Hi Ramesh,
On Wed, Oct 12, 2016 at 4:10 PM, Ramesh Shanmugasundaram
<ramesh.shanmugasunda...@bp.renesas.com> wrote:
> This patch adds Digital Radio Interface (DRIF) support to R-Car Gen3 SoCs.
> The driver exposes each instance of DRIF as a V4L2 SDR device. A DRIF
> device represents a channel and each channel can have one or two
> sub-channels respectively depending on the target board.
>
> DRIF supports only Rx functionality. It receives samples from a RF
> frontend tuner chip it is interfaced with. The combination of DRIF and the
> tuner device, which is registered as a sub-device, determines the receive
> sample rate and format.
>
> In order to be compliant as a V4L2 SDR device, DRIF needs to bind with
> the tuner device, which can be provided by a third party vendor. DRIF acts
> as a slave device and the tuner device acts as a master transmitting the
> samples. The driver allows asynchronous binding of a tuner device that
> is registered as a v4l2 sub-device. The driver can learn about the tuner
> it is interfaced with based on port endpoint properties of the device in
> device tree. The V4L2 SDR device inherits the controls exposed by the
> tuner device.
>
> The device can also be configured to use either one or both of the data
> pins at runtime based on the master (tuner) configuration.
Thanks for your patch!
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/renesas,drif.txt
> @@ -0,0 +1,109 @@
> +Renesas R-Car Gen3 DRIF controller (DRIF)
> +-----------------------------------------
> +
> +Required properties:
> +--------------------
> +- compatible: "renesas,drif-r8a7795" if DRIF controller is a part of R8A7795
> SoC.
"renesas,r8a7795-drif", as Rob already pointed out.
> + "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 each sub-channel.
> +- interrupts: associated with each sub-channel.
> +- clocks: phandles and clock specifiers for each sub-channel.
> +- clock-names: clock input name strings: "fck0", "fck1".
> +- pinctrl-0: pin control group to be used for this controller.
> +- pinctrl-names: must be "default".
> +- dmas: phandles to the DMA channels for each sub-channel.
> +- dma-names: names for the DMA channels: "rx0", "rx1".
> +
> +Required child nodes:
> +---------------------
> +- Each DRIF channel can have one or both of the sub-channels enabled in a
> + setup. The sub-channels are represented as a child node. The name of the
> + child nodes are "sub-channel0" and "sub-channel1" respectively. Each child
> + node supports the "status" property only, which is used to enable/disable
> + the respective sub-channel.
> +Example
> +--------
> +
> +SoC common dtsi file
> +
> +drif0: rif@e6f40000 {
> + compatible = "renesas,drif-r8a7795",
> + "renesas,rcar-gen3-drif";
> + reg = <0 0xe6f40000 0 0x64>, <0 0xe6f50000 0 0x64>;
> + interrupts = <GIC_SPI 12 IRQ_TYPE_LEVEL_HIGH>,
> + <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>;
> + clocks = <&cpg CPG_MOD 515>, <&cpg CPG_MOD 514>;
> + clock-names = "fck0", "fck1";
> + dmas = <&dmac1 0x20>, <&dmac1 0x22>;
> + dma-names = "rx0", "rx1";
I could not find the DMAC channels in the datasheet?
Most modules are either tied to dmac0, or two both dmac1 and dmac2.
In the latter case, you want to list two sets of dmas, one for each DMAC.
> + power-domains = <&sysc R8A7795_PD_ALWAYS_ON>;
> + status = "disabled";
> +
> + sub-channel0 {
> + status = "disabled";
> + };
> +
> + sub-channel1 {
> + status = "disabled";
> + };
> +
> +};
As you're modelling this in DT under a single device node, this means you
cannot use runtime PM to manage the module clocks of the individual channels.
An alternative could be to have two separate nodes for each channel,
and tie them together using a phandle.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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