CRAS: iodev: Add cras_iodev_get_use_case

Allow query of use case from an iodev for reporting metrics and dumping
debug info from cras_test_client. alsa_io implements the callback based
on UCM files. If the callback is NULL, CRAS_USE_CASE_HIFI is returned by
default.

BUG=b:250544745
TEST=Check iodev use cases reported by cras_test_client on Redrix with
the rest of the patch series.

Change-Id: I530a29ce2269703fe3a6edaa94f924075ef02a12
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5170386
Commit-Queue: Ben Zhang <benzh@chromium.org>
Tested-by: chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com <chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com>
Reviewed-by: Curtis Malainey <cujomalainey@chromium.org>

cras/src/server/cras_alsa_io.c

@@ -2126,6 +2126,12 @@ static struct alsa_io_group* create_iodev_group(struct cras_iodev* iodev) {
   return group;
 }
 
+enum CRAS_USE_CASE get_use_case(const struct cras_iodev* iodev) {
+  const struct alsa_io* aio = (const struct alsa_io*)iodev;
+
+  return aio->use_case;
+}
+
 /*
  * Exported Interface.
  */
@@ -2223,6 +2229,7 @@ struct cras_iodev* alsa_iodev_create(
   iodev->get_dev_group = get_dev_group;
   iodev->get_dev_group_id = get_dev_group_id;
   iodev->should_attach_stream = should_attach_stream;
+  iodev->get_use_case = get_use_case;
   iodev->get_htimestamp = cras_alsa_common_get_htimestamp;
 
   iodev->ramp = cras_ramp_create();

cras/src/server/cras_iodev.h

@@ -17,6 +17,7 @@
 #include <stdbool.h>
 #include <time.h>
 
+#include "cras/src/common/cras_types_internal.h"
 #include "cras/src/server/cras_dsp.h"
 #include "cras/src/server/cras_nc.h"
 #include "cras/src/server/ewma_power.h"
@@ -282,6 +283,8 @@ struct cras_iodev {
   // on the iodev's use case and stream parameters.
   int (*should_attach_stream)(const struct cras_iodev* iodev,
                               const struct cras_rstream* stream);
+  // (Optional) Gets the use case of the iodev.
+  enum CRAS_USE_CASE (*get_use_case)(const struct cras_iodev* iodev);
   // (Optional) Obtain the hardware timestamp for the last update
   // The hardware timestamp should be using the MONOTONIC_RAW clock
   // For playback, the timestamp is the last time the iodev wrote into the
@@ -1183,6 +1186,21 @@ static inline int cras_iodev_group_has_dev(const struct cras_iodev* iodev,
   return false;
 }
 
+/* Gets the use case of the iodev. e.g. HiFi, LowLatency.
+ * Args:
+ *    iodev - The device
+ * Returns:
+ *    Use case of the device.
+ */
+static inline enum CRAS_USE_CASE cras_iodev_get_use_case(
+    const struct cras_iodev* iodev) {
+  if (iodev->get_use_case) {
+    return iodev->get_use_case(iodev);
+  }
+
+  return CRAS_USE_CASE_HIFI;
+}
+
 /* Gets the hardware timestamp of the last update. If there is no hardware
  * timestamp, returns the current time as the timestamp.
  * Args: