pciea.c

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/*
 * Copyright (C) 2016 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 <stdint.h>
#include <errno.h>
#include <ipxe/pci.h>
#include <ipxe/pciea.h>
 
/** @file
 *
 * PCI Enhanced Allocation
 *
 */
 
/**
 * Locate PCI Enhanced Allocation BAR equivalent entry
 *
 * @v pci               PCI device
 * @v bei               BAR equivalent indicator
 * @ret offset          PCI Enhanced Allocation entry offset, or negative error
 */
static int pciea_offset ( struct pci_device *pci, unsigned int bei ) {
        uint8_t entries;
        uint32_t desc;
        unsigned int i;
        int offset;
 
        /* Locate Enhanced Allocation capability */
        offset = pci_find_capability ( pci, PCI_CAP_ID_EA );
        if ( offset < 0 )
                return offset;
 
        /* Get number of entries */
        pci_read_config_byte ( pci, ( offset + PCIEA_ENTRIES ), &entries );
        entries &= PCIEA_ENTRIES_MASK;
 
        /* Locate first entry */
        offset += PCIEA_FIRST;
 
        /* Search for a matching entry */
        for ( i = 0 ; i < entries ; i++ ) {
 
                /* Read entry descriptor */
                pci_read_config_dword ( pci, offset, &desc );
 
                /* Check for a matching entry */
                if ( ( desc & PCIEA_DESC_ENABLED ) &&
                     ( bei == PCIEA_DESC_BEI ( desc ) ) )
                        return offset;
 
                /* Move to next entry */
                offset += ( ( PCIEA_DESC_SIZE ( desc ) + 1 ) << 2 );
        }
 
        return -ENOENT;
}
 
/**
 * Read PCI Enhanced Allocation BAR equivalent value
 *
 * @v pci               PCI device
 * @v bei               BAR equivalent indicator
 * @v low_offset        Offset to low dword of value
 * @ret value           BAR equivalent value
 */
static unsigned long pciea_bar_value ( struct pci_device *pci, unsigned int bei,
                                       unsigned int low_offset ) {
        uint32_t low;
        uint32_t high;
        int offset;
 
        /* Locate Enhanced Allocation offset for this BEI */
        offset = pciea_offset ( pci, bei );
        if ( offset < 0 )
                return 0;
 
        /* Read BAR equivalent */
        offset += low_offset;
        pci_read_config_dword ( pci, offset, &low );
        if ( low & PCIEA_LOW_ATTR_64BIT ) {
                offset += PCIEA_LOW_HIGH;
                pci_read_config_dword ( pci, offset, &high );
                if ( high ) {
                        if ( sizeof ( unsigned long ) > sizeof ( uint32_t ) ) {
                                return ( ( ( uint64_t ) high << 32 ) | low );
                        } else {
                                DBGC ( pci, PCI_FMT " unhandled 64-bit EA BAR "
                                       "%08x%08x\n",
                                       PCI_ARGS ( pci ), high, low );
                                return 0;
                        }
                }
        }
        return low;
}
 
/**
 * Find the start of a PCI Enhanced Allocation BAR equivalent
 *
 * @v pci               PCI device
 * @v bei               BAR equivalent indicator
 * @ret start           BAR start address
 *
 * If the address exceeds the size of an unsigned long (i.e. if a
 * 64-bit BAR has a non-zero high dword on a 32-bit machine), the
 * return value will be zero.
 */
unsigned long pciea_bar_start ( struct pci_device *pci, unsigned int bei ) {
        unsigned long base;
 
        base = pciea_bar_value ( pci, bei, PCIEA_LOW_BASE );
        return ( base & ~PCIEA_LOW_ATTR_MASK );
}
 
/**
 * Find the size of a PCI Enhanced Allocation BAR equivalent
 *
 * @v pci               PCI device
 * @v bei               BAR equivalent indicator
 * @ret size            BAR size
 */
unsigned long pciea_bar_size ( struct pci_device *pci, unsigned int bei ) {
        unsigned long limit;
 
        limit = pciea_bar_value ( pci, bei, PCIEA_LOW_LIMIT );
        return ( limit ? ( ( limit | PCIEA_LOW_ATTR_MASK ) + 1 ) : 0 );
}