Documentation/devicetree/bindings/media/video-interfaces.txt

   1 Common bindings for video receiver and transmitter interfaces
   2
   3 General concept
   4 ---------------
   5
   6 Video data pipelines usually consist of external devices, e.g. camera sensors,
   7 controlled over an I2C, SPI or UART bus, and SoC internal IP blocks, including
   8 video DMA engines and video data processors.
   9
  10 SoC internal blocks are described by DT nodes, placed similarly to other SoC
  11 blocks.  External devices are represented as child nodes of their respective
  12 bus controller nodes, e.g. I2C.
  13
  14 Data interfaces on all video devices are described by their child 'port' nodes.
  15 Configuration of a port depends on other devices participating in the data
  16 transfer and is described by 'endpoint' subnodes.
  17
  18 device {
  19         ...
  20         ports {
  21                 #address-cells = <1>;
  22                 #size-cells = <0>;
  23
  24                 port@0 {
  25                         ...
  26                         endpoint@0 { ... };
  27                         endpoint@1 { ... };
  28                 };
  29                 port@1 { ... };
  30         };
  31 };
  32
  33 If a port can be configured to work with more than one remote device on the same
  34 bus, an 'endpoint' child node must be provided for each of them.  If more than
  35 one port is present in a device node or there is more than one endpoint at a
  36 port, or port node needs to be associated with a selected hardware interface,
  37 a common scheme using '#address-cells', '#size-cells' and 'reg' properties is
  38 used.
  39
  40 All 'port' nodes can be grouped under optional 'ports' node, which allows to
  41 specify #address-cells, #size-cells properties independently for the 'port'
  42 and 'endpoint' nodes and any child device nodes a device might have.
  43
  44 Two 'endpoint' nodes are linked with each other through their 'remote-endpoint'
  45 phandles.  An endpoint subnode of a device contains all properties needed for
  46 configuration of this device for data exchange with other device.  In most
  47 cases properties at the peer 'endpoint' nodes will be identical, however they
  48 might need to be different when there is any signal modifications on the bus
  49 between two devices, e.g. there are logic signal inverters on the lines.
  50
  51 It is allowed for multiple endpoints at a port to be active simultaneously,
  52 where supported by a device.  For example, in case where a data interface of
  53 a device is partitioned into multiple data busses, e.g. 16-bit input port
  54 divided into two separate ITU-R BT.656 8-bit busses.  In such case bus-width
  55 and data-shift properties can be used to assign physical data lines to each
  56 endpoint node (logical bus).
  57
  58 Documenting bindings for devices
  59 --------------------------------
  60
  61 All required and optional bindings the device supports shall be explicitly
  62 documented in device DT binding documentation. This also includes port and
  63 endpoint nodes for the device, including unit-addresses and reg properties where
  64 relevant.
  65
  66 Please also see Documentation/devicetree/bindings/graph.txt .
  67
  68 Required properties
  69 -------------------
  70
  71 If there is more than one 'port' or more than one 'endpoint' node or 'reg'
  72 property is present in port and/or endpoint nodes the following properties
  73 are required in a relevant parent node:
  74
  75  - #address-cells : number of cells required to define port/endpoint
  76                     identifier, should be 1.
  77  - #size-cells    : should be zero.
  78
  79
  80 Optional properties
  81 -------------------
  82
  83 - flash-leds: An array of phandles, each referring to a flash LED, a sub-node
  84   of the LED driver device node.
  85
  86 - lens-focus: A phandle to the node of the focus lens controller.
  87
  88
  89 Optional endpoint properties
  90 ----------------------------
  91
  92 - remote-endpoint: phandle to an 'endpoint' subnode of a remote device node.
  93 - slave-mode: a boolean property indicating that the link is run in slave mode.
  94   The default when this property is not specified is master mode. In the slave
  95   mode horizontal and vertical synchronization signals are provided to the
  96   slave device (data source) by the master device (data sink). In the master
  97   mode the data source device is also the source of the synchronization signals.
  98 - bus-type: data bus type. Possible values are:
  99   0 - autodetect based on other properties (MIPI CSI-2 D-PHY, parallel or Bt656)
 100   1 - MIPI CSI-2 C-PHY
 101   2 - MIPI CSI1
 102   3 - CCP2
 103 - bus-width: number of data lines actively used, valid for the parallel busses.
 104 - data-shift: on the parallel data busses, if bus-width is used to specify the
 105   number of data lines, data-shift can be used to specify which data lines are
 106   used, e.g. "bus-width=<8>; data-shift=<2>;" means, that lines 9:2 are used.
 107 - hsync-active: active state of the HSYNC signal, 0/1 for LOW/HIGH respectively.
 108 - vsync-active: active state of the VSYNC signal, 0/1 for LOW/HIGH respectively.
 109   Note, that if HSYNC and VSYNC polarities are not specified, embedded
 110   synchronization may be required, where supported.
 111 - data-active: similar to HSYNC and VSYNC, specifies data line polarity.
 112 - field-even-active: field signal level during the even field data transmission.
 113 - pclk-sample: sample data on rising (1) or falling (0) edge of the pixel clock
 114   signal.
 115 - sync-on-green-active: active state of Sync-on-green (SoG) signal, 0/1 for
 116   LOW/HIGH respectively.
 117 - data-lanes: an array of physical data lane indexes. Position of an entry
 118   determines the logical lane number, while the value of an entry indicates
 119   physical lane, e.g. for 2-lane MIPI CSI-2 bus we could have
 120   "data-lanes = <1 2>;", assuming the clock lane is on hardware lane 0.
 121   If the hardware does not support lane reordering, monotonically
 122   incremented values shall be used from 0 or 1 onwards, depending on
 123   whether or not there is also a clock lane. This property is valid for
 124   serial busses only (e.g. MIPI CSI-2).
 125 - clock-lanes: an array of physical clock lane indexes. Position of an entry
 126   determines the logical lane number, while the value of an entry indicates
 127   physical lane, e.g. for a MIPI CSI-2 bus we could have "clock-lanes = <0>;",
 128   which places the clock lane on hardware lane 0. This property is valid for
 129   serial busses only (e.g. MIPI CSI-2). Note that for the MIPI CSI-2 bus this
 130   array contains only one entry.
 131 - clock-noncontinuous: a boolean property to allow MIPI CSI-2 non-continuous
 132   clock mode.
 133 - link-frequencies: Allowed data bus frequencies. For MIPI CSI-2, for
 134   instance, this is the actual frequency of the bus, not bits per clock per
 135   lane value. An array of 64-bit unsigned integers.
 136 - lane-polarities: an array of polarities of the lanes starting from the clock
 137   lane and followed by the data lanes in the same order as in data-lanes.
 138   Valid values are 0 (normal) and 1 (inverted). The length of the array
 139   should be the combined length of data-lanes and clock-lanes properties.
 140   If the lane-polarities property is omitted, the value must be interpreted
 141   as 0 (normal). This property is valid for serial busses only.
 142 - strobe: Whether the clock signal is used as clock (0) or strobe (1). Used
 143   with CCP2, for instance.
 144
 145 Example
 146 -------
 147
 148 The example snippet below describes two data pipelines.  ov772x and imx074 are
 149 camera sensors with a parallel and serial (MIPI CSI-2) video bus respectively.
 150 Both sensors are on the I2C control bus corresponding to the i2c0 controller
 151 node.  ov772x sensor is linked directly to the ceu0 video host interface.
 152 imx074 is linked to ceu0 through the MIPI CSI-2 receiver (csi2). ceu0 has a
 153 (single) DMA engine writing captured data to memory.  ceu0 node has a single
 154 'port' node which may indicate that at any time only one of the following data
 155 pipelines can be active: ov772x -> ceu0 or imx074 -> csi2 -> ceu0.
 156
 157         ceu0: ceu@0xfe910000 {
 158                 compatible = "renesas,sh-mobile-ceu";
 159                 reg = <0xfe910000 0xa0>;
 160                 interrupts = <0x880>;
 161
 162                 mclk: master_clock {
 163                         compatible = "renesas,ceu-clock";
 164                         #clock-cells = <1>;
 165                         clock-frequency = <50000000>;   /* Max clock frequency */
 166                         clock-output-names = "mclk";
 167                 };
 168
 169                 port {
 170                         #address-cells = <1>;
 171                         #size-cells = <0>;
 172
 173                         /* Parallel bus endpoint */
 174                         ceu0_1: endpoint@1 {
 175                                 reg = <1>;              /* Local endpoint # */
 176                                 remote = <&ov772x_1_1>; /* Remote phandle */
 177                                 bus-width = <8>;        /* Used data lines */
 178                                 data-shift = <2>;       /* Lines 9:2 are used */
 179
 180                                 /* If hsync-active/vsync-active are missing,
 181                                    embedded BT.656 sync is used */
 182                                 hsync-active = <0>;     /* Active low */
 183                                 vsync-active = <0>;     /* Active low */
 184                                 data-active = <1>;      /* Active high */
 185                                 pclk-sample = <1>;      /* Rising */
 186                         };
 187
 188                         /* MIPI CSI-2 bus endpoint */
 189                         ceu0_0: endpoint@0 {
 190                                 reg = <0>;
 191                                 remote = <&csi2_2>;
 192                         };
 193                 };
 194         };
 195
 196         i2c0: i2c@0xfff20000 {
 197                 ...
 198                 ov772x_1: camera@0x21 {
 199                         compatible = "ovti,ov772x";
 200                         reg = <0x21>;
 201                         vddio-supply = <&regulator1>;
 202                         vddcore-supply = <&regulator2>;
 203
 204                         clock-frequency = <20000000>;
 205                         clocks = <&mclk 0>;
 206                         clock-names = "xclk";
 207
 208                         port {
 209                                 /* With 1 endpoint per port no need for addresses. */
 210                                 ov772x_1_1: endpoint {
 211                                         bus-width = <8>;
 212                                         remote-endpoint = <&ceu0_1>;
 213                                         hsync-active = <1>;
 214                                         vsync-active = <0>; /* Who came up with an
 215                                                                inverter here ?... */
 216                                         data-active = <1>;
 217                                         pclk-sample = <1>;
 218                                 };
 219                         };
 220                 };
 221
 222                 imx074: camera@0x1a {
 223                         compatible = "sony,imx074";
 224                         reg = <0x1a>;
 225                         vddio-supply = <&regulator1>;
 226                         vddcore-supply = <&regulator2>;
 227
 228                         clock-frequency = <30000000>;   /* Shared clock with ov772x_1 */
 229                         clocks = <&mclk 0>;
 230                         clock-names = "sysclk";         /* Assuming this is the
 231                                                            name in the datasheet */
 232                         port {
 233                                 imx074_1: endpoint {
 234                                         clock-lanes = <0>;
 235                                         data-lanes = <1 2>;
 236                                         remote-endpoint = <&csi2_1>;
 237                                 };
 238                         };
 239                 };
 240         };
 241
 242         csi2: csi2@0xffc90000 {
 243                 compatible = "renesas,sh-mobile-csi2";
 244                 reg = <0xffc90000 0x1000>;
 245                 interrupts = <0x17a0>;
 246                 #address-cells = <1>;
 247                 #size-cells = <0>;
 248
 249                 port@1 {
 250                         compatible = "renesas,csi2c";   /* One of CSI2I and CSI2C. */
 251                         reg = <1>;                      /* CSI-2 PHY #1 of 2: PHY_S,
 252                                                            PHY_M has port address 0,
 253                                                            is unused. */
 254                         csi2_1: endpoint {
 255                                 clock-lanes = <0>;
 256                                 data-lanes = <2 1>;
 257                                 remote-endpoint = <&imx074_1>;
 258                         };
 259                 };
 260                 port@2 {
 261                         reg = <2>;                      /* port 2: link to the CEU */
 262
 263                         csi2_2: endpoint {
 264                                 remote-endpoint = <&ceu0_0>;
 265                         };
 266                 };
 267         };