dev/pci/pci_bus_count.c

0001 /*
0002  * This software is Copyright (C) 1998 by T.sqware - all rights limited
0003  * It is provided in to the public domain "as is", can be freely modified
0004  * as far as this copyight notice is kept unchanged, but does not imply
0005  * an endorsement by T.sqware of the product in which it is included.
0006  */
0007
0008 #include <rtems.h>
0009 #include <rtems/pci.h>
0010 #include <rtems/bspIo.h>
0011
0012 static uint8_t pci_number_of_buses = 0xff;
0013
0014 unsigned char pci_bus_count(void)
0015 {
0016   if ( pci_number_of_buses != 0xff ) {
0017     return pci_number_of_buses;
0018   }
0019
0020   uint8_t  bus;
0021   uint8_t  device;
0022   uint8_t  function;
0023   uint8_t  number_of_functions;
0024   uint8_t  header = 0;
0025   uint8_t  buses = 0;
0026   uint32_t vendor = 0;
0027   uint32_t class_rev = 0;
0028
0029   pci_number_of_buses = 0;
0030
0031   for (bus=0; bus < 0xff; bus++) {
0032     for (device=0; device < PCI_MAX_DEVICES; device++) {
0033
0034        pci_read_config_dword(bus, device, 0, PCI_VENDOR_ID, &vendor);
0035        if ( vendor == -1 ) {
0036          continue;
0037        }
0038
0039        pci_read_config_byte(bus, device, 0, PCI_HEADER_TYPE, &header);
0040        number_of_functions = (header & 0x80) ? PCI_MAX_FUNCTIONS : 1;
0041
0042        for ( function=0; function < number_of_functions; function++ ) {
0043          pci_read_config_dword(bus, device, function, PCI_VENDOR_ID, &vendor);
0044          if ( vendor == -1 ) {
0045            continue;
0046          }
0047
0048          pci_read_config_dword(bus, device, function, PCI_CLASS_REVISION, &class_rev);
0049          if ( (class_rev >> 16) == PCI_CLASS_BRIDGE_PCI ) {
0050             pci_read_config_byte(bus, device, function, PCI_SUBORDINATE_BUS, &buses);
0051             if ( buses > pci_number_of_buses ) {
0052               pci_number_of_buses = buses;
0053             }
0054          }
0055        }
0056     }
0057   }
0058
0059   if ( pci_number_of_buses == 0 ) {
0060     printk("pci_bus_count() found 0 busses, assuming 1\n");
0061     pci_number_of_buses = 1;
0062   } else if ( pci_number_of_buses == 0xff ) {
0063     printk("pci_bus_count() found 0xff busses, assuming 1\n");
0064     pci_number_of_buses = 1;
0065   }
0066
0067   return pci_number_of_buses;
0068 }