eal: introduce device class abstraction

This abstraction exists since the infancy of DPDK.
It needs to be fleshed out however, to allow a generic
description of devices properties and capabilities.

A device class is the northbound interface of the device, intended
for applications to know what it can be used for.

It is conceptually just above buses.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>

lib/librte_eal/bsdapp/eal/Makefile

@@ -52,6 +52,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_hypervisor.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_string_fns.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_hexdump.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_devargs.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_class.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_bus.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_dev.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_options.c

lib/librte_eal/common/Makefile

@@ -11,7 +11,7 @@ INC += rte_per_lcore.h rte_random.h
 INC += rte_tailq.h rte_interrupts.h rte_alarm.h
 INC += rte_string_fns.h rte_version.h
 INC += rte_eal_memconfig.h rte_malloc_heap.h
-INC += rte_hexdump.h rte_devargs.h rte_bus.h rte_dev.h
+INC += rte_hexdump.h rte_devargs.h rte_bus.h rte_dev.h rte_class.h
 INC += rte_pci_dev_feature_defs.h rte_pci_dev_features.h
 INC += rte_malloc.h rte_keepalive.h rte_time.h
 INC += rte_service.h rte_service_component.h

lib/librte_eal/common/eal_common_class.c

@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2018 Gaëtan Rivet
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/queue.h>
+
+#include <rte_class.h>
+#include <rte_debug.h>
+
+struct rte_class_list rte_class_list =
+	TAILQ_HEAD_INITIALIZER(rte_class_list);
+
+__rte_experimental void
+rte_class_register(struct rte_class *class)
+{
+	RTE_VERIFY(class);
+	RTE_VERIFY(class->name && strlen(class->name));
+
+	TAILQ_INSERT_TAIL(&rte_class_list, class, next);
+	RTE_LOG(DEBUG, EAL, "Registered [%s] device class.\n", class->name);
+}
+
+__rte_experimental void
+rte_class_unregister(struct rte_class *class)
+{
+	TAILQ_REMOVE(&rte_class_list, class, next);
+	RTE_LOG(DEBUG, EAL, "Unregistered [%s] device class.\n", class->name);
+}
+
+__rte_experimental
+struct rte_class *
+rte_class_find(const struct rte_class *start, rte_class_cmp_t cmp,
+	       const void *data)
+{
+	struct rte_class *cls;
+
+	if (start != NULL)
+		cls = TAILQ_NEXT(start, next);
+	else
+		cls = TAILQ_FIRST(&rte_class_list);
+	while (cls != NULL) {
+		if (cmp(cls, data) == 0)
+			break;
+		cls = TAILQ_NEXT(cls, next);
+	}
+	return cls;
+}
+
+static int
+cmp_class_name(const struct rte_class *class, const void *_name)
+{
+	const char *name = _name;
+
+	return strcmp(class->name, name);
+}
+
+__rte_experimental
+struct rte_class *
+rte_class_find_by_name(const char *name)
+{
+	return rte_class_find(NULL, cmp_class_name, (const void *)name);
+}

lib/librte_eal/common/include/rte_class.h

@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2018 Gaëtan Rivet
+ */
+
+#ifndef _RTE_CLASS_H_
+#define _RTE_CLASS_H_
+
+/**
+ * @file
+ *
+ * DPDK device class interface.
+ *
+ * This file describes the interface of the device class
+ * abstraction layer.
+ *
+ * A device class defines the type of function a device
+ * will be used for e.g.: Ethernet adapter (eth),
+ * cryptographic coprocessor (crypto), etc.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/queue.h>
+
+#include <rte_dev.h>
+
+/** Double linked list of classes */
+TAILQ_HEAD(rte_class_list, rte_class);
+
+/**
+ * A structure describing a generic device class.
+ */
+struct rte_class {
+	TAILQ_ENTRY(rte_class) next; /**< Next device class in linked list */
+	const char *name; /**< Name of the class */
+};
+
+/**
+ * Class comparison function.
+ *
+ * @param cls
+ *	Class under test.
+ *
+ * @param data
+ *	Data to compare against.
+ *
+ * @return
+ *	0 if the class matches the data.
+ *	!0 if the class does not match.
+ *	<0 if ordering is possible and the class is lower than the data.
+ *	>0 if ordering is possible and the class is greater than the data.
+ */
+typedef int (*rte_class_cmp_t)(const struct rte_class *cls, const void *data);
+
+/**
+ * Class iterator to find a particular class.
+ *
+ * This function compares each registered class to find one that matches
+ * the data passed as parameter.
+ *
+ * If the comparison function returns zero this function will stop iterating
+ * over any more classes. To continue a search the class of a previous search
+ * can be passed via the start parameter.
+ *
+ * @param start
+ *	Starting point for the iteration.
+ *
+ * @param cmp
+ *	Comparison function.
+ *
+ * @param data
+ *	 Data to pass to comparison function.
+ *
+ * @return
+ *	 A pointer to a rte_class structure or NULL in case no class matches
+ */
+__rte_experimental
+struct rte_class *
+rte_class_find(const struct rte_class *start, rte_class_cmp_t cmp,
+	       const void *data);
+
+/**
+ * Find the registered class for a given name.
+ */
+__rte_experimental
+struct rte_class *
+rte_class_find_by_name(const char *name);
+
+/**
+ * Register a Class handle.
+ *
+ * @param cls
+ *   A pointer to a rte_class structure describing the class
+ *   to be registered.
+ */
+__rte_experimental
+void rte_class_register(struct rte_class *cls);
+
+/**
+ * Unregister a Class handle.
+ *
+ * @param cls
+ *   A pointer to a rte_class structure describing the class
+ *   to be unregistered.
+ */
+__rte_experimental
+void rte_class_unregister(struct rte_class *cls);
+
+/**
+ * Helper for Class registration.
+ * The constructor has lower priority than Bus constructors.
+ * The constructor has higher priority than PMD constructors.
+ */
+#define RTE_REGISTER_CLASS(nm, cls) \
+RTE_INIT_PRIO(classinitfn_ ##nm, CLASS) \
+{\
+	(cls).name = RTE_STR(nm); \
+	rte_class_register(&cls); \
+}
+
+#define RTE_UNREGISTER_CLASS(nm, cls) \
+RTE_FINI_PRIO(classfinifn_ ##nm, CLASS) \
+{ \
+	rte_class_unregister(&cls); \
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_CLASS_H_ */

lib/librte_eal/common/include/rte_common.h

@@ -83,6 +83,7 @@ typedef uint16_t unaligned_uint16_t;
 
 #define RTE_PRIORITY_LOG 101
 #define RTE_PRIORITY_BUS 110
+#define RTE_PRIORITY_CLASS 120
 #define RTE_PRIORITY_LAST 65535
 
 #define RTE_PRIO(prio) \

lib/librte_eal/common/meson.build

@@ -8,6 +8,7 @@ common_objs = []
 common_sources = files(
 	'eal_common_bus.c',
 	'eal_common_cpuflags.c',
+	'eal_common_class.c',
 	'eal_common_devargs.c',
 	'eal_common_dev.c',
 	'eal_common_errno.c',
@@ -47,6 +48,7 @@ common_headers = files(
 	'include/rte_branch_prediction.h',
 	'include/rte_bus.h',
 	'include/rte_bitmap.h',
+	'include/rte_class.h',
 	'include/rte_common.h',
 	'include/rte_debug.h',
 	'include/rte_devargs.h',

lib/librte_eal/linuxapp/eal/Makefile

@@ -60,6 +60,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_hypervisor.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_string_fns.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_hexdump.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_devargs.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_class.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_bus.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_dev.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_options.c

lib/librte_eal/rte_eal_version.map

@@ -254,6 +254,10 @@ DPDK_18.08 {
 EXPERIMENTAL {
 	global:
 
+	rte_class_find;
+	rte_class_find_by_name;
+	rte_class_register;
+	rte_class_unregister;
 	rte_ctrl_thread_create;
 	rte_dev_event_callback_register;
 	rte_dev_event_callback_unregister;