Messages in this thread | | | Date | Mon, 21 Nov 2011 23:37:18 +0800 | From | Shawn Guo <> | Subject | Re: [RFC 6/8] of: add clock providers |
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On Tue, Nov 08, 2011 at 06:19:41PM -0700, Grant Likely wrote: > Based on work by Ben Herrenschmidt and Jeremy Kerr, this patch adds an > of_clk_get function to allow platforms to retrieve clock data from the > device tree. > > Platform register a provider through of_clk_add_provider, which will be > called when a device references the provider's OF node for a clock > reference. > > Signed-off-by: Grant Likely <grant.likely@secretlab.ca> > --- > .../devicetree/bindings/clock/clock-bindings.txt | 109 +++++++++++++++++ > drivers/of/Kconfig | 6 + > drivers/of/Makefile | 1 + > drivers/of/clock.c | 129 ++++++++++++++++++++ > include/linux/of_clk.h | 37 ++++++ > 5 files changed, 282 insertions(+), 0 deletions(-) > create mode 100644 Documentation/devicetree/bindings/clock/clock-bindings.txt > create mode 100644 drivers/of/clock.c > create mode 100644 include/linux/of_clk.h > > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > new file mode 100644 > index 0000000..4770c7e > --- /dev/null > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > @@ -0,0 +1,109 @@ > +This binding is a work-in-progress, and are based on some experimental > +work by benh[1]. > + > +Sources of clock signal can be represented by any node in the device > +tree. Those nodes are designated as clock providers. Clock consumer > +nodes use a phandle and clock specifier pair to connect clock provider > +outputs to clock inputs. Similar to the gpio specifiers, a clock > +specifier is an array of one more more cells identifying the clock > +output on a device. The length of a clock specifier is defined by the > +value of a #clock-cells property in the clock provider node. > + > +[1] http://patchwork.ozlabs.org/patch/31551/ > + > +==Clock providers== > + > +Required properties: > +#clock-cells: Number of cells in a clock specifier; typically will be > + set to 1 > + > +Optional properties: > +clock-output-name: Recommended to be a list of strings of clock output signal > + names indexed by the first cell in the clock specifier. > + However, the meaning of clock-output-names is domain
s/clock-output-names/clock-output-name?
> + specific to the clock provider, and is only provided to > + encourage using the same meaning for the majority of clock > + providers. This format may not work for clock providers > + using a complex clock specifier format. In those cases it > + is recommended to omit this property and create a binding > + specific names property. > + > + Clock consumer nodes must never directly reference > + the provider's clock-output-names property.
s/clock-output-names/clock-output-name?
> + > +For example: > + > + oscillator { > + #clock-cells = <1>; > + clock-output-name = "ckil", "ckih"; > + }; > + > +- this node defines a device with two clock outputs, the first named > + "ckil" and the second named "ckih". Consumer nodes always reference > + clocks by index. The names should reflect the clock output signal > + names for the device. > + > +==Clock consumers== > + > +Required properties: > +clock-input: List of phandle and clock specifier pairs, one pair > + for each clock input to the device. > +clock-input-name: List of clock input name strings sorted in the same > + order as the clock-input property. Consumers drivers > + will use clock-input-name to match clock input names > + with clock-input specifiers. > + > +For example: > + > + uart { > + clock-input = <&osc 1> <&ref 0>; ^ Comma is missed?
> + clock-input-name = "baud", "register"; > + };
[...]
> +struct clk *of_clk_get(struct device_node *np, int index) > +{ > + struct of_phandle_args clkspec; > + struct clk *clk; > + int rc; > + > + if (index < 0) > + return NULL; > + > + rc = of_parse_phandle_with_args(np, "clock", "#clock-cells", index,
According to binding document above, s/clock/clock-input?
> + &clkspec); > + if (rc) > + return NULL; > + > + clk = __of_clk_get_from_provider(&clkspec); > + of_node_put(clkspec.np); > + return clk; > +} > + > +struct clk *of_clk_get_by_name(struct device_node *np, const char *name) > +{ > + int index = 0; > + > + if (name) > + index = of_property_match_string(np, "clock-input-names", name);
If it fails to match name, we may want to force 'index' back to 0.
Also according to binding document above, s/clock-input-names/clock-input-name? Hope you do not want to change binding document to get them aligned. I have written code per binding document :)
Regards, Shawn
> + return of_clk_get(np, index); > +}
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