1 files changed, 37 insertions, 3 deletions

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 2bf1c57e0981..4869c0059c98 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -68,6 +68,7 @@
 #define AML_UART_BAUD_MASK		0x7fffff
 #define AML_UART_BAUD_USE		BIT(23)
 #define AML_UART_BAUD_XTAL		BIT(24)
+#define AML_UART_BAUD_XTAL_DIV2		BIT(27)
 
 #define AML_UART_PORT_NUM		12
 #define AML_UART_PORT_OFFSET		6
@@ -80,6 +81,10 @@ static struct uart_driver meson_uart_driver;
 
 static struct uart_port *meson_ports[AML_UART_PORT_NUM];
 
+struct meson_uart_data {
+	bool has_xtal_div2;
+};
+
 static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 }
@@ -253,6 +258,14 @@ static const char *meson_uart_type(struct uart_port *port)
 	return (port->type == PORT_MESON) ? "meson_uart" : NULL;
 }
 
+/*
+ * This function is called only from probe() using a temporary io mapping
+ * in order to perform a reset before setting up the device. Since the
+ * temporarily mapped region was successfully requested, there can be no
+ * console on this port at this time. Hence it is not necessary for this
+ * function to acquire the port->lock. (Since there is no console on this
+ * port at this time, the port->lock is not initialized yet.)
+ */
 static void meson_uart_reset(struct uart_port *port)
 {
 	u32 val;
@@ -267,9 +280,12 @@ static void meson_uart_reset(struct uart_port *port)
 
 static int meson_uart_startup(struct uart_port *port)
 {
+	unsigned long flags;
 	u32 val;
 	int ret = 0;
 
+	spin_lock_irqsave(&port->lock, flags);
+
 	val = readl(port->membase + AML_UART_CONTROL);
 	val |= AML_UART_CLEAR_ERR;
 	writel(val, port->membase + AML_UART_CONTROL);
@@ -285,6 +301,8 @@ static int meson_uart_startup(struct uart_port *port)
 	val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2));
 	writel(val, port->membase + AML_UART_MISC);
 
+	spin_unlock_irqrestore(&port->lock, flags);
+
 	ret = request_irq(port->irq, meson_uart_interrupt, 0,
 			  port->name, port);
 
@@ -293,16 +311,23 @@ static int meson_uart_startup(struct uart_port *port)
 
 static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
 {
-	u32 val;
+	const struct meson_uart_data *private_data = port->private_data;
+	u32 val = 0;
 
 	while (!meson_uart_tx_empty(port))
 		cpu_relax();
 
 	if (port->uartclk == 24000000) {
-		val = ((port->uartclk / 3) / baud) - 1;
+		unsigned int xtal_div = 3;
+
+		if (private_data && private_data->has_xtal_div2) {
+			xtal_div = 2;
+			val |= AML_UART_BAUD_XTAL_DIV2;
+		}
+		val |= DIV_ROUND_CLOSEST(port->uartclk / xtal_div, baud) - 1;
 		val |= AML_UART_BAUD_XTAL;
 	} else {
-		val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
+		val =  DIV_ROUND_CLOSEST(port->uartclk / 4, baud) - 1;
 	}
 	val |= AML_UART_BAUD_USE;
 	writel(val, port->membase + AML_UART_REG5);
@@ -749,6 +774,7 @@ static int meson_uart_probe(struct platform_device *pdev)
 	port->x_char = 0;
 	port->ops = &meson_uart_ops;
 	port->fifosize = fifosize;
+	port->private_data = (void *)device_get_match_data(&pdev->dev);
 
 	meson_ports[pdev->id] = port;
 	platform_set_drvdata(pdev, port);
@@ -777,11 +803,19 @@ static int meson_uart_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static struct meson_uart_data s4_uart_data = {
+	.has_xtal_div2 = true,
+};
+
 static const struct of_device_id meson_uart_dt_match[] = {
 	{ .compatible = "amlogic,meson6-uart" },
 	{ .compatible = "amlogic,meson8-uart" },
 	{ .compatible = "amlogic,meson8b-uart" },
 	{ .compatible = "amlogic,meson-gx-uart" },
+	{
+		.compatible = "amlogic,meson-s4-uart",
+		.data = (void *)&s4_uart_data,
+	},
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, meson_uart_dt_match);