i2cslave: add i2cslave api and basic non functional implementation

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/i2cslave.h

@@ -0,0 +1,149 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed 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.
+ */
+
+#pragma once
+
+#include <stdio.h>
+#include <fcntl.h>
+#include "smbus.hpp"
+
+namespace maa {
+
+/** An I2C Slave, used for communicating with an I2C Master device
+ *
+ * Example:
+ * @code
+ * // Simple I2C responder
+ * #include <mbed.h>
+ *
+ * I2CSlave slave(p9, p10);
+ *
+ * int main() {
+ *     char buf[10];
+ *     char msg[] = "Slave!";
+ *
+ *     slave.address(0xA0);
+ *     while (1) {
+ *         int i = slave.receive();
+ *         switch (i) {
+ *             case I2CSlave::ReadAddressed:
+ *                 slave.write(msg, strlen(msg) + 1); // Includes null char
+ *                 break;
+ *             case I2CSlave::WriteGeneral:
+ *                 slave.read(buf, 10);
+ *                 printf("Read G: %s\n", buf);
+ *                 break;
+ *             case I2CSlave::WriteAddressed:
+ *                 slave.read(buf, 10);
+ *                 printf("Read A: %s\n", buf);
+ *                 break;
+ *         }
+ *         for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
+ *     }
+ * }
+ * @endcode
+ */
+class I2CSlave {
+
+public:
+    enum RxStatus {
+        NoData         = 0,
+        ReadAddressed  = 1,
+        WriteGeneral   = 2,
+        WriteAddressed = 3
+    };
+
+    /** Create an I2C Slave interface, connected to the specified pins.
+     *
+     *  @param sda I2C data line pin
+     *  @param scl I2C clock line pin
+     */
+    I2CSlave(unsigned int sda, unsigned int scl);
+
+    /** Set the frequency of the I2C interface
+     *
+     *  @param hz The bus frequency in hertz
+     */
+    void frequency(int hz);
+
+    /** Checks to see if this I2C Slave has been addressed.
+     *
+     *  @returns
+     *  A status indicating if the device has been addressed, and how
+     *  - NoData            - the slave has not been addressed
+     *  - ReadAddressed     - the master has requested a read from this slave
+     *  - WriteAddressed    - the master is writing to this slave
+     *  - WriteGeneral      - the master is writing to all slave
+     */
+    int receive(void);
+
+    /** Read from an I2C master.
+     *
+     *  @param data pointer to the byte array to read data in to
+     *  @param length maximum number of bytes to read
+     *
+     *  @returns
+     *       0 on success,
+     *   non-0 otherwise
+     */
+    int read(char *data, int length);
+
+    /** Read a single byte from an I2C master.
+     *
+     *  @returns
+     *    the byte read
+     */
+    int read(void);
+
+    /** Write to an I2C master.
+     *
+     *  @param data pointer to the byte array to be transmitted
+     *  @param length the number of bytes to transmite
+     *
+     *  @returns
+     *       0 on success,
+     *   non-0 otherwise
+     */
+    int write(const char *data, int length);
+
+    /** Write a single byte to an I2C master.
+     *
+     *  @data the byte to write
+     *
+     *  @returns
+     *    '1' if an ACK was received,
+     *    '0' otherwise
+     */
+    int write(int data);
+
+    /** Sets the I2C slave address.
+     *
+     *  @param address The address to set for the slave (ignoring the least
+     *  signifcant bit). If set to 0, the slave will only respond to the
+     *  general call address.
+     */
+    void address(int address);
+
+    /** Reset the I2C slave back into the known ready receiving state.
+     */
+    void stop(void);
+
+protected:
+    int _hz;
+    int i2c_handle;
+};
+
+}

src/i2c/i2cslave.cxx

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) Intel Corporation.
+ *
+ * Author: Brendan Le Foll
+ *                                                                                                                                                             
+ * Copyright © 2014 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "i2cslave.h"
+
+using namespace maa;
+
+I2CSlave::I2CSlave(unsigned int sda, unsigned int scl)
+{
+    // Galileo only has one I2CSlave device which is always /dev/i2c-0
+    // reliability is a fickle friend!
+    if (i2c_handle = open("/dev/i2c-0", O_RDWR) < 1) {
+        fprintf(stderr, "Failed to open requested i2c port");
+    }
+}
+
+void
+I2CSlave::frequency(int hz)
+{
+    _hz = hz;
+}
+
+int
+I2CSlave::read(char *data, int length)
+{
+    return 0;
+}
+
+int
+I2CSlave::read(void)
+{
+    int byte;
+    if (byte = i2c_smbus_read_byte(i2c_handle) < 0) {
+        return -1;
+    }
+    return byte;
+}
+
+int
+I2CSlave::write(const char *data, int length)
+{
+    if (i2c_smbus_write_i2c_block_data(i2c_handle, data[0], length, (uint8_t*) data) < 0) {
+        fprintf(stderr, "Failed to write to I2CSlave slave\n");
+	return -1;
+    }
+    return 0;
+}
+
+int
+I2CSlave::write(int data)
+{
+    if (i2c_smbus_write_byte(i2c_handle, data) < 0) {
+        fprintf(stderr, "Failed to write to I2CSlave slave\n");
+	return -1;
+    }
+    return 0;
+}
+
+void
+I2CSlave::address(int address)
+{
+}
+
+void
+I2CSlave::stop()
+{
+}