dm: PTM: Add a few pci utility functions

Add a few pci utility functions to help easy access of pci
    functionalities.
    1. pci_find_capability(): find position of specified pci capability register
    2. pci_find_ext_cap(): find extend capability register position from cap_id
    3. pci_pcie_type(): find pci-e device type
    4. is_root_port(): check whether pdev is a pci root port
    5. is_bridge(): check whether pdev is a bridge

Tracked-On: #5915
Signed-off-by: Rong Liu <rong.l.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>

devicemodel/Makefile

@@ -130,6 +130,7 @@ SRCS += hw/pci/hostbridge.c
 SRCS += hw/pci/platform_gsi_info.c
 SRCS += hw/pci/gsi_sharing.c
 SRCS += hw/pci/passthrough.c
+SRCS += hw/pci/pci_util.c
 SRCS += hw/pci/virtio/virtio_audio.c
 SRCS += hw/pci/virtio/virtio_net.c
 SRCS += hw/pci/virtio/virtio_rnd.c

devicemodel/hw/pci/pci_util.c

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2021 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <sys/queue.h>
+#include <stdlib.h>
+
+#include "pcireg.h"
+#include "pciaccess.h"
+#include "pci_core.h"
+#include "pci_util.h"
+#include "log.h"
+
+/* find position of specified pci capability register*/
+int pci_find_cap(struct pci_device *pdev, const int cap_id)
+{
+	uint8_t cap_pos, cap_data;
+	uint16_t status = 0;
+
+	pci_device_cfg_read_u16(pdev, &status, PCIR_STATUS);
+	if (status & PCIM_STATUS_CAPPRESENT) {
+		pci_device_cfg_read_u8(pdev, &cap_pos, PCIR_CAP_PTR);
+
+		while (cap_pos != 0 && cap_pos != 0xff) {
+			pci_device_cfg_read_u8(pdev, &cap_data,
+					cap_pos + PCICAP_ID);
+
+			if (cap_data == cap_id)
+				return cap_pos;
+
+			pci_device_cfg_read_u8(pdev, &cap_pos,
+					cap_pos + PCICAP_NEXTPTR);
+		}
+	}
+
+	return 0;
+}
+
+/* find extend capability register position from cap_id */
+int pci_find_ext_cap(struct pci_device *pdev, int cap_id)
+{
+	int offset = 0;
+	uint32_t data = 0;
+
+	offset = PCIR_EXTCAP;
+
+	do {
+		/* PCI Express Extended Capability must have 4 bytes header */
+		pci_device_cfg_read_u32(pdev, &data, offset);
+
+		if (PCI_EXTCAP_ID(data) == cap_id)
+			break;
+
+		offset = PCI_EXTCAP_NEXTPTR(data);
+	} while (offset != 0);
+
+	return offset;
+}
+
+/* find pci-e device type */
+int pci_get_pcie_type(struct pci_device *dev)
+{
+	uint8_t data = 0;
+	int pcie_type;
+	int pos = 0;
+
+	if (dev == NULL)
+		return -EINVAL;
+
+	pos = pci_find_cap(dev, PCIY_EXPRESS);
+	if (!pos)
+		return -EINVAL;
+
+	pci_device_cfg_read_u8(dev, &data, pos + PCIER_FLAGS);
+	pcie_type = data & PCIEM_FLAGS_TYPE;
+
+	return pcie_type;
+}
+
+/* check whether pdev is a pci root port */
+bool is_root_port(struct pci_device *pdev)
+{
+	int pcie_type;
+
+	pcie_type = pci_get_pcie_type(pdev);
+
+	return (pcie_type == PCIEM_TYPE_ROOT_PORT);
+}
+
+/* check whether pdev is a bridge */
+bool is_bridge(struct pci_device *pdev)
+{
+	uint8_t hdr_type;
+
+	pci_device_cfg_read_u8(pdev, &hdr_type, PCIR_HDRTYPE);
+
+	return ((hdr_type & PCIM_HDRTYPE) == PCIM_HDRTYPE_BRIDGE);
+}

devicemodel/include/pci_util.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2021 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef __PCI_UTIL_H
+#define __PCI_UTIL_H
+
+#include <stdbool.h>
+#include "pciaccess.h"
+
+int pci_find_cap(struct pci_device *pdev, const int cap_id);
+int pci_find_ext_cap(struct pci_device *pdev, int cap_id);
+int pci_get_pcie_type(struct pci_device *dev);
+bool is_root_port(struct pci_device *pdev);
+bool is_bridge(struct pci_device *pdev);
+
+#endif