Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7d78cbef authored by Heiko Stübner's avatar Heiko Stübner Committed by Greg Kroah-Hartman
Browse files

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: default avatarHeiko Stuebner <heiko@sntech.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d8782c74

Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt

+31 −0
Original line number Diff line number Diff line
@@ -4,7 +4,15 @@ Required properties: 
- compatible : "snps,dw-apb-uart"

- reg : offset and length of the register set for the device.

- interrupts : should contain uart interrupt.



Clock handling:

The clock rate of the input clock needs to be supplied by one of

- clock-frequency : the input clock frequency for the UART.

- clocks : phandle to the input clock



The supplying peripheral clock can also be handled, needing a second property

- clock-names: tuple listing input clock names.

	Required elements: "baudclk", "apb_pclk"



Optional properties:

- reg-shift : quantity to shift the register offsets by.  If this property is
@@ -23,3 +31,26 @@ Example: 
		reg-shift = <2>;

		reg-io-width = <4>;

	};



Example with one clock:



	uart@80230000 {

		compatible = "snps,dw-apb-uart";

		reg = <0x80230000 0x100>;

		clocks = <&baudclk>;

		interrupts = <10>;

		reg-shift = <2>;

		reg-io-width = <4>;

	};



Example with two clocks:



	uart@80230000 {

		compatible = "snps,dw-apb-uart";

		reg = <0x80230000 0x100>;

		clocks = <&baudclk>, <&apb_pclk>;

		clock-names = "baudclk", "apb_pclk";

		interrupts = <10>;

		reg-shift = <2>;

		reg-io-width = <4>;

	};

drivers/tty/serial/8250/8250_dw.c

+28 −3
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ struct dw8250_data { 
	int			last_mcr;

	int			line;

	struct clk		*clk;

	struct clk		*pclk;

	struct uart_8250_dma	dma;

};
@@ -359,12 +360,27 @@ static int dw8250_probe(struct platform_device *pdev) 
		return -ENOMEM;



	data->usr_reg = DW_UART_USR;

	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);

		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;

	data->dma.tx_chan_id = -1;

	data->dma.rx_param = data;
@@ -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);