tty: serial: meson: retrieve port FIFO size from DT

Now the DT bindings has a property to get the FIFO size for a particular port,
retrieve it and use to setup the FIFO interrupts threshold.
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20210518075833.3736038-3-narmstrong@baylibre.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/meson_uart.c

@@ -715,6 +715,7 @@ static int meson_uart_probe(struct platform_device *pdev)
 {
 	struct resource *res_mem, *res_irq;
 	struct uart_port *port;
+	u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */
 	int ret = 0;
 
 	if (pdev->dev.of_node)
@@ -742,6 +743,8 @@ static int meson_uart_probe(struct platform_device *pdev)
 	if (!res_irq)
 		return -ENODEV;
 
+	of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize);
+
 	if (meson_ports[pdev->id]) {
 		dev_err(&pdev->dev, "port %d already allocated\n", pdev->id);
 		return -EBUSY;
@@ -771,7 +774,7 @@ static int meson_uart_probe(struct platform_device *pdev)
 	port->type = PORT_MESON;
 	port->x_char = 0;
 	port->ops = &meson_uart_ops;
-	port->fifosize = 64;
+	port->fifosize = fifosize;
 
 	meson_ports[pdev->id] = port;
 	platform_set_drvdata(pdev, port);