new file mode 100644
@@ -0,0 +1,374 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+mgb4 sysfs interface
+====================
+
+The mgb4 driver provides a sysfs interface, that is used to configure video
+stream related parameters (some of them must be set properly before the v4l2
+device can be opened) and obtain the video device/stream status.
+
+There are two types of parameters - global / PCI card related, found under
+``/sys/class/video4linux/videoX/device`` and module specific found under
+``/sys/class/video4linux/videoX``.
+
+
+Global (PCI card) parameters
+============================
+
+**module_type** (R):
+ Module type.
+
+ | 0 - No module present
+ | 1 - FPDL3
+ | 2 - GMSL
+
+**module_version** (R):
+ Module version number. Zero in case of a missing module.
+
+**fw_type** (R):
+ Firmware type.
+
+ | 1 - FPDL3
+ | 2 - GMSL
+
+**fw_version** (R):
+ Firmware version number.
+
+**serial_number** (R):
+ Card serial number. The format is::
+
+ PRODUCT-REVISION-SERIES-SERIAL
+
+ where each component is a 8b number.
+
+
+Common FPDL3/GMSL input parameters
+==================================
+
+**input_id** (R):
+ Input number ID, zero based.
+
+**oldi_lane_width** (RW):
+ Number of deserializer output lanes.
+
+ | 0 - single
+ | 1 - dual (default)
+
+**color_mapping** (RW):
+ Mapping of the incoming bits in the signal to the colour bits of the pixels.
+
+ | 0 - OLDI/JEIDA
+ | 1 - SPWG/VESA (default)
+
+**link_status** (R):
+ Video link status. If the link is locked, chips are properly connected and
+ communicating at the same speed and protocol. The link can be locked without
+ an active video stream.
+
+ A value of 0 is equivalent to the V4L2_IN_ST_NO_SYNC flag of the V4L2
+ VIDIOC_ENUMINPUT status bits.
+
+ | 0 - unlocked
+ | 1 - locked
+
+**stream_status** (R):
+ Video stream status. A stream is detected if the link is locked, the input
+ pixel clock is running and the DE signal is moving.
+
+ A value of 0 is equivalent to the V4L2_IN_ST_NO_SIGNAL flag of the V4L2
+ VIDIOC_ENUMINPUT status bits.
+
+ | 0 - not detected
+ | 1 - detected
+
+**video_width** (R):
+ Video stream width. This is the actual width as detected by the HW.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in the width
+ field of the v4l2_bt_timings struct.
+
+**video_height** (R):
+ Video stream height. This is the actual height as detected by the HW.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in the height
+ field of the v4l2_bt_timings struct.
+
+**vsync_status** (R):
+ The type of VSYNC pulses as detected by the video format detector.
+
+ The value is equivalent to the flags returned by VIDIOC_QUERY_DV_TIMINGS in
+ the polarities field of the v4l2_bt_timings struct.
+
+ | 0 - active low
+ | 1 - active high
+ | 2 - not available
+
+**hsync_status** (R):
+ The type of HSYNC pulses as detected by the video format detector.
+
+ The value is equivalent to the flags returned by VIDIOC_QUERY_DV_TIMINGS in
+ the polarities field of the v4l2_bt_timings struct.
+
+ | 0 - active low
+ | 1 - active high
+ | 2 - not available
+
+**vsync_gap_length** (RW):
+ If the incoming video signal does not contain synchronization VSYNC and
+ HSYNC pulses, these must be generated internally in the FPGA to achieve
+ the correct frame ordering. This value indicates, how many "empty" pixels
+ (pixels with deasserted Data Enable signal) are necessary to generate the
+ internal VSYNC pulse.
+
+**hsync_gap_length** (RW):
+ If the incoming video signal does not contain synchronization VSYNC and
+ HSYNC pulses, these must be generated internally in the FPGA to achieve
+ the correct frame ordering. This value indicates, how many "empty" pixels
+ (pixels with deasserted Data Enable signal) are necessary to generate the
+ internal HSYNC pulse. The value must be greater than 1 and smaller than
+ vsync_gap_length.
+
+**pclk_frequency** (R):
+ Input pixel clock frequency in kHz.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the pixelclock field of the v4l2_bt_timings struct.
+
+ *Note: The frequency_range parameter must be set properly first to get
+ a valid frequency here.*
+
+**hsync_width** (R):
+ Width of the HSYNC signal in PCLK clock ticks.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the hsync field of the v4l2_bt_timings struct.
+
+**vsync_width** (R):
+ Width of the VSYNC signal in PCLK clock ticks.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the vsync field of the v4l2_bt_timings struct.
+
+**hback_porch** (R):
+ Number of PCLK pulses between deassertion of the HSYNC signal and the first
+ valid pixel in the video line (marked by DE=1).
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the hbackporch field of the v4l2_bt_timings struct.
+
+**hfront_porch** (R):
+ Number of PCLK pulses between the end of the last valid pixel in the video
+ line (marked by DE=1) and assertion of the HSYNC signal.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the hfrontporch field of the v4l2_bt_timings struct.
+
+**vback_porch** (R):
+ Number of video lines between deassertion of the VSYNC signal and the video
+ line with the first valid pixel (marked by DE=1).
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the vbackporch field of the v4l2_bt_timings struct.
+
+**vfront_porch** (R):
+ Number of video lines between the end of the last valid pixel line (marked
+ by DE=1) and assertion of the VSYNC signal.
+
+ The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+ the vfrontporch field of the v4l2_bt_timings struct.
+
+**frequency_range** (RW)
+ PLL frequency range of the OLDI input clock generator. The PLL frequency is
+ derived from the Pixel Clock Frequency (PCLK) and is equal to PCLK if
+ oldi_lane_width is set to "single" and PCLK/2 if oldi_lane_width is set to
+ "dual".
+
+ | 0 - PLL < 50MHz (default)
+ | 1 - PLL >= 50MHz
+
+ *Note: This parameter can not be changed while the input v4l2 device is
+ open.*
+
+
+Common FPDL3/GMSL output parameters
+===================================
+
+**output_id** (R):
+ Output number ID, zero based.
+
+**video_source** (RW):
+ Output video source. If set to 0 or 1, the source is the corresponding card
+ input and the v4l2 output devices are disabled. If set to 2 or 3, the source
+ is the corresponding v4l2 video output device. The default is
+ the corresponding v4l2 output, i.e. 2 for OUT1 and 3 for OUT2.
+
+ | 0 - input 0
+ | 1 - input 1
+ | 2 - v4l2 output 0
+ | 3 - v4l2 output 1
+
+ *Note: This parameter can not be changed while ANY of the input/output v4l2
+ devices is open.*
+
+**display_width** (RW):
+ Display width. There is no autodetection of the connected display, so the
+ proper value must be set before the start of streaming. The default width
+ is 1280.
+
+ *Note: This parameter can not be changed while the output v4l2 device is
+ open.*
+
+**display_height** (RW):
+ Display height. There is no autodetection of the connected display, so the
+ proper value must be set before the start of streaming. The default height
+ is 640.
+
+ *Note: This parameter can not be changed while the output v4l2 device is
+ open.*
+
+**frame_rate** (RW):
+ Output video frame rate in frames per second. The default frame rate is
+ 60Hz.
+
+**hsync_polarity** (RW):
+ HSYNC signal polarity.
+
+ | 0 - active low (default)
+ | 1 - active high
+
+**vsync_polarity** (RW):
+ VSYNC signal polarity.
+
+ | 0 - active low (default)
+ | 1 - active high
+
+**de_polarity** (RW):
+ DE signal polarity.
+
+ | 0 - active low
+ | 1 - active high (default)
+
+**pclk_frequency** (RW):
+ Output pixel clock frequency. Allowed values are between 25000-190000(kHz)
+ and there is a non-linear stepping between two consecutive allowed
+ frequencies. The driver finds the nearest allowed frequency to the given
+ value and sets it. When reading this property, you get the exact
+ frequency set by the driver. The default frequency is 70000kHz.
+
+ *Note: This parameter can not be changed while the output v4l2 device is
+ open.*
+
+**hsync_width** (RW):
+ Width of the HSYNC signal in pixels. The default value is 16.
+
+**vsync_width** (RW):
+ Width of the VSYNC signal in video lines. The default value is 2.
+
+**hback_porch** (RW):
+ Number of PCLK pulses between deassertion of the HSYNC signal and the first
+ valid pixel in the video line (marked by DE=1). The default value is 32.
+
+**hfront_porch** (RW):
+ Number of PCLK pulses between the end of the last valid pixel in the video
+ line (marked by DE=1) and assertion of the HSYNC signal. The default value
+ is 32.
+
+**vback_porch** (RW):
+ Number of video lines between deassertion of the VSYNC signal and the video
+ line with the first valid pixel (marked by DE=1). The default value is 2.
+
+**vfront_porch** (RW):
+ Number of video lines between the end of the last valid pixel line (marked
+ by DE=1) and assertion of the VSYNC signal. The default value is 2.
+
+
+FPDL3 specific input parameters
+===============================
+
+**fpdl3_input_width** (RW):
+ Number of deserializer input lines.
+
+ | 0 - auto (default)
+ | 1 - single
+ | 2 - dual
+
+FPDL3 specific output parameters
+================================
+
+**fpdl3_output_width** (RW):
+ Number of serializer output lines.
+
+ | 0 - auto (default)
+ | 1 - single
+ | 2 - dual
+
+GMSL specific input parameters
+==============================
+
+**gmsl_mode** (RW):
+ GMSL speed mode.
+
+ | 0 - 12Gb/s (default)
+ | 1 - 6Gb/s
+ | 2 - 3Gb/s
+ | 3 - 1.5Gb/s
+
+**gmsl_stream_id** (RW):
+ The GMSL multi-stream contains up to four video streams. This parameter
+ selects which stream is captured by the video input. The value is the
+ zero-based index of the stream. The default stream id is 0.
+
+ *Note: This parameter can not be changed while the input v4l2 device is
+ open.*
+
+**gmsl_fec** (RW):
+ GMSL Forward Error Correction (FEC).
+
+ | 0 - disabled
+ | 1 - enabled (default)
+
+
+====================
+mgb4 mtd partitions
+====================
+
+The mgb4 driver creates a MTD device with two partitions:
+ - mgb4-fw.X - FPGA firmware.
+ - mgb4-data.X - Factory settings, e.g. card serial number.
+
+The *mgb4-fw* partition is writable and is used for FW updates, *mgb4-data* is
+read-only. The *X* attached to the partition name represents the card number.
+Depending on the CONFIG_MTD_PARTITIONED_MASTER kernel configuration, you may
+also have a third partition named *mgb4-flash* available in the system. This
+partition represents the whole, unpartitioned, card's FLASH memory and one should
+not fiddle with it...
+
+====================
+mgb4 iio (triggers)
+====================
+
+The mgb4 driver creates an Industrial I/O (IIO) device that provides trigger and
+signal level status capability. The following scan elements are available:
+
+**activity**:
+ The trigger levels and pending status.
+
+ | bit 1 - trigger 1 pending
+ | bit 2 - trigger 2 pending
+ | bit 5 - trigger 1 level
+ | bit 6 - trigger 2 level
+
+**timestamp**:
+ The trigger event timestamp.
+
+The iio device can operate either in "raw" mode where you can fetch the signal
+levels (activity bits 5 and 6) using sysfs access or in triggered buffer mode.
+In the triggered buffer mode you can follow the signal level changes (activity
+bits 1 and 2) using the iio device in /dev. If you enable the timestamps, you
+will also get the exact trigger event time that can be matched to a video frame
+(every mgb4 video frame has a timestamp with the same clock source).
+
+*Note: although the activity sample always contains all the status bits, it makes
+no sense to get the pending bits in raw mode or the level bits in the triggered
+buffer mode - the values do not represent valid data in such case.*
@@ -77,6 +77,7 @@ ipu3-cio2 Intel ipu3-cio2 driver
ivtv Conexant cx23416/cx23415 MPEG encoder/decoder
ivtvfb Conexant cx23415 framebuffer
mantis MANTIS based cards
+mgb4 Digiteq Automotive MGB4 frame grabber
mxb Siemens-Nixdorf 'Multimedia eXtension Board'
netup-unidvb NetUP Universal DVB card
ngene Micronas nGene
@@ -17,6 +17,7 @@ Video4Linux (V4L) driver-specific documentation
imx7
ipu3
ivtv
+ mgb4
omap3isp
omap4_camera
philips