Re: [PATCHv9 08/43] clk: ti: add composite clock support

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On 10/31/2013 06:32 PM, Nishanth Menon wrote:
On 10/31/2013 11:27 AM, Nishanth Menon wrote:
On 10/25/2013 10:57 AM, Tero Kristo wrote:
This is a multipurpose clock node, which contains support for multiple
sub-clocks. Uses basic composite clock type to implement the actual
functionality, and TI specific gate, mux and divider clocks.

Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
  .../devicetree/bindings/clock/ti/composite.txt     |   54 +++++
  drivers/clk/ti/Makefile                            |    2 +-
  drivers/clk/ti/composite.c                         |  222 ++++++++++++++++++++
  include/linux/clk/ti.h                             |    8 +
  4 files changed, 285 insertions(+), 1 deletion(-)
  create mode 100644 Documentation/devicetree/bindings/clock/ti/composite.txt
  create mode 100644 drivers/clk/ti/composite.c

diff --git a/Documentation/devicetree/bindings/clock/ti/composite.txt b/Documentation/devicetree/bindings/clock/ti/composite.txt
new file mode 100644
index 0000000..5f43c47
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/ti/composite.txt
@@ -0,0 +1,54 @@
+Binding for TI composite clock.
+
+Binding status: Unstable - ABI compatibility may be broken in the future
+
+This binding uses the common clock binding[1]. It assumes a
+register-mapped composite clock with multiple different sub-types;
+
+a multiplexer clock with multiple input clock signals or parents, one
+of which can be selected as output, this behaves exactly as [2]
+
+an adjustable clock rate divider, this behaves exactly as [3]
+
+a gating function which can be used to enable and disable the output
+clock, this behaves exactly as [4]
+
+The binding must provide a list of the component clocks that shall be
+merged to this clock. The component clocks shall be of one of the
+"ti,*composite*-clock" types.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/clock/ti/mux.txt
+[3] Documentation/devicetree/bindings/clock/ti/divider.txt
+[4] Documentation/devicetree/bindings/clock/ti/gate.txt
+
+Required properties:
+- compatible : shall be: "ti,composite-clock"
+- clocks : link phandles of component clocks
+- #clock-cells : from common clock binding; shall be set to 0.
+
+Examples:
+
+usb_l4_gate_ick: usb_l4_gate_ick {
+	#clock-cells = <0>;
+	compatible = "ti,composite-interface-clock";
+	clocks = <&l4_ick>;
+	ti,bit-shift = <5>;
+	reg = <0x0a10>;
+};
+
+usb_l4_div_ick: usb_l4_div_ick {
+	#clock-cells = <0>;
+	compatible = "ti,composite-divider-clock";
+	clocks = <&l4_ick>;
+	ti,bit-shift = <4>;
+	ti,max-div = <1>;
+	reg = <0x0a40>;
+	ti,index-starts-at-one;
+};
+
+usb_l4_ick: usb_l4_ick {
+	#clock-cells = <0>;
+	compatible = "ti,composite-clock";
+	clocks = <&usb_l4_gate_ick>, <&usb_l4_div_ick>;
+};

 From Topology perspective, would this be a better approach?

usb_l4_ick: usb_l4_ick {
	#clock-cells = <0>;
	compatible = "ti,composite-clock";

	usb_l4_gate_ick: usb_l4_gate_ick {
		#clock-cells = <0>;
		compatible = "ti,composite-interface-clock";
		clocks = <&l4_ick>;
		ti,bit-shift = <5>;
		reg = <0x0a10>;
	};

	usb_l4_div_ick: usb_l4_div_ick {
		#clock-cells = <0>;
		compatible = "ti,composite-divider-clock";
		clocks = <&l4_ick>;
		ti,bit-shift = <4>;
		ti,max-div = <1>;
		reg = <0x0a40>;
		ti,index-starts-at-one;
	};
};

Well I was considering this, however this would require extra level of registration also:

of_ti_composite_clk_setup ->
  (match children against composite types)
  of_ti_composite_divider_setup
  of_ti_composite_gate_setup

Might be cleaner overall though, so I can take a look at this.

-Tero
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