On Tue, May 05, 2015 at 05:41:16PM +0200, Matthias Brugger wrote:
> 2015-04-27 8:49 GMT+02:00 Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>:
> > The mtk 8250 needs two clocks, one for providing the baudrate and
> > one that needs to be enabled for register accesses. The latter has
> > not been supported, this patch adds support for it. It is optional
> > for now since not all SoCs provide a bus clock.
> >
> > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > ---
> > .../devicetree/bindings/serial/mtk-uart.txt | 12 ++++++++--
> > drivers/tty/serial/8250/8250_mtk.c | 28 ++++++++++++++++++----
> > 2 files changed, 34 insertions(+), 6 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/serial/mtk-uart.txt b/Documentation/devicetree/bindings/serial/mtk-uart.txt
> > index 4415226..8d63f1d 100644
> > --- a/Documentation/devicetree/bindings/serial/mtk-uart.txt
> > +++ b/Documentation/devicetree/bindings/serial/mtk-uart.txt
> > @@ -14,7 +14,14 @@ Required properties:
> >
> > - interrupts: A single interrupt specifier.
> >
> > -- clocks: Clock driving the hardware.
> > +- clocks : Must contain an entry for each entry in clock-names.
> > + See ../clocks/clock-bindings.txt for details.
> > +- clock-names:
> > + - "baud": The clock the baudrate is derived from
> > + - "bus": The bus clock for register accesses (optional)
> > +
> > +For compatibility with older device trees an unnamed clock is used for the
> > +baud clock if the baudclk does not exist. Do not use this for new designs.
> >
> > Example:
> >
> > @@ -22,5 +29,6 @@ Example:
> > compatible = "mediatek,mt6589-uart", "mediatek,mt6577-uart";
> > reg = <0x11006000 0x400>;
> > interrupts = <GIC_SPI 51 IRQ_TYPE_LEVEL_LOW>;
> > - clocks = <&uart_clk>;
> > + clocks = <&uart_clk>, <&bus_clk>;
> > + clock-names = "baud", "bus";
> > };
> > diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> > index 2f28bd0..8eb3876 100644
> > --- a/drivers/tty/serial/8250/8250_mtk.c
> > +++ b/drivers/tty/serial/8250/8250_mtk.c
> > @@ -34,6 +34,7 @@
> > struct mtk8250_data {
> > int line;
> > struct clk *uart_clk;
> > + struct clk *bus_clk;
> > };
>
> Not sure if it would be better to rename the uart_clk to baud_clk
> which reflects the new naming scheme.
Can do.
>
> >
> > static void
> > @@ -120,6 +121,7 @@ static int mtk8250_runtime_suspend(struct device *dev)
> > struct mtk8250_data *data = dev_get_drvdata(dev);
> >
> > clk_disable_unprepare(data->uart_clk);
> > + clk_disable_unprepare(data->bus_clk);
>
> bus_clk can be NULL.
The clk core handles NULL clks just fine. They are considered dummy
clks. You can prepare/enable them, clk_get_rate of course returns
nothing useful.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
