pciextra.c

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FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <gpxe/pci.h>

/**
 * Look for a PCI capability
 *
 * @v pci               PCI device to query
 * @v cap               Capability code
 * @ret address         Address of capability, or 0 if not found
 *
 * Determine whether or not a device supports a given PCI capability.
 * Returns the address of the requested capability structure within
 * the device's PCI configuration space, or 0 if the device does not
 * support it.
 */
int pci_find_capability ( struct pci_device *pci, int cap ) {
        uint16_t status;
        uint8_t pos, id;
        uint8_t hdr_type;
        int ttl = 48;

        pci_read_config_word ( pci, PCI_STATUS, &status );
        if ( ! ( status & PCI_STATUS_CAP_LIST ) )
                return 0;

        pci_read_config_byte ( pci, PCI_HEADER_TYPE, &hdr_type );
        switch ( hdr_type & 0x7F ) {
        case PCI_HEADER_TYPE_NORMAL:
        case PCI_HEADER_TYPE_BRIDGE:
        default:
                pci_read_config_byte ( pci, PCI_CAPABILITY_LIST, &pos );
                break;
        case PCI_HEADER_TYPE_CARDBUS:
                pci_read_config_byte ( pci, PCI_CB_CAPABILITY_LIST, &pos );
                break;
        }
        while ( ttl-- && pos >= 0x40 ) {
                pos &= ~3;
                pci_read_config_byte ( pci, pos + PCI_CAP_LIST_ID, &id );
                DBG ( "PCI Capability: %d\n", id );
                if ( id == 0xff )
                        break;
                if ( id == cap )
                        return pos;
                pci_read_config_byte ( pci, pos + PCI_CAP_LIST_NEXT, &pos );
        }
        return 0;
}

/**
 * Find the size of a PCI BAR
 *
 * @v pci               PCI device
 * @v reg               PCI register number
 * @ret size            BAR size
 *
 * It should not be necessary for any Etherboot code to call this
 * function.
 */
unsigned long pci_bar_size ( struct pci_device *pci, unsigned int reg ) {
        uint16_t cmd;
        uint32_t start, size;

        /* Save the original command register */
        pci_read_config_word ( pci, PCI_COMMAND, &cmd );
        /* Save the original bar */
        pci_read_config_dword ( pci, reg, &start );
        /* Compute which bits can be set */
        pci_write_config_dword ( pci, reg, ~0 );
        pci_read_config_dword ( pci, reg, &size );
        /* Restore the original size */
        pci_write_config_dword ( pci, reg, start );
        /* Find the significant bits */
        /* Restore the original command register. This reenables decoding. */
        pci_write_config_word ( pci, PCI_COMMAND, cmd );
        if ( start & PCI_BASE_ADDRESS_SPACE_IO ) {
                size &= PCI_BASE_ADDRESS_IO_MASK;
        } else {
                size &= PCI_BASE_ADDRESS_MEM_MASK;
        }
        /* Find the lowest bit set */
        size = size & ~( size - 1 );
        return size;
}