Re: [PATCH v5 6/7] dt-bindings: media: Add Renesas R-Car DRIF binding

[Rob Herring]

On Tue, May 9, 2017 at 8:37 AM, Ramesh Shanmugasundaram
 wrote:
> Add binding documentation for Renesas R-Car Digital Radio Interface
> (DRIF) controller.
>
> Signed-off-by: Ramesh Shanmugasundaram 
> 
> ---
> v5:
>  - Addressed Rob's comments on v4:
> - Formatted compatible string entries.
> - Removed "status".
> - Removed board and SoC specific bindings classification example.
> - Removed pinctrl nodes.
> ---
>  .../devicetree/bindings/media/renesas,drif.txt | 177 
> +
>  1 file changed, 177 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/renesas,drif.txt

Acked-by: Rob Herring 

[PATCH v5 6/7] dt-bindings: media: Add Renesas R-Car DRIF binding

[Ramesh Shanmugasundaram]

Add binding documentation for Renesas R-Car Digital Radio Interface
(DRIF) controller.

Signed-off-by: Ramesh Shanmugasundaram 
---
v5:
 - Addressed Rob's comments on v4:
- Formatted compatible string entries.
- Removed "status".
- Removed board and SoC specific bindings classification example.
- Removed pinctrl nodes.
---
 .../devicetree/bindings/media/renesas,drif.txt | 177 +
 1 file changed, 177 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 ..ec718c8bd937
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/renesas,drif.txt
@@ -0,0 +1,177 @@
+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 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 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
+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 corresponding to the data input, in accordance with
+   the video interface bindings defined in
+   Documentation/devicetree/bindings/media/video-interfaces.txt. The port
+   node must contain at least one endpoint.
+
+Optional endpoint property:
+---
+- 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).
+
+Example:
+
+
+(1) Both internal channels enabled:
+---
+
+When interfacing with a third party tuner