serial: 8250_dw: add ability to handle the peripheral clock
From: Heiko Stuebner <heiko@...> Date: Mon, 16 Jun 2014 15:14:49 +0200
Commit-Message
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@...>
Patch-Comment
.../bindings/serial/snps-dw-apb-uart.txt | 31 ++++++++++++++++++++++ drivers/tty/serial/8250/8250_dw.c | 31 +++++++++++++++++++--- 2 files changed, 59 insertions(+), 3 deletions(-)
Statistics
- 59 lines added
- 3 lines removed
Changes
-------- Documentation/devicetree/bindings/serial/snps-dw-apb-uart.txt ---------
index f13f1c5..3601399 100644
@@ -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 -----------------------
index 51b307a..024cd58 100644
@@ -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, "baudclk");
+ if (IS_ERR(data->clk))
+ data->clk = devm_clk_get(&pdev->dev, NULL);
if (!IS_ERR(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);