Add basic support for MCP23017 I/O Expander

include/nuttx/ioexpander/mcp23x17.h

@@ -0,0 +1,108 @@
+/****************************************************************************
+ * include/nuttx/ioexpander/mcp23x17.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 __INCLUDE_NUTTX_IOEXPANDER_MCP23X17_H
+#define __INCLUDE_NUTTX_IOEXPANDER_MCP23X17_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/i2c/i2c_master.h>
+
+#include <stdbool.h>
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* A reference to a structure of this type must be passed to the mcp23x17
+ * driver when the driver is instantiated. This structure provides
+ * information about the configuration of the mcp23x17 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. The
+ * memory must be writeable because, under certain circumstances, the driver
+ * may modify the frequency.
+ */
+
+struct mcp23x17_config_s
+{
+  /* Device characterization */
+
+  uint8_t address;     /* 7-bit I2C address (only bits 0-6 used) */
+  uint32_t frequency;  /* I2C or SPI frequency */
+
+  /* Sets the state of the MCP23X17's nReset pin */
+
+  CODE void (*set_nreset_pin)(bool state);
+
+#ifdef CONFIG_IOEXPANDER_INT_ENABLE
+  /* If multiple mcp23x17 devices are supported, then an IRQ number must
+   * be provided for each so that their interrupts can be distinguished.
+   */
+
+  /* IRQ/GPIO access callbacks.  These operations all hidden behind
+   * callbacks to isolate the mcp23x17 driver from differences in GPIO
+   * interrupt handling by varying boards and MCUs.
+   *
+   * attach  - Attach the mcp23x17 interrupt handler to the GPIO interrupt
+   * enable  - Enable or disable the GPIO interrupt
+   */
+
+  CODE int  (*attach)(FAR struct mcp23x17_config_s *state, xcpt_t isr,
+                      FAR void *arg);
+  CODE void (*enable)(FAR struct mcp23x17_config_s *state, bool enable);
+#endif
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: mcp23x17_initialize
+ *
+ * Description:
+ *   Initialize a MCP23X17 I2C device.
+ *
+ * TODO: Add support for more than one device.
+ *
+ ****************************************************************************/
+
+FAR struct ioexpander_dev_s *mcp23x17_initialize(
+                              FAR struct i2c_master_s *i2cdev,
+                              FAR struct mcp23x17_config_s *config);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INCLUDE_NUTTX_IOEXPANDER_MCP23X17_H */