imx_serial: Generate interrupt on receive data ready if enabled

Generate an interrupt if USR2_RDR and UCR4_DREN are both set.

Signed-off-by: Hans-Erik Floryd <hans-erik.floryd@rt-labs.com>
Message-id: 1534341354-11956-1-git-send-email-hans-erik.floryd@rt-labs.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/char/imx_serial.c

@@ -74,8 +74,9 @@ static void imx_update(IMXSerialState *s)
     mask = (s->ucr1 & UCR1_TXMPTYEN) ? USR2_TXFE : 0;
     /*
      * TCEN and TXDC are both bit 3
+     * RDR and DREN are both bit 0
      */
-    mask |= s->ucr4 & UCR4_TCEN;
+    mask |= s->ucr4 & (UCR4_TCEN | UCR4_DREN);
 
     usr2 = s->usr2 & mask;
 

include/hw/char/imx_serial.h

@@ -68,6 +68,7 @@
 #define UCR2_RXEN       (1<<1)    /* Receiver enable */
 #define UCR2_SRST       (1<<0)    /* Reset complete */
 
+#define UCR4_DREN       BIT(0)    /* Receive Data Ready interrupt enable */
 #define UCR4_TCEN       BIT(3)    /* TX complete interrupt enable */
 
 #define UTS1_TXEMPTY    (1<<6)