Audio: Add a NULL audio device that can be used to simply unit-level testing of audio decoders

configs/sama5d4-ek/src/Makefile

@@ -84,6 +84,10 @@ endif
 endif
 endif
 
+ifeq ($(CONFIG_AUDIO_NULL),y)
+CSRCS += sam_audio_null.c
+endif
+
 ifeq ($(CONFIG_SAMA5_HSMCI0),y)
 CSRCS += sam_hsmci.c
 else

configs/sama5d4-ek/src/sam_audio_null.c

@@ -0,0 +1,168 @@
+/************************************************************************************
+ * configs/sama5d4-ek/src/sam_audio_null.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <debug.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <nuttx/audio/audio.h>
+#include <nuttx/audio/pcm.h>
+#include <nuttx/audio/audio_null.h>
+
+#include "sama5d4-ek.h"
+
+#ifdef HAVE_AUDIO_NULL
+
+/****************************************************************************
+ * Pre-Processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sam_audio_null_initialize
+ *
+ * Description:
+ *   Set up to use the NULL audio device for PCM unit-level testing.
+ *
+ * Input Parameters:
+ *   minor - The input device minor number
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int sam_audio_null_initialize(int minor)
+{
+  FAR struct audio_lowerhalf_s *nullaudio;
+  FAR struct audio_lowerhalf_s *pcm;
+  static bool initialized = false;
+  char devname[12];
+  int ret;
+
+  auddbg("minor %d\n", minor);
+  DEBUGASSERT(minor >= 0 && minor <= 25);
+
+  /* Have we already initialized?  Since we never uninitialize we must prevent
+   * multiple initializations.  This is necessary, for example, when the
+   * touchscreen example is used as a built-in application in NSH and can be
+   * called numerous time.  It will attempt to initialize each time.
+   */
+
+  if (!initialized)
+    {
+      /* Get a null audio interface
+       */
+
+      nullaudio = audio_null_initialize();
+      if (!nullaudio)
+        {
+          auddbg("Failed to get the NULL audio interface\n");
+          ret = -ENODEV;
+          goto errout;
+        }
+
+      /* No we can embed the null audio interface into a PCM decoder
+       * instance so that we will have a PCM front end for the NULL
+       * audio driver.
+       */
+
+      pcm = pcm_decode_initialize(nullaudio);
+      if (!pcm)
+        {
+          auddbg("ERROR: Failed create the PCM decoder\n");
+          ret = -ENODEV;
+          goto errout_with_nullaudio;
+        }
+
+      /* Create a device name */
+
+      snprintf(devname, 12, "pcm%d",  minor);
+
+      /* Finally, we can register the PCM/NULL audio device. */
+
+      ret = audio_register(devname, pcm);
+      if (ret < 0)
+        {
+          auddbg("ERROR: Failed to register /dev/%s device: %d\n", devname, ret);
+          goto errout_with_pcm;
+        }
+
+      /* Now we are initialized */
+
+      initialized = true;
+    }
+
+  return OK;
+
+  /* Error exits.  Unfortunately there is no mechanism in place now to
+   * recover resources from most errors on initialization failures.
+   */
+
+errout_with_nullaudio:
+errout_with_pcm:
+errout:
+  return ret;
+}
+
+#endif /* HAVE_AUDIO_NULL */

configs/sama5d4-ek/src/sam_nsh.c

@@ -158,7 +158,7 @@ int nsh_archinitialize(void)
 #endif
 
 #ifdef HAVE_WM8904
-  /* Start the USB Monitor */
+  /* Configure WM8904 audio */
 
   ret = sam_wm8904_initialize(0);
   if (ret != OK)
@@ -167,6 +167,16 @@ int nsh_archinitialize(void)
     }
 #endif
 
+#ifdef HAVE_AUDIO_NULL
+  /* Configure the NULL audio device */
+
+  ret = sam_audio_null_initialize(0);
+  if (ret != OK)
+    {
+      message("ERROR: Failed to initialize the NULL audio device: %d\n", ret);
+    }
+#endif
+
   /* If we got here then perhaps not all initialization was successful, but
    * at least enough succeeded to bring-up NSH with perhaps reduced
    * capabilities.

configs/sama5d4-ek/src/sam_wm8904.c

@@ -334,7 +334,7 @@ int sam_wm8904_initialize(int minor)
   return OK;
 
   /* Error exits.  Unfortunately there is no mechanism in place now to
-   * recover from most errors on initialization failures.
+   * recover resources from most errors on initialization failures.
    */
 
 errout_with_pcm:

configs/sama5d4-ek/src/sama5d4-ek.h

@@ -65,6 +65,7 @@
 #define HAVE_NETWORK    1
 #define HAVE_MAXTOUCH   1
 #define HAVE_WM8904     1
+#define HAVE_AUDIO_NULL 1
 
 /* HSMCI */
 /* Can't support MMC/SD if the card interface(s) are not enable */
@@ -317,7 +318,7 @@
 #endif
 
 /* Audio */
-/* Default configuration values */
+/* PCM/WM8904 driver */
 
 #ifndef CONFIG_AUDIO_WM8904
 #  undef HAVE_WM8904
@@ -351,6 +352,23 @@
 #  endif
 #endif
 
+/* PCM/null driver */
+
+#ifndef CONFIG_AUDIO_NULL
+#  undef HAVE_AUDIO_NULL
+#endif
+
+#ifdef HAVE_WM8904
+#  undef HAVE_AUDIO_NULL
+#endif
+
+#ifdef HAVE_AUDIO_NULL
+#  ifndef CONFIG_AUDIO_FORMAT_PCM
+#    warning CONFIG_AUDIO_FORMAT_PCM is required for audio support
+#    undef HAVE_AUDIO_NULL
+#  endif
+#endif
+
 /* LEDs *****************************************************************************/
 /* There are 3 LEDs on the SAMA5D4-EK:
  *
@@ -925,6 +943,25 @@ int nsh_archinitialize(void);
 int sam_wm8904_initialize(int minor);
 #endif /* HAVE_WM8904 */
 
+/****************************************************************************
+ * Name: sam_audio_null_initialize
+ *
+ * Description:
+ *   Set up to use the NULL audio device for PCM unit-level testing.
+ *
+ * Input Parameters:
+ *   minor - The input device minor number
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+#ifdef HAVE_AUDIO_NULL
+int sam_audio_null_initialize(int minor);
+#endif /* HAVE_AUDIO_NULL */
+
 #endif /* __ASSEMBLY__ */
 #endif /* __CONFIGS_SAMA5D4_EK_SRC_SAMA5D4_EK_H */