[PATCH] serial: a3720: Implement pending method for output direction

["Pali Rohár" <pali@kernel.org>]

To check if some output characters are waiting either in Transmitter
Holding Register or Transmitter Shift Register we need to look at
TX_EMPTY bit of UART Status Register.

Signed-off-by: Pali Roh?r <pali@kernel.org>
---
 drivers/serial/serial_mvebu_a3700.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c
index fb43f88eaf..909901c9f0 100644
--- a/drivers/serial/serial_mvebu_a3700.c
+++ b/drivers/serial/serial_mvebu_a3700.c
@@ -23,6 +23,7 @@ struct mvebu_platdata {
 #define UART_POSSR_REG		0x14
 
 #define UART_STATUS_RX_RDY	0x10
+#define UART_STATUS_TX_EMPTY	0x40
 #define UART_STATUS_TXFIFO_FULL	0x800
 
 #define UART_CTRL_RXFIFO_RESET	0x4000
@@ -59,8 +60,13 @@ static int mvebu_serial_pending(struct udevice *dev, bool input)
 	struct mvebu_platdata *plat = dev_get_platdata(dev);
 	void __iomem *base = plat->base;
 
-	if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
-		return 1;
+	if (input) {
+		if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
+			return 1;
+	} else {
+		if (!(readl(base + UART_STATUS_REG) & UART_STATUS_TX_EMPTY))
+			return 1;
+	}
 
 	return 0;
 }
-- 
2.20.1