On Tue, Feb 07, 2017 at 03:02:36PM +0000, Ramesh Shanmugasundaram wrote:
> Add binding documentation for Renesas R-Car Digital Radio Interface
> (DRIF) controller.
>
> Signed-off-by: Ramesh Shanmugasundaram
> <ramesh.shanmugasunda...@bp.renesas.com>
> ---
> .../devicetree/bindings/media/renesas,drif.txt | 186
> +++++++++++++++++++++
> 1 file changed, 186 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/media/renesas,drif.txt
>
> diff --git a/Documentation/devicetree/bindings/media/renesas,drif.txt
> b/Documentation/devicetree/bindings/media/renesas,drif.txt
> new file mode 100644
> index 0000000..6315609
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/renesas,drif.txt
> @@ -0,0 +1,186 @@
> +Renesas R-Car Gen3 Digital Radio Interface controller (DRIF)
> +------------------------------------------------------------
> +
> +R-Car Gen3 DRIF is a SPI like receive only slave device. A general
> +representation of DRIF interfacing with a master device is shown below.
> +
> ++---------------------+ +---------------------+
> +| |-----SCK------->|CLK |
> +| Master |-----SS-------->|SYNC DRIFn (slave) |
> +| |-----SD0------->|D0 |
> +| |-----SD1------->|D1 |
> ++---------------------+ +---------------------+
> +
> +As per the datasheet, each DRIF channel (drifn) is made up of two internal
> +channels (drifn0 & drifn1). These two internal channels share the common
> +CLK & SYNC. Each internal channel has its own dedicated resources like
> +irq, dma channels, address space & clock. This internal split is not
> +visible to the external master device.
> +
> +The device tree model represents each internal channel as a separate node.
> +The internal channels sharing the CLK & SYNC are tied together by their
> +phandles using a new property called "renesas,bonding". For the rest of
> +the documentation, unless explicitly stated, the word channel implies an
> +internal channel.
> +
> +When both internal channels are enabled they need to be managed together
> +as one (i.e.) they cannot operate alone as independent devices. Out of the
> +two, one of them needs to act as a primary device that accepts common
> +properties of both the internal channels. This channel is identified by a
> +new property called "renesas,primary-bond".
> +
> +To summarize,
> + - When both the internal channels that are bonded together are enabled,
> + the zeroth channel is selected as primary-bond. This channels accepts
> + properties common to all the members of the bond.
> + - When only one of the bonded channels need to be enabled, the property
> + "renesas,bonding" or "renesas,primary-bond" will have no effect. That
> + enabled channel can act alone as any other independent device.
> +
> +Required properties of an internal channel:
> +-------------------------------------------
> +- compatible: "renesas,r8a7795-drif" if DRIF controller is a part of R8A7795
> SoC.
> + "renesas,rcar-gen3-drif" for a generic R-Car Gen3 compatible
> device.
> + When compatible with the generic version, nodes must list the
> + SoC-specific version corresponding to the platform first
> + followed by the generic version.
> +- reg: offset and length of that channel.
> +- interrupts: associated with that channel.
> +- clocks: phandle and clock specifier of that channel.
> +- clock-names: clock input name string: "fck".
> +- dmas: phandles to the DMA channels.
> +- dma-names: names of the DMA channel: "rx".
> +- renesas,bonding: phandle to the other channel.
> +
> +Optional properties of an internal channel:
> +-------------------------------------------
> +- power-domains: phandle to the respective power domain.
> +
> +Required properties of an internal channel when:
> + - It is the only enabled channel of the bond (or)
> + - If it acts as primary among enabled bonds
> +--------------------------------------------------------
> +- pinctrl-0: pin control group to be used for this channel.
> +- pinctrl-names: must be "default".
> +- renesas,primary-bond: empty property indicating the channel acts as primary
> + among the bonded channels.
> +- port: child port node of a channel that defines the local and remote
> + endpoints. The remote endpoint is assumed to be a third party tuner
> + device endpoint.
> +
> +Optional endpoint property:
> +---------------------------
> +- renesas,sync-active : Indicates sync signal polarity, 0/1 for low/high
> + respectively. This property maps to SYNCAC bit in the
> + hardware manual. The default is 1 (active high)
Why does this belong in the endpoint? I'd prefer to not have vendor
specific properties in endpoints. Is this a property of the tuner or
DRIF?
> +
> +Example
> +--------
> +
> +SoC common dtsi file
> +
> + drif00: rif@e6f40000 {
> + compatible = "renesas,r8a7795-drif",
> + "renesas,rcar-gen3-drif";
> + reg = <0 0xe6f40000 0 0x64>;
> + interrupts = <GIC_SPI 12 IRQ_TYPE_LEVEL_HIGH>;
> + clocks = <&cpg CPG_MOD 515>;
> + clock-names = "fck";
> + dmas = <&dmac1 0x20>, <&dmac2 0x20>;
> + dma-names = "rx", "rx";
> + power-domains = <&sysc R8A7795_PD_ALWAYS_ON>;
> + renesas,bonding = <&drif01>;
> + status = "disabled";
Don't put "status" in examples.
> + };
> +
> + drif01: rif@e6f50000 {
> + compatible = "renesas,r8a7795-drif",
> + "renesas,rcar-gen3-drif";
> + reg = <0 0xe6f50000 0 0x64>;
> + interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>;
> + clocks = <&cpg CPG_MOD 514>;
> + clock-names = "fck";
> + dmas = <&dmac1 0x22>, <&dmac2 0x22>;
> + dma-names = "rx", "rx";
> + power-domains = <&sysc R8A7795_PD_ALWAYS_ON>;
> + renesas,bonding = <&drif00>;
> + status = "disabled";
> + };
> +
> +
> +Board specific dts file
Chip vs. board in not relevant to the binding doc. Please combine them
here in your example.
Rob
