[PATCH 2/3] hw/char: cadence_uart: Disable transmit when input clock is disabled

[Bin Meng <bmeng.cn@gmail.com>]

At present when input clock is disabled, any character transmitted
to tx fifo can still show on the serial line, which is wrong.

Fixes: b636db306e06 ("hw/char/cadence_uart: add clock support")
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 hw/char/cadence_uart.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index b4b5e8a3ee..154be34992 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -327,6 +327,11 @@ static gboolean cadence_uart_xmit(void *do_not_use, GIOCondition cond,
 static void uart_write_tx_fifo(CadenceUARTState *s, const uint8_t *buf,
                                int size)
 {
+    /* ignore characters when unclocked or in reset */
+    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
+        return;
+    }
+
     if ((s->r[R_CR] & UART_CR_TX_DIS) || !(s->r[R_CR] & UART_CR_TX_EN)) {
         return;
     }
-- 
2.25.1