i2c: add clean {write, read}data functions

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

api/mraa/i2c.h

@@ -78,7 +78,8 @@ mraa_i2c_context mraa_i2c_init_raw(unsigned int bus);
 mraa_result_t mraa_i2c_frequency(mraa_i2c_context dev, int hz);
 
 /**
- * Read from an i2c context
+ * Simple bulk read from an i2c context, this will always begin with the i2c
+ * offset 0x0
  *
  * @param dev The i2c context
  * @param data pointer to the byte array to read data in to
@@ -88,7 +89,8 @@ mraa_result_t mraa_i2c_frequency(mraa_i2c_context dev, int hz);
 int mraa_i2c_read(mraa_i2c_context dev, uint8_t *data, int length);
 
 /**
- * Read a single byte from the i2c context
+ * Simple read for a single byte from the i2c context, this will always begin
+ * with the i2c offset 0x0
  *
  * @param dev The i2c context
  * @return The result of the read or -1 if failed
@@ -102,10 +104,19 @@ uint8_t mraa_i2c_read_byte(mraa_i2c_context dev);
  * @param command The register
  * @return The result of the read or -1 if failed
  */
-uint8_t mraa_i2c_read_byte_data(mraa_i2c_context dev, uint8_t command);
+uint8_t mraa_i2c_read_byte_data(mraa_i2c_context dev, const uint8_t command);
 
 /**
- * Write to an i2c context
+ * Read a single word from i2c context, from designated register
+ *
+ * @param dev The i2c context
+ * @param command The register
+ * @return The result of the read or -1 if failed
+ */
+uint16_t mraa_i2c_read_word_data(mraa_i2c_context dev, const uint8_t command);
+
+/**
+ * Perform a simple write to an i2c context, always at offset 0x0
  *
  * @param dev The i2c context
  * @param data pointer to the byte array to be written
@@ -115,7 +126,7 @@ uint8_t mraa_i2c_read_byte_data(mraa_i2c_context dev, uint8_t command);
 mraa_result_t mraa_i2c_write(mraa_i2c_context dev, const uint8_t *data, int length);
 
 /**
- * Write a single byte to an i2c context
+ * Write a single byte to an i2c context, always at offset 0x0
  *
  * @param dev The i2c context
  * @param data The byte to write
@@ -123,6 +134,26 @@ mraa_result_t mraa_i2c_write(mraa_i2c_context dev, const uint8_t *data, int leng
  */
 mraa_result_t mraa_i2c_write_byte(mraa_i2c_context dev, const uint8_t data);
 
+/**
+ * Write a single byte to an i2c context
+ *
+ * @param dev The i2c context
+ * @param data The byte to write
+ * @param command The register
+ * @return Result of operation
+ */
+mraa_result_t mraa_i2c_write_byte_data(mraa_i2c_context dev, const uint8_t data, const uint8_t command);
+
+/**
+ * Write a single word to an i2c context
+ *
+ * @param dev The i2c context
+ * @param data The word to write
+ * @param command The register
+ * @return Result of operation
+ */
+mraa_result_t mraa_i2c_write_word_data(mraa_i2c_context dev, const uint16_t data, const uint8_t command);
+
 /**
  * Sets the i2c context address.
  *

api/mraa/i2c.hpp

@@ -128,18 +128,7 @@ class I2c {
         }
 
         /**
-         * Write one byte to the bus
+         * Read byte from an i2c register
-         *
-         * @param data Buffer to send on the bus
-         * @param length Size of buffer to send
-         * @return Result of operation
-         */
-        mraa_result_t write(char* data, size_t length) {
-            return mraa_i2c_write(m_i2c, (const unsigned char *)data, (int) length);
-        }
-
-        /**
-         * Read an i2c register
          *
          * @param reg Register to read from
          * @return char read from register
@@ -148,6 +137,16 @@ class I2c {
             return mraa_i2c_read_byte_data(m_i2c, reg);
         }
 
+        /**
+         * Read word from an i2c register
+         *
+         * @param reg Register to read from
+         * @return char read from register
+         */
+        uint16_t readWordReg(uint8_t reg) {
+            return mraa_i2c_read_byte_data(m_i2c, reg);
+        }
+
         /**
          * Write a byte on the bus
          *
@@ -159,15 +158,36 @@ class I2c {
         }
 
         /**
-         * Write to an i2c register
+         * Write length bytes to the bus
+         *
+         * @param data Buffer to send on the bus
+         * @param length Size of buffer to send
+         * @return Result of operation
+         */
+        mraa_result_t write(char* data, size_t length) {
+            return mraa_i2c_write(m_i2c, (const unsigned char *)data, (int) length);
+        }
+
+        /**
+         * Write a byte to an i2c register
          *
          * @param reg Register to write to
          * @param data Value to write to register
          * @return Result of operation
          */
         mraa_result_t writeReg(uint8_t reg, uint8_t data) {
-            const uint8_t buf[2] = {reg, data};
+            return mraa_i2c_write_byte_data(m_i2c, data, reg);
-            return mraa_i2c_write(m_i2c, buf, 2);
+        }
+
+        /**
+         * Write a word to an i2c register
+         *
+         * @param reg Register to write to
+         * @param data Value to write to register
+         * @return Result of operation
+         */
+        mraa_result_t writeWordReg(uint8_t reg, uint16_t data) {
+            return mraa_i2c_write_word_data(m_i2c, data, reg);
         }
     private:
         mraa_i2c_context m_i2c;

src/i2c/i2c.c

@@ -121,8 +121,13 @@ mraa_i2c_read_byte(mraa_i2c_context dev)
 uint8_t
 mraa_i2c_read_byte_data(mraa_i2c_context dev, uint8_t command)
 {
-    uint8_t byte = i2c_smbus_read_byte_data(dev->fh, command);
+    return (uint8_t) i2c_smbus_read_byte_data(dev->fh, command);
-    return byte;
+}
+
+uint16_t
+mraa_i2c_read_word_data(mraa_i2c_context dev, uint8_t command)
+{
+    return (uint16_t) i2c_smbus_read_word_data(dev->fh, command);
 }
 
 mraa_result_t
@@ -145,6 +150,26 @@ mraa_i2c_write_byte(mraa_i2c_context dev, const uint8_t data)
     return MRAA_SUCCESS;
 }
 
+mraa_result_t
+mraa_i2c_write_byte_data(mraa_i2c_context dev, const uint8_t data, const uint8_t command)
+{
+    if (i2c_smbus_write_byte_data(dev->fh, command, data) < 0) {
+        syslog(LOG_ERR, "i2c: Failed to write");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+    return MRAA_SUCCESS;
+}
+
+mraa_result_t
+mraa_i2c_write_word_data(mraa_i2c_context dev, const uint16_t data, const uint8_t command)
+{
+    if (i2c_smbus_write_word_data(dev->fh, command, data) < 0) {
+        syslog(LOG_ERR, "i2c: Failed to write");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+    return MRAA_SUCCESS;
+}
+
 mraa_result_t
 mraa_i2c_address(mraa_i2c_context dev, uint8_t addr)
 {