From: Bin Meng <bmeng.cn@gmail.com>

Read or write to uart registers when unclocked or in reset should be
ignored. Add the check there, and as a result of this, the check in
uart_write_tx_fifo() is now unnecessary.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210901124521.30599-6-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/char/cadence_uart.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index 8bcf2b718a0..5f5a4645ac0 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -335,11 +335,6 @@ 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;
     }
@@ -416,6 +411,11 @@ static MemTxResult uart_write(void *opaque, hwaddr offset,
 {
     CadenceUARTState *s = opaque;
 
+    /* ignore access when unclocked or in reset */
+    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
+        return MEMTX_ERROR;
+    }
+
     DB_PRINT(" offset:%x data:%08x\n", (unsigned)offset, (unsigned)value);
     offset >>= 2;
     if (offset >= CADENCE_UART_R_MAX) {
@@ -476,6 +476,11 @@ static MemTxResult uart_read(void *opaque, hwaddr offset,
     CadenceUARTState *s = opaque;
     uint32_t c = 0;
 
+    /* ignore access when unclocked or in reset */
+    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
+        return MEMTX_ERROR;
+    }
+
     offset >>= 2;
     if (offset >= CADENCE_UART_R_MAX) {
         return MEMTX_DECODE_ERROR;
-- 
2.20.1