doc: Add object core documentation

Adds documentation for both object cores and object core statistics.

Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>

doc/kernel/index.rst

@@ -12,6 +12,7 @@ Kernel
    memory_management/index.rst
    data_structures/index.rst
    timing_functions/index.rst
+   object_cores/index.rst
    timeutil.rst
    util/index.rst
    iterable_sections/index.rst

doc/kernel/object_cores/index.rst

@@ -0,0 +1,234 @@
+.. _object_cores_api:
+
+Object Cores
+############
+
+Object cores are a kernel debugging tool that can be used to both identify and
+perform operations on registered objects.
+
+.. contents::
+    :local:
+    :depth: 2
+
+Object Core Concepts
+********************
+
+Each instance of an object has embedded within it an object core field named
+`obj_core`. Objects of the same type are linked together via their respective
+object cores to form a singly linked list. Each object core also links to the
+their respective object type. Each object type contains a singly linked list
+linking together all the object cores of that type. Object types are also
+linked together via a singly linked list. Together, this can allow debugging
+tools to traverse all the objects in the system.
+
+Object cores have been integrated into following kernel objects:
+ * Condition Variables
+ * Events
+ * FIFOs and LIFOs
+ * Mailboxes
+ * Memory Slabs
+ * Message Queues
+ * Mutexes
+ * Pipes
+ * Semaphores
+ * Timers
+ * System Memory Blocks
+
+Developers are free to integrate them if desired into other objects within
+their projects.
+
+Object Core Statistics Concepts
+*******************************
+A variety of kernel objects allow for the gathering and reporting of statistics.
+Object cores provide a uniform means to retrieve that information via object
+core statistics. When enabled, the object type contains a pointer to a
+statistics descriptor that defines the various operations that have been
+enabled for interfacing with the object's statistics. Additionally, the object
+core contains a pointer to the "raw" statistical information associated with
+that object. Raw data is the raw, unmanipulated data associated with the
+statistics. Queried data may be "raw", but it may also have been manipulated in
+some way by calculation (such as determining an average).
+
+Object core statistics have been integrated into the following kernel objects:
+The following table indicates both what objects have been integrated into the
+object core statistics as well as the structures used for both "raw" and
+"queried" data.
+
+=====================  ============================== ==============================
+Object                 Raw Data Type                  Query Data Type
+=====================  ============================== ==============================
+struct mem_slab        struct mem_slab_info            struct sys_memory_stats
+struct sys_mem_blocks  struct sys_mem_blocks_info      struct sys_memory_stats
+struct k_thread        struct k_cycle_stats            struct k_thread_runtime_stats
+struct _cpu            struct k_cycle_stats            struct k_thread_runtime_stats
+struct z_kernel        struct k_cycle_stats[num CPUs]  struct k_thread_runtime_stats
+=====================  ============================== ==============================
+
+Implementation
+**************
+
+Defining a New Object Type
+==========================
+
+An object type is defined using a global variable of type
+:c:struct:`k_obj_type`. It must be initialized before any objects of that type
+are initialized. The following code shows how a new object type can be
+initialized for use with object cores and object core statistics.
+
+.. code-block:: c
+
+    /* Unique object type ID */
+
+    #define K_OBJ_TYPE_MY_NEW_TYPE  K_OBJ_TYPE_ID_GEN("UNIQ")
+    struct k_obj_type  my_obj_type;
+
+    struct my_obj_type_raw_info {
+        ...
+    };
+
+    struct my_obj_type_query_stats {
+        ...
+    };
+
+    struct my_new_obj {
+        ...
+        struct k_obj_core obj_core;
+        struct my_obj_type_raw_info  info;
+    };
+
+    struct k_obj_core_stats_desc my_obj_type_stats_desc = {
+        .raw_size = sizeof(struct my_obj_type_raw_stats),
+        .query_size = sizeof(struct my_obj_type_query_stats),
+        .raw = my_obj_type_stats_raw,
+        .query = my_obj_type_stats_query,
+        .reset = my_obj_type_stats_reset,
+        .disable = NULL,    /* Stats gathering is always on */
+        .enable = NULL,     /* Stats gathering is always on */
+    };
+
+    void my_obj_type_init(void)
+    {
+        z_obj_type_init(&my_obj_type, K_OBJ_TYPE_MY_NEW_TYPE,
+                        offsetof(struct my_new_type, obj_core);
+        k_obj_type_stats_init(&my_obj_type, &my_obj_type_stats_desc);
+    }
+
+Initializing a New Object Core
+==============================
+
+Kernel objects that have already been integrated into the object core framework
+automatically have their object cores initialized when the object is
+initialized. However, developers that wish to add their own objects into the
+framework need to both initialize the object core and link it. The following
+code builds on the example above and initializes the object core.
+
+.. code-block:: c
+
+    void my_new_obj_init(struct my_new_obj *new_obj)
+    {
+        ...
+        k_obj_core_init(K_OBJ_CORE(new_obj), &my_obj_type);
+        k_obj_core_link(K_OBJ_CORE(new_obj));
+        k_obj_core_stats_register(K_OBJ_CORE(new_obj), &new_obj->raw_stats,
+                                  sizeof(struct my_obj_type_raw_info));
+    }
+
+Walking a List of Object Cores
+==============================
+
+Two routines exist for walking the list of object cores linked to an object
+type. These are :c:func:`k_obj_type_walk_locked` and
+:c:func:`k_obj_type_walk_unlocked`. The following code builds upon the example
+above and prints the addresses of all the objects of that new object type.
+
+.. code-block:: c
+
+    int walk_op(struct k_obj_core *obj_core, void *data)
+    {
+        uint8_t *ptr;
+
+        ptr = obj_core;
+        ptr -= obj_core->type->obj_core_offset;
+
+        printk("%p\n", ptr);
+
+        return 0;
+    }
+
+    void print_object_addresses(void)
+    {
+        struct k_obj_type *obj_type;
+
+        /* Find the object type */
+
+        obj_type = k_obj_type_find(K_OBJ_TYPE_MY_NEW_TYPE);
+
+        /* Walk the list of objects */
+
+        k_obj_type_walk_unlocked(obj_type, walk_op, NULL);
+    }
+
+Object Core Statistics Querying
+===============================
+
+The following code builds on the examples above and shows how an object
+integrated into the object core statistics framework can both retrieve queried
+data and reset the stats associated with the object.
+
+.. code-block:: c
+
+    struct my_new_obj my_obj;
+
+    ...
+
+    void my_func(void)
+    {
+        struct my_obj_type_query_stats  my_stats;
+        int  status;
+
+        my_obj_type_init(&my_obj);
+
+        ...
+
+        status = k_obj_core_stats_query(K_OBJ_CORE(&my_obj),
+                                        &my_stats, sizeof(my_stats));
+        if (status != 0) {
+            /* Failed to get stats */
+            ...
+        } else {
+            k_obj_core_stats_reset(K_OBJ_CORE(&my_obj));
+        }
+
+        ...
+    }
+
+Configuration Options
+*********************
+
+Related configuration options:
+
+* :kconfig:option:`CONFIG_OBJ_CORE`
+* :kconfig:option:`CONFIG_OBJ_CORE_CONDVAR`
+* :kconfig:option:`CONFIG_OBJ_CORE_EVENT`
+* :kconfig:option:`CONFIG_OBJ_CORE_FIFO`
+* :kconfig:option:`CONFIG_OBJ_CORE_LIFO`
+* :kconfig:option:`CONFIG_OBJ_CORE_MAILBOX`
+* :kconfig:option:`CONFIG_OBJ_CORE_MEM_SLAB`
+* :kconfig:option:`CONFIG_OBJ_CORE_MSGQ`
+* :kconfig:option:`CONFIG_OBJ_CORE_MUTEX`
+* :kconfig:option:`CONFIG_OBJ_CORE_PIPE`
+* :kconfig:option:`CONFIG_OBJ_CORE_SEM`
+* :kconfig:option:`CONFIG_OBJ_CORE_STACK`
+* :kconfig:option:`CONFIG_OBJ_CORE_TIMER`
+* :kconfig:option:`CONFIG_OBJ_CORE_SYS_MEM_BLOCKS`
+* :kconfig:option:`CONFIG_OBJ_CORE_STATS`
+* :kconfig:option:`CONFIG_OBJ_CORE_STATS_MEM_SLAB`
+* :kconfig:option:`CONFIG_OBJ_CORE_STATS_THREAD`
+* :kconfig:option:`CONFIG_OBJ_CORE_STATS_SYSTEM`
+* :kconfig:option:`CONFIG_OBJ_CORE_STATS_SYS_MEM_BLOCKS`
+
+API Reference
+*************
+
+.. doxygengroup:: obj_core_apis
+.. doxygengroup:: obj_core_stats_apis