source: bootcd/isolinux/syslinux-6.03/gpxe/src/net/netdevice.c

/*
 * Copyright (C) 2006 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 <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <byteswap.h>
#include <string.h>
#include <errno.h>
#include <gpxe/if_ether.h>
#include <gpxe/iobuf.h>
#include <gpxe/tables.h>
#include <gpxe/process.h>
#include <gpxe/init.h>
#include <gpxe/device.h>
#include <gpxe/errortab.h>
#include <gpxe/netdevice.h>

/** @file
 *
 * Network device management
 *
 */

/** List of network devices */
struct list_head net_devices = LIST_HEAD_INIT ( net_devices );

/** List of open network devices, in reverse order of opening */
static struct list_head open_net_devices = LIST_HEAD_INIT ( open_net_devices );

/** Default link status code */
#define EUNKNOWN_LINK_STATUS EINPROGRESS

/** Human-readable message for the default link status */
struct errortab netdev_errors[] __errortab = {
        { EUNKNOWN_LINK_STATUS, "Unknown" },
};

/**
 * Mark network device as having link down
 *
 * @v netdev            Network device
 */
void netdev_link_down ( struct net_device *netdev ) {

        switch ( netdev->link_rc ) {
        case 0:
        case -EUNKNOWN_LINK_STATUS:
                netdev->link_rc = -ENOTCONN;
                break;
        default:
                /* Avoid clobbering a more detailed link status code,
                 * if one is already set.
                 */
                break;
        }
}

/**
 * Record network device statistic
 *
 * @v stats             Network device statistics
 * @v rc                Status code
 */
static void netdev_record_stat ( struct net_device_stats *stats, int rc ) {
        struct net_device_error *error;
        struct net_device_error *least_common_error;
        unsigned int i;

        /* If this is not an error, just update the good counter */
        if ( rc == 0 ) {
                stats->good++;
                return;
        }

        /* Update the bad counter */
        stats->bad++;

        /* Locate the appropriate error record */
        least_common_error = &stats->errors[0];
        for ( i = 0 ; i < ( sizeof ( stats->errors ) /
                            sizeof ( stats->errors[0] ) ) ; i++ ) {
                error = &stats->errors[i];
                /* Update matching record, if found */
                if ( error->rc == rc ) {
                        error->count++;
                        return;
                }
                if ( error->count < least_common_error->count )
                        least_common_error = error;
        }

        /* Overwrite the least common error record */
        least_common_error->rc = rc;
        least_common_error->count = 1;
}

/**
 * Transmit raw packet via network device
 *
 * @v netdev            Network device
 * @v iobuf             I/O buffer
 * @ret rc              Return status code
 *
 * Transmits the packet via the specified network device.  This
 * function takes ownership of the I/O buffer.
 */
int netdev_tx ( struct net_device *netdev, struct io_buffer *iobuf ) {
        int rc;

        DBGC ( netdev, "NETDEV %p transmitting %p (%p+%zx)\n",
               netdev, iobuf, iobuf->data, iob_len ( iobuf ) );

        list_add_tail ( &iobuf->list, &netdev->tx_queue );

        if ( ! ( netdev->state & NETDEV_OPEN ) ) {
                rc = -ENETUNREACH;
                goto err;
        }
                
        if ( ( rc = netdev->op->transmit ( netdev, iobuf ) ) != 0 )
                goto err;

        return 0;

 err:
        netdev_tx_complete_err ( netdev, iobuf, rc );
        return rc;
}

/**
 * Complete network transmission
 *
 * @v netdev            Network device
 * @v iobuf             I/O buffer
 * @v rc                Packet status code
 *
 * The packet must currently be in the network device's TX queue.
 */
void netdev_tx_complete_err ( struct net_device *netdev,
                              struct io_buffer *iobuf, int rc ) {

        /* Update statistics counter */
        netdev_record_stat ( &netdev->tx_stats, rc );
        if ( rc == 0 ) {
                DBGC ( netdev, "NETDEV %p transmission %p complete\n",
                       netdev, iobuf );
        } else {
                DBGC ( netdev, "NETDEV %p transmission %p failed: %s\n",
                       netdev, iobuf, strerror ( rc ) );
        }

        /* Catch data corruption as early as possible */
        assert ( iobuf->list.next != NULL );
        assert ( iobuf->list.prev != NULL );

        /* Dequeue and free I/O buffer */
        list_del ( &iobuf->list );
        free_iob ( iobuf );
}

/**
 * Complete network transmission
 *
 * @v netdev            Network device
 * @v rc                Packet status code
 *
 * Completes the oldest outstanding packet in the TX queue.
 */
void netdev_tx_complete_next_err ( struct net_device *netdev, int rc ) {
        struct io_buffer *iobuf;

        list_for_each_entry ( iobuf, &netdev->tx_queue, list ) {
                netdev_tx_complete_err ( netdev, iobuf, rc );
                return;
        }
}

/**
 * Flush device's transmit queue
 *
 * @v netdev            Network device
 */
static void netdev_tx_flush ( struct net_device *netdev ) {

        /* Discard any packets in the TX queue */
        while ( ! list_empty ( &netdev->tx_queue ) ) {
                netdev_tx_complete_next_err ( netdev, -ECANCELED );
        }
}

/**
 * Add packet to receive queue
 *
 * @v netdev            Network device
 * @v iobuf             I/O buffer, or NULL
 *
 * The packet is added to the network device's RX queue.  This
 * function takes ownership of the I/O buffer.
 */
void netdev_rx ( struct net_device *netdev, struct io_buffer *iobuf ) {

        DBGC ( netdev, "NETDEV %p received %p (%p+%zx)\n",
               netdev, iobuf, iobuf->data, iob_len ( iobuf ) );

        /* Enqueue packet */
        list_add_tail ( &iobuf->list, &netdev->rx_queue );

        /* Update statistics counter */
        netdev_record_stat ( &netdev->rx_stats, 0 );
}

/**
 * Discard received packet
 *
 * @v netdev            Network device
 * @v iobuf             I/O buffer, or NULL
 * @v rc                Packet status code
 *
 * The packet is discarded and an RX error is recorded.  This function
 * takes ownership of the I/O buffer.  @c iobuf may be NULL if, for
 * example, the net device wishes to report an error due to being
 * unable to allocate an I/O buffer.
 */
void netdev_rx_err ( struct net_device *netdev,
                     struct io_buffer *iobuf, int rc ) {

        DBGC ( netdev, "NETDEV %p failed to receive %p: %s\n",
               netdev, iobuf, strerror ( rc ) );

        /* Discard packet */
        free_iob ( iobuf );

        /* Update statistics counter */
        netdev_record_stat ( &netdev->rx_stats, rc );
}

/**
 * Poll for completed and received packets on network device
 *
 * @v netdev            Network device
 *
 * Polls the network device for completed transmissions and received
 * packets.  Any received packets will be added to the RX packet queue
 * via netdev_rx().
 */
void netdev_poll ( struct net_device *netdev ) {

        if ( netdev->state & NETDEV_OPEN )
                netdev->op->poll ( netdev );
}

/**
 * Remove packet from device's receive queue
 *
 * @v netdev            Network device
 * @ret iobuf           I/O buffer, or NULL
 *
 * Removes the first packet from the device's RX queue and returns it.
 * Ownership of the packet is transferred to the caller.
 */
struct io_buffer * netdev_rx_dequeue ( struct net_device *netdev ) {
        struct io_buffer *iobuf;

        list_for_each_entry ( iobuf, &netdev->rx_queue, list ) {
                list_del ( &iobuf->list );
                return iobuf;
        }
        return NULL;
}

/**
 * Flush device's receive queue
 *
 * @v netdev            Network device
 */
static void netdev_rx_flush ( struct net_device *netdev ) {
        struct io_buffer *iobuf;

        /* Discard any packets in the RX queue */
        while ( ( iobuf = netdev_rx_dequeue ( netdev ) ) ) {
                netdev_rx_err ( netdev, iobuf, -ECANCELED );
        }
}

/**
 * Free network device
 *
 * @v refcnt            Network device reference counter
 */
static void free_netdev ( struct refcnt *refcnt ) {
        struct net_device *netdev =
                container_of ( refcnt, struct net_device, refcnt );
        
        netdev_tx_flush ( netdev );
        netdev_rx_flush ( netdev );
        clear_settings ( netdev_settings ( netdev ) );
        free ( netdev );
}

/**
 * Allocate network device
 *
 * @v priv_size         Size of private data area (net_device::priv)
 * @ret netdev          Network device, or NULL
 *
 * Allocates space for a network device and its private data area.
 */
struct net_device * alloc_netdev ( size_t priv_size ) {
        struct net_device *netdev;
        size_t total_len;

        total_len = ( sizeof ( *netdev ) + priv_size );
        netdev = zalloc ( total_len );
        if ( netdev ) {
                netdev->refcnt.free = free_netdev;
                netdev->link_rc = -EUNKNOWN_LINK_STATUS;
                INIT_LIST_HEAD ( &netdev->tx_queue );
                INIT_LIST_HEAD ( &netdev->rx_queue );
                netdev_settings_init ( netdev );
                netdev->priv = ( ( ( void * ) netdev ) + sizeof ( *netdev ) );
        }
        return netdev;
}

/**
 * Register network device
 *
 * @v netdev            Network device
 * @ret rc              Return status code
 *
 * Gives the network device a name and adds it to the list of network
 * devices.
 */
int register_netdev ( struct net_device *netdev ) {
        static unsigned int ifindex = 0;
        int rc;

        /* Create device name */
        snprintf ( netdev->name, sizeof ( netdev->name ), "net%d",
                   ifindex++ );

        /* Set initial link-layer address */
        netdev->ll_protocol->init_addr ( netdev->hw_addr, netdev->ll_addr );

        /* Register per-netdev configuration settings */
        if ( ( rc = register_settings ( netdev_settings ( netdev ),
                                        NULL ) ) != 0 ) {
                DBGC ( netdev, "NETDEV %p could not register settings: %s\n",
                       netdev, strerror ( rc ) );
                return rc;
        }

        /* Add to device list */
        netdev_get ( netdev );
        list_add_tail ( &netdev->list, &net_devices );
        DBGC ( netdev, "NETDEV %p registered as %s (phys %s hwaddr %s)\n",
               netdev, netdev->name, netdev->dev->name,
               netdev_addr ( netdev ) );

        return 0;
}

/**
 * Open network device
 *
 * @v netdev            Network device
 * @ret rc              Return status code
 */
int netdev_open ( struct net_device *netdev ) {
        int rc;

        /* Do nothing if device is already open */
        if ( netdev->state & NETDEV_OPEN )
                return 0;

        DBGC ( netdev, "NETDEV %p opening\n", netdev );

        /* Open the device */
        if ( ( rc = netdev->op->open ( netdev ) ) != 0 )
                return rc;

        /* Mark as opened */
        netdev->state |= NETDEV_OPEN;

        /* Add to head of open devices list */
        list_add ( &netdev->open_list, &open_net_devices );

        return 0;
}

/**
 * Close network device
 *
 * @v netdev            Network device
 */
void netdev_close ( struct net_device *netdev ) {

        /* Do nothing if device is already closed */
        if ( ! ( netdev->state & NETDEV_OPEN ) )
                return;

        DBGC ( netdev, "NETDEV %p closing\n", netdev );

        /* Close the device */
        netdev->op->close ( netdev );

        /* Flush TX and RX queues */
        netdev_tx_flush ( netdev );
        netdev_rx_flush ( netdev );

        /* Mark as closed */
        netdev->state &= ~NETDEV_OPEN;

        /* Remove from open devices list */
        list_del ( &netdev->open_list );
}

/**
 * Unregister network device
 *
 * @v netdev            Network device
 *
 * Removes the network device from the list of network devices.
 */
void unregister_netdev ( struct net_device *netdev ) {

        /* Ensure device is closed */
        netdev_close ( netdev );

        /* Unregister per-netdev configuration settings */
        unregister_settings ( netdev_settings ( netdev ) );

        /* Remove from device list */
        list_del ( &netdev->list );
        netdev_put ( netdev );
        DBGC ( netdev, "NETDEV %p unregistered\n", netdev );
}

/** Enable or disable interrupts
 *
 * @v netdev            Network device
 * @v enable            Interrupts should be enabled
 */
void netdev_irq ( struct net_device *netdev, int enable ) {
        netdev->op->irq ( netdev, enable );
}

/**
 * Get network device by name
 *
 * @v name              Network device name
 * @ret netdev          Network device, or NULL
 */
struct net_device * find_netdev ( const char *name ) {
        struct net_device *netdev;

        list_for_each_entry ( netdev, &net_devices, list ) {
                if ( strcmp ( netdev->name, name ) == 0 )
                        return netdev;
        }

        return NULL;
}

/**
 * Get network device by PCI bus:dev.fn address
 *
 * @v bus_type          Bus type
 * @v location          Bus location
 * @ret netdev          Network device, or NULL
 */
struct net_device * find_netdev_by_location ( unsigned int bus_type,
                                              unsigned int location ) {
        struct net_device *netdev;

        list_for_each_entry ( netdev, &net_devices, list ) {
                if ( ( netdev->dev->desc.bus_type == bus_type ) &&
                     ( netdev->dev->desc.location == location ) )
                        return netdev;
        }

        return NULL;    
}

/**
 * Get most recently opened network device
 *
 * @ret netdev          Most recently opened network device, or NULL
 */
struct net_device * last_opened_netdev ( void ) {
        struct net_device *netdev;

        list_for_each_entry ( netdev, &open_net_devices, open_list ) {
                assert ( netdev->state & NETDEV_OPEN );
                return netdev;
        }

        return NULL;
}

/**
 * Transmit network-layer packet
 *
 * @v iobuf             I/O buffer
 * @v netdev            Network device
 * @v net_protocol      Network-layer protocol
 * @v ll_dest           Destination link-layer address
 * @ret rc              Return status code
 *
 * Prepends link-layer headers to the I/O buffer and transmits the
 * packet via the specified network device.  This function takes
 * ownership of the I/O buffer.
 */
int net_tx ( struct io_buffer *iobuf, struct net_device *netdev,
             struct net_protocol *net_protocol, const void *ll_dest ) {
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
        int rc;

        /* Force a poll on the netdevice to (potentially) clear any
         * backed-up TX completions.  This is needed on some network
         * devices to avoid excessive losses due to small TX ring
         * sizes.
         */
        netdev_poll ( netdev );

        /* Add link-layer header */
        if ( ( rc = ll_protocol->push ( netdev, iobuf, ll_dest, netdev->ll_addr,
                                        net_protocol->net_proto ) ) != 0 ) {
                free_iob ( iobuf );
                return rc;
        }

        /* Transmit packet */
        return netdev_tx ( netdev, iobuf );
}

/**
 * Process received network-layer packet
 *
 * @v iobuf             I/O buffer
 * @v netdev            Network device
 * @v net_proto         Network-layer protocol, in network-byte order
 * @v ll_source         Source link-layer address
 * @ret rc              Return status code
 */
int net_rx ( struct io_buffer *iobuf, struct net_device *netdev,
             uint16_t net_proto, const void *ll_source ) {
        struct net_protocol *net_protocol;

        /* Hand off to network-layer protocol, if any */
        for_each_table_entry ( net_protocol, NET_PROTOCOLS ) {
                if ( net_protocol->net_proto == net_proto )
                        return net_protocol->rx ( iobuf, netdev, ll_source );
        }

        DBGC ( netdev, "NETDEV %p unknown network protocol %04x\n",
               netdev, ntohs ( net_proto ) );
        free_iob ( iobuf );
        return 0;
}

/**
 * Single-step the network stack
 *
 * @v process           Network stack process
 *
 * This polls all interfaces for received packets, and processes
 * packets from the RX queue.
 */
static void net_step ( struct process *process __unused ) {
        struct net_device *netdev;
        struct io_buffer *iobuf;
        struct ll_protocol *ll_protocol;
        const void *ll_dest;
        const void *ll_source;
        uint16_t net_proto;
        int rc;

        /* Poll and process each network device */
        list_for_each_entry ( netdev, &net_devices, list ) {

                /* Poll for new packets */
                netdev_poll ( netdev );

                /* Process at most one received packet.  Give priority
                 * to getting packets out of the NIC over processing
                 * the received packets, because we advertise a window
                 * that assumes that we can receive packets from the
                 * NIC faster than they arrive.
                 */
                if ( ( iobuf = netdev_rx_dequeue ( netdev ) ) ) {

                        DBGC ( netdev, "NETDEV %p processing %p (%p+%zx)\n",
                               netdev, iobuf, iobuf->data,
                               iob_len ( iobuf ) );

                        /* Remove link-layer header */
                        ll_protocol = netdev->ll_protocol;
                        if ( ( rc = ll_protocol->pull ( netdev, iobuf,
                                                        &ll_dest, &ll_source,
                                                        &net_proto ) ) != 0 ) {
                                free_iob ( iobuf );
                                continue;
                        }

                        net_rx ( iobuf, netdev, net_proto, ll_source );
                }
        }
}

/** Networking stack process */
struct process net_process __permanent_process = {
        .list = LIST_HEAD_INIT ( net_process.list ),
        .step = net_step,
};