Subject: [PATCH v5 3/3] Documentation: Add documentation for APM X-Gene clock binding

From: [email-masked] (Mike Turquette)
Date: Thu, 25 Jul 2013 13:59:53 -0700

Quoting Loc Ho (2013-06-26 10:56:11)
> Documentation: Add documentation for APM X-Gene clock binding with PLL and
> device clocks.
> 
> Signed-off-by: Loc Ho <[email-masked]>
> Signed-off-by: Kumar Sankaran <[email-masked]>
> Signed-off-by: Vinayak Kale <[email-masked]>
> Signed-off-by: Feng Kan <[email-masked]>
> ---
>  Documentation/devicetree/bindings/clock/xgene.txt |  111 +++++++++++++++++++++
>  1 files changed, 111 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/clock/xgene.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/xgene.txt b/Documentation/devicetree/bindings/clock/xgene.txt
> new file mode 100644
> index 0000000..1c4ef77
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/xgene.txt
> @@ -0,0 +1,111 @@
> +Device Tree Clock bindings for APM X-Gene
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible : shall be one of the following:
> +       "apm,xgene-socpll-clock" - for a X-Gene SoC PLL clock
> +       "apm,xgene-pcppll-clock" - for a X-Gene PCP PLL clock
> +       "apm,xgene-device-clock" - for a X-Gene device clock
> +
> +Required properties for SoC or PCP PLL clocks:
> +- reg : shall be the physical PLL register address for the pll clock.
> +- clocks : shall be the input parent clock phandle for the clock. This should
> +       be the reference clock.
> +- #clock-cells : shall be set to 1.
> +- clock-output-names : shall be the name of the PLL referenced by derive
> +  clock.
> +Optional properties for PLL clocks:
> +- clock-names : shall be the name of the PLL. If missing, use the device name.
> +
> +Required properties for device clocks:
> +- reg : shall be a list of address and length pairs describing the CSR
> +         reset and/or the divider. Either may be omitted, but at least
> +         one must be present.
> + - reg-names : shall be a string list describing the reg resource. This
> +               may include "csr-reg" and/or "div-reg". If this property
> +               is not present, the reg property is assumed to describe
> +               only "csr-reg".

Where is reg-names used? I see it used in your DTS but I don't see
clk-xgene.c doing anything with it.

> +- clocks : shall be the input parent clock phandle for the clock.
> +- #clock-cells : shall be set to 1.
> +- clock-output-names : shall be the name of the device referenced.
> +Optional properties for device clocks:
> +- clock-names : shall be the name of the device clock. If missing, use the
> +                device name.
> +- csr-offset : Offset to the CSR reset register from the reset address base.
> +               Default is 0.
> +- csr-mask : CSR reset mask bit. Default is 0xF.
> +- enable-offset : Offset to the enable register from the reset address base.
> +                  Default is 0x8.
> +- enable-mask : CSR enable mask bit. Default is 0xF.
> +- divider-offset : Offset to the divider CSR register from the divider base.
> +                   Default is 0x0.
> +- divider-width : Width of the divider register. Default is 0.
> +- divider-shift : Bit shift of the divider register. Default is 0.

There is a general push to not have register-level details in DT. How
many clocks do you think you'll end up defining in the future? If you
have a lot then this binding could grow fairly large.

Regards,
Mike

> +
> +For example:
> +
> +       pcppll: pcppll at 17000100 {
> +               compatible = "apm,xgene-pcppll-clock";
> +               #clock-cells = <1>;
> +               clocks = <&refclk 0>;
> +               clock-names = "pcppll";
> +               reg = <0x0 0x17000100 0x0 0x1000>;
> +               clock-output-names = "pcppll";
> +               type = <0>;
> +       };
> +
> +       socpll: socpll at 17000120 {
> +               compatible = "apm,xgene-socpll-clock";
> +               #clock-cells = <1>;
> +               clocks = <&refclk 0>;
> +               clock-names = "socpll";
> +               reg = <0x0 0x17000120 0x0 0x1000>;
> +               clock-output-names = "socpll";
> +               type = <1>;
> +       };
> +
> +       qmlclk: qmlclk {
> +               compatible = "apm,xgene-device-clock";
> +               #clock-cells = <1>;
> +               clocks = <&socplldiv2 0>;
> +               clock-names = "qmlclk";
> +               reg = <0x0 0x1703C000 0x0 0x1000>;
> +               reg-name = "csr-reg";
> +               clock-output-names = "qmlclk";
> +       };
> +
> +       ethclk: ethclk {
> +               compatible = "apm,xgene-device-clock";
> +               #clock-cells = <1>;
> +               clocks = <&socplldiv2 0>;
> +               clock-names = "ethclk";
> +               reg = <0x0 0x17000000 0x0 0x1000>;
> +               reg-names = "div-reg";
> +               divider-offset = <0x238>;
> +               divider-width = <0x9>;
> +               divider-shift = <0x0>;
> +               clock-output-names = "ethclk";
> +       };
> +
> +       apbclk: apbclk {
> +               compatible = "apm,xgene-device-clock";
> +               #clock-cells = <1>;
> +               clocks = <&ahbclk 0>;
> +               clock-names = "apbclk";
> +               reg = <0x0 0x1F2AC000 0x0 0x1000
> +                       0x0 0x1F2AC000 0x0 0x1000>;
> +               reg-names = "csr-reg", "div-reg";
> +               csr-offset = <0x0>;
> +               csr-mask = <0x200>;
> +               enable-offset = <0x8>;
> +               enable-mask = <0x200>;
> +               divider-offset = <0x10>;
> +               divider-width = <0x2>;
> +               divider-shift = <0x0>;
> +               flags = <0x8>;
> +               clock-output-names = "apbclk";
> +       };
> +
> -- 
> 1.5.5