eal: add device iterator interface

A device iterator allows iterating over a set of devices.
This set is defined by the two descriptions offered,

  * rte_bus
  * rte_class

Only one description can be provided, or both. It is not allowed to
provide no description at all.

Each layer of abstraction then performs a filter based on the
description provided. This filtering allows iterating on their internal
set of devices, stopping when a match is valid and returning the current
iteration context.

This context allows starting the next iteration from the same point and
going forward.

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

diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
index 88f99d5..b7b5b08 100644 (file)
--- a/lib/librte_eal/common/include/rte_bus.h
+++ b/lib/librte_eal/common/include/rte_bus.h
@@ -211,6 +211,7 @@ struct rte_bus {
        rte_bus_parse_t parse;       /**< Parse a device name */
        struct rte_bus_conf conf;    /**< Bus configuration */
        rte_bus_get_iommu_class_t get_iommu_class; /**< Get iommu class */
+       rte_dev_iterate_t dev_iterate; /**< Device iterator. */
 };
 
 /**

diff --git a/lib/librte_eal/common/include/rte_class.h b/lib/librte_eal/common/include/rte_class.h
index 70edb40..276c91e 100644 (file)
--- a/lib/librte_eal/common/include/rte_class.h
+++ b/lib/librte_eal/common/include/rte_class.h
@@ -35,6 +35,7 @@ TAILQ_HEAD(rte_class_list, rte_class);
 struct rte_class {
        TAILQ_ENTRY(rte_class) next; /**< Next device class in linked list */
        const char *name; /**< Name of the class */
+       rte_dev_iterate_t dev_iterate; /**< Device iterator. */
 };
 
 /**

diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
index 963ddeb..d16bc8c 100644 (file)
--- a/lib/librte_eal/common/include/rte_dev.h
+++ b/lib/librte_eal/common/include/rte_dev.h
@@ -283,6 +283,53 @@ __attribute__((used)) = str
 static const char DRV_EXP_TAG(name, kmod_dep_export)[] \
 __attribute__((used)) = str
 
+/**
+ * Iteration context.
+ *
+ * This context carries over the current iteration state.
+ */
+struct rte_dev_iterator {
+       const char *dev_str; /**< device string. */
+       const char *bus_str; /**< bus-related part of device string. */
+       const char *cls_str; /**< class-related part of device string. */
+       struct rte_bus *bus; /**< bus handle. */
+       struct rte_class *cls; /**< class handle. */
+       struct rte_device *device; /**< current position. */
+       void *class_device; /**< additional specialized context. */
+};
+
+/**
+ * Device iteration function.
+ *
+ * Find the next device matching properties passed in parameters.
+ * The function takes an additional ``start`` parameter, that is
+ * used as starting context when relevant.
+ *
+ * The function returns the current element in the iteration.
+ * This return value will potentially be used as a start parameter
+ * in subsequent calls to the function.
+ *
+ * The additional iterator parameter is only there if a specific
+ * implementation needs additional context. It must not be modified by
+ * the iteration function itself.
+ *
+ * @param start
+ *   Starting iteration context.
+ *
+ * @param devstr
+ *   Device description string.
+ *
+ * @param it
+ *   Device iterator.
+ *
+ * @return
+ *   The address of the current element matching the device description
+ *   string.
+ */
+typedef void *(*rte_dev_iterate_t)(const void *start,
+                                  const char *devstr,
+                                  const struct rte_dev_iterator *it);
+
 #ifdef __cplusplus
 }
 #endif