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[pci] Generalise pci_num_bus() to pci_discover()

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Allow pci_find_next() to discover devices beyond the first PCI
segment, by generalising pci_num_bus() (which implicitly assumes that
there is only a single PCI segment) with pci_discover() (which has the
ability to return an arbitrary contiguous chunk of PCI bus:dev.fn
address space).

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2022-09-15 16:47:04 +01:00
parent 56b30364c5
commit ff228f745c
10 changed files with 78 additions and 43 deletions
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34
src/drivers/bus/pci.c
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@@ -233,18 +233,23 @@ int pci_read_config ( struct pci_device *pci ) {
* @ret rc Return status code
*/
int pci_find_next ( struct pci_device *pci, uint32_t *busdevfn ) {
static unsigned int end;
unsigned int sub_end;
static struct pci_range range;
uint8_t hdrtype;
uint8_t sub;
uint32_t end;
unsigned int count;
int rc;
/* Determine number of PCI buses */
if ( ! end )
end = PCI_BUSDEVFN ( 0, pci_num_bus(), 0, 0 );
/* Find next PCI device, if any */
for ( ; *busdevfn < end ; (*busdevfn)++ ) {
do {
/* Find next PCI bus:dev.fn address range, if necessary */
if ( ( *busdevfn - range.start ) >= range.count ) {
pci_discover ( *busdevfn, &range );
if ( *busdevfn < range.start )
*busdevfn = range.start;
if ( ( *busdevfn - range.start ) >= range.count )
break;
}
/* Check for PCI device existence */
memset ( pci, 0, sizeof ( *pci ) );
@@ -252,24 +257,27 @@ int pci_find_next ( struct pci_device *pci, uint32_t *busdevfn ) {
if ( ( rc = pci_read_config ( pci ) ) != 0 )
continue;
/* If device is a bridge, expand the number of PCI
* buses as needed.
/* If device is a bridge, expand the PCI bus:dev.fn
* address range as needed.
*/
pci_read_config_byte ( pci, PCI_HEADER_TYPE, &hdrtype );
hdrtype &= PCI_HEADER_TYPE_MASK;
if ( hdrtype == PCI_HEADER_TYPE_BRIDGE ) {
pci_read_config_byte ( pci, PCI_SUBORDINATE, &sub );
sub_end = PCI_BUSDEVFN ( 0, ( sub + 1 ), 0, 0 );
if ( end < sub_end ) {
end = PCI_BUSDEVFN ( PCI_SEG ( *busdevfn ),
( sub + 1 ), 0, 0 );
count = ( end - range.start );
if ( count > range.count ) {
DBGC ( pci, PCI_FMT " found subordinate bus "
"%#02x\n", PCI_ARGS ( pci ), sub );
end = sub_end;
range.count = count;
}
}
/* Return this device */
return 0;
}
} while ( ++(*busdevfn) );
return -ENODEV;
}