276 lines
9.9 KiB
Plaintext
276 lines
9.9 KiB
Plaintext
Common bindings for video receiver and transmitter interfaces
|
|
|
|
General concept
|
|
---------------
|
|
|
|
Video data pipelines usually consist of external devices, e.g. camera sensors,
|
|
controlled over an I2C, SPI or UART bus, and SoC internal IP blocks, including
|
|
video DMA engines and video data processors.
|
|
|
|
SoC internal blocks are described by DT nodes, placed similarly to other SoC
|
|
blocks. External devices are represented as child nodes of their respective
|
|
bus controller nodes, e.g. I2C.
|
|
|
|
Data interfaces on all video devices are described by their child 'port' nodes.
|
|
Configuration of a port depends on other devices participating in the data
|
|
transfer and is described by 'endpoint' subnodes.
|
|
|
|
device {
|
|
...
|
|
ports {
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
port@0 {
|
|
...
|
|
endpoint@0 { ... };
|
|
endpoint@1 { ... };
|
|
};
|
|
port@1 { ... };
|
|
};
|
|
};
|
|
|
|
If a port can be configured to work with more than one remote device on the same
|
|
bus, an 'endpoint' child node must be provided for each of them. If more than
|
|
one port is present in a device node or there is more than one endpoint at a
|
|
port, or port node needs to be associated with a selected hardware interface,
|
|
a common scheme using '#address-cells', '#size-cells' and 'reg' properties is
|
|
used.
|
|
|
|
All 'port' nodes can be grouped under optional 'ports' node, which allows to
|
|
specify #address-cells, #size-cells properties independently for the 'port'
|
|
and 'endpoint' nodes and any child device nodes a device might have.
|
|
|
|
Two 'endpoint' nodes are linked with each other through their 'remote-endpoint'
|
|
phandles. An endpoint subnode of a device contains all properties needed for
|
|
configuration of this device for data exchange with other device. In most
|
|
cases properties at the peer 'endpoint' nodes will be identical, however they
|
|
might need to be different when there is any signal modifications on the bus
|
|
between two devices, e.g. there are logic signal inverters on the lines.
|
|
|
|
It is allowed for multiple endpoints at a port to be active simultaneously,
|
|
where supported by a device. For example, in case where a data interface of
|
|
a device is partitioned into multiple data busses, e.g. 16-bit input port
|
|
divided into two separate ITU-R BT.656 8-bit busses. In such case bus-width
|
|
and data-shift properties can be used to assign physical data lines to each
|
|
endpoint node (logical bus).
|
|
|
|
Documenting bindings for devices
|
|
--------------------------------
|
|
|
|
All required and optional bindings the device supports shall be explicitly
|
|
documented in device DT binding documentation. This also includes port and
|
|
endpoint nodes for the device, including unit-addresses and reg properties where
|
|
relevant.
|
|
|
|
Please also see Documentation/devicetree/bindings/graph.txt .
|
|
|
|
Required properties
|
|
-------------------
|
|
|
|
If there is more than one 'port' or more than one 'endpoint' node or 'reg'
|
|
property is present in port and/or endpoint nodes the following properties
|
|
are required in a relevant parent node:
|
|
|
|
- #address-cells : number of cells required to define port/endpoint
|
|
identifier, should be 1.
|
|
- #size-cells : should be zero.
|
|
|
|
|
|
Optional properties
|
|
-------------------
|
|
|
|
- flash-leds: An array of phandles, each referring to a flash LED, a sub-node
|
|
of the LED driver device node.
|
|
|
|
- lens-focus: A phandle to the node of the focus lens controller.
|
|
|
|
- rotation: The device, typically an image sensor, is not mounted upright,
|
|
but a number of degrees counter clockwise. Typical values are 0 and 180
|
|
(upside down).
|
|
|
|
|
|
Optional endpoint properties
|
|
----------------------------
|
|
|
|
- remote-endpoint: phandle to an 'endpoint' subnode of a remote device node.
|
|
- slave-mode: a boolean property indicating that the link is run in slave mode.
|
|
The default when this property is not specified is master mode. In the slave
|
|
mode horizontal and vertical synchronization signals are provided to the
|
|
slave device (data source) by the master device (data sink). In the master
|
|
mode the data source device is also the source of the synchronization signals.
|
|
- bus-type: data bus type. Possible values are:
|
|
1 - MIPI CSI-2 C-PHY
|
|
2 - MIPI CSI1
|
|
3 - CCP2
|
|
4 - MIPI CSI-2 D-PHY
|
|
5 - Parallel
|
|
6 - Bt.656
|
|
- bus-width: number of data lines actively used, valid for the parallel busses.
|
|
- data-shift: on the parallel data busses, if bus-width is used to specify the
|
|
number of data lines, data-shift can be used to specify which data lines are
|
|
used, e.g. "bus-width=<8>; data-shift=<2>;" means, that lines 9:2 are used.
|
|
- hsync-active: active state of the HSYNC signal, 0/1 for LOW/HIGH respectively.
|
|
- vsync-active: active state of the VSYNC signal, 0/1 for LOW/HIGH respectively.
|
|
Note, that if HSYNC and VSYNC polarities are not specified, embedded
|
|
synchronization may be required, where supported.
|
|
- data-active: similar to HSYNC and VSYNC, specifies data line polarity.
|
|
- data-enable-active: similar to HSYNC and VSYNC, specifies the data enable
|
|
signal polarity.
|
|
- field-even-active: field signal level during the even field data transmission.
|
|
- pclk-sample: sample data on rising (1) or falling (0) edge of the pixel clock
|
|
signal.
|
|
- sync-on-green-active: active state of Sync-on-green (SoG) signal, 0/1 for
|
|
LOW/HIGH respectively.
|
|
- data-lanes: an array of physical data lane indexes. Position of an entry
|
|
determines the logical lane number, while the value of an entry indicates
|
|
physical lane, e.g. for 2-lane MIPI CSI-2 bus we could have
|
|
"data-lanes = <1 2>;", assuming the clock lane is on hardware lane 0.
|
|
If the hardware does not support lane reordering, monotonically
|
|
incremented values shall be used from 0 or 1 onwards, depending on
|
|
whether or not there is also a clock lane. This property is valid for
|
|
serial busses only (e.g. MIPI CSI-2).
|
|
- clock-lanes: an array of physical clock lane indexes. Position of an entry
|
|
determines the logical lane number, while the value of an entry indicates
|
|
physical lane, e.g. for a MIPI CSI-2 bus we could have "clock-lanes = <0>;",
|
|
which places the clock lane on hardware lane 0. This property is valid for
|
|
serial busses only (e.g. MIPI CSI-2). Note that for the MIPI CSI-2 bus this
|
|
array contains only one entry.
|
|
- clock-noncontinuous: a boolean property to allow MIPI CSI-2 non-continuous
|
|
clock mode.
|
|
- link-frequencies: Allowed data bus frequencies. For MIPI CSI-2, for
|
|
instance, this is the actual frequency of the bus, not bits per clock per
|
|
lane value. An array of 64-bit unsigned integers.
|
|
- lane-polarities: an array of polarities of the lanes starting from the clock
|
|
lane and followed by the data lanes in the same order as in data-lanes.
|
|
Valid values are 0 (normal) and 1 (inverted). The length of the array
|
|
should be the combined length of data-lanes and clock-lanes properties.
|
|
If the lane-polarities property is omitted, the value must be interpreted
|
|
as 0 (normal). This property is valid for serial busses only.
|
|
- strobe: Whether the clock signal is used as clock (0) or strobe (1). Used
|
|
with CCP2, for instance.
|
|
|
|
Example
|
|
-------
|
|
|
|
The example snippet below describes two data pipelines. ov772x and imx074 are
|
|
camera sensors with a parallel and serial (MIPI CSI-2) video bus respectively.
|
|
Both sensors are on the I2C control bus corresponding to the i2c0 controller
|
|
node. ov772x sensor is linked directly to the ceu0 video host interface.
|
|
imx074 is linked to ceu0 through the MIPI CSI-2 receiver (csi2). ceu0 has a
|
|
(single) DMA engine writing captured data to memory. ceu0 node has a single
|
|
'port' node which may indicate that at any time only one of the following data
|
|
pipelines can be active: ov772x -> ceu0 or imx074 -> csi2 -> ceu0.
|
|
|
|
ceu0: ceu@fe910000 {
|
|
compatible = "renesas,sh-mobile-ceu";
|
|
reg = <0xfe910000 0xa0>;
|
|
interrupts = <0x880>;
|
|
|
|
mclk: master_clock {
|
|
compatible = "renesas,ceu-clock";
|
|
#clock-cells = <1>;
|
|
clock-frequency = <50000000>; /* Max clock frequency */
|
|
clock-output-names = "mclk";
|
|
};
|
|
|
|
port {
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
/* Parallel bus endpoint */
|
|
ceu0_1: endpoint@1 {
|
|
reg = <1>; /* Local endpoint # */
|
|
remote = <&ov772x_1_1>; /* Remote phandle */
|
|
bus-width = <8>; /* Used data lines */
|
|
data-shift = <2>; /* Lines 9:2 are used */
|
|
|
|
/* If hsync-active/vsync-active are missing,
|
|
embedded BT.656 sync is used */
|
|
hsync-active = <0>; /* Active low */
|
|
vsync-active = <0>; /* Active low */
|
|
data-active = <1>; /* Active high */
|
|
pclk-sample = <1>; /* Rising */
|
|
};
|
|
|
|
/* MIPI CSI-2 bus endpoint */
|
|
ceu0_0: endpoint@0 {
|
|
reg = <0>;
|
|
remote = <&csi2_2>;
|
|
};
|
|
};
|
|
};
|
|
|
|
i2c0: i2c@fff20000 {
|
|
...
|
|
ov772x_1: camera@21 {
|
|
compatible = "ovti,ov772x";
|
|
reg = <0x21>;
|
|
vddio-supply = <®ulator1>;
|
|
vddcore-supply = <®ulator2>;
|
|
|
|
clock-frequency = <20000000>;
|
|
clocks = <&mclk 0>;
|
|
clock-names = "xclk";
|
|
|
|
port {
|
|
/* With 1 endpoint per port no need for addresses. */
|
|
ov772x_1_1: endpoint {
|
|
bus-width = <8>;
|
|
remote-endpoint = <&ceu0_1>;
|
|
hsync-active = <1>;
|
|
vsync-active = <0>; /* Who came up with an
|
|
inverter here ?... */
|
|
data-active = <1>;
|
|
pclk-sample = <1>;
|
|
};
|
|
};
|
|
};
|
|
|
|
imx074: camera@1a {
|
|
compatible = "sony,imx074";
|
|
reg = <0x1a>;
|
|
vddio-supply = <®ulator1>;
|
|
vddcore-supply = <®ulator2>;
|
|
|
|
clock-frequency = <30000000>; /* Shared clock with ov772x_1 */
|
|
clocks = <&mclk 0>;
|
|
clock-names = "sysclk"; /* Assuming this is the
|
|
name in the datasheet */
|
|
port {
|
|
imx074_1: endpoint {
|
|
clock-lanes = <0>;
|
|
data-lanes = <1 2>;
|
|
remote-endpoint = <&csi2_1>;
|
|
};
|
|
};
|
|
};
|
|
};
|
|
|
|
csi2: csi2@ffc90000 {
|
|
compatible = "renesas,sh-mobile-csi2";
|
|
reg = <0xffc90000 0x1000>;
|
|
interrupts = <0x17a0>;
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
port@1 {
|
|
compatible = "renesas,csi2c"; /* One of CSI2I and CSI2C. */
|
|
reg = <1>; /* CSI-2 PHY #1 of 2: PHY_S,
|
|
PHY_M has port address 0,
|
|
is unused. */
|
|
csi2_1: endpoint {
|
|
clock-lanes = <0>;
|
|
data-lanes = <2 1>;
|
|
remote-endpoint = <&imx074_1>;
|
|
};
|
|
};
|
|
port@2 {
|
|
reg = <2>; /* port 2: link to the CEU */
|
|
|
|
csi2_2: endpoint {
|
|
remote-endpoint = <&ceu0_0>;
|
|
};
|
|
};
|
|
};
|