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path: root/src/device/pci_early.c
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/*
 * This file is part of the coreboot project.
 *
 * 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; version 2 of the License.
 *
 * 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 St, Fifth Floor, Boston, MA, 02110-1301 USA
 */

#include <arch/io.h>
#include <device/pci.h>
#include <device/pci_def.h>

unsigned pci_find_next_capability(device_t dev, unsigned cap, unsigned last)
{
	unsigned pos = 0;
	u16 status;
	unsigned reps = 48;

	status = pci_read_config16(dev, PCI_STATUS);
	if (!(status & PCI_STATUS_CAP_LIST))
		return 0;

	u8 hdr_type = pci_read_config8(dev, PCI_HEADER_TYPE);
	switch (hdr_type & 0x7f) {
	case PCI_HEADER_TYPE_NORMAL:
	case PCI_HEADER_TYPE_BRIDGE:
		pos = PCI_CAPABILITY_LIST;
		break;
	case PCI_HEADER_TYPE_CARDBUS:
		pos = PCI_CB_CAPABILITY_LIST;
		break;
	default:
		return 0;
	}

	pos = pci_read_config8(dev, pos);
	while (reps-- && (pos >= 0x40)) { /* Loop through the linked list. */
		int this_cap;

		pos &= ~3;
		this_cap = pci_read_config8(dev, pos + PCI_CAP_LIST_ID);
		if (this_cap == 0xff)
			break;

		if (!last && (this_cap == cap))
			return pos;

		if (last == pos)
			last = 0;

		pos = pci_read_config8(dev, pos + PCI_CAP_LIST_NEXT);
	}
	return 0;
}

unsigned pci_find_capability(device_t dev, unsigned cap)
{
	return pci_find_next_capability(dev, cap, 0);
}