bus: add scanning

Scan for bus discovers the devices available on the bus and adds them
to a bus specific device list. Each bus mandatorily implements this
method.

Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>

lib/librte_eal/bsdapp/eal/eal.c

@@ -577,6 +577,9 @@ rte_eal_init(int argc, char **argv)
 		rte_config.master_lcore, thread_id, cpuset,
 		ret == 0 ? "" : "...");
 
+	if (rte_bus_scan())
+		rte_panic("Cannot scan the buses for devices\n");
+
 	RTE_LCORE_FOREACH_SLAVE(i) {
 
 		/*

lib/librte_eal/bsdapp/eal/rte_eal_version.map

@@ -180,6 +180,7 @@ DPDK_17.02 {
 
 	rte_bus_dump;
 	rte_bus_register;
+	rte_bus_scan;
 	rte_bus_unregister;
 
 } DPDK_16.11;

lib/librte_eal/common/eal_common_bus.c

@@ -47,6 +47,8 @@ rte_bus_register(struct rte_bus *bus)
 {
 	RTE_VERIFY(bus);
 	RTE_VERIFY(bus->name && strlen(bus->name));
+	/* A bus should mandatorily have the scan implemented */
+	RTE_VERIFY(bus->scan);
 
 	TAILQ_INSERT_TAIL(&rte_bus_list, bus, next);
 	RTE_LOG(DEBUG, EAL, "Registered [%s] bus.\n", bus->name);
@@ -59,6 +61,25 @@ rte_bus_unregister(struct rte_bus *bus)
 	RTE_LOG(DEBUG, EAL, "Unregistered [%s] bus.\n", bus->name);
 }
 
+/* Scan all the buses for registered devices */
+int
+rte_bus_scan(void)
+{
+	int ret;
+	struct rte_bus *bus = NULL;
+
+	TAILQ_FOREACH(bus, &rte_bus_list, next) {
+		ret = bus->scan();
+		if (ret) {
+			RTE_LOG(ERR, EAL, "Scan for (%s) bus failed.\n",
+				bus->name);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 /* Dump information of a single bus */
 static int
 bus_dump_one(FILE *f, struct rte_bus *bus)

lib/librte_eal/common/include/rte_bus.h

@@ -56,12 +56,26 @@ extern "C" {
 /** Double linked list of buses */
 TAILQ_HEAD(rte_bus_list, rte_bus);
 
+/**
+ * Bus specific scan for devices attached on the bus.
+ * For each bus object, the scan would be reponsible for finding devices and
+ * adding them to its private device list.
+ *
+ * A bus should mandatorily implement this method.
+ *
+ * @return
+ *	0 for successful scan
+ *	<0 for unsuccessful scan with error value
+ */
+typedef int (*rte_bus_scan_t)(void);
+
 /**
  * A structure describing a generic bus.
  */
 struct rte_bus {
 	TAILQ_ENTRY(rte_bus) next;   /**< Next bus object in linked list */
 	const char *name;            /**< Name of the bus */
+	rte_bus_scan_t scan;         /**< Scan for devices attached to bus */
 };
 
 /**
@@ -82,6 +96,15 @@ void rte_bus_register(struct rte_bus *bus);
  */
 void rte_bus_unregister(struct rte_bus *bus);
 
+/**
+ * Scan all the buses.
+ *
+ * @return
+ *   0 in case of success in scanning all buses
+ *  !0 in case of failure to scan
+ */
+int rte_bus_scan(void);
+
 /**
  * Dump information of all the buses registered with EAL.
  *

lib/librte_eal/linuxapp/eal/eal.c

@@ -69,6 +69,7 @@
 #include <rte_string_fns.h>
 #include <rte_cpuflags.h>
 #include <rte_interrupts.h>
+#include <rte_bus.h>
 #include <rte_pci.h>
 #include <rte_dev.h>
 #include <rte_devargs.h>
@@ -844,6 +845,9 @@ rte_eal_init(int argc, char **argv)
 	if (rte_eal_intr_init() < 0)
 		rte_panic("Cannot init interrupt-handling thread\n");
 
+	if (rte_bus_scan())
+		rte_panic("Cannot scan the buses for devices\n");
+
 	RTE_LCORE_FOREACH_SLAVE(i) {
 
 		/*

lib/librte_eal/linuxapp/eal/rte_eal_version.map

@@ -184,6 +184,7 @@ DPDK_17.02 {
 
 	rte_bus_dump;
 	rte_bus_register;
+	rte_bus_scan;
 	rte_bus_unregister;
 
 } DPDK_16.11;