Framework for a WM8904 audio driver. The initial driver check-in is simply Ken Pettit's VS1053 driver forced to compile with only WM8904 definitions

drivers/audio/Kconfig

@@ -82,3 +82,25 @@ config VS1053_BUFFER_SIZE
 endif # AUDIO_DRIVER_SPECIFIC_BUFFERS
 
 endif # VS1053
+
+config AUDIO_WM8904
+	bool "WM8904 audio chip"
+	default n
+	depends on EXPERIMENTAL
+	---help---
+		Select to enable support for the WM8904 Audio codec by Wolfson
+		Microelectonics.  This chip is a lower level audio chip.. basically
+		an exotic D-to-A.  It includes no builtin support for audion CODECS
+		The WM8904 provides:
+
+			- Low power consumption
+			- High SNR
+			- Stereo digital microphone input
+			- Digital Dynamic Range Controller (compressor / limiter)
+			- Digital sidetone mixing
+			- Ground-referenced headphone driver
+			- Ground-referenced line outputs
+
+if AUDIO_WM8904
+endif # AUDIO_WM8904
+

drivers/audio/Make.defs

@@ -37,12 +37,16 @@
 
 # Include Audio drivers
 
-ifeq ($(CONFIG_AUDIO),y)
+ifeq ($(CONFIG_AUDIO_DEVICES),y)
 
 ifeq ($(CONFIG_VS1053),y)
 CSRCS += vs1053.c
 endif
 
+ifeq ($(CONFIG_AUDIO_WM8904),y)
+CSRCS += wm8904.c
+endif
+
 ifeq ($(CONFIG_AUDIO_I2SCHAR),y)
 CSRCS += i2schar.c
 endif

drivers/audio/wm8904.h

@@ -60,8 +60,8 @@
 #define WM8904_SWRST_ID              0x00 /* SW Reset and ID */
 #define WM8904_BIAS_CTRL             0x04 /* Bias Control */
 #define WM8904_VMID_CTRL             0x05 /* VMID Control */
-#define WM8904_MIC_BIAS_CTRL         0x06 /* Mic Bias Control */
+#define WM8904_MIC_BIAS_CTRL0        0x06 /* Mic Bias Control 0 */
-#define WM8904_MIC_BIAS_CTRL         0x07 /* Mic Bias Control */
+#define WM8904_MIC_BIAS_CTRL1        0x07 /* Mic Bias Control 1 */
 #define WM8904_ANALOG_ADC            0x0a /* Analogue ADC */
 #define WM8904_PM0                   0x0c /* Power Management 0 */
 #define WM8904_PM2                   0x0e /* Power Management 2 */
@@ -181,7 +181,7 @@
 #  define WM8904_VMID_RES_FASTSTART  (3 << WM8904_VMID_RES_SHIFT) /* 2 x 5k divider */
 #define WM8904_VMID_ENA              (1 << 0)  /* Bit 0:  VMID buffer enable */
 
-/* 0x06 Mic Bias Control */
+/* 0x06 Mic Bias Control 0 */
 
 #define WM8904_MICDET_THR_SHIFT      (4)       /* Bits 4-6: MICBIAS current detect threshold */
 #define WM8904_MICDET_THR_MASK       (7 << WM8904_MICDET_THR_SHIFT)
@@ -192,7 +192,7 @@
 #define WM8904_MICDET_ENA            (1 << 1)  /* Bit 1:  MICBIAS current/short circuit detect enable */
 #define WM8904_MICBIAS_ENA           (1 << 0)  /* Bit 0:  MICBIAS enable */
 
-/* 0x07 Mic Bias Control */
+/* 0x07 Mic Bias Control 1 */
 
 #define WM8904_MICBIAS_SEL_MASK      (0x0007)  /* Bits 0-2: Selects MICBIAS voltage */
 
@@ -264,7 +264,7 @@
 /* 0x18 Audio Interface 0 */
 
 #define WM8904_DACL_DATINV           (1 << 12) /* Bit 12: Left DAC invert */
-#define WM8904_DACR_DATINV           (1 << 11) /* Bit 11: Right DAC invert* /
+#define WM8904_DACR_DATINV           (1 << 11) /* Bit 11: Right DAC invert */
 #define WM8904_DAC_BOOST_SHIFT       (9)       /* Bits 9-10: DAC digital input volume boost */
 #define WM8904_DAC_BOOST_MASK        (3 << WM8904_DAC_BOOST_SHIFT)
 #  define WM8904_DAC_BOOST_0DB       (0 << WM8904_DAC_BOOST_SHIFT)

include/nuttx/audio/i2s.h

@@ -177,7 +177,7 @@
  *              performed in the context of the worker thread.
  *   arg      - An opaque argument that will be provided to the callback
  *              when the transfer complete.
- *   timeout  - The timeout value to use.  The transfer will be canceled
+ *   timeout  - The timeout value to use.  The transfer will be cancelled
  *              and an ETIMEDOUT error will be reported if this timeout
  *              elapsed without completion of the DMA transfer.  Units
  *              are system clock ticks.  Zero means no timeout.

include/nuttx/audio/wm8904.h

@@ -61,8 +61,24 @@
 
 /* Pre-requisistes */
 
+#ifndef CONFIG_AUDIO
+#  error CONFIG_AUDIO is required for audio subsystem support
+#endif
+
+#ifndef CONFIG_I2S
+#  error CONFIG_I2S is required by the WM8904 driver
+#endif
+
+#ifndef CONFIG_I2C
+#  error CONFIG_I2C is required by the WM8904 driver
+#endif
+
 #ifndef CONFIG_I2C_TRANSFER
-#  error "CONFIG_I2C_TRANSFER is required in the I2C configuration"
+#  error CONFIG_I2C_TRANSFER is required in the I2C configuration
+#endif
+
+#ifndef CONFIG_SCHED_WORKQUEUE
+#  error CONFIG_SCHED_WORKQUEUE is required by the WM8904 driver
 #endif
 
 /* Default configuration values */
@@ -73,7 +89,6 @@
 #define WM8904_DETACH(s)         ((s)->attach(s,NULL,NULL))
 #define WM8904_ENABLE(s)         ((s)->enable(s,true))
 #define WM8904_DISABLE(s)        ((s)->enable(s,false))
-#define WM8904_CLEAR(s)          ((s)->clear(s))
 
 /****************************************************************************
  * Public Types
@@ -109,15 +124,14 @@ struct wm8904_lower_s
    * 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 GPIO interrupt
+   * attach  - Attach or detacth the WM8904 interrupt handler to the GPIO
+   *           interrupt
    * enable  - Enable or disable the GPIO interrupt
-   * clear   - Acknowledge/clear any pending GPIO interrupt
    */
 
   int  (*attach)(FAR const struct wm8904_lower_s *lower, wm8904_handler_t isr,
                  FAR void *arg);
   void (*enable)(FAR const struct wm8904_lower_s *lower, bool enable);
-  void (*clear)(FAR const struct wm8904_lower_s *lower);
 };
 
 /****************************************************************************
@@ -137,7 +151,7 @@ extern "C"
  ****************************************************************************/
 
 /****************************************************************************
- * Name: wm8904_register
+ * Name: wm8904_initialize
  *
  * Description:
  *   Initialize the WM8904 device.