libhardware: add concept of module classes
Needed for things like audio and audio effects. Provides a
new interface to loading modules named 'hw_get_module_by_class'.
This takes two parameters: 'class_id' and 'instance' which are
used to construct the filename for the module to be loaded. If
instance is NULL, then this function acts identically to
hw_get_module where 'class_id' == 'id' (and in fact the latter
implemented exactly this way).
For audio, this new mechanism allows us to load multiple audio
interfaces by doing:
hw_get_module_by_class("audio", "primary", &module);
hw_get_module_by_class("audio", "a2dp", &module);
hw_get_module_by_class("audio", "usb", &module);
...
In the future we will likely want to add the ability to load a set of
module instances based on a config file, which will have a standard
syntax and the mechanism will be provided by libhardware.
Change-Id: I9976cc6d59a85a414b18e7b398a36edfbce4abd8
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/include/hardware/hardware.h b/include/hardware/hardware.h
index d9cc0dc..2251593 100644
--- a/include/hardware/hardware.h
+++ b/include/hardware/hardware.h
@@ -113,10 +113,25 @@
/**
* Get the module info associated with a module by id.
- * @return: 0 == success, <0 == error and *pHmi == NULL
+ *
+ * @return: 0 == success, <0 == error and *module == NULL
*/
int hw_get_module(const char *id, const struct hw_module_t **module);
+/**
+ * Get the module info associated with a module instance by class 'class_id'
+ * and instance 'inst'.
+ *
+ * Some modules types necessitate multiple instances. For example audio supports
+ * multiple concurrent interfaces and thus 'audio' is the module class
+ * and 'primary' or 'a2dp' are module interfaces. This implies that the files
+ * providing these modules would be named audio.primary.<variant>.so and
+ * audio.a2dp.<variant>.so
+ *
+ * @return: 0 == success, <0 == error and *module == NULL
+ */
+int hw_get_module_by_class(const char *class_id, const char *inst,
+ const struct hw_module_t **module);
/**
* pixel format definitions