efi_pci.c

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/*
 * 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., 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 );
FILE_SECBOOT ( PERMITTED );

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ipxe/pci.h>
#include <ipxe/acpi.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/efi_pci.h>
#include <ipxe/efi/efi_driver.h>
#include <ipxe/efi/Protocol/PciIo.h>
#include <ipxe/efi/Protocol/PciRootBridgeIo.h>

/** @file
 *
 * iPXE PCI I/O API for EFI
 *
 */

/* Disambiguate the various error causes */
#define EINFO_EEFI_PCI                                                  \
        __einfo_uniqify ( EINFO_EPLATFORM, 0x01,                        \
                          "Could not open PCI I/O protocol" )
#define EINFO_EEFI_PCI_NOT_PCI                                          \
        __einfo_platformify ( EINFO_EEFI_PCI, EFI_UNSUPPORTED,          \
                              "Not a PCI device" )
#define EEFI_PCI_NOT_PCI __einfo_error ( EINFO_EEFI_PCI_NOT_PCI )
#define EINFO_EEFI_PCI_IN_USE                                           \
        __einfo_platformify ( EINFO_EEFI_PCI, EFI_ACCESS_DENIED,        \
                              "PCI device already has a driver" )
#define EEFI_PCI_IN_USE __einfo_error ( EINFO_EEFI_PCI_IN_USE )
#define EEFI_PCI( efirc )                                               \
        EPLATFORM ( EINFO_EEFI_PCI, efirc,                              \
                    EEFI_PCI_NOT_PCI, EEFI_PCI_IN_USE )

/******************************************************************************
 *
 * iPXE PCI API
 *
 ******************************************************************************
 */

/**
 * Find closest bus:dev.fn address range within a root bridge
 *
 * @v pci               Starting PCI device
 * @v handle            EFI PCI root bridge handle
 * @v range             PCI bus:dev.fn address range to fill in
 * @ret rc              Return status code
 */
static int efipci_discover_one ( struct pci_device *pci, EFI_HANDLE handle,
                                 struct pci_range *range ) {
        EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *root;
        union {
                union acpi_resource *res;
                void *raw;
        } acpi;
        uint32_t best = 0;
        uint32_t start;
        uint32_t count;
        uint32_t index;
        unsigned int tag;
        EFI_STATUS efirc;
        int rc;

        /* Return empty range on error */
        range->start = 0;
        range->count = 0;

        /* Open root bridge I/O protocol */
        if ( ( rc = efi_open ( handle, &efi_pci_root_bridge_io_protocol_guid,
                               &root ) ) != 0 ) {
                DBGC ( pci, "EFIPCI " PCI_FMT " cannot open %s: %s\n",
                       PCI_ARGS ( pci ), efi_handle_name ( handle ),
                       strerror ( rc ) );
                return rc;
        }

        /* Get ACPI resource descriptors */
        if ( ( efirc = root->Configuration ( root, &acpi.raw ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " cannot get configuration for "
                       "%s: %s\n", PCI_ARGS ( pci ),
                       efi_handle_name ( handle ), strerror ( rc ) );
                return rc;
        }

        /* Parse resource descriptors */
        for ( ; ( ( tag = acpi_resource_tag ( acpi.res ) ) !=
                  ACPI_END_RESOURCE ) ;
              acpi.res = acpi_resource_next ( acpi.res ) ) {

                /* Ignore anything other than a bus number range descriptor */
                if ( tag != ACPI_QWORD_ADDRESS_SPACE_RESOURCE )
                        continue;
                if ( acpi.res->qword.type != ACPI_ADDRESS_TYPE_BUS )
                        continue;

                /* Get range for this descriptor */
                start = PCI_BUSDEVFN ( root->SegmentNumber,
                                       le64_to_cpu ( acpi.res->qword.min ),
                                       0, 0 );
                count = PCI_BUSDEVFN ( 0, le64_to_cpu ( acpi.res->qword.len ),
                                       0, 0 );
                DBGC2 ( pci, "EFIPCI " PCI_FMT " found %04x:[%02x-%02x] via "
                        "%s\n", PCI_ARGS ( pci ), root->SegmentNumber,
                        PCI_BUS ( start ), PCI_BUS ( start + count - 1 ),
                        efi_handle_name ( handle ) );

                /* Check for a matching or new closest range */
                index = ( pci->busdevfn - start );
                if ( ( index < count ) || ( index > best ) ) {
                        range->start = start;
                        range->count = count;
                        best = index;
                }

                /* Stop if this range contains the target bus:dev.fn address */
                if ( index < count )
                        break;
        }

        /* If no range descriptors were seen, assume that the root
         * bridge has a single bus.
         */
        if ( ! range->count ) {
                range->start = PCI_BUSDEVFN ( root->SegmentNumber, 0, 0, 0 );
                range->count = PCI_BUSDEVFN ( 0, 1, 0, 0 );
        }

        return 0;
}

/**
 * Find closest bus:dev.fn address range within any root bridge
 *
 * @v pci               Starting PCI device
 * @v range             PCI bus:dev.fn address range to fill in
 * @v handle            PCI root bridge I/O handle to fill in
 * @ret rc              Return status code
 */
static int efipci_discover_any ( struct pci_device *pci,
                                 struct pci_range *range,
                                 EFI_HANDLE *handle ) {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        uint32_t best = 0;
        uint32_t index;
        struct pci_range tmp;
        EFI_HANDLE *handles;
        UINTN num_handles;
        UINTN i;
        EFI_STATUS efirc;
        int rc;

        /* Return an empty range and no handle on error */
        range->start = 0;
        range->count = 0;
        *handle = NULL;

        /* Enumerate all root bridge I/O protocol handles */
        if ( ( efirc = bs->LocateHandleBuffer ( ByProtocol,
                        &efi_pci_root_bridge_io_protocol_guid,
                        NULL, &num_handles, &handles ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " cannot locate root bridges: "
                       "%s\n", PCI_ARGS ( pci ), strerror ( rc ) );
                goto err_locate;
        }

        /* Iterate over all root bridge I/O protocols */
        for ( i = 0 ; i < num_handles ; i++ ) {

                /* Get matching or closest range for this root bridge */
                if ( ( rc = efipci_discover_one ( pci, handles[i],
                                                  &tmp ) ) != 0 )
                        continue;

                /* Check for a matching or new closest range */
                index = ( pci->busdevfn - tmp.start );
                if ( ( index < tmp.count ) || ( index > best ) ) {
                        range->start = tmp.start;
                        range->count = tmp.count;
                        best = index;
                }

                /* Stop if this range contains the target bus:dev.fn address */
                if ( index < tmp.count ) {
                        *handle = handles[i];
                        break;
                }
        }

        /* Check for a range containing the target bus:dev.fn address */
        if ( ! *handle ) {
                rc = -ENOENT;
                goto err_range;
        }

        /* Success */
        rc = 0;

 err_range:
        bs->FreePool ( handles );
 err_locate:
        return rc;
}

/**
 * Find next PCI bus:dev.fn address range in system
 *
 * @v busdevfn          Starting PCI bus:dev.fn address
 * @v range             PCI bus:dev.fn address range to fill in
 */
static void efipci_discover ( uint32_t busdevfn, struct pci_range *range ) {
        struct pci_device pci;
        EFI_HANDLE handle;

        /* Find range */
        memset ( &pci, 0, sizeof ( pci ) );
        pci_init ( &pci, busdevfn );
        efipci_discover_any ( &pci, range, &handle );
}

/**
 * Open EFI PCI root bridge I/O protocol for ephemeral use
 *
 * @v pci               PCI device
 * @ret handle          EFI PCI root bridge handle
 * @ret root            EFI PCI root bridge I/O protocol, or NULL if not found
 * @ret rc              Return status code
 */
static int efipci_root_open ( struct pci_device *pci, EFI_HANDLE *handle,
                              EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL **root ) {
        struct pci_range tmp;
        int rc;

        /* Find matching root bridge I/O protocol handle */
        if ( ( rc = efipci_discover_any ( pci, &tmp, handle ) ) != 0 )
                return rc;

        /* Open PCI root bridge I/O protocol */
        if ( ( rc = efi_open ( *handle, &efi_pci_root_bridge_io_protocol_guid,
                               root ) ) != 0 ) {
                DBGC ( pci, "EFIPCI " PCI_FMT " cannot open %s: %s\n",
                       PCI_ARGS ( pci ), efi_handle_name ( *handle ),
                       strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Calculate EFI PCI configuration space address
 *
 * @v pci               PCI device
 * @v location          Encoded offset and width
 * @ret address         EFI PCI address
 */
static unsigned long efipci_address ( struct pci_device *pci,
                                      unsigned long location ) {

        return EFI_PCI_ADDRESS ( PCI_BUS ( pci->busdevfn ),
                                 PCI_SLOT ( pci->busdevfn ),
                                 PCI_FUNC ( pci->busdevfn ),
                                 EFIPCI_OFFSET ( location ) );
}

/**
 * Read from PCI configuration space
 *
 * @v pci               PCI device
 * @v location          Encoded offset and width
 * @ret value           Value
 * @ret rc              Return status code
 */
int efipci_read ( struct pci_device *pci, unsigned long location,
                  void *value ) {
        EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *root;
        EFI_HANDLE handle;
        EFI_STATUS efirc;
        int rc;

        /* Open root bridge */
        if ( ( rc = efipci_root_open ( pci, &handle, &root ) ) != 0 )
                return rc;

        /* Read from configuration space */
        if ( ( efirc = root->Pci.Read ( root, EFIPCI_WIDTH ( location ),
                                        efipci_address ( pci, location ), 1,
                                        value ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " config read from offset %02lx "
                       "failed: %s\n", PCI_ARGS ( pci ),
                       EFIPCI_OFFSET ( location ), strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Write to PCI configuration space
 *
 * @v pci               PCI device
 * @v location          Encoded offset and width
 * @v value             Value
 * @ret rc              Return status code
 */
int efipci_write ( struct pci_device *pci, unsigned long location,
                   unsigned long value ) {
        EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *root;
        EFI_HANDLE handle;
        EFI_STATUS efirc;
        int rc;

        /* Open root bridge */
        if ( ( rc = efipci_root_open ( pci, &handle, &root ) ) != 0 )
                return rc;

        /* Read from configuration space */
        if ( ( efirc = root->Pci.Write ( root, EFIPCI_WIDTH ( location ),
                                         efipci_address ( pci, location ), 1,
                                         &value ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " config write to offset %02lx "
                       "failed: %s\n", PCI_ARGS ( pci ),
                       EFIPCI_OFFSET ( location ), strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Map PCI bus address as an I/O address
 *
 * @v bus_addr          PCI bus address
 * @v len               Length of region
 * @ret io_addr         I/O address, or NULL on error
 */
void * efipci_ioremap ( struct pci_device *pci, unsigned long bus_addr,
                        size_t len ) {
        union {
                union acpi_resource *res;
                void *raw;
        } u;
        EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *root;
        EFI_HANDLE handle;
        unsigned int tag;
        uint64_t offset;
        uint64_t start;
        uint64_t end;
        EFI_STATUS efirc;
        int rc;

        /* Open root bridge */
        if ( ( rc = efipci_root_open ( pci, &handle, &root ) ) != 0 )
                goto err_root;

        /* Get ACPI resource descriptors */
        if ( ( efirc = root->Configuration ( root, &u.raw ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " cannot get configuration: "
                       "%s\n", PCI_ARGS ( pci ), strerror ( rc ) );
                goto err_config;
        }

        /* Parse resource descriptors */
        for ( ; ( ( tag = acpi_resource_tag ( u.res ) ) != ACPI_END_RESOURCE ) ;
              u.res = acpi_resource_next ( u.res ) ) {

                /* Ignore anything other than a memory range descriptor */
                if ( tag != ACPI_QWORD_ADDRESS_SPACE_RESOURCE )
                        continue;
                if ( u.res->qword.type != ACPI_ADDRESS_TYPE_MEM )
                        continue;

                /* Ignore descriptors that do not cover this memory range */
                offset = le64_to_cpu ( u.res->qword.offset );
                start = ( offset + le64_to_cpu ( u.res->qword.min ) );
                end = ( start + le64_to_cpu ( u.res->qword.len ) );
                DBGC2 ( pci, "EFIPCI " PCI_FMT " found range [%08llx,%08llx) "
                        "-> [%08llx,%08llx)\n", PCI_ARGS ( pci ), start, end,
                        ( start - offset ), ( end - offset ) );
                if ( ( bus_addr < start ) || ( ( bus_addr + len ) > end ) )
                        continue;

                /* Use this address space descriptor */
                DBGC2 ( pci, "EFIPCI " PCI_FMT " %08lx+%zx -> ",
                        PCI_ARGS ( pci ), bus_addr, len );
                bus_addr -= offset;
                DBGC2 ( pci, "%08lx\n", bus_addr );
                break;
        }
        if ( tag == ACPI_END_RESOURCE ) {
                DBGC ( pci, "EFIPCI " PCI_FMT " %08lx+%zx is not within "
                       "root bridge address space\n",
                       PCI_ARGS ( pci ), bus_addr, len );
        }

 err_config:
 err_root:
        return ioremap ( bus_addr, len );
}

PROVIDE_PCIAPI_INLINE ( efi, pci_can_probe );
PROVIDE_PCIAPI ( efi, pci_discover, efipci_discover );
PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_byte );
PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_word );
PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_dword );
PROVIDE_PCIAPI_INLINE ( efi, pci_write_config_byte );
PROVIDE_PCIAPI_INLINE ( efi, pci_write_config_word );
PROVIDE_PCIAPI_INLINE ( efi, pci_write_config_dword );
PROVIDE_PCIAPI ( efi, pci_ioremap, efipci_ioremap );
PROVIDE_PCIAPI_RUNTIME ( efi, PCIAPI_PRIORITY_EFI );

/******************************************************************************
 *
 * EFI PCI DMA mappings
 *
 ******************************************************************************
 */

/**
 * Map buffer for DMA
 *
 * @v dma               DMA device
 * @v map               DMA mapping to fill in
 * @v addr              Buffer address
 * @v len               Length of buffer
 * @v flags             Mapping flags
 * @ret rc              Return status code
 */
static int efipci_dma_map ( struct dma_device *dma, struct dma_mapping *map,
                            void *addr, size_t len, int flags ) {
        struct efi_pci_device *efipci =
                container_of ( dma, struct efi_pci_device, pci.dma );
        struct pci_device *pci = &efipci->pci;
        EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;
        EFI_PCI_IO_PROTOCOL_OPERATION op;
        EFI_PHYSICAL_ADDRESS bus;
        UINTN count;
        VOID *mapping;
        physaddr_t phys;
        EFI_STATUS efirc;
        int rc;

        /* Sanity check */
        assert ( map->dma == NULL );
        assert ( map->offset == 0 );
        assert ( map->token == NULL );

        /* Determine operation */
        switch ( flags ) {
        case DMA_TX:
                op = EfiPciIoOperationBusMasterRead;
                break;
        case DMA_RX:
                op = EfiPciIoOperationBusMasterWrite;
                break;
        default:
                op = EfiPciIoOperationBusMasterCommonBuffer;
                break;
        }

        /* Map buffer (if non-zero length) */
        phys = virt_to_phys ( addr );
        count = len;
        if ( len ) {
                if ( ( efirc = pci_io->Map ( pci_io, op, addr, &count, &bus,
                                             &mapping ) ) != 0 ) {
                        rc = -EEFI ( efirc );
                        DBGC ( pci, "EFIPCI " PCI_FMT " cannot map %p+%zx: "
                               "%s\n", PCI_ARGS ( pci ), addr, len,
                               strerror ( rc ) );
                        goto err_map;
                }
        } else {
                bus = phys;
                mapping = NULL;
        }

        /* Check that full length was mapped.  The UEFI specification
         * allows for multiple mappings to be required, but even the
         * EDK2 PCI device drivers will fail if a platform ever
         * requires this.
         */
        if ( count != len ) {
                DBGC ( pci, "EFIPCI " PCI_FMT " attempted split mapping for "
                       "%p+%zx\n", PCI_ARGS ( pci ), addr, len );
                rc = -ENOTSUP;
                goto err_len;
        }

        /* Populate mapping */
        map->dma = dma;
        map->offset = ( bus - phys );
        map->token = mapping;

        /* Increment mapping count (for debugging) */
        if ( DBG_LOG )
                dma->mapped++;

        return 0;

 err_len:
        pci_io->Unmap ( pci_io, mapping );
 err_map:
        return rc;
}

/**
 * Unmap buffer
 *
 * @v dma               DMA device
 * @v map               DMA mapping
 * @v len               Used length
 */
static void efipci_dma_unmap ( struct dma_device *dma,
                               struct dma_mapping *map, size_t len __unused ) {
        struct efi_pci_device *efipci =
                container_of ( dma, struct efi_pci_device, pci.dma );
        EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;

        /* Unmap buffer (if non-zero length) */
        if ( map->token )
                pci_io->Unmap ( pci_io, map->token );

        /* Clear mapping */
        map->dma = NULL;
        map->offset = 0;
        map->token = NULL;

        /* Decrement mapping count (for debugging) */
        if ( DBG_LOG )
                dma->mapped--;
}

/**
 * Allocate and map DMA-coherent buffer
 *
 * @v dma               DMA device
 * @v map               DMA mapping to fill in
 * @v len               Length of buffer
 * @v align             Physical alignment
 * @ret addr            Buffer address, or NULL on error
 */
static void * efipci_dma_alloc ( struct dma_device *dma,
                                 struct dma_mapping *map,
                                 size_t len, size_t align __unused ) {
        struct efi_pci_device *efipci =
                container_of ( dma, struct efi_pci_device, pci.dma );
        struct pci_device *pci = &efipci->pci;
        EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;
        unsigned int pages;
        VOID *addr;
        EFI_STATUS efirc;
        int rc;

        /* Calculate number of pages */
        pages = ( ( len + EFI_PAGE_SIZE - 1 ) / EFI_PAGE_SIZE );

        /* Allocate (page-aligned) buffer */
        if ( ( efirc = pci_io->AllocateBuffer ( pci_io, AllocateAnyPages,
                                                EfiBootServicesData, pages,
                                                &addr, 0 ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " could not allocate %zd bytes: "
                       "%s\n", PCI_ARGS ( pci ), len, strerror ( rc ) );
                goto err_alloc;
        }

        /* Clear buffer */
        memset ( addr, 0, ( pages * EFI_PAGE_SIZE ) );

        /* Map buffer */
        if ( ( rc = efipci_dma_map ( dma, map, addr, ( pages * EFI_PAGE_SIZE ),
                                     DMA_BI ) ) != 0 )
                goto err_map;

        /* Increment allocation count (for debugging) */
        if ( DBG_LOG )
                dma->allocated++;

        return addr;

        efipci_dma_unmap ( dma, map, len );
 err_map:
        pci_io->FreeBuffer ( pci_io, pages, addr );
 err_alloc:
        return NULL;
}

/**
 * Unmap and free DMA-coherent buffer
 *
 * @v dma               DMA device
 * @v map               DMA mapping
 * @v addr              Buffer address
 * @v len               Length of buffer
 */
static void efipci_dma_free ( struct dma_device *dma, struct dma_mapping *map,
                              void *addr, size_t len ) {
        struct efi_pci_device *efipci =
                container_of ( dma, struct efi_pci_device, pci.dma );
        EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;
        unsigned int pages;

        /* Calculate number of pages */
        pages = ( ( len + EFI_PAGE_SIZE - 1 ) / EFI_PAGE_SIZE );

        /* Unmap buffer */
        efipci_dma_unmap ( dma, map, len );

        /* Free buffer */
        pci_io->FreeBuffer ( pci_io, pages, addr );

        /* Decrement allocation count (for debugging) */
        if ( DBG_LOG )
                dma->allocated--;
}

/**
 * Set addressable space mask
 *
 * @v dma               DMA device
 * @v mask              Addressable space mask
 */
static void efipci_dma_set_mask ( struct dma_device *dma, physaddr_t mask ) {
        struct efi_pci_device *efipci =
                container_of ( dma, struct efi_pci_device, pci.dma );
        struct pci_device *pci = &efipci->pci;
        EFI_PCI_IO_PROTOCOL *pci_io = efipci->io;
        EFI_PCI_IO_PROTOCOL_ATTRIBUTE_OPERATION op;
        UINT64 attrs;
        int is64;
        EFI_STATUS efirc;
        int rc;

        /* Set dual address cycle attribute for 64-bit capable devices */
        is64 = ( ( ( ( uint64_t ) mask ) + 1 ) == 0 );
        op = ( is64 ? EfiPciIoAttributeOperationEnable :
               EfiPciIoAttributeOperationDisable );
        attrs = EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE;
        if ( ( efirc = pci_io->Attributes ( pci_io, op, attrs, NULL ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( pci, "EFIPCI " PCI_FMT " could not %sable DAC: %s\n",
                       PCI_ARGS ( pci ), ( is64 ? "en" : "dis" ),
                       strerror ( rc ) );
                /* Ignore failure: errors will manifest in mapping attempts */
                return;
        }
}

/** EFI PCI DMA operations */
static struct dma_operations efipci_dma_operations = {
        .map = efipci_dma_map,
        .unmap = efipci_dma_unmap,
        .alloc = efipci_dma_alloc,
        .free = efipci_dma_free,
        .umalloc = efipci_dma_alloc,
        .ufree = efipci_dma_free,
        .set_mask = efipci_dma_set_mask,
};

/******************************************************************************
 *
 * EFI PCI device instantiation
 *
 ******************************************************************************
 */

/**
 * Get EFI PCI device information
 *
 * @v device            EFI device handle
 * @v efipci            EFI PCI device to fill in
 * @ret rc              Return status code
 */
int efipci_info ( EFI_HANDLE device, struct efi_pci_device *efipci ) {
        EFI_PCI_IO_PROTOCOL *pci_io;
        UINTN pci_segment, pci_bus, pci_dev, pci_fn;
        unsigned int busdevfn;
        EFI_STATUS efirc;
        int rc;

        /* See if device is a PCI device */
        if ( ( rc = efi_open ( device, &efi_pci_io_protocol_guid,
                               &pci_io ) ) != 0 ) {
                DBGCP ( device, "EFIPCI %s cannot open PCI protocols: %s\n",
                        efi_handle_name ( device ), strerror ( rc ) );
                return rc;
        }
        efipci->io = pci_io;

        /* Get PCI bus:dev.fn address */
        if ( ( efirc = pci_io->GetLocation ( pci_io, &pci_segment, &pci_bus,
                                             &pci_dev, &pci_fn ) ) != 0 ) {
                rc = -EEFI ( efirc );
                DBGC ( device, "EFIPCI %s could not get PCI location: %s\n",
                       efi_handle_name ( device ), strerror ( rc ) );
                return rc;
        }
        busdevfn = PCI_BUSDEVFN ( pci_segment, pci_bus, pci_dev, pci_fn );
        pci_init ( &efipci->pci, busdevfn );
        dma_init ( &efipci->pci.dma, &efipci_dma_operations );
        DBGCP ( device, "EFIPCI " PCI_FMT " is %s\n",
                PCI_ARGS ( &efipci->pci ), efi_handle_name ( device ) );

        /* Try to enable I/O cycles, memory cycles, and bus mastering.
         * Some platforms will 'helpfully' report errors if these bits
         * can't be enabled (for example, if the card doesn't actually
         * support I/O cycles).  Work around any such platforms by
         * enabling bits individually and simply ignoring any errors.
         */
        pci_io->Attributes ( pci_io, EfiPciIoAttributeOperationEnable,
                             EFI_PCI_IO_ATTRIBUTE_IO, NULL );
        pci_io->Attributes ( pci_io, EfiPciIoAttributeOperationEnable,
                             EFI_PCI_IO_ATTRIBUTE_MEMORY, NULL );
        pci_io->Attributes ( pci_io, EfiPciIoAttributeOperationEnable,
                             EFI_PCI_IO_ATTRIBUTE_BUS_MASTER, NULL );

        /* Populate PCI device */
        if ( ( rc = pci_read_config ( &efipci->pci ) ) != 0 ) {
                DBGC ( device, "EFIPCI " PCI_FMT " cannot read PCI "
                       "configuration: %s\n",
                       PCI_ARGS ( &efipci->pci ), strerror ( rc ) );
                return rc;
        }

        return 0;
}

/******************************************************************************
 *
 * EFI PCI driver
 *
 ******************************************************************************
 */

/**
 * Check to see if driver supports a device
 *
 * @v device            EFI device handle
 * @ret rc              Return status code
 */
static int efipci_supported ( EFI_HANDLE device ) {
        struct efi_pci_device efipci;
        uint8_t hdrtype;
        int rc;

        /* Get PCI device information */
        if ( ( rc = efipci_info ( device, &efipci ) ) != 0 )
                return rc;

        /* Do not attempt to drive bridges */
        hdrtype = efipci.pci.hdrtype;
        if ( ( hdrtype & PCI_HEADER_TYPE_MASK ) != PCI_HEADER_TYPE_NORMAL ) {
                DBGC ( device, "EFIPCI " PCI_FMT " type %02x is not type %02x\n",
                       PCI_ARGS ( &efipci.pci ), hdrtype,
                       PCI_HEADER_TYPE_NORMAL );
                return -ENOTTY;
        }

        /* Look for a driver */
        if ( ( rc = pci_find_driver ( &efipci.pci ) ) != 0 ) {
                DBGC ( device, "EFIPCI " PCI_FMT " (%04x:%04x class %06x) "
                       "has no driver\n", PCI_ARGS ( &efipci.pci ),
                       efipci.pci.vendor, efipci.pci.device,
                       efipci.pci.class );
                return rc;
        }
        DBGC ( device, "EFIPCI " PCI_FMT " (%04x:%04x class %06x) has driver "
               "\"%s\"\n", PCI_ARGS ( &efipci.pci ), efipci.pci.vendor,
               efipci.pci.device, efipci.pci.class, efipci.pci.id->name );

        return 0;
}

/**
 * Exclude existing drivers
 *
 * @v device            EFI device handle
 * @ret rc              Return status code
 */
static int efipci_exclude ( EFI_HANDLE device ) {
        EFI_GUID *protocol = &efi_pci_io_protocol_guid;
        int rc;

        /* Exclude existing PCI I/O protocol drivers */
        if ( ( rc = efi_driver_exclude ( device, protocol ) ) != 0 ) {
                DBGC ( device, "EFIPCI %s could not exclude drivers: %s\n",
                       efi_handle_name ( device ), strerror ( rc ) );
                return rc;
        }

        return 0;
}

/**
 * Attach driver to device
 *
 * @v efidev            EFI device
 * @ret rc              Return status code
 */
static int efipci_start ( struct efi_device *efidev ) {
        EFI_HANDLE device = efidev->device;
        struct efi_pci_device *efipci;
        int rc;

        /* Allocate PCI device */
        efipci = zalloc ( sizeof ( *efipci ) );
        if ( ! efipci ) {
                rc = -ENOMEM;
                goto err_alloc;
        }

        /* Get PCI device information */
        if ( ( rc = efipci_info ( device, efipci ) ) != 0 )
                goto err_info;

        /* Open PCI I/O protocol */
        if ( ( rc = efi_open_by_driver ( device, &efi_pci_io_protocol_guid,
                                         &efipci->io ) ) != 0 ) {
                DBGC ( device, "EFIPCI %s could not open PCI device: %s\n",
                       efi_handle_name ( device ), strerror ( rc ) );
                DBGC_EFI_OPENERS ( device, device, &efi_pci_io_protocol_guid );
                goto err_open;
        }

        /* Find driver */
        if ( ( rc = pci_find_driver ( &efipci->pci ) ) != 0 ) {
                DBGC ( device, "EFIPCI " PCI_FMT " has no driver\n",
                       PCI_ARGS ( &efipci->pci ) );
                goto err_find_driver;
        }

        /* Mark PCI device as a child of the EFI device */
        efipci->pci.dev.parent = &efidev->dev;
        list_add ( &efipci->pci.dev.siblings, &efidev->dev.children );

        /* Probe driver */
        if ( ( rc = pci_probe ( &efipci->pci ) ) != 0 ) {
                DBGC ( device, "EFIPCI " PCI_FMT " could not probe driver "
                       "\"%s\": %s\n", PCI_ARGS ( &efipci->pci ),
                       efipci->pci.id->name, strerror ( rc ) );
                goto err_probe;
        }
        DBGC ( device, "EFIPCI " PCI_FMT " using driver \"%s\"\n",
               PCI_ARGS ( &efipci->pci ), efipci->pci.id->name );

        efidev_set_drvdata ( efidev, efipci );
        return 0;

        pci_remove ( &efipci->pci );
 err_probe:
        list_del ( &efipci->pci.dev.siblings );
 err_find_driver:
        efi_close_by_driver ( device, &efi_pci_io_protocol_guid );
 err_open:
 err_info:
        free ( efipci );
 err_alloc:
        return rc;
}

/**
 * Detach driver from device
 *
 * @v efidev            EFI device
  */
static void efipci_stop ( struct efi_device *efidev ) {
        struct efi_pci_device *efipci = efidev_get_drvdata ( efidev );
        EFI_HANDLE device = efidev->device;

        pci_remove ( &efipci->pci );
        list_del ( &efipci->pci.dev.siblings );
        assert ( efipci->pci.dma.mapped == 0 );
        assert ( efipci->pci.dma.allocated == 0 );
        efi_close_by_driver ( device, &efi_pci_io_protocol_guid );
        free ( efipci );
}

/** EFI PCI driver */
struct efi_driver efipci_driver __efi_driver ( EFI_DRIVER_HARDWARE ) = {
        .name = "PCI",
        .supported = efipci_supported,
        .exclude = efipci_exclude,
        .start = efipci_start,
        .stop = efipci_stop,
};