adc: Implement ADC driver interface for MCP3008 over SPI. Includes documentation page for the driver, and inclusion of driver registration code for RP2040-based boards.

include/nuttx/analog/ioctl.h

@@ -111,6 +111,11 @@
 #define AN_SAMV7_AFEC_FIRST (AN_MCP48XX_FIRST + AN_MCP48XX_NCMDS)
 #define AN_SAMV7_AFEC_NCMDS 1
 
+/* See include/nuttx/analog/mcp3008.h */
+
+#define AN_MCP3008_FIRST (AN_SAMV7_AFEC_FIRST + AN_SAMV7_AFEC_NCMDS)
+#define AN_MCP3008_NCMDS 1
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/

include/nuttx/analog/mcp3008.h

@@ -0,0 +1,52 @@
+/****************************************************************************
+ * include/nuttx/analog/mcp3008.h
+ *
+ * Contributed by Matteo Golin
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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 __INCLUDE_NUTTX_ANALOG_MCP3008_H
+#define __INCLUDE_NUTTX_ANALOG_MCP3008_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/analog/ioctl.h>
+#include <nuttx/config.h>
+#include <nuttx/spi/spi.h>
+
+/****************************************************************************
+ * Preprocessor definitions
+ ****************************************************************************/
+
+/* IOCTL Commands
+ * Cmd: ANIOC_MCP3008_DIFF      Arg: 1 for differential, 0 for single-ended
+ */
+
+#define ANIOC_MCP3008_DIFF      _ANIOC(AN_MCP3008_FIRST + 0)
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+FAR struct adc_dev_s *mcp3008_initialize(FAR struct spi_dev_s *spi);
+
+#endif /* __INCLUDE_NUTTX_ANALOG_MCP3008_H */