snpdev, "SNPDEV %p TX could not construct "
                               "header: %s\n", snpdev, strerror ( rc ) );
                        efirc = RC_TO_EFIRC ( rc );
                        goto err_ll_push;
                }
        }

        /* Transmit packet */
        if ( ( rc = netdev_tx ( snpdev->netdev, iob_disown ( iobuf ) ) ) != 0){
                DBGC ( snpdev, "SNPDEV %p TX could not transmit: %s\n",
                       snpdev, strerror ( rc ) );
                efirc = RC_TO_EFIRC ( rc );
                goto err_tx;
        }

        /* Record transmission as outstanding */
        snpdev->tx_count_interrupts++;
        snpdev->tx_count_txbufs++;

        return 0;

 err_tx:
 err_ll_push:
        free_iob ( iobuf );
 err_alloc_iob:
 err_sanity:
        return efirc;
}

/**
 * Receive packet
 *
 * @v snp               SNP interface
 * @v ll_header_len     Link-layer header length, if to be filled in
 * @v len               Length of data buffer
 * @v data              Data buffer
 * @v ll_src            Link-layer source address, if specified
 * @v ll_dest           Link-layer destination address, if specified
 * @v net_proto         Network-layer protocol (in host order)
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_receive ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
                  UINTN *ll_header_len, UINTN *len, VOID *data,
                  EFI_MAC_ADDRESS *ll_src, EFI_MAC_ADDRESS *ll_dest,
                  UINT16 *net_proto ) {
        struct efi_snp_device *snpdev =
                container_of ( snp, struct efi_snp_device, snp );
        struct ll_protocol *ll_protocol = snpdev->netdev->ll_protocol;
        struct io_buffer *iobuf;
        const void *iob_ll_dest;
        const void *iob_ll_src;
        uint16_t iob_net_proto;
        int rc;
        EFI_STATUS efirc;

        DBGC2 ( snpdev, "SNPDEV %p RECEIVE %p(+%lx)", snpdev, data,
                ( ( unsigned long ) *len ) );

        /* Poll the network device */
        efi_snp_poll ( snpdev );

        /* Dequeue a packet, if one is available */
        iobuf = netdev_rx_dequeue ( snpdev->netdev );
        if ( ! iobuf ) {
                DBGC2 ( snpdev, "\n" );
                efirc = EFI_NOT_READY;
                goto out_no_packet;
        }
        DBGC2 ( snpdev, "+%zx\n", iob_len ( iobuf ) );

        /* Return packet to caller */
        memcpy ( data, iobuf->data, iob_len ( iobuf ) );
        *len = iob_len ( iobuf );

        /* Attempt to decode link-layer header */
        if ( ( rc = ll_protocol->pull ( snpdev->netdev, iobuf, &iob_ll_dest,
                                        &iob_ll_src, &iob_net_proto ) ) != 0 ){
                DBGC ( snpdev, "SNPDEV %p could not parse header: %s\n",
                       snpdev, strerror ( rc ) );
                efirc = RC_TO_EFIRC ( rc );
                goto out_bad_ll_header;
        }

        /* Return link-layer header parameters to caller, if required */
        if ( ll_header_len )
                *ll_header_len = ll_protocol->ll_header_len;
        if ( ll_src )
                memcpy ( ll_src, iob_ll_src, ll_protocol->ll_addr_len );
        if ( ll_dest )
                memcpy ( ll_dest, iob_ll_dest, ll_protocol->ll_addr_len );
        if ( net_proto )
                *net_proto = ntohs ( iob_net_proto );

        efirc = 0;

 out_bad_ll_header:
        free_iob ( iobuf );
out_no_packet:
        return efirc;
}

/**
 * Poll event
 *
 * @v event             Event
 * @v context           Event context
 */
static VOID EFIAPI efi_snp_wait_for_packet ( EFI_EVENT event,
                                             VOID *context ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        struct efi_snp_device *snpdev = context;

        DBGCP ( snpdev, "SNPDEV %p WAIT_FOR_PACKET\n", snpdev );

        /* Do nothing unless the net device is open */
        if ( ! ( snpdev->netdev->state & NETDEV_OPEN ) )
                return;

        /* Poll the network device */
        efi_snp_poll ( snpdev );

        /* Fire event if packets have been received */
        if ( snpdev->rx_count_events != 0 ) {
                DBGC2 ( snpdev, "SNPDEV %p firing WaitForPacket event\n",
                        snpdev );
                bs->SignalEvent ( event );
                snpdev->rx_count_events--;
        }
}

/** SNP interface */
static EFI_SIMPLE_NETWORK_PROTOCOL efi_snp_device_snp = {
        .Revision       = EFI_SIMPLE_NETWORK_PROTOCOL_REVISION,
        .Start          = efi_snp_start,
        .Stop           = efi_snp_stop,
        .Initialize     = efi_snp_initialize,
        .Reset          = efi_snp_reset,
        .Shutdown       = efi_snp_shutdown,
        .ReceiveFilters = efi_snp_receive_filters,
        .StationAddress = efi_snp_station_address,
        .Statistics     = efi_snp_statistics,
        .MCastIpToMac   = efi_snp_mcast_ip_to_mac,
        .NvData         = efi_snp_nvdata,
        .GetStatus      = efi_snp_get_status,
        .Transmit       = efi_snp_transmit,
        .Receive        = efi_snp_receive,
};

/**
 * Locate net device corresponding to EFI device
 *
 * @v driver            EFI driver
 * @v device            EFI device
 * @ret netdev          Net device, or NULL if not found
 */
static struct net_device *
efi_snp_netdev ( EFI_DRIVER_BINDING_PROTOCOL *driver, EFI_HANDLE device ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        union {
                EFI_PCI_IO_PROTOCOL *pci;
                void *interface;
        } u;
        UINTN pci_segment, pci_bus, pci_dev, pci_fn;
        unsigned int pci_busdevfn;
        struct net_device *netdev = NULL;
        EFI_STATUS efirc;

        /* See if device is a PCI device */
        if ( ( efirc = bs->OpenProtocol ( device,
                                          &efi_pci_io_protocol_guid,
                                          &u.interface,
                                          driver->DriverBindingHandle,
                                          device,
                                          EFI_OPEN_PROTOCOL_BY_DRIVER )) !=0 ){
                DBGCP ( driver, "SNPDRV %p device %p is not a PCI device\n",
                        driver, device );
                goto out_no_pci_io;
        }

        /* Get PCI bus:dev.fn address */
        if ( ( efirc = u.pci->GetLocation ( u.pci, &pci_segment, &pci_bus,
                                            &pci_dev, &pci_fn ) ) != 0 ) {
                DBGC ( driver, "SNPDRV %p device %p could not get PCI "
                       "location: %s\n",
                       driver, device, efi_strerror ( efirc ) );
                goto out_no_pci_location;
        }
        DBGCP ( driver, "SNPDRV %p device %p is PCI %04lx:%02lx:%02lx.%lx\n",
                driver, device, ( ( unsigned long ) pci_segment ),
                ( ( unsigned long ) pci_bus ), ( ( unsigned long ) pci_dev ),
                ( ( unsigned long ) pci_fn ) );

        /* Look up corresponding network device */
        pci_busdevfn = PCI_BUSDEVFN ( pci_bus, PCI_DEVFN ( pci_dev, pci_fn ) );
        if ( ( netdev = find_netdev_by_location ( BUS_TYPE_PCI,
                                                  pci_busdevfn ) ) == NULL ) {
                DBGCP ( driver, "SNPDRV %p device %p is not a gPXE network "
                        "device\n", driver, device );
                goto out_no_netdev;
        }
        DBGC ( driver, "SNPDRV %p device %p is %s\n",
               driver, device, netdev->name );

 out_no_netdev:
 out_no_pci_location:
        bs->CloseProtocol ( device, &efi_pci_io_protocol_guid,
                            driver->DriverBindingHandle, device );
 out_no_pci_io:
        return netdev;
}

/**
 * Locate SNP corresponding to EFI device
 *
 * @v driver            EFI driver
 * @v device            EFI device
 * @ret snp             EFI SNP, or NULL if not found
 */
static struct efi_snp_device *
efi_snp_snpdev ( EFI_DRIVER_BINDING_PROTOCOL *driver, EFI_HANDLE device ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        union {
                EFI_SIMPLE_NETWORK_PROTOCOL *snp;
                void *interface;
        } u;
        struct efi_snp_device *snpdev = NULL;
        EFI_STATUS efirc;

        if ( ( efirc = bs->OpenProtocol ( device,
                                          &efi_simple_network_protocol_guid,
                                          &u.interface,
                                          driver->DriverBindingHandle,
                                          device,
                                          EFI_OPEN_PROTOCOL_GET_PROTOCOL))!=0){
                DBGC ( driver, "SNPDRV %p device %p could not locate SNP: "
                       "%s\n", driver, device, efi_strerror ( efirc ) );
                goto err_no_snp;
        }

        snpdev =  container_of ( u.snp, struct efi_snp_device, snp );
        DBGCP ( driver, "SNPDRV %p device %p is SNPDEV %p\n",
                driver, device, snpdev );

        bs->CloseProtocol ( device, &efi_simple_network_protocol_guid,
                            driver->DriverBindingHandle, device );
 err_no_snp:
        return snpdev;
}

/**
 * Check to see if driver supports a device
 *
 * @v driver            EFI driver
 * @v device            EFI device
 * @v child             Path to child device, if any
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_driver_supported ( EFI_DRIVER_BINDING_PROTOCOL *driver,
                           EFI_HANDLE device,
                           EFI_DEVICE_PATH_PROTOCOL *child ) {
        struct net_device *netdev;

        DBGCP ( driver, "SNPDRV %p DRIVER_SUPPORTED %p (%p)\n",
                driver, device, child );

        netdev = efi_snp_netdev ( driver, device );
        return ( netdev ? 0 : EFI_UNSUPPORTED );
}

/**
 * Attach driver to device
 *
 * @v driver            EFI driver
 * @v device            EFI device
 * @v child             Path to child device, if any
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_driver_start ( EFI_DRIVER_BINDING_PROTOCOL *driver,
                       EFI_HANDLE device,
                       EFI_DEVICE_PATH_PROTOCOL *child ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        EFI_DEVICE_PATH_PROTOCOL *path;
        EFI_DEVICE_PATH_PROTOCOL *subpath;
        MAC_ADDR_DEVICE_PATH *macpath;
        struct efi_snp_device *snpdev;
        struct net_device *netdev;
        size_t subpath_len;
        size_t path_prefix_len = 0;
        unsigned int i;
        EFI_STATUS efirc;

        DBGCP ( driver, "SNPDRV %p DRIVER_START %p (%p)\n",
                driver, device, child );

        /* Determine device path prefix length */
        if ( ( efirc = bs->OpenProtocol ( device,
                                          &efi_device_path_protocol_guid,
                                          ( void * ) &path,
                                          driver->DriverBindingHandle,
                                          device,
                                          EFI_OPEN_PROTOCOL_BY_DRIVER )) !=0 ){
                DBGCP ( driver, "SNPDRV %p device %p has no device path\n",
                        driver, device );
                goto err_no_device_path;
        }
        subpath = path;
        while ( subpath->Type != END_DEVICE_PATH_TYPE ) {
                subpath_len = ( ( subpath->Length[1] << 8 ) |
                                subpath->Length[0] );
                path_prefix_len += subpath_len;
                subpath = ( ( ( void * ) subpath ) + subpath_len );
        }

        /* Allocate the SNP device */
        snpdev = zalloc ( sizeof ( *snpdev ) + path_prefix_len +
                          sizeof ( *macpath ) );
        if ( ! snpdev ) {
                efirc = EFI_OUT_OF_RESOURCES;
                goto err_alloc_snp;
        }

        /* Identify the net device */
        netdev = efi_snp_netdev ( driver, device );
        if ( ! netdev ) {
                DBGC ( snpdev, "SNPDEV %p cannot find netdev for device %p\n",
                       snpdev, device );
                efirc = EFI_UNSUPPORTED;
                goto err_no_netdev;
        }
        snpdev->netdev = netdev_get ( netdev );

        /* Sanity check */
        if ( netdev->ll_protocol->ll_addr_len > sizeof ( EFI_MAC_ADDRESS ) ) {
                DBGC ( snpdev, "SNPDEV %p cannot support link-layer address "
                       "length %d for %s\n", snpdev,
                       netdev->ll_protocol->ll_addr_len, netdev->name );
                efirc = EFI_INVALID_PARAMETER;
                goto err_ll_addr_len;
        }

        /* Populate the SNP structure */
        memcpy ( &snpdev->snp, &efi_snp_device_snp, sizeof ( snpdev->snp ) );
        snpdev->snp.Mode = &snpdev->mode;
        if ( ( efirc = bs->CreateEvent ( EVT_NOTIFY_WAIT, TPL_NOTIFY,
                                         efi_snp_wait_for_packet, snpdev,
                                         &snpdev->snp.WaitForPacket ) ) != 0 ){
                DBGC ( snpdev, "SNPDEV %p could not create event: %s\n",
                       snpdev, efi_strerror ( efirc ) );
                goto err_create_event;
        }

        /* Populate the SNP mode structure */
        snpdev->mode.State = EfiSimpleNetworkStopped;
        efi_snp_set_mode ( snpdev );

        /* Populate the NII structure */
        snpdev->nii.Revision =
                EFI_NETWORK_INTERFACE_IDENTIFIER_PROTOCOL_REVISION;
        strncpy ( snpdev->nii.StringId, "gPXE",
                  sizeof ( snpdev->nii.StringId ) );

        /* Populate the device name */
        for ( i = 0 ; i < sizeof ( netdev->name ) ; i++ ) {
                /* Damn Unicode names */
                assert ( i < ( sizeof ( snpdev->name ) /
                               sizeof ( snpdev->name[0] ) ) );
                snpdev->name[i] = netdev->name[i];
        }

        /* Populate the device path */
        memcpy ( &snpdev->path, path, path_prefix_len );
        macpath = ( ( ( void * ) &snpdev->path ) + path_prefix_len );
        subpath = ( ( void * ) ( macpath + 1 ) );
        memset ( macpath, 0, sizeof ( *macpath ) );
        macpath->Header.Type = MESSAGING_DEVICE_PATH;
        macpath->Header.SubType = MSG_MAC_ADDR_DP;
        macpath->Header.Length[0] = sizeof ( *macpath );
        memcpy ( &macpath->MacAddress, netdev->ll_addr,
                 sizeof ( macpath->MacAddress ) );
        macpath->IfType = ntohs ( netdev->ll_protocol->ll_proto );
        memset ( subpath, 0, sizeof ( *subpath ) );
        subpath->Type = END_DEVICE_PATH_TYPE;
        subpath->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
        subpath->Length[0] = sizeof ( *subpath );

        /* Install the SNP */
        if ( ( efirc = bs->InstallMultipleProtocolInterfaces (
                        &snpdev->handle,
                        &efi_simple_network_protocol_guid, &snpdev->snp,
                        &efi_device_path_protocol_guid, &snpdev->path,
                        &efi_nii_protocol_guid, &snpdev->nii,
                        &efi_nii31_protocol_guid, &snpdev->nii,
                        NULL ) ) != 0 ) {
                DBGC ( snpdev, "SNPDEV %p could not install protocols: "
                       "%s\n", snpdev, efi_strerror ( efirc ) );
                goto err_install_protocol_interface;
        }

        DBGC ( snpdev, "SNPDEV %p installed for %s as device %p\n",
               snpdev, netdev->name, snpdev->handle );
        return 0;

        bs->UninstallMultipleProtocolInterfaces (
                        snpdev->handle,
                        &efi_simple_network_protocol_guid, &snpdev->snp,
                        &efi_device_path_protocol_guid, &snpdev->path,
                        &efi_nii_protocol_guid, &snpdev->nii,
                        &efi_nii31_protocol_guid, &snpdev->nii,
                        NULL );
 err_install_protocol_interface:
        bs->CloseEvent ( snpdev->snp.WaitForPacket );
 err_create_event:
 err_ll_addr_len:
        netdev_put ( netdev );
 err_no_netdev:
        free ( snpdev );
 err_alloc_snp:
        bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
                            driver->DriverBindingHandle, device );
 err_no_device_path:
        return efirc;
}

/**
 * Detach driver from device
 *
 * @v driver            EFI driver
 * @v device            EFI device
 * @v num_children      Number of child devices
 * @v children          List of child devices
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_driver_stop ( EFI_DRIVER_BINDING_PROTOCOL *driver,
                      EFI_HANDLE device,
                      UINTN num_children,
                      EFI_HANDLE *children ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        struct efi_snp_device *snpdev;

        DBGCP ( driver, "SNPDRV %p DRIVER_STOP %p (%ld %p)\n",
                driver, device, ( ( unsigned long ) num_children ), children );

        /* Locate SNP device */
        snpdev = efi_snp_snpdev ( driver, device );
        if ( ! snpdev ) {
                DBGC ( driver, "SNPDRV %p device %p could not find SNPDEV\n",
                       driver, device );
                return EFI_DEVICE_ERROR;
        }

        /* Uninstall the SNP */
        bs->UninstallMultipleProtocolInterfaces (
                        snpdev->handle,
                        &efi_simple_network_protocol_guid, &snpdev->snp,
                        &efi_device_path_protocol_guid, &snpdev->path,
                        &efi_nii_protocol_guid, &snpdev->nii,
                        &efi_nii31_protocol_guid, &snpdev->nii,
                        NULL );
        bs->CloseEvent ( snpdev->snp.WaitForPacket );
        netdev_put ( snpdev->netdev );
        free ( snpdev );
        bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
                            driver->DriverBindingHandle, device );
        return 0;
}

/** EFI SNP driver binding */
static EFI_DRIVER_BINDING_PROTOCOL efi_snp_binding = {
        efi_snp_driver_supported,
        efi_snp_driver_start,
        efi_snp_driver_stop,
        0x10,
        NULL,
        NULL
};

/**
 * Look up driver name
 *
 * @v wtf               Component name protocol
 * @v language          Language to use
 * @v driver_name       Driver name to fill in
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_get_driver_name ( EFI_COMPONENT_NAME2_PROTOCOL *wtf __unused,
                          CHAR8 *language __unused, CHAR16 **driver_name ) {

        *driver_name = L"" PRODUCT_SHORT_NAME " Driver";
        return 0;
}

/**
 * Look up controller name
 *
 * @v wtf               Component name protocol
 * @v device            Device
 * @v child             Child device, or NULL
 * @v language          Language to use
 * @v driver_name       Device name to fill in
 * @ret efirc           EFI status code
 */
static EFI_STATUS EFIAPI
efi_snp_get_controller_name ( EFI_COMPONENT_NAME2_PROTOCOL *wtf __unused,
                              EFI_HANDLE device __unused,
                              EFI_HANDLE child __unused,
                              CHAR8 *language __unused,
                              CHAR16 **controller_name __unused ) {

        /* Just let EFI use the default Device Path Name */
        return EFI_UNSUPPORTED;
}

/** EFI SNP component name protocol */
static EFI_COMPONENT_NAME2_PROTOCOL efi_snp_name = {
        efi_snp_get_driver_name,
        efi_snp_get_controller_name,
        "en"
};

/**
 * Install EFI SNP driver
 *
 * @ret rc              Return status code
 */
int efi_snp_install ( void ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        EFI_DRIVER_BINDING_PROTOCOL *driver = &efi_snp_binding;
        EFI_STATUS efirc;

        driver->ImageHandle = efi_image_handle;
        if ( ( efirc = bs->InstallMultipleProtocolInterfaces (
                        &driver->DriverBindingHandle,
                        &efi_driver_binding_protocol_guid, driver,
                        &efi_component_name2_protocol_guid, &efi_snp_name,
                        NULL ) ) != 0 ) {
                DBGC ( driver, "SNPDRV %p could not install protocols: "
                       "%s\n", driver, efi_strerror ( efirc ) );
                return EFIRC_TO_RC ( efirc );
        }

        DBGC ( driver, "SNPDRV %p driver binding installed as %p\n",
               driver, driver->DriverBindingHandle );
        return 0;
}