Document the DT bindings for the CSI2/CCP2 receiver peripheral
(known as Unicam) on BCM283x SoCs.
Signed-off-by: Dave Stevenson <dave.steven...@raspberrypi.org>
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+Broadcom BCM283x Camera Interface (Unicam)
+------------------------------------------
+
+The Unicam block on BCM283x SoCs is the receiver for either
+CSI-2 or CCP2 data from image sensors or similar devices.
+
+There are two camera drivers in the kernel for BCM283x - this one
+and bcm2835-camera (currently in staging).
+
+This driver is purely the kernel controlling the Unicam peripheral - there
+is no involvement with the VideoCore firmware. Unicam receives CSI-2
+(or CCP2) data and writes it into SDRAM. There is no additional processing
+performed.
+It should be possible to connect it to any sensor with a
+suitable output interface and V4L2 subdevice driver.
+
+bcm2835-camera uses the VideoCore firmware to control the sensor,
+Unicam, ISP, and various tuner control loops. Fully processed frames are
+delivered to the driver by the firmware. It only has sensor drivers
+for Omnivision OV5647, and Sony IMX219 sensors, and is closed source.
+
+The two drivers are mutually exclusive for the same Unicam instance.
+The firmware checks the device tree configuration during boot. If
+it finds device tree nodes called csi0 or csi1 then it will block the
+firmware from accessing the peripheral, and bcm2835-camera will
+not be able to stream data.
+It should be possible to use bcm2835-camera on one camera interface
+and bcm2835-unicam on the other interface if there is a need to.
+
+Required properties:
+===================
+- compatible : must be "brcm,bcm2835-unicam".
+- reg : physical base address and length of the register sets for the
+ device.
+- interrupts : should contain the IRQ line for this Unicam instance.
+- clocks : list of clock specifiers, corresponding to entries in
+ clock-names property.
+- clock-names : must contain an "lp_clock" entry, matching entries
+ in the clocks property.
+
+Unicam supports a single port node. It should contain one 'port' child node
+with child 'endpoint' node. Please refer to the bindings defined in
+Documentation/devicetree/bindings/media/video-interfaces.txt.
+
+Within the endpoint node, the following properties are mandatory:
+- remote-endpoint : links to the source device endpoint.
+- data-lanes : An array denoting how many data lanes are physically
+ present for this CSI-2 receiver instance. This can
+ be limited by either the SoC itself, or by the
+ breakout on the platform.
+ Lane reordering is not supported, so lanes must be
+ in order, starting at 1.
+
+Lane reordering is not supported on the clock lane, so the optional property
+"clock-lane" will implicitly be <0>.
+Similarly lane inversion is not supported, therefore "lane-polarities" will
+implicitly be <0 0 0 0 0>.
+Neither of these values will be checked.
+
+Example:
+ csi1: csi@7e801000 {
+ compatible = "brcm,bcm2835-unicam";
+ reg = <0x7e801000 0x800>,
+ <0x7e802004 0x4>;
+ interrupts = <2 7>;
+ clocks = <&clocks BCM2835_CLOCK_CAM1>;
+ clock-names = "lp_clock";
+
+ port {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ csi1_ep: endpoint {
+ remote-endpoint = <&tc358743_0>;
+ data-lanes = <1 2>;
+ };
+ };
+ };
+
+ i2c0: i2c@7e205000 {
+
+ tc358743: csi-hdmi-bridge@0f {
+ compatible = "toshiba,tc358743";
+ reg = <0x0f>;
+ status = "okay";
+
+ clocks = <&tc358743_clk>;
+ clock-names = "refclk";
+
+ tc358743_clk: bridge-clk {
+ compatible = "fixed-clock";
+ #clock-cells = <0>;
+ clock-frequency = <27000000>;
+ };
+
+ port {
+ tc358743_0: endpoint {
+ remote-endpoint = <&csi1_ep>;
+ clock-lanes = <0>;
+ data-lanes = <1 2>;
+ clock-noncontinuous;
+ link-frequencies =
+ /bits/ 64 <297000000>;
+ };
+ };
+ };
+ };
--
2.7.4
