firmata: Added option to set uart non blocking state

Signed-off-by: Shiran Ben-Melech <shiran.ben-melech@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/uart.h

@@ -118,6 +118,15 @@ mraa_result_t mraa_uart_set_flowcontrol(mraa_uart_context dev, mraa_boolean_t xo
  */
 mraa_result_t mraa_uart_set_timeout(mraa_uart_context dev, int read, int write, int interchar);
 
+/**
+ * Set the blocking state for write operations
+ *
+ * @param dev The UART context
+ * @param nonblock new nonblocking state
+ * @return Result of operation
+ */
+mraa_result_t mraa_uart_set_non_blocking(mraa_uart_context dev, mraa_boolean_t nonblock);
+
 /**
  * Get Char pointer with tty device path within Linux
  * For example. Could point to "/dev/ttyS0"

api/mraa/uart.hpp

@@ -236,6 +236,19 @@ class Uart
         return (Result) mraa_uart_set_timeout(m_uart, read, write, interchar);
     }
 
+    /**
+     * Set the blocking state for write operations
+     *
+     * @param dev The UART context
+     * @param nonblock new nonblocking state
+     * @return Result of operation
+     */
+    Result
+    SetNonBlocking(bool nonblock)
+    {
+        return (Result) mraa_uart_set_non_blocking(m_uart, nonblock);
+    }
+
   private:
     mraa_uart_context m_uart;
 };

src/uart/uart.c

@@ -451,6 +451,28 @@ mraa_uart_set_timeout(mraa_uart_context dev, int read, int write, int interchar)
     return MRAA_SUCCESS;
 }
 
+mraa_result_t
+mraa_uart_set_non_blocking(mraa_uart_context dev, mraa_boolean_t nonblock)
+{
+    // get current flags
+    int flags = fcntl(dev->fd, F_GETFL);
+
+    // update flags with new blocking state according to nonblock bool
+    if (nonblock) {
+        flags |= O_NONBLOCK;
+    } else {
+        flags &= ~O_NONBLOCK;
+    }
+
+    // set new flags
+    if (fcntl(dev->fd, F_SETFL, flags) < 0) {
+        syslog(LOG_ERR, "failed changing fd blocking state");
+        return MRAA_ERROR_UNSPECIFIED;
+    }
+
+    return MRAA_SUCCESS;
+}
+
 const char*
 mraa_uart_get_dev_path(mraa_uart_context dev)
 {