SAMV7 WM8904: Leverage WM8904 logic from the SAMA5D4-EK

8 files changed, 761 insertions, 4 deletions

diff --git a/nuttx/configs/sama5d4-ek/src/sama5d4-ek.h b/nuttx/configs/sama5d4-ek/src/sama5d4-ek.h
index 79c068ca3..b9c8a7262 100644
--- a/nuttx/configs/sama5d4-ek/src/sama5d4-ek.h
+++ b/nuttx/configs/sama5d4-ek/src/sama5d4-ek.h
@@ -415,7 +415,7 @@
 
 #  if !defined(CONFIG_SAMA5_PIOE_IRQ)
 #    warning CONFIG_SAMA5_PIOE_IRQ is required for audio support
-#    undef HAVE_HSMCI
+#    undef HAVE_WM8904
 #  endif
 
 #  ifndef CONFIG_AUDIO_FORMAT_PCM
diff --git a/nuttx/configs/samv71-xult/Kconfig b/nuttx/configs/samv71-xult/Kconfig
index b1e2cd175..b6cddcc03 100644
--- a/nuttx/configs/samv71-xult/Kconfig
+++ b/nuttx/configs/samv71-xult/Kconfig
@@ -68,4 +68,30 @@ config SAMV71XULT_HSMCI0_AUTOMOUNT_UDELAY
 
 endif # SAMV71XULT_HSMCI0_AUTOMOUNT
 
+if AUDIO_WM8904
+
+config SAMV71XULT_WM8904_I2CFREQUENCY
+	int "WM8904 I2C Frequency"
+	default 400000
+	range 1 400000
+	---help---
+		This option selects the I2C frequency to use when communicating with
+		the WM8904 device.  The default, 400KHz, is the maximum supported by
+		the WM8904.  If you have problems communicating with the WM8904,
+		then you might want to try lowering this rate.
+
+choice
+	prompt "WM8904 MCLK source"
+	default SAMV71XULT_WM8904_SRCMAIN
+
+config SAMV71XULT_WM8904_SRCMAIN
+	bool "Main Clock (12MHz)"
+
+config SAMV71XULT_WM8904_SRCSCK
+	bool "Slow XTAL (32.768KHz)"
+	select SAMV71XULT_SLOWCLOCK
+
+endchoice # WM8904 MCLK source
+endif # AUDIO_WM8904
+
 endif # ARCH_BOARD_SAMV71_XULT
diff --git a/nuttx/configs/samv71-xult/README.txt b/nuttx/configs/samv71-xult/README.txt
index a6ec3ec1a..d1db40806 100644
--- a/nuttx/configs/samv71-xult/README.txt
+++ b/nuttx/configs/samv71-xult/README.txt
@@ -18,6 +18,7 @@ Contents
   - LEDs and Buttons
   - AT24MAC402 Serial EEPROM
   - Networking
+  - Audio Interface
   - maXTouch Xplained Pro
   - Debugging
   - Configurations
@@ -694,6 +695,27 @@ additional settings.
     CONFIG_NSH_NETINIT_RETRYMSEC=2000     : Configure the network monitor as you like
     CONFIG_NSH_NETINIT_SIGNO=18
 
+Audio Interface
+===============
+
+WM8904 Audio Codec
+------------------
+
+  SAMV71 Interface        WM8904 Interface
+  ---- ------------ ------- ----------------------------------
+  PIO  Usage        Pin     Function
+  ---- ------------ ------- ----------------------------------
+  PA3  TWD0         SDA     I2C control interface, data line
+  PA4  TWCK0        SCLK    I2C control interface, clock line
+  PA10 RD           ADCDAT  Digital audio output (microphone)
+  PB18 PCK2         MCLK    Master clock
+  PB0  TF           LRCLK   Left/right data alignment clock
+  PB1  TK           BCLK    Bit clock, for synchronization
+  PD11 GPIO         IRQ     Audio interrupt
+  PD24 RF           LRCLK   Left/right data alignment clock
+  PD26 TD           DACDAT  Digital audio input (headphone)
+  ---- ------------ ------- ----------------------------------
+
 maXTouch Xplained Pro
 =====================
 
diff --git a/nuttx/configs/samv71-xult/include/board.h b/nuttx/configs/samv71-xult/include/board.h
index 64a07adab..6bcb55252 100644
--- a/nuttx/configs/samv71-xult/include/board.h
+++ b/nuttx/configs/samv71-xult/include/board.h
@@ -329,7 +329,24 @@
  *    There are no alternative pin selections for USART1.
  */
 
-/* SSC
+/* WM8904 Audio Codec
+ *
+ * SAMV71 Interface        WM8904 Interface
+ * ---- ------------ ------- ----------------------------------
+ * PIO  Usage        Pin     Function
+ * ---- ------------ ------- ----------------------------------
+ * PA3  TWD0         SDA     I2C control interface, data line
+ * PA4  TWCK0        SCLK    I2C control interface, clock line
+ * PA10 RD           ADCDAT  Digital audio output (microphone)
+ * PB18 PCK2         MCLK    Master clock
+ * PB0  TF           LRCLK   Left/right data alignment clock
+ * PB1  TK           BCLK    Bit clock, for synchronization
+ * PD11 GPIO         IRQ     Audio interrupt
+ * PD24 RF           LRCLK   Left/right data alignment clock
+ * PD26 TD           DACDAT  Digital audio input (headphone)
+ * ---- ------------ ------- ----------------------------------
+ *
+ * SSC
  *
  * Alternative pin selections are available only for SSC0 TD.
  * On the SAMV71-XULT board, PD26 supports the I2S TD function
diff --git a/nuttx/configs/samv71-xult/src/Makefile b/nuttx/configs/samv71-xult/src/Makefile
index 4e31999d5..0853d3bbe 100644
--- a/nuttx/configs/samv71-xult/src/Makefile
+++ b/nuttx/configs/samv71-xult/src/Makefile
@@ -86,6 +86,18 @@ ifeq ($(CONFIG_USBMSC),y)
 CSRCS += sam_usbmsc.c
 endif
 
+ifeq ($(CONFIG_AUDIO_WM8904),y)
+ifeq ($(CONFIG_SAMA5_TWI0),y)
+ifeq ($(CONFIG_SAMA5_SSC0),y)
+CSRCS += sam_wm8904.c
+endif
+endif
+endif
+
+ifeq ($(CONFIG_AUDIO_NULL),y)
+CSRCS += sam_audio_null.c
+endif
+
 ifeq ($(CONFIG_MTD_CONFIG),y)
 ifeq ($(CONFIG_SAMV7_TWIHS0),y)
 ifeq ($(CONFIG_MTD_AT24XX),y)
diff --git a/nuttx/configs/samv71-xult/src/sam_audio_null.c b/nuttx/configs/samv71-xult/src/sam_audio_null.c
new file mode 100644
index 000000000..49c4d9546
--- /dev/null
+++ b/nuttx/configs/samv71-xult/src/sam_audio_null.c
@@ -0,0 +1,168 @@
+/************************************************************************************
+ * configs/samv71-xult/src/sam_audio_null.c
+ *
+ *   Copyright (C) 2015 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 "samv71-xult.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 */
diff --git a/nuttx/configs/samv71-xult/src/sam_wm8904.c b/nuttx/configs/samv71-xult/src/sam_wm8904.c
new file mode 100644
index 000000000..cd10d72ff
--- /dev/null
+++ b/nuttx/configs/samv71-xult/src/sam_wm8904.c
@@ -0,0 +1,382 @@
+/************************************************************************************
+ * configs/samv71-xult/src/sam_wm8904.c
+ *
+ *   Copyright (C) 2015 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/i2c.h>
+#include <nuttx/audio/i2s.h>
+#include <nuttx/audio/pcm.h>
+#include <nuttx/audio/wm8904.h>
+
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "sam_gpio.h"
+#include "sam_twihs.h"
+#include "sam_ssc.h"
+#include "sam_pck.h"
+
+#include "samv71-xult.h"
+
+#ifdef HAVE_WM8904
+
+/****************************************************************************
+ * Pre-Processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct samv7xult_mwinfo_s
+{
+  /* Standard MW8904 interface */
+
+  struct wm8904_lower_s lower;
+
+  /* Extensions for the samv7xult board */
+
+  wm8904_handler_t handler;
+  FAR void *arg;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* IRQ/PIO access callbacks.  These operations all hidden behind
+ * callbacks to isolate the WM8904 driver from differences in PIO
+ * interrupt handling by varying boards and MCUs.  If possible,
+ * interrupts should be configured on both rising and falling edges
+ * so that contact and loss-of-contact events can be detected.
+ *
+ *   attach  - Attach the WM8904 interrupt handler to the PIO interrupt
+ *   enable  - Enable or disable the PIO interrupt
+ */
+
+static int  wm8904_attach(FAR const struct wm8904_lower_s *lower,
+                          wm8904_handler_t isr, FAR void *arg);
+static bool wm8904_enable(FAR const struct wm8904_lower_s *lower,
+                          bool enable);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* A reference to a structure of this type must be passed to the WM8904
+ * driver.  This structure provides information about the configuration
+ * of the WM8904 and provides some board-specific hooks.
+ *
+ * Memory for this structure is provided by the caller.  It is not copied
+ * by the driver and is presumed to persist while the driver is active.
+ */
+
+static struct samv7xult_mwinfo_s g_wm8904info =
+{
+  .lower =
+  {
+    .address   = WM8904_I2C_ADDRESS,
+    .frequency = CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY,
+#ifdef CONFIG_SAMV7D4EK_WM8904_SRCSCK
+    .mclk      = BOARD_SLOWCLK_FREQUENCY,
+#else
+    .mclk      = BOARD_MAINCK_FREQUENCY,
+#endif
+
+    .attach    = wm8904_attach,
+    .enable    = wm8904_enable,
+  },
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * IRQ/PIO access callbacks.  These operations all hidden behind
+ * callbacks to isolate the WM8904 driver from differences in PIO
+ * interrupt handling by varying boards and MCUs.  If possible,
+ * interrupts should be configured on both rising and falling edges
+ * so that contact and loss-of-contact events can be detected.
+ *
+ *   attach  - Attach the WM8904 interrupt handler to the PIO interrupt
+ *   enable  - Enable or disable the PIO interrupt
+ *   clear   - Acknowledge/clear any pending PIO interrupt
+ *
+ ****************************************************************************/
+
+static int wm8904_attach(FAR const struct wm8904_lower_s *lower,
+                         wm8904_handler_t isr,  FAR void *arg)
+{
+  if (isr)
+    {
+      /* Just save the address of the handler and its argument for now.  The
+       * new handler will called via wm8904_interrupt() when the interrupt occurs.
+       */
+
+      audvdbg("Attaching %p\n", isr);
+      g_wm8904info.handler = isr;
+      g_wm8904info.arg = arg;
+    }
+  else
+    {
+      audvdbg("Detaching %p\n", g_wm8904info.handler);
+      (void)wm8904_enable(lower, false);
+      g_wm8904info.handler = NULL;
+      g_wm8904info.arg = NULL;
+    }
+
+  return OK;
+}
+
+static bool wm8904_enable(FAR const struct wm8904_lower_s *lower, bool enable)
+{
+  static bool enabled;
+  irqstate_t flags;
+  bool ret;
+
+  /* Has the interrupt state changed */
+
+  flags = irqsave();
+  if (enable != enabled)
+    {
+      /* Enable or disable interrupts */
+
+      if (enable && g_wm8904info.handler)
+        {
+          audvdbg("Enabling\n");
+          sam_gpioirqenable(IRQ_INT_WM8904);
+          enabled = true;
+        }
+      else
+        {
+          audvdbg("Disabling\n");
+          sam_gpioirqdisable(IRQ_INT_WM8904);
+          enabled = false;
+        }
+    }
+
+  ret = enabled;
+  irqrestore(flags);
+  return ret;
+}
+
+static int wm8904_interrupt(int irq, FAR void *context)
+{
+  /* Just forward the interrupt to the WM8904 driver */
+
+  audvdbg("handler %p\n", g_wm8904info.handler);
+  if (g_wm8904info.handler)
+    {
+      return g_wm8904info.handler(&g_wm8904info.lower, g_wm8904info.arg);
+    }
+
+  /* We got an interrupt with no handler.  This should not
+   * happen.
+   */
+
+  sam_gpioirqdisable(IRQ_INT_WM8904);
+  return OK;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sam_wm8904_initialize
+ *
+ * Description:
+ *   This function is called by platform-specific, setup logic to configure
+ *   and register the WM8904 device.  This function will register the driver
+ *   as /dev/wm8904[x] where x is determined by the minor device number.
+ *
+ * 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_wm8904_initialize(int minor)
+{
+  FAR struct audio_lowerhalf_s *wm8904;
+  FAR struct audio_lowerhalf_s *pcm;
+  FAR struct i2c_dev_s *i2c;
+  FAR struct i2s_dev_s *i2s;
+  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)
+    {
+      /* Configure the WM8904 interrupt pin */
+
+      (void)sam_configgpio(GPIO_INT_WM8904);
+
+      /* Get an instance of the I2C interface for the WM8904 chip select */
+
+      i2c = up_i2cinitialize(WM8904_TWI_BUS);
+      if (!i2c)
+        {
+          auddbg("Failed to initialize TWI%d\n", WM8904_TWI_BUS);
+          ret = -ENODEV;
+          goto errout;
+        }
+
+      /* Get an instance of the I2S interface for the WM8904 data channel */
+
+      i2s = sam_ssc_initialize(WM8904_SSC_BUS);
+      if (!i2s)
+        {
+          auddbg("Failed to initialize SSC%d\n", WM8904_SSC_BUS);
+          ret = -ENODEV;
+          goto errout_with_i2c;
+        }
+
+      /* Configure the DAC master clock.  This clock is provided by PCK2 (PB10)
+       * that is connected to the WM8904 MCLK.
+       */
+
+#ifdef CONFIG_SAMV7D4EK_WM8904_SRCSCK
+      /* Drive the DAC with the slow clock (32.768 KHz).  The slow clock was
+       * enabled in sam_boot.c if needed.
+       */
+
+      (void)sam_pck_configure(PCK2, PCKSRC_SCK, BOARD_SLOWCLK_FREQUENCY);
+#else
+      /* Drive the DAC with the main clock (12 MHz) */
+
+      (void)sam_pck_configure(PCK2, PCKSRC_MAINCK, BOARD_MAINCK_FREQUENCY);
+#endif
+
+      /* Enable the DAC master clock */
+
+      sam_pck_enable(PCK2, true);
+
+      /* Configure WM8904 interrupts */
+
+      sam_gpioirq(GPIO_INT_WM8904);
+      ret = irq_attach(IRQ_INT_WM8904, wm8904_interrupt);
+      if (ret < 0)
+        {
+          auddbg("ERROR: Failed to attach WM8904 interrupt: %d\n", ret);
+          goto errout_with_i2s;
+        }
+
+      /* Now we can use these I2C and I2S interfaces to initialize the
+       * MW8904 which will return an audio interface.
+       */
+
+      wm8904 = wm8904_initialize(i2c, i2s, &g_wm8904info.lower);
+      if (!wm8904)
+        {
+          auddbg("Failed to initialize the WM8904\n");
+          ret = -ENODEV;
+          goto errout_with_irq;
+        }
+
+      /* No we can embed the WM8904/I2C/I2S conglomerate into a PCM decoder
+       * instance so that we will have a PCM front end for the the WM8904
+       * driver.
+       */
+
+      pcm = pcm_decode_initialize(wm8904);
+      if (!pcm)
+        {
+          auddbg("ERROR: Failed create the PCM decoder\n");
+          ret = -ENODEV;
+          goto errout_with_wm8904;
+        }
+
+      /* Create a device name */
+
+      snprintf(devname, 12, "pcm%d",  minor);
+
+      /* Finally, we can register the PCM/WM8904/I2C/I2S audio device.
+       *
+       * Is anyone young enough to remember Rube Goldberg?
+       */
+
+      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_pcm:
+errout_with_wm8904:
+errout_with_irq:
+  irq_detach(IRQ_INT_WM8904);
+errout_with_i2s:
+errout_with_i2c:
+errout:
+  return ret;
+}
+
+#endif /* HAVE_WM8904 */
diff --git a/nuttx/configs/samv71-xult/src/samv71-xult.h b/nuttx/configs/samv71-xult/src/samv71-xult.h
index 51b71a9d2..43a5ba635 100644
--- a/nuttx/configs/samv71-xult/src/samv71-xult.h
+++ b/nuttx/configs/samv71-xult/src/samv71-xult.h
@@ -61,6 +61,8 @@
 #define HAVE_NETWORK     1
 #define HAVE_MACADDR     1
 #define HAVE_MTDCONFIG   1
+#define HAVE_WM8904      1
+#define HAVE_AUDIO_NULL  1
 
 /* HSMCI */
 /* Can't support MMC/SD if the card interface is not enabled */
@@ -179,6 +181,63 @@
 #  undef HAVE_MTDCONFIG
 #endif
 
+/* Audio */
+/* PCM/WM8904 driver */
+
+#ifndef CONFIG_AUDIO_WM8904
+#  undef HAVE_WM8904
+#endif
+
+#ifdef HAVE_WM8904
+#  ifndef CONFIG_SAMV7_TWI0
+#    warning CONFIG_SAMV7_TWI0 is required for audio support
+#    undef HAVE_WM8904
+#  endif
+
+#  ifndef CONFIG_SAMV7_SSC0
+#    warning CONFIG_SAMV7_SSC0 is required for audio support
+#    undef HAVE_WM8904
+#  endif
+
+#  if !defined(CONFIG_SAMV7_PIOD_IRQ)
+#    warning CONFIG_SAMV7_PIOD_IRQ is required for audio support
+#    undef HAVE_WM8904
+#  endif
+
+#  ifndef CONFIG_AUDIO_FORMAT_PCM
+#    warning CONFIG_AUDIO_FORMAT_PCM is required for audio support
+#    undef HAVE_WM8904
+#  endif
+
+#  ifndef CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY
+#    warning Defaulting to maximum WM8904 I2C frequency
+#    define CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY 400000
+#  endif
+
+#  if CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY > 400000
+#    warning WM8904 I2C frequency cannot exceed 400KHz
+#    undef CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY
+#    define CONFIG_SAMV7D4EK_WM8904_I2CFREQUENCY 400000
+#  endif
+#endif
+
+/* PCM/null driver */
+
+#ifndef CONFIG_AUDIO_NULL
+#  undef HAVE_AUDIO_NULL
+#endif
+
+#ifndef 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
+
 /* SAMV71-XULT GPIO Pin Definitions *************************************************/
 
 /* Ethernet MAC.
@@ -304,10 +363,41 @@
 #define GPIO_VBUSON (GPIO_OUTPUT | GPIO_CFG_DEFAULT | GPIO_OUTPUT_SET | \
                      GPIO_PORT_PIOC | GPIO_PIN16)
 
-/* SPI Chip Selects
- * to be provided
+/* WM8904 Audio Codec ***************************************************************/
+/* SAMV71 Interface        WM8904 Interface
+ * ---- ------------ ------- ----------------------------------
+ * PIO  Usage        Pin     Function
+ * ---- ------------ ------- ----------------------------------
+ * PA3  TWD0         SDA     I2C control interface, data line
+ * PA4  TWCK0        SCLK    I2C control interface, clock line
+ * PA10 RD           ADCDAT  Digital audio output (microphone)
+ * PB18 PCK2         MCLK    Master clock
+ * PB0  TF           LRCLK   Left/right data alignment clock
+ * PB1  TK           BCLK    Bit clock, for synchronization
+ * PD11 GPIO         IRQ     Audio interrupt
+ * PD24 RF           LRCLK   Left/right data alignment clock
+ * PD26 TD           DACDAT  Digital audio input (headphone)
+ * ---- ------------ ------- ----------------------------------
+ */
+
+/* Audio Interrupt. All interrupts are default, active high level.  Pull down
+ * internally in the WM8904.  So we want no pull-up/downs and we want to
+ * interrupt on the high level.
  */
 
+#define GPIO_INT_WM8904    (PIO_INPUT | PIO_CFG_DEFAULT | PIO_CFG_DEGLITCH | \
+                            PIO_INT_HIGHLEVEL | PIO_PORT_PIOD | PIO_PIN11)
+#define IRQ_INT_WM8904     SAM_IRQ_PD11
+
+/* The MW8904 communicates on TWI0, I2C address 0x1a for control operations */
+
+#define WM8904_TWI_BUS     0
+#define WM8904_I2C_ADDRESS 0x1a
+
+/* The MW8904 transfers data on SSC0 */
+
+#define WM8904_SSC_BUS     0
+
 /************************************************************************************
  * Public Types
  ************************************************************************************/
@@ -519,5 +609,45 @@ bool sam_writeprotected(int slotno);
 int sam_at24config(void);
 #endif
 
+/****************************************************************************
+ * Name: sam_wm8904_initialize
+ *
+ * Description:
+ *   This function is called by platform-specific, setup logic to configure
+ *   and register the WM8904 device.  This function will register the driver
+ *   as /dev/wm8904[x] where x is determined by the minor device number.
+ *
+ * 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_WM8904
+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_SAMV71_XULT_SRC_SAMV71_XULT_H */