serial: 8250_dw: add ability to handle the peripheral clock

First try to find the named clock variants then fall back to the already
existing handling of a nameless declared baudclk.

This also adds the missing documentation for this already existing variant.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 28 insertions, 3 deletions

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a1450ae6f9c1..c531fa42f838 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -59,6 +59,7 @@ struct dw8250_data {
 	int			last_mcr;
 	int			line;
 	struct clk		*clk;
+	struct clk		*pclk;
 	struct uart_8250_dma	dma;
 };
 
@@ -359,10 +360,25 @@ static int dw8250_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	data->usr_reg = DW_UART_USR;
-	data->clk = devm_clk_get(&pdev->dev, NULL);
+	data->clk = devm_clk_get(&pdev->dev, "baudclk");
+	if (IS_ERR(data->clk))
+		data->clk = devm_clk_get(&pdev->dev, NULL);
 	if (!IS_ERR(data->clk)) {
-		clk_prepare_enable(data->clk);
-		uart.port.uartclk = clk_get_rate(data->clk);
+		err = clk_prepare_enable(data->clk);
+		if (err)
+			dev_warn(&pdev->dev, "could not enable optional baudclk: %d\n",
+				 err);
+		else
+			uart.port.uartclk = clk_get_rate(data->clk);
+	}
+
+	data->pclk = devm_clk_get(&pdev->dev, "apb_pclk");
+	if (!IS_ERR(data->pclk)) {
+		err = clk_prepare_enable(data->pclk);
+		if (err) {
+			dev_err(&pdev->dev, "could not enable apb_pclk\n");
+			return err;
+		}
 	}
 
 	data->dma.rx_chan_id = -1;
@@ -408,6 +424,9 @@ static int dw8250_remove(struct platform_device *pdev)
 
 	serial8250_unregister_port(data->line);
 
+	if (!IS_ERR(data->pclk))
+		clk_disable_unprepare(data->pclk);
+
 	if (!IS_ERR(data->clk))
 		clk_disable_unprepare(data->clk);
 
@@ -445,6 +464,9 @@ static int dw8250_runtime_suspend(struct device *dev)
 	if (!IS_ERR(data->clk))
 		clk_disable_unprepare(data->clk);
 
+	if (!IS_ERR(data->pclk))
+		clk_disable_unprepare(data->pclk);
+
 	return 0;
 }
 
@@ -452,6 +474,9 @@ static int dw8250_runtime_resume(struct device *dev)
 {
 	struct dw8250_data *data = dev_get_drvdata(dev);
 
+	if (!IS_ERR(data->pclk))
+		clk_prepare_enable(data->pclk);
+
 	if (!IS_ERR(data->clk))
 		clk_prepare_enable(data->clk);