xtensa/esp32s2: add initial support for I2S

Add initial support for the I2S peripheral on ESP32S2.
Add I2S character driver and generic I2S audio driver.
Include i2schar defconfig for ESP32-S2-Saola-1 board.

arch/xtensa/src/esp32s2/Kconfig

@@ -205,7 +205,7 @@ choice ESP32S2_FLASH_FREQ
 	default ESP32S2_FLASH_FREQ_40M
 	---help---
 		SPI FLASH frequency
-		
+
 	config ESP32S2_FLASH_FREQ_80M
 	bool "80 MHz"
 
@@ -256,6 +256,126 @@ config ESP32S2_RNG
 	---help---
 		ESP32-S2 supports a RNG that passed on Dieharder test suite.
 
+config ESP32S2_I2S
+	bool "I2S"
+	default n
+	select I2S
+	select ARCH_DMA
+	select ESP32S2_GPIO_IRQ
+	---help---
+		See the Board Selection menu to configure the pins used by I2S.
+
+if ESP32S2_I2S
+
+config ESP32S2_I2S_RX
+	bool "Enable I2S receiver"
+	default y
+	---help---
+		Enable I2S receive logic
+
+config ESP32S2_I2S_TX
+	bool "Enable I2S transmitter"
+	default y
+	---help---
+		Enable I2S transmit logic
+
+choice
+	prompt "I2S role"
+	default ESP32S2_I2S_ROLE_MASTER
+	---help---
+		Selects the operation role of the I2S.
+
+config ESP32S2_I2S_ROLE_MASTER
+	bool "Master"
+
+config ESP32S2_I2S_ROLE_SLAVE
+	bool "Slave"
+
+endchoice
+
+choice
+	prompt "Bit width"
+	---help---
+		Selects the valid data bits per sample.
+		Note that this option may be overwritten by the audio
+		according to the bit width of the file being played
+
+config ESP32S2_I2S_DATA_BIT_WIDTH_8BIT
+	bool "8 bits"
+
+config ESP32S2_I2S_DATA_BIT_WIDTH_16BIT
+	bool "16 bits"
+
+config ESP32S2_I2S_DATA_BIT_WIDTH_24BIT
+	bool "24 bits"
+
+config ESP32S2_I2S_DATA_BIT_WIDTH_32BIT
+	bool "32 bits"
+
+endchoice
+
+config ESP32S2_I2S_DATA_BIT_WIDTH
+	int
+	default 8 if ESP32S2_I2S_DATA_BIT_WIDTH_8BIT
+	default 16 if ESP32S2_I2S_DATA_BIT_WIDTH_16BIT
+	default 24 if ESP32S2_I2S_DATA_BIT_WIDTH_24BIT
+	default 32 if ESP32S2_I2S_DATA_BIT_WIDTH_32BIT
+
+config ESP32S2_I2S_SAMPLE_RATE
+	int "I2S sample rate"
+	default 44100
+	range 8000 48000
+	---help---
+		Selects the sample rate.
+		Note that this option may be overwritten by the audio
+		according to the bit width of the file being played
+
+config ESP32S2_I2S_BCLKPIN
+	int "I2S BCLK pin"
+	default 35
+	range 0 45 if ESP32S2_I2S_ROLE_MASTER
+	range 0 46 if ESP32S2_I2S_ROLE_SLAVE
+
+config ESP32S2_I2S_WSPIN
+	int "I2S WS pin"
+	default 34
+	range 0 45 if ESP32S2_I2S_ROLE_MASTER
+	range 0 46 if ESP32S2_I2S_ROLE_SLAVE
+
+config ESP32S2_I2S_DINPIN
+	int "I2S DOUT pin"
+	depends on ESP32S2_I2S_RX
+	default 37
+	range 0 46
+
+config ESP32S2_I2S_DOUTPIN
+	int "I2S DOUT pin"
+	depends on ESP32S2_I2S_TX
+	default 36
+	range 0 45
+
+config ESP32S2_I2S_MCLK
+	bool "Enable I2S Master Clock"
+	depends on ESP32S2_I2S_ROLE_MASTER
+	default n
+	---help---
+		Enable I2S master clock
+
+config ESP32S2_I2S_MCLKPIN
+	int "I2S MCLK pin"
+	depends on ESP32S2_I2S_MCLK
+	default 33
+	range 0 45
+
+config I2S_DMADESC_NUM
+	int "I2S DMA maximum number of descriptors"
+	default 2
+	---help---
+		Configure the maximum number of out-link/in-link descriptors to
+		be chained for a I2S DMA transfer.
+
+endif #ESP32S2_I2S
+
 config ESP32S2_SPI2
 	bool "SPI 2"
 	default n

arch/xtensa/src/esp32s2/Make.defs

@@ -30,6 +30,7 @@ HEAD_CSRC  = esp32s2_start.c esp32s2_wdt.c
 CHIP_CSRCS  = esp32s2_allocateheap.c esp32s2_clockconfig.c esp32s2_irq.c
 CHIP_CSRCS += esp32s2_gpio.c esp32s2_region.c esp32s2_user.c
 CHIP_CSRCS += esp32s2_timerisr.c esp32s2_lowputc.c esp32s2_systemreset.c
+CHIP_CSRCS += esp32s2_dma.c
 
 # Configuration-dependent ESP32-S2 files
 
@@ -49,6 +50,10 @@ ifeq ($(CONFIG_ESP32S2_I2C),y)
 CHIP_CSRCS += esp32s2_i2c.c
 endif
 
+ifeq ($(CONFIG_ESP32S2_I2S),y)
+CHIP_CSRCS += esp32s2_i2s.c
+endif
+
 ifeq ($(CONFIG_ESP32S2_SPI),y)
 CHIP_CSRCS += esp32s2_spi.c
 endif

arch/xtensa/src/esp32s2/esp32s2_dma.c

@@ -0,0 +1,186 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32s2/esp32s2_dma.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <assert.h>
+#include <sys/types.h>
+
+#include "hardware/esp32s2_dma.h"
+#include "esp32s2_dma.h"
+
+/****************************************************************************
+ * Preprocessor Definitions
+ ****************************************************************************/
+
+#ifndef MIN
+#  define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef ALIGN_UP
+#  define ALIGN_UP(num, align) (((num) + ((align) - 1)) & ~((align) - 1))
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: esp32s2_dma_init
+ *
+ * Description:
+ *   Initialize DMA outlink descriptors and bind the target buffer to
+ *   these DMA descriptors.
+ *
+ * Input Parameters:
+ *   dmadesc - Pointer to the DMA descriptors
+ *   num     - Number of DMA descriptors
+ *   pbuf    - RX/TX buffer pointer
+ *   len     - RX/TX buffer length
+ *
+ * Returned Value:
+ *   Bound pbuf data bytes
+ *
+ ****************************************************************************/
+
+uint32_t esp32s2_dma_init(struct esp32s2_dmadesc_s *dmadesc, uint32_t num,
+                          uint8_t *pbuf, uint32_t len)
+{
+  int i;
+  uint32_t bytes = len;
+  uint8_t *pdata = pbuf;
+  uint32_t data_len;
+  uint32_t buf_len;
+
+  DEBUGASSERT(dmadesc != NULL);
+  DEBUGASSERT(pbuf != NULL);
+  DEBUGASSERT(len > 0);
+
+  for (i = 0; i < num; i++)
+    {
+      data_len = MIN(bytes, ESP32S2_DMA_DATALEN_MAX);
+
+      /* Buffer length must be rounded to next 32-bit boundary. */
+
+      buf_len = ALIGN_UP(data_len, sizeof(uintptr_t));
+
+      dmadesc[i].ctrl = (data_len << DMA_CTRL_DATALEN_S) |
+                        (buf_len << DMA_CTRL_BUFLEN_S) |
+                        DMA_CTRL_OWN;
+      dmadesc[i].pbuf = pdata;
+      dmadesc[i].next = &dmadesc[i + 1];
+
+      bytes -= data_len;
+      if (bytes == 0)
+        {
+          break;
+        }
+
+      pdata += data_len;
+    }
+
+  dmadesc[i].ctrl |= DMA_CTRL_EOF;
+  dmadesc[i].next  = NULL;
+
+  return len - bytes;
+}
+
+/****************************************************************************
+ * Name: esp32s2_dma_init_with_padding
+ *
+ * Description:
+ *   Initialize DMA outlink descriptors and bind the target buffer to
+ *   these DMA descriptors. If len is not word-aligned, add a new descriptor
+ *   containing a 4-byte variable to make the outlink data world-aligned.
+ *
+ * Input Parameters:
+ *   dmadesc - Pointer to the DMA descriptors
+ *   num     - Number of DMA descriptors
+ *   pbuf    - RX/TX buffer pointer
+ *   len     - RX/TX buffer length
+ *   stuff   - Value to be padded with the buffer
+ *
+ * Returned Value:
+ *   Bound pbuf data bytes
+ *
+ ****************************************************************************/
+
+uint32_t esp32s2_dma_init_with_padding(struct esp32s2_dmadesc_s *dmadesc,
+                                       uint32_t num,
+                                       uint8_t *pbuf,
+                                       uint32_t len,
+                                       uint32_t *stuff)
+{
+  int i;
+  uint32_t bytes = len;
+  uint8_t *pdata = pbuf;
+  uint32_t data_len = 0;
+  uint32_t buf_len = 0;
+
+  DEBUGASSERT(dmadesc != NULL);
+  DEBUGASSERT(pbuf != NULL);
+  DEBUGASSERT(len > 0);
+
+  for (i = 0; i < num - 1; i++)
+    {
+      data_len = MIN(bytes, ESP32S2_DMA_DATALEN_MAX);
+
+      /* Buffer length must be rounded to next 32-bit boundary. */
+
+      buf_len = ALIGN_UP(data_len, sizeof(uintptr_t));
+
+      dmadesc[i].ctrl = (data_len << DMA_CTRL_DATALEN_S) |
+                        (buf_len << DMA_CTRL_BUFLEN_S) |
+                        DMA_CTRL_OWN;
+      dmadesc[i].pbuf = pdata;
+      dmadesc[i].next = &dmadesc[i + 1];
+
+      bytes -= data_len;
+      if (bytes == 0)
+        {
+          break;
+        }
+
+      pdata += data_len;
+    }
+
+  /* Check if the data_len of the last descriptor is different from buf_len.
+   * If so, it's necessary to add the padding bytes to a new descriptor on
+   * outlink.
+   */
+
+  if (data_len != buf_len)
+    {
+      i++;
+      dmadesc[i].ctrl = ((buf_len - data_len) << DMA_CTRL_DATALEN_S) |
+                        (4 << DMA_CTRL_BUFLEN_S) |
+                        DMA_CTRL_OWN;
+      dmadesc[i].pbuf = (uint8_t *)stuff;
+    }
+
+  dmadesc[i].ctrl |= DMA_CTRL_EOF;
+  dmadesc[i].next  = NULL;
+
+  return len - bytes;
+}

arch/xtensa/src/esp32s2/esp32s2_dma.h

@@ -0,0 +1,124 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32s2/esp32s2_dma.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#ifndef __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_DMA_H
+#define __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_DMA_H
+
+#include <nuttx/config.h>
+#include <stdint.h>
+
+#ifndef __ASSEMBLY__
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Pre-processor Macros
+ ****************************************************************************/
+
+/* DMA max data length */
+
+#define ESP32S2_DMA_DATALEN_MAX       (0x1000 - 4)
+
+/* DMA max buffer length */
+
+#define ESP32S2_DMA_BUFLEN_MAX        ESP32S2_DMA_DATALEN_MAX
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* DMA descriptor type */
+
+struct esp32s2_dmadesc_s
+{
+  uint32_t ctrl;                    /* DMA control block */
+  uint8_t *pbuf;                    /* DMA TX/RX buffer address */
+  struct esp32s2_dmadesc_s *next;   /* Next DMA descriptor address */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: esp32s2_dma_init
+ *
+ * Description:
+ *   Initialize DMA outlink descriptors and bind the target buffer to
+ *   these DMA descriptors.
+ *
+ * Input Parameters:
+ *   dmadesc - Pointer to the DMA descriptors
+ *   num     - Number of DMA descriptors
+ *   pbuf    - RX/TX buffer pointer
+ *   len     - RX/TX buffer length
+ *
+ * Returned Value:
+ *   Bound pbuf data bytes
+ *
+ ****************************************************************************/
+
+uint32_t esp32s2_dma_init(struct esp32s2_dmadesc_s *dmadesc, uint32_t num,
+                          uint8_t *pbuf, uint32_t len);
+
+/****************************************************************************
+ * Name: esp32s2_dma_init_with_padding
+ *
+ * Description:
+ *   Initialize DMA outlink descriptors and bind the target buffer to
+ *   these DMA descriptors. If len is not word-aligned, add a new descriptor
+ *   containing a 4-byte variable to make the outlink data world-aligned.
+ *
+ * Input Parameters:
+ *   dmadesc - Pointer to the DMA descriptors
+ *   num     - Number of DMA descriptors
+ *   pbuf    - RX/TX buffer pointer
+ *   len     - RX/TX buffer length
+ *   stuff   - Value to be padded with the buffer
+ *
+ * Returned Value:
+ *   Bound pbuf data bytes
+ *
+ ****************************************************************************/
+
+uint32_t esp32s2_dma_init_with_padding(struct esp32s2_dmadesc_s *dmadesc,
+                                       uint32_t num,
+                                       uint8_t *pbuf,
+                                       uint32_t len,
+                                       uint32_t *stuff);
+
+#ifdef __cplusplus
+}
+#endif
+#undef EXTERN
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_DMA_H */

arch/xtensa/src/esp32s2/esp32s2_i2s.h

@@ -0,0 +1,74 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32s2/esp32s2_i2s.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_I2S_H
+#define __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_I2S_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/audio/i2s.h>
+
+#ifndef __ASSEMBLY__
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+#ifdef CONFIG_ESP32S2_I2S
+
+#define ESP32S2_I2S0 0
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: esp32s2_i2sbus_initialize
+ *
+ * Description:
+ *   Initialize the selected I2S port
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   Valid I2S device structure reference on success; a NULL on failure
+ *
+ ****************************************************************************/
+
+struct i2s_dev_s *esp32s2_i2sbus_initialize(void);
+
+#endif /* CONFIG_ESP32S2_I2S */
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_XTENSA_SRC_ESP32S2_ESP32S2_I2S_H */

arch/xtensa/src/esp32s2/hardware/esp32s2_dma.h

@@ -0,0 +1,36 @@
+/****************************************************************************
+ * arch/xtensa/src/esp32s2/hardware/esp32s2_dma.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_XTENSA_SRC_ESP32S2_HARDWARE_ESP32S2_DMA_H
+#define __ARCH_XTENSA_SRC_ESP32S2_HARDWARE_ESP32S2_DMA_H
+
+/* DMA descriptor */
+
+#define DMA_CTRL_OWN          (1 << 31)   /* Owned by DMA */
+#define DMA_CTRL_EOF          (1 << 30)   /* End of frame */
+#define DMA_CTRL_SOSF         (1 << 29)   /* Start of sub-frame */
+#define DMA_CTRL_OFFSET_S     (24)        /* buffer offset shift */
+#define DMA_CTRL_OFFSET_V     (0x1f)      /* buffer offset value */
+#define DMA_CTRL_DATALEN_S    (12)        /* received/sent data length shift */
+#define DMA_CTRL_DATALEN_V    (0xfff)     /* received/sent data length value */
+#define DMA_CTRL_BUFLEN_S     (0)         /* received/sent buffer length shift */
+#define DMA_CTRL_BUFLEN_V     (0xfff)     /* received/sent buffer length value */
+
+#endif /* __ARCH_XTENSA_SRC_ESP32S2_HARDWARE_ESP32S2_DMA_H */

boards/xtensa/esp32s2/common/src/Make.defs

@@ -28,6 +28,10 @@ ifeq ($(CONFIG_SENSORS_MAX6675),y)
   CSRCS += esp32s2_max6675.c
 endif
 
+ifeq ($(CONFIG_ESP32S2_I2S),y)
+  CSRCS += esp32s2_board_i2sdev.c
+endif
+
 DEPPATH += --dep-path src
 VPATH += :src
 CFLAGS += $(shell $(INCDIR) "$(CC)" $(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)src)

boards/xtensa/esp32s2/common/src/esp32s2_board_i2sdev.c

@@ -0,0 +1,113 @@
+/****************************************************************************
+ * boards/xtensa/esp32s2/common/src/esp32s2_board_i2sdev.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdio.h>
+#include <debug.h>
+#include <errno.h>
+
+#include <nuttx/audio/audio.h>
+#include <nuttx/audio/audio_i2s.h>
+#include <nuttx/audio/i2s.h>
+#include <nuttx/audio/pcm.h>
+
+#include <arch/board/board.h>
+
+#include "esp32s2_i2s.h"
+
+#if defined(CONFIG_ESP32S2_I2S) && !defined(CONFIG_AUDIO_CS4344)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: board_i2sdev_initialize
+ *
+ * Description:
+ *   This function is called by platform-specific, setup logic to configure
+ *   and register the generic I2S audio driver.  This function will register
+ *   the driver as /dev/audio/pcm[x] where x is determined by the I2S port
+ *   number.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int board_i2sdev_initialize(void)
+{
+  struct audio_lowerhalf_s *audio_i2s;
+  struct audio_lowerhalf_s *pcm;
+  struct i2s_dev_s *i2s;
+  char devname[5];
+  int ret;
+
+  ainfo("Initializing I2S\n");
+
+  i2s = esp32s2_i2sbus_initialize();
+
+#ifdef CONFIG_AUDIO_I2SCHAR
+  ret = i2schar_register(i2s, 0);
+  if (ret < 0)
+    {
+      aerr("ERROR: i2schar_register failed: %d\n", ret);
+      return ret;
+    }
+#endif
+
+  audio_i2s = audio_i2s_initialize(i2s, true);
+
+  if (!audio_i2s)
+    {
+      auderr("ERROR: Failed to initialize the Generic I2S audio driver\n");
+      return -ENODEV;
+    }
+
+  pcm = pcm_decode_initialize(audio_i2s);
+
+  if (!pcm)
+    {
+      auderr("ERROR: Failed create the PCM decoder\n");
+      return  -ENODEV;
+    }
+
+  snprintf(devname, 5, "pcm0");
+
+  ret = audio_register(devname, pcm);
+
+  if (ret < 0)
+    {
+      auderr("ERROR: Failed to register /dev/%s device: %d\n", devname, ret);
+    }
+
+  return ret;
+}
+
+#endif /* (CONFIG_ESP32S2_I2S) && !defined (CONFIG_AUDIO_CS4344) */

boards/xtensa/esp32s2/esp32s2-saola-1/configs/i2schar/defconfig

@@ -0,0 +1,60 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_ARCH_LEDS is not set
+# CONFIG_ESP32S2_I2S_RX is not set
+# CONFIG_NDEBUG is not set
+# CONFIG_NSH_ARGCAT is not set
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+# CONFIG_NSH_CMDPARMS is not set
+CONFIG_ARCH="xtensa"
+CONFIG_ARCH_BOARD="esp32s2-saola-1"
+CONFIG_ARCH_BOARD_COMMON=y
+CONFIG_ARCH_BOARD_ESP32S2_SAOLA_1=y
+CONFIG_ARCH_CHIP="esp32s2"
+CONFIG_ARCH_CHIP_ESP32S2=y
+CONFIG_ARCH_CHIP_ESP32S2WROVER=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_ARCH_XTENSA=y
+CONFIG_AUDIO=y
+CONFIG_AUDIO_I2S=y
+CONFIG_AUDIO_I2SCHAR=y
+CONFIG_BOARD_LOOPSPERMSEC=16717
+CONFIG_BUILTIN=y
+CONFIG_DEBUG_FULLOPT=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DRIVERS_AUDIO=y
+CONFIG_ESP32S2_I2S=y
+CONFIG_ESP32S2_I2S_MCLK=y
+CONFIG_ESP32S2_UART0=y
+CONFIG_EXAMPLES_I2SCHAR=y
+CONFIG_EXAMPLES_I2SCHAR_TX=y
+CONFIG_EXAMPLES_I2SCHAR_TXSTACKSIZE=4096
+CONFIG_FS_PROCFS=y
+CONFIG_HAVE_CXX=y
+CONFIG_HAVE_CXXINITIALIZE=y
+CONFIG_IDLETHREAD_STACKSIZE=3072
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_INIT_STACKSIZE=4096
+CONFIG_INTELHEX_BINARY=y
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_LINELEN=64
+CONFIG_NSH_READLINE=y
+CONFIG_PREALLOC_TIMERS=4
+CONFIG_RAM_SIZE=114688
+CONFIG_RAM_START=0x20000000
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_HPWORK=y
+CONFIG_SCHED_LPWORK=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_START_DAY=6
+CONFIG_START_MONTH=12
+CONFIG_START_YEAR=2011
+CONFIG_SYSTEM_NSH=y
+CONFIG_UART0_SERIAL_CONSOLE=y

boards/xtensa/esp32s2/esp32s2-saola-1/src/esp32s2-saola-1.h

@@ -152,5 +152,27 @@ int board_i2c_init(void);
 int board_bmp180_initialize(int devno, int busno);
 #endif
 
+/****************************************************************************
+ * Name: board_i2sdev_initialize
+ *
+ * Description:
+ *   This function is called by platform-specific, setup logic to configure
+ *   and register the generic I2S audio driver.  This function will register
+ *   the driver as /dev/audio/pcm[x] where x is determined by the I2S port
+ *   number.
+ *
+ * Input Parameters:
+ *   None.
+ *
+ * Returned Value:
+ *   Zero is returned on success.  Otherwise, a negated errno value is
+ *   returned to indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ESP32S2_I2S
+int board_i2sdev_initialize(void);
+#endif
+
 #endif /* __ASSEMBLY__ */
 #endif /* __BOARDS_XTENSA_ESP32S2_ESP32S2_SAOLA_1_SRC_ESP32S2_SAOLA_1_H */

boards/xtensa/esp32s2/esp32s2-saola-1/src/esp32s2_bringup.c

@@ -229,6 +229,18 @@ int esp32s2_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_ESP32S2_I2S
+
+  /* Configure I2S generic audio on I2S0 */
+
+  ret = board_i2sdev_initialize();
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "Failed to initialize I2S0 driver: %d\n", ret);
+    }
+
+#endif /* CONFIG_ESP32S2_I2S */
+
   /* If we got here then perhaps not all initialization was successful, but
    * at least enough succeeded to bring-up NSH with perhaps reduced
    * capabilities.