drivers: add generic i2c bitbang driver

include/nuttx/i2c/i2c_bitbang.h

@@ -0,0 +1,82 @@
+/****************************************************************************
+ * drivers/i2c/i2c_bitbang.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 __DRIVERS_I2C_I2C_BITBANG_H
+#define __DRIVERS_I2C_I2C_BITBANG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/i2c/i2c_master.h>
+#include <stdbool.h>
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+struct i2c_bitbang_lower_dev_s;
+
+struct i2c_bitbang_lower_ops_s
+{
+  /* Initialize pins to appropriate state (usually open-drain) */
+
+  CODE void (*initialize)(FAR struct i2c_bitbang_lower_dev_s *lower);
+
+  /* Set high/low level for SCL/SDA pins */
+
+  CODE void (*set_scl)(FAR struct i2c_bitbang_lower_dev_s *lower, bool high);
+  CODE void (*set_sda)(FAR struct i2c_bitbang_lower_dev_s *lower, bool high);
+
+  /* Read level of SCL/SDA pins */
+
+  CODE bool (*get_scl)(FAR struct i2c_bitbang_lower_dev_s *lower);
+  CODE bool (*get_sda)(FAR struct i2c_bitbang_lower_dev_s *lower);
+};
+
+struct i2c_bitbang_lower_dev_s
+{
+  FAR const struct i2c_bitbang_lower_ops_s *ops;
+  FAR void *priv;
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: i2c_bitbang_initialize
+ *
+ * Description:
+ *   Initialize a bitbang I2C device instance
+ *
+ * Input Parameters:
+ *   lower  - Lower half of driver
+ *
+ * Returned Value:
+ *   Pointer to a the I2C instance
+ *
+ ****************************************************************************/
+
+FAR struct i2c_master_s *i2c_bitbang_initialize(
+    FAR struct i2c_bitbang_lower_dev_s *lower);
+
+#endif /* __DRIVERS_I2C_I2C_BITBANG_H */