[v4,1/6] drivers: add generic API to find PCI extended cap

diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
index a8e5fd52c..98c1f8155 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -665,6 +665,49 @@  rte_pci_get_iommu_class(void)
 	return iova_mode;
 }
 
+off_t
+rte_pci_find_next_ext_capability(struct rte_pci_device *dev, uint32_t cap)
+{
+	off_t offset = RTE_PCI_CFG_SPACE_SIZE;
+	uint32_t header;
+	int ttl;
+
+	/* minimum 8 bytes per capability */
+	ttl = (RTE_PCI_CFG_SPACE_EXP_SIZE - RTE_PCI_CFG_SPACE_SIZE) / 8;
+
+	if (rte_pci_read_config(dev, &header, 4, offset) < 0) {
+		RTE_LOG(ERR, EAL, "error in reading extended capabilities\n");
+		return -1;
+	}
+
+	/*
+	 * If we have no capabilities, this is indicated by cap ID,
+	 * cap version and next pointer all being 0.
+	 */
+	if (header == 0)
+		return 0;
+
+	while (ttl != 0) {
+		if (RTE_PCI_EXT_CAP_ID(header) == cap)
+			return offset;
+
+		offset = RTE_PCI_EXT_CAP_NEXT(header);
+
+		if (offset < RTE_PCI_CFG_SPACE_SIZE)
+			break;
+
+		if (rte_pci_read_config(dev, &header, 4, offset) < 0) {
+			RTE_LOG(ERR, EAL,
+				"error in reading extended capabilities\n");
+			return -1;
+		}
+
+		ttl--;
+	}
+
+	return 0;
+}
+
 struct rte_pci_bus rte_pci_bus = {
 	.bus = {
 		.scan = rte_pci_scan,
diff --git a/drivers/bus/pci/rte_bus_pci.h b/drivers/bus/pci/rte_bus_pci.h
index 29bea6d70..f11af3762 100644
--- a/drivers/bus/pci/rte_bus_pci.h
+++ b/drivers/bus/pci/rte_bus_pci.h
@@ -224,6 +224,26 @@  void rte_pci_unmap_device(struct rte_pci_device *dev);
  */
 void rte_pci_dump(FILE *f);
 
+/**
+ * Find device's extended PCI capability.
+ *
+ *  @param dev
+ *    A pointer to rte_pci_device structure.
+ *
+ *  @param cap
+ *    Extended capability to be found, which can be any from
+ *    RTE_PCI_EXT_CAP_ID_*, defined in librte_pci.
+ *
+ *  @return
+ *  > 0: The offset of the next matching extended capability structure
+ *       within the device's PCI configuration space.
+ *  < 0: An error in PCI config space read.
+ *  = 0: Device does not support it.
+ */
+__rte_experimental
+off_t rte_pci_find_next_ext_capability(struct rte_pci_device *dev,
+				       uint32_t cap);
+
 /**
  * Register a PCI driver.
  *
diff --git a/drivers/bus/pci/rte_bus_pci_version.map b/drivers/bus/pci/rte_bus_pci_version.map
index 012d817e1..b5322660d 100644
--- a/drivers/bus/pci/rte_bus_pci_version.map
+++ b/drivers/bus/pci/rte_bus_pci_version.map
@@ -16,3 +16,9 @@  DPDK_20.0 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	global:
+
+	rte_pci_find_next_ext_capability;
+};
diff --git a/drivers/net/ice/ice_ethdev.c b/drivers/net/ice/ice_ethdev.c
index 7dd3fcd27..6c8cbea5c 100644
--- a/drivers/net/ice/ice_ethdev.c
+++ b/drivers/net/ice/ice_ethdev.c
@@ -1730,53 +1730,6 @@  ice_pf_setup(struct ice_pf *pf)
 	return 0;
 }
 
-/* PCIe configuration space setting */
-#define PCI_CFG_SPACE_SIZE          256
-#define PCI_CFG_SPACE_EXP_SIZE      4096
-#define PCI_EXT_CAP_ID(header)      (int)((header) & 0x0000ffff)
-#define PCI_EXT_CAP_NEXT(header)    (((header) >> 20) & 0xffc)
-#define PCI_EXT_CAP_ID_DSN          0x03
-
-static int
-ice_pci_find_next_ext_capability(struct rte_pci_device *dev, int cap)
-{
-	uint32_t header;
-	int ttl;
-	int pos = PCI_CFG_SPACE_SIZE;
-
-	/* minimum 8 bytes per capability */
-	ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
-
-	if (rte_pci_read_config(dev, &header, 4, pos) < 0) {
-		PMD_INIT_LOG(ERR, "ice error reading extended capabilities\n");
-		return -1;
-	}
-
-	/*
-	 * If we have no capabilities, this is indicated by cap ID,
-	 * cap version and next pointer all being 0.
-	 */
-	if (header == 0)
-		return 0;
-
-	while (ttl-- > 0) {
-		if (PCI_EXT_CAP_ID(header) == cap)
-			return pos;
-
-		pos = PCI_EXT_CAP_NEXT(header);
-
-		if (pos < PCI_CFG_SPACE_SIZE)
-			break;
-
-		if (rte_pci_read_config(dev, &header, 4, pos) < 0) {
-			PMD_INIT_LOG(ERR, "ice error reading extended capabilities\n");
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
 /*
  * Extract device serial number from PCIe Configuration Space and
  * determine the pkg file path according to the DSN.
@@ -1784,12 +1737,12 @@  ice_pci_find_next_ext_capability(struct rte_pci_device *dev, int cap)
 static int
 ice_pkg_file_search_path(struct rte_pci_device *pci_dev, char *pkg_file)
 {
-	int pos;
+	off_t pos;
 	char opt_ddp_filename[ICE_MAX_PKG_FILENAME_SIZE];
 	uint32_t dsn_low, dsn_high;
 	memset(opt_ddp_filename, 0, ICE_MAX_PKG_FILENAME_SIZE);
 
-	pos = ice_pci_find_next_ext_capability(pci_dev, PCI_EXT_CAP_ID_DSN);
+	pos = rte_pci_find_next_ext_capability(pci_dev, RTE_PCI_EXT_CAP_ID_DSN);
 
 	if (pos) {
 		rte_pci_read_config(pci_dev, &dsn_low, 4, pos + 4);
diff --git a/drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c b/drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c
index 0b9db974e..dbab4f8cb 100644
--- a/drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c
+++ b/drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c
@@ -746,59 +746,15 @@  nfp6000_set_interface(struct rte_pci_device *dev, struct nfp_cpp *cpp)
 	return 0;
 }
 
-#define PCI_CFG_SPACE_SIZE	256
-#define PCI_CFG_SPACE_EXP_SIZE	4096
-#define PCI_EXT_CAP_ID(header)		(int)(header & 0x0000ffff)
-#define PCI_EXT_CAP_NEXT(header)	((header >> 20) & 0xffc)
-#define PCI_EXT_CAP_ID_DSN	0x03
-static int
-nfp_pci_find_next_ext_capability(struct rte_pci_device *dev, int cap)
-{
-	uint32_t header;
-	int ttl;
-	int pos = PCI_CFG_SPACE_SIZE;
-
-	/* minimum 8 bytes per capability */
-	ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
-
-	if (rte_pci_read_config(dev, &header, 4, pos) < 0) {
-		printf("nfp error reading extended capabilities\n");
-		return -1;
-	}
-
-	/*
-	 * If we have no capabilities, this is indicated by cap ID,
-	 * cap version and next pointer all being 0.
-	 */
-	if (header == 0)
-		return 0;
-
-	while (ttl-- > 0) {
-		if (PCI_EXT_CAP_ID(header) == cap)
-			return pos;
-
-		pos = PCI_EXT_CAP_NEXT(header);
-		if (pos < PCI_CFG_SPACE_SIZE)
-			break;
-
-		if (rte_pci_read_config(dev, &header, 4, pos) < 0) {
-			printf("nfp error reading extended capabilities\n");
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
 static int
 nfp6000_set_serial(struct rte_pci_device *dev, struct nfp_cpp *cpp)
 {
 	uint16_t tmp;
 	uint8_t serial[6];
 	int serial_len = 6;
-	int pos;
+	off_t pos;
 
-	pos = nfp_pci_find_next_ext_capability(dev, PCI_EXT_CAP_ID_DSN);
+	pos = rte_pci_find_next_ext_capability(dev, RTE_PCI_EXT_CAP_ID_DSN);
 	if (pos <= 0) {
 		printf("PCI_EXT_CAP_ID_DSN not found. nfp set serial failed\n");
 		return -1;
diff --git a/drivers/raw/ifpga/ifpga_rawdev.c b/drivers/raw/ifpga/ifpga_rawdev.c
index cc25c662b..f8205a3c7 100644
--- a/drivers/raw/ifpga/ifpga_rawdev.c
+++ b/drivers/raw/ifpga/ifpga_rawdev.c
@@ -41,12 +41,6 @@ 
 #include "ifpga_rawdev.h"
 #include "ipn3ke_rawdev_api.h"
 
-#define RTE_PCI_EXT_CAP_ID_ERR           0x01	/* Advanced Error Reporting */
-#define RTE_PCI_CFG_SPACE_SIZE           256
-#define RTE_PCI_CFG_SPACE_EXP_SIZE       4096
-#define RTE_PCI_EXT_CAP_ID(header)       (int)(header & 0x0000ffff)
-#define RTE_PCI_EXT_CAP_NEXT(header)     ((header >> 20) & 0xffc)
-
 #define PCI_VENDOR_ID_INTEL          0x8086
 /* PCI Device ID */
 #define PCIE_DEVICE_ID_PF_INT_5_X    0xBCBD
diff --git a/lib/librte_pci/rte_pci.h b/lib/librte_pci/rte_pci.h
index a03235da1..fec51e15a 100644
--- a/lib/librte_pci/rte_pci.h
+++ b/lib/librte_pci/rte_pci.h
@@ -22,6 +22,22 @@  extern "C" {
 #include <inttypes.h>
 #include <sys/types.h>
 
+
+/*
+ * Conventional PCI and PCI-X Mode 1 devices have 256 bytes of
+ * configuration space.  PCI-X Mode 2 and PCIe devices have 4096 bytes of
+ * configuration space.
+ */
+#define RTE_PCI_CFG_SPACE_SIZE		256
+#define RTE_PCI_CFG_SPACE_EXP_SIZE	4096
+
+/* Extended Capabilities (PCI-X 2.0 and Express) */
+#define RTE_PCI_EXT_CAP_ID(header)	(header & 0x0000ffff)
+#define RTE_PCI_EXT_CAP_NEXT(header)	((header >> 20) & 0xffc)
+
+#define RTE_PCI_EXT_CAP_ID_ERR	0x01	/* Advanced Error Reporting */
+#define RTE_PCI_EXT_CAP_ID_DSN	0x03	/* Device Serial Number */
+
 /** Formatting string for PCI device identifier: Ex: 0000:00:01.0 */
 #define PCI_PRI_FMT "%.4" PRIx32 ":%.2" PRIx8 ":%.2" PRIx8 ".%" PRIx8
 #define PCI_PRI_STR_SIZE sizeof("XXXXXXXX:XX:XX.X")