[PATCH] serial: 8250_dw: add ability to handle the peripheral clock
From: heiko@sntech.de (Heiko Stübner)
Date: 2014-06-16 13:26:05
Also in:
linux-devicetree, linux-serial, lkml
Subsystem:
8250/16?50 (and clone uarts) serial driver, open firmware and flattened device tree bindings, synopsys designware 8250 uart driver, the rest, tty layer and serial drivers · Maintainers:
Greg Kroah-Hartman, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Ilpo Järvinen, Linus Torvalds, Jiri Slaby
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 at 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 at 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