[dpdk-dev] [PATCH 04/13] eal/bus: add scan and match support

[Shreyansh Jain <shreyansh.jain@nxp.com>]

When a PMD is registred, it will associate itself with a bus.

A bus is responsible for 'scan' of all the devices attached to it.
All the scanned devices are attached to bus specific device_list.

During the probe operation, 'match' of the drivers and devices would
be done.

This patch also adds necessary test framework to test the scan and
match callbacks.

Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
---
 app/test/test_bus.c                     | 265 ++++++++++++++++++++++++++++++++
 lib/librte_eal/common/eal_common_bus.c  |   3 +
 lib/librte_eal/common/include/rte_bus.h |  46 ++++++
 3 files changed, 314 insertions(+)

diff --git a/app/test/test_bus.c b/app/test/test_bus.c
index 760d40a..ed95479 100644
--- a/app/test/test_bus.c
+++ b/app/test/test_bus.c
@@ -80,12 +80,32 @@ struct dummy_bus {
 struct rte_bus_list orig_bus_list =
 	TAILQ_HEAD_INITIALIZER(orig_bus_list);
 
+/* Forward declarations for callbacks from bus */
+
+/* Bus A
+ * Scan would register devA1 and devA2 to bus
+ */
+int scan_fn_for_busA(struct rte_bus *bus);
+
+/* Bus B
+ * Scan would register devB1 and devB2 to bus
+ */
+int scan_fn_for_busB(struct rte_bus *bus);
+
+/* generic implementations wrapped around by above declarations */
+static int generic_scan_fn(struct rte_bus *bus);
+static int generic_match_fn(struct rte_driver *drv, struct rte_device *dev);
+
 struct rte_bus busA = {
 	.name = "busA", /* "busA" */
+	.scan = scan_fn_for_busA,
+	.match = generic_match_fn,
 };
 
 struct rte_bus busB = {
 	.name = "busB", /* "busB */
+	.scan = scan_fn_for_busB,
+	.match = generic_match_fn,
 };
 
 struct rte_driver driverA = {
@@ -184,6 +204,92 @@ dump_device_tree(void)
 	printf("------>8-------\n");
 }
 
+/* @internal
+ * Move over the dummy_buses and find the entry matching the bus object
+ * passed as argument.
+ * For each device in that dummy_buses list, register.
+ *
+ * @param bus
+ *	bus to scan againt test entry
+ * @return
+ *	0 for successful scan, even if no devices are found
+ *	!0 for any error in scanning (like, invalid bus)
+ */
+static int
+generic_scan_fn(struct rte_bus *bus)
+{
+	int i = 0;
+	struct rte_device *dev = NULL;
+	struct dummy_bus *db = NULL;
+
+	if (!bus)
+		return -1;
+
+	/* Extract the device tree node using the bus passed */
+	for (i = 0; dummy_buses[i].name; i++) {
+		if (!strcmp(dummy_buses[i].name, bus->name)) {
+			db = &dummy_buses[i];
+			break;
+		}
+	}
+
+	if (!db)
+		return -1;
+
+	/* For all the devices in the device tree (dummy_buses), add device */
+	for (i = 0; db->devices[i]; i++) {
+		dev = &(db->devices[i]->dev);
+		rte_eal_bus_add_device(bus, dev);
+	}
+
+	return 0;
+}
+
+/* @internal
+ * Obtain bus from driver object. Match the address of rte_device object
+ * with all the devices associated with that bus.
+ *
+ * Being a test function, all this does is validate that device object
+ * provided is available on the same bus to which driver is registered.
+ *
+ * @param drv
+ *	driver to which matching is to be performed
+ * @param dev
+ *	device object to match with driver
+ * @return
+ *	0 for successful match
+ *	!0 for failed match
+ */
+static int
+generic_match_fn(struct rte_driver *drv, struct rte_device *dev)
+{
+	struct rte_bus *bus;
+	struct rte_device *dev_p = NULL;
+
+	/* Match is based entirely on address of 'dev' and 'dev_p' extracted
+	 * from bus->device_list.
+	 */
+
+	/* a driver is registered with the bus *before* the scan. */
+	bus = drv->bus;
+	TAILQ_FOREACH(dev_p, &bus->device_list, next) {
+		if (dev == dev_p)
+			return 0;
+	}
+
+	return 1;
+}
+
+int
+scan_fn_for_busA(struct rte_bus *bus) {
+	return generic_scan_fn(bus);
+}
+
+int
+scan_fn_for_busB(struct rte_bus *bus) {
+	return generic_scan_fn(bus);
+}
+
 static int
 test_bus_setup(void)
 {
@@ -391,6 +497,155 @@ test_driver_unregistration_on_bus(void)
 
 }
 
+static int
+test_device_unregistration_on_bus(void)
+{
+	int i;
+	struct rte_bus *bus = NULL;
+	struct rte_device *dev;
+
+	for (i = 0; dummy_buses[i].name; i++) {
+		bus = rte_eal_get_bus(dummy_buses[i].name);
+		if (!bus) {
+			printf("Unable to find bus (%s)\n",
+			       dummy_buses[i].name);
+			return -1;
+		}
+
+		/* For bus 'bus', unregister all devices */
+		TAILQ_FOREACH(dev, &bus->device_list, next) {
+			rte_eal_bus_remove_device(dev);
+		}
+	}
+
+	for (i = 0; dummy_buses[i].name; i++) {
+		bus = rte_eal_get_bus(dummy_buses[i].name);
+
+		if (!TAILQ_EMPTY(&bus->device_list)) {
+			printf("Unable to remove all devices on bus (%s)\n",
+			       bus->name);
+			return -1;
+		}
+	}
+
+	/* All devices from all buses have been removed */
+	printf("All devices on all buses unregistered.\n");
+	dump_device_tree();
+
+	return 0;
+}
+
+/* @internal
+ * For each bus registered, call the scan function to identify devices
+ * on the bus.
+ *
+ * @param void
+ * @return
+ *	0 for successful scan
+ *	!0 for unsuccessful scan
+ *
+ */
+static int
+test_bus_scan(void)
+{
+	int ret;
+	struct rte_bus *bus;
+
+	TAILQ_FOREACH(bus, &rte_bus_list, next) {
+		/* Call the scan function for each bus */
+		ret = bus->scan(bus);
+		if (ret) {
+			printf("Scan of buses failed.\n");
+			return -1;
+		}
+	}
+
+	printf("Scan of all buses completed.\n");
+	dump_device_tree();
+
+	return 0;
+}
+
+/* @internal
+ * Function to perform 'probe' and link devices and drivers on a bus.
+ * This would work over all the buses registered, and all devices and drivers
+ * registered with it - call match on each pair.
+ * Aim is to test the match_fn for each bus.
+ *
+ * @param void
+ * @return
+ *	0 for successful probe
+ *	!0 for failure in probe
+ *
+ */
+static int
+test_probe_on_bus(void)
+{
+	int ret = 0;
+	int i, j;
+	struct rte_bus *bus = NULL;
+	struct rte_device *dev = NULL;
+	struct rte_driver *drv = NULL;
+
+	/* In case of this test:
+	* 1. for each bus in rte_bus_list
+	* 2.  for each device in bus->device_list
+	* 3.   for each driver in bus->driver_list
+	* 4.    call match
+	* 5.    link driver and device
+	* 6. Verify the linkage.
+	*/
+	for (i = 0; dummy_buses[i].name; i++) {
+		/* get bus pointer from dummy_buses itself rather than
+		 * rte_eal_get_bus
+		 */
+		bus = dummy_buses[i].bus;
+
+		TAILQ_FOREACH(dev, &bus->device_list, next) {
+			TAILQ_FOREACH(drv, &bus->driver_list, next) {
+				if (!bus->match) {
+					printf("Incorrect bus without match "
+					       "fn: (%s).\n", bus->name);
+					return -1;
+				}
+
+				ret = bus->match(drv, dev);
+				if (ret) {
+					printf("Device and driver don't "
+					       "belong to same bus.\n");
+					return -1;
+				}
+				dev->driver = drv;
+
+				/* As match is generic, it always results in
+				 * dev->drv pointing to first driver entry in
+				 * dummy_buses[i]
+				 */
+			}
+		}
+	}
+
+	/* Verify the linkage. All devices belonging to a dummy_buses[i]
+	 * should have same driver (first driver entry of dummy_buses[i])
+	 */
+	for (i = 0; dummy_buses[i].name; i++) {
+		drv = dummy_buses[i].drivers[0];
+
+		for (j = 0; dummy_buses[i].devices[j]; j++) {
+			dev = &(dummy_buses[i].devices[j]->dev);
+			if (dev->driver != drv) {
+				printf("Incorrect driver<->device linkage.\n");
+				return -1;
+			}
+		}
+	}
+
+	printf("Probe on all buses successful.\n");
+	dump_device_tree();
+
+	return 0;
+}
+
 int
 test_bus(void)
 {
@@ -407,6 +662,16 @@ test_bus(void)
 	if (test_driver_registration_on_bus())
 		return -1;
 
+	if (test_bus_scan())
+		return -1;
+
+	/* Now that the devices and drivers are registered, perform probe */
+	if (test_probe_on_bus())
+		return -1;
+
+	if (test_device_unregistration_on_bus())
+		return -1;
+
 	if (test_driver_unregistration_on_bus())
 		return -1;
 
diff --git a/lib/librte_eal/common/eal_common_bus.c b/lib/librte_eal/common/eal_common_bus.c
index 612f64e..2473fe4 100644
--- a/lib/librte_eal/common/eal_common_bus.c
+++ b/lib/librte_eal/common/eal_common_bus.c
@@ -132,6 +132,9 @@ rte_eal_bus_register(struct rte_bus *bus)
 {
 	RTE_VERIFY(bus);
 	RTE_VERIFY(bus->name && strlen(bus->name));
+	/* A bus should mandatorily have the scan and match implemented */
+	RTE_VERIFY(bus->scan);
+	RTE_VERIFY(bus->match);
 
 	/* Initialize the driver and device list associated with the bus */
 	TAILQ_INIT(&(bus->driver_list));
diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
index f0297a9..b41105c 100644
--- a/lib/librte_eal/common/include/rte_bus.h
+++ b/lib/librte_eal/common/include/rte_bus.h
@@ -59,6 +59,49 @@ TAILQ_HEAD(rte_bus_list, rte_bus);
 /* Global Bus list */
 extern struct rte_bus_list rte_bus_list;
 
+/**
+ * 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.
+ *
+ * Successful detection of a device results in rte_device object which is
+ * embedded within the respective device type (rte_pci_device, for example).
+ * Thereafter, PCI specific bus would need to perform
+ * container_of(rte_pci_device) to obtain PCI device object.
+ *
+ * Scan failure of a bus is not treated as exit criteria for application. Scan
+ * for all other buses would still continue.
+ *
+ * A bus should mandatorily implement this method.
+ *
+ * @param bus
+ *	Reference to the bus on which device is added
+ * @return
+ *	0 for successful scan
+ *	!0 (<0) for unsuccessful scan with error value
+ */
+typedef int (*bus_scan_t)(struct rte_bus *bus);
+
+/**
+ * Bus specific match for devices and drivers which can service them.
+ * For each scanned device, rte_driver->probe would be called for driver
+ * specific initialization of the device.
+ *
+ * It is the work of each bus handler to obtain the specific device object
+ * using container_of (or typecasting, as a less preferred way).
+ *
+ * A bus should mandatorily implement this method.
+ *
+ * @param drv
+ *	Driver object attached to the bus
+ * @param dev
+ *	Device object which is being probed.
+ * @return
+ *	0 for successful match
+ *	!0 for unsuccessful match
+ */
+typedef int (*bus_match_t)(struct rte_driver *drv, struct rte_device *dev);
+
 struct rte_bus {
 	TAILQ_ENTRY(rte_bus) next;   /**< Next bus object in linked list */
 	struct rte_driver_list driver_list;
@@ -66,6 +109,9 @@ struct rte_bus {
 	struct rte_device_list device_list;
 				     /**< List of all devices on bus */
 	const char *name;            /**< Name of the bus */
+	bus_scan_t scan;            /**< Scan for devices attached to bus */
+	bus_match_t match;
+	/**< Match device with drivers associated with the bus */
 };
 
 /** @internal
-- 
2.7.4