[PATCH 09/12] hw/char/pl011: Check if transmitter is enabled

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Do not transmit characters when UART or transmitter are disabled.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/char/pl011.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/char/pl011.c b/hw/char/pl011.c
index c55ef41fbf..30bedeac15 100644
--- a/hw/char/pl011.c
+++ b/hw/char/pl011.c
@@ -76,6 +76,10 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr)
 #define LCR_FEN     (1 << 4)
 #define LCR_BRK     (1 << 0)
 
+/* Control Register, UARTCR */
+#define CR_TXE      (1 << 8)
+#define CR_UARTEN   (1 << 0)
+
 static const unsigned char pl011_id_arm[8] =
   { 0x11, 0x10, 0x14, 0x00, 0x0d, 0xf0, 0x05, 0xb1 };
 static const unsigned char pl011_id_luminary[8] =
@@ -151,7 +155,9 @@ static inline void pl011_reset_tx_fifo(PL011State *s)
 
 static void pl011_write_tx(PL011State *s, const uint8_t *buf, int length)
 {
-    /* ??? Check if transmitter is enabled.  */
+    if (!(s->cr & (CR_UARTEN | CR_TXE))) {
+        return;
+    }
 
     /* XXX this blocks entire thread. Rewrite to use
      * qemu_chr_fe_write and background I/O callbacks */
-- 
2.38.1