[PATCH] serial: 8250_dw: add ability to handle the peripheral clock

[PATCH] serial: 8250_dw: add ability to handle the peripheral clock

[Heiko Stübner]

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>
---
 .../bindings/serial/snps-dw-apb-uart.txt           | 31 ++++++++++++++++++++++
 drivers/tty/serial/8250/8250_dw.c                  | 31 +++++++++++++++++++---
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
index f13f1c5..3601399 100644
--- a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
+++ b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
@@ -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>;
+	};
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 51b307a..024cd58 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;
 };
 
@@ -402,10 +403,25 @@ 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;
@@ -451,6 +467,9 @@ 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);
 
@@ -488,6 +507,9 @@ 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;
 }
 
@@ -495,6 +517,9 @@ 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);
 
-- 
1.9.0

Re: [PATCH] serial: 8250_dw: add ability to handle the peripheral clock

[Heiko Stübner]

Am Montag, 16. Juni 2014, 15:25:17 schrieb Heiko Stübner:
> 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>

any comments?


Thanks
Heiko


> ---
>  .../bindings/serial/snps-dw-apb-uart.txt           | 31
> ++++++++++++++++++++++ drivers/tty/serial/8250/8250_dw.c                  |
> 31 +++++++++++++++++++--- 2 files changed, 59 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
> b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt index
> f13f1c5..3601399 100644
> --- a/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
> +++ b/Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt
> @@ -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>;
> +	};
> diff --git a/drivers/tty/serial/8250/8250_dw.c
> b/drivers/tty/serial/8250/8250_dw.c index 51b307a..024cd58 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;
>  };
> 
> @@ -402,10 +403,25 @@ 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;
> @@ -451,6 +467,9 @@ 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);
> 
> @@ -488,6 +507,9 @@ 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;
>  }
> 
> @@ -495,6 +517,9 @@ 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);

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