pcibridge.c

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/*
 * Copyright (C) 2022 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 (at your option) 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.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stddef.h>
#include <stdint.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/pci.h>
#include <ipxe/pcibridge.h>

/** @file
 *
 * PCI-to-PCI bridge
 *
 */

/** List of all PCI bridges */
static LIST_HEAD ( pcibridges );

/**
 * Find bridge attached to a PCI device
 *
 * @v pci               PCI device
 * @ret bridge          PCI bridge, or NULL
 */
struct pci_bridge * pcibridge_find ( struct pci_device *pci ) {
        unsigned int bus = PCI_BUS ( pci->busdevfn );
        struct pci_bridge *bridge;

        /* Find matching bridge */
        list_for_each_entry ( bridge, &pcibridges, list ) {
                if ( bus == bridge->secondary )
                        return bridge;
        }

        return NULL;
}

/**
 * Probe PCI device
 *
 * @v pci               PCI device
 * @ret rc              Return status code
 */
static int pcibridge_probe ( struct pci_device *pci ) {
        struct pci_bridge *bridge;
        uint16_t base;
        uint16_t limit;
        int rc;

        /* Allocate and initialise structure */
        bridge = zalloc ( sizeof ( *bridge ) );
        if ( ! bridge ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        bridge->pci = pci;

        /* Read configuration */
        pci_read_config_dword ( pci, PCI_PRIMARY, &bridge->buses );
        cpu_to_le32s ( &buses );
        pci_read_config_word ( pci, PCI_MEM_BASE, &base );
        bridge->membase = ( ( base & ~PCI_MEM_MASK ) << 16 );
        pci_read_config_word ( pci, PCI_MEM_LIMIT, &limit );
        bridge->memlimit = ( ( ( ( limit | PCI_MEM_MASK ) + 1 ) << 16 ) - 1 );
        DBGC ( bridge, "BRIDGE " PCI_FMT " bus %02x to [%02x,%02x) mem "
               "[%08x,%08x)\n", PCI_ARGS ( pci ), bridge->primary,
               bridge->secondary, bridge->subordinate, bridge->membase,
               bridge->memlimit );

        /* Add to list of PCI bridges */
        list_add ( &bridge->list, &pcibridges );

        pci_set_drvdata ( pci, bridge );
        return 0;

        free ( bridge );
 err_alloc:
        return rc;
}

/**
 * Remove PCI device
 *
 * @v pci               PCI device
 */
static void pcibridge_remove ( struct pci_device *pci ) {
        struct pci_bridge *bridge = pci_get_drvdata ( pci );

        /* Remove from list of bridges */
        list_del ( &bridge->list );

        /* Free device */
        free ( bridge );
}

/** Bridge PCI device IDs */
static struct pci_device_id pcibridge_ids[] = {
        PCI_ROM ( 0xffff, 0xffff, "bridge", "Bridge", 0 ),
};

/** Bridge PCI driver */
struct pci_driver pcibridge_driver __pci_driver = {
        .ids = pcibridge_ids,
        .id_count = ( sizeof ( pcibridge_ids ) / sizeof ( pcibridge_ids[0] ) ),
        .class = PCI_CLASS_ID ( PCI_CLASS_BRIDGE, PCI_CLASS_BRIDGE_PCI,
                                PCI_ANY_ID ),
        .probe = pcibridge_probe,
        .remove = pcibridge_remove,
};