uart: add uart device read and write functionality

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

api/mraa/uart.h

@@ -93,6 +93,27 @@ mraa_result_t mraa_uart_open_dev(mraa_uart_context dev, speed_t baud);
  */
 mraa_result_t mraa_uart_close_dev(mraa_uart_context dev);
 
+/**
+ * Read bytes from the device into a buffer
+ *
+ * @param dev uart context
+ * @param buf buffer pointer
+ * @param len maximum size of buffer
+ * @return the number of bytes read, or -1 if an error occurred
+ */
+int mraa_uart_read(mraa_uart_context dev, char *buf, size_t len);
+
+/**
+ * Write bytes in buffer to a device
+ *
+ * @param dev uart context
+ * @param buf buffer pointer
+ * @param len maximum size of buffer
+ * @return the number of bytes written, or -1 if an error occurred
+ */
+int mraa_uart_write(mraa_uart_context dev, char *buf, size_t len);
+
+
 #ifdef __cplusplus
 }
 #endif

api/mraa/uart.hpp

@@ -102,6 +102,32 @@ class Uart
         return mraa_uart_close_dev(m_uart);
     }
 
+    /**
+     * Read bytes from the device into a buffer
+     *
+     * @param buf buffer pointer
+     * @param len maximum size of buffer
+     * @return the number of bytes read, or -1 if an error occurred
+     */
+    int
+    read(char *buf, size_t len)
+    {
+        return mraa_uart_read(m_uart, buf, len);
+    }
+
+    /**
+     * Write bytes in buffer to a device
+     *
+     * @param buf buffer pointer
+     * @param len maximum size of buffer
+     * @return the number of bytes written, or -1 if an error occurred
+     */
+    int
+    write(char *buf, size_t len)
+    {
+        return mraa_uart_write(m_uart, buf, len);
+    }
+
   private:
     mraa_uart_context m_uart;
 };

src/uart/uart.c

@@ -172,3 +172,35 @@ mraa_uart_close_dev(mraa_uart_context dev)
     dev->fd = -1;
     return MRAA_SUCCESS;
 }
+
+int
+mraa_uart_read(mraa_uart_context dev, char *buf, size_t len)
+{
+    if (!dev) {
+        syslog(LOG_ERR, "uart: read: context is NULL");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+
+    if (dev->fd < 0) {
+        syslog(LOG_ERR, "uart: port is not open");
+        return MRAA_ERROR_INVALID_RESOURCE;
+    }
+
+    return read(dev->fd, buf, len);
+}
+
+int
+mraa_uart_write(mraa_uart_context dev, char *buf, size_t len)
+{
+    if (!dev) {
+        syslog(LOG_ERR, "uart: write: context is NULL");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+
+    if (dev->fd < 0) {
+        syslog(LOG_ERR, "uart: port is not open");
+        return MRAA_ERROR_INVALID_RESOURCE;
+    }
+
+    return write(dev->fd, buf, len);
+}