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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6 1/1] cameraif: add ABI for para-virtual camera
On 3/22/19 8:37 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>
> This is the ABI for the two halves of a para-virtualized
> camera driver which extends Xen's reach multimedia capabilities even
> farther enabling it for video conferencing, In-Vehicle Infotainment,
> high definition maps etc.
>
> The initial goal is to support most needed functionality with the
> final idea to make it possible to extend the protocol if need be:
>
> 1. Provide means for base virtual device configuration:
> - pixel formats
> - resolutions
> - frame rates
> 2. Support basic camera controls:
> - contrast
> - brightness
> - hue
> - saturation
> 3. Support streaming control
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
Looks good!
Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Thank you for all your work on this.
Regards,
Hans
> ---
> xen/include/public/io/cameraif.h | 1374 ++++++++++++++++++++++++++++++
> 1 file changed, 1374 insertions(+)
> create mode 100644 xen/include/public/io/cameraif.h
>
> diff --git a/xen/include/public/io/cameraif.h
> b/xen/include/public/io/cameraif.h
> new file mode 100644
> index 000000000000..acbcbf3bd411
> --- /dev/null
> +++ b/xen/include/public/io/cameraif.h
> @@ -0,0 +1,1374 @@
> +/******************************************************************************
> + * cameraif.h
> + *
> + * Unified camera device I/O interface for Xen guest OSes.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> copy
> + * of this software and associated documentation files (the "Software"), to
> + * deal in the Software without restriction, including without limitation the
> + * rights to use, copy, modify, merge, publish, distribute, sublicense,
> and/or
> + * sell copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> + * DEALINGS IN THE SOFTWARE.
> + *
> + * Copyright (C) 2018-2019 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> + */
> +
> +#ifndef __XEN_PUBLIC_IO_CAMERAIF_H__
> +#define __XEN_PUBLIC_IO_CAMERAIF_H__
> +
> +#include "ring.h"
> +#include "../grant_table.h"
> +
> +/*
> +
> ******************************************************************************
> + * Protocol version
> +
> ******************************************************************************
> + */
> +#define XENCAMERA_PROTOCOL_VERSION "1"
> +
> +/*
> +
> ******************************************************************************
> + * Feature and Parameter Negotiation
> +
> ******************************************************************************
> + *
> + * Front->back notifications: when enqueuing a new request, sending a
> + * notification can be made conditional on xencamera_req (i.e., the generic
> + * hold-off mechanism provided by the ring macros). Backends must set
> + * xencamera_req appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
> + *
> + * Back->front notifications: when enqueuing a new response, sending a
> + * notification can be made conditional on xencamera_resp (i.e., the generic
> + * hold-off mechanism provided by the ring macros). Frontends must set
> + * xencamera_resp appropriately (e.g., using
> RING_FINAL_CHECK_FOR_RESPONSES()).
> + *
> + * The two halves of a para-virtual camera driver utilize nodes within
> + * XenStore to communicate capabilities and to negotiate operating
> parameters.
> + * This section enumerates these nodes which reside in the respective front
> and
> + * backend portions of XenStore, following the XenBus convention.
> + *
> + * All data in XenStore is stored as strings. Nodes specifying numeric
> + * values are encoded in decimal. Integer value ranges listed below are
> + * expressed as fixed sized integer types capable of storing the conversion
> + * of a properly formatted node string, without loss of information.
> + *
> +
> ******************************************************************************
> + * Example configuration
> +
> ******************************************************************************
> + *
> + * This is an example of backend and frontend configuration:
> + *
> + *--------------------------------- Backend
> -----------------------------------
> + *
> + * /local/domain/0/backend/vcamera/1/0/frontend-id = "1"
> + * /local/domain/0/backend/vcamera/1/0/frontend =
> "/local/domain/1/device/vcamera/0"
> + * /local/domain/0/backend/vcamera/1/0/state = "4"
> + * /local/domain/0/backend/vcamera/1/0/versions = "1,2"
> + *
> + *--------------------------------- Frontend
> ----------------------------------
> + *
> + * /local/domain/1/device/vcamera/0/backend-id = "0"
> + * /local/domain/1/device/vcamera/0/backend =
> "/local/domain/0/backend/vcamera/1"
> + * /local/domain/1/device/vcamera/0/state = "4"
> + * /local/domain/1/device/vcamera/0/version = "1"
> + * /local/domain/1/device/vcamera/0/be-alloc = "1"
> + *
> + *---------------------------- Device 0 configuration
> -------------------------
> + *
> + * /local/domain/1/device/vcamera/0/max-buffers = "3"
> + * /local/domain/1/device/vcamera/0/controls = "contrast,hue"
> + * /local/domain/1/device/vcamera/0/formats/YUYV/640x480/frame-rates =
> "30/1,15/1"
> + * /local/domain/1/device/vcamera/0/formats/YUYV/1920x1080/frame-rates =
> "15/2"
> + * /local/domain/1/device/vcamera/0/formats/BGRA/640x480/frame-rates =
> "15/1,15/2"
> + * /local/domain/1/device/vcamera/0/formats/BGRA/1200x720/frame-rates =
> "15/2"
> + * /local/domain/1/device/vcamera/0/unique-id = "0"
> + * /local/domain/1/device/vcamera/0/req-ring-ref = "2832"
> + * /local/domain/1/device/vcamera/0/req-event-channel = "15"
> + * /local/domain/1/device/vcamera/0/evt-ring-ref = "387"
> + * /local/domain/1/device/vcamera/0/evt-event-channel = "16"
> + *
> + *---------------------------- Device 1 configuration
> -------------------------
> + *
> + * /local/domain/1/device/vcamera/1/max-buffers = "8"
> + * /local/domain/1/device/vcamera/1/controls = "brightness,saturation,hue"
> + * /local/domain/1/device/vcamera/1/formats/YUYV/640x480/frame-rates =
> "30/1,15/2"
> + * /local/domain/1/device/vcamera/1/formats/YUYV/1920x1080/frame-rates =
> "15/2"
> + * /local/domain/1/device/vcamera/1/unique-id = "1"
> + * /local/domain/1/device/vcamera/1/req-ring-ref = "2833"
> + * /local/domain/1/device/vcamera/1/req-event-channel = "17"
> + * /local/domain/1/device/vcamera/1/evt-ring-ref = "388"
> + * /local/domain/1/device/vcamera/1/evt-event-channel = "18"
> + *
> +
> ******************************************************************************
> + * Backend XenBus Nodes
> +
> ******************************************************************************
> + *
> + *----------------------------- Protocol version
> ------------------------------
> + *
> + * versions
> + * Values: <string>
> + *
> + * List of XENCAMERA_LIST_SEPARATOR separated protocol versions
> supported
> + * by the backend. For example "1,2,3".
> + *
> +
> ******************************************************************************
> + * Frontend XenBus Nodes
> +
> ******************************************************************************
> + *
> + *-------------------------------- Addressing
> ---------------------------------
> + *
> + * dom-id
> + * Values: <uint16_t>
> + *
> + * Domain identifier.
> + *
> + * dev-id
> + * Values: <uint16_t>
> + *
> + * Device identifier.
> + *
> + * /local/domain/<dom-id>/device/vcamera/<dev-id>/...
> + *
> + *----------------------------- Protocol version
> ------------------------------
> + *
> + * version
> + * Values: <string>
> + *
> + * Protocol version, chosen among the ones supported by the backend.
> + *
> + *------------------------- Backend buffer allocation
> -------------------------
> + *
> + * be-alloc
> + * Values: "0", "1"
> + *
> + * If value is set to "1", then backend will be the buffer
> + * provider/allocator for this domain during XENCAMERA_OP_BUF_CREATE
> + * operation.
> + * If value is not "1" or omitted frontend must allocate buffers itself.
> + *
> + *------------------------------- Camera settings
> -----------------------------
> + *
> + * unique-id
> + * Values: <string>
> + *
> + * After device instance initialization each camera is assigned a
> + * unique ID, so it can be identified by the backend by this ID.
> + * This can be UUID or such.
> + *
> + * max-buffers
> + * Values: <uint8_t>
> + *
> + * Maximum number of camera buffers this frontend may use.
> + *
> + * controls
> + * Values: <list of string>
> + *
> + * List of supported camera controls separated by
> XENCAMERA_LIST_SEPARATOR.
> + * Camera controls are expressed as a list of string values w/o any
> + * ordering requirement.
> + *
> + * formats
> + * Values: <format, char[7]>
> + *
> + * Formats are organized as a set of directories one per each
> + * supported pixel format. The name of the directory is the
> + * corresponding FOURCC string label. The next level of
> + * the directory under <formats> represents supported resolutions.
> + * If the format represents a big-endian variant of a little
> + * endian format, then the "-BE" suffix must be added. E.g. 'AR15' vs
> + * 'AR15-BE'.
> + * If FOURCC string label has spaces then those are only allowed to
> + * be at the end of the label and must be trimmed, for example
> + * 'Y16' and 'Y16-BE' will be trimmed.
> + *
> + * resolution
> + * Values: <width, uint32_t>x<height, uint32_t>
> + *
> + * Resolutions are organized as a set of directories one per each
> + * supported resolution under corresponding <formats> directory.
> + * The name of the directory is the supported width and height
> + * of the camera resolution in pixels.
> + *
> + * frame-rates
> + * Values: <numerator, uint32_t>/<denominator, uint32_t>
> + *
> + * List of XENCAMERA_FRAME_RATE_SEPARATOR separated supported frame
> rates
> + * of the camera expressed as numerator and denominator of the
> + * corresponding frame rate.
> + *
> + *------------------- Camera Request Transport Parameters
> ---------------------
> + *
> + * This communication path is used to deliver requests from frontend to
> backend
> + * and get the corresponding responses from backend to frontend,
> + * set up per virtual camera device.
> + *
> + * req-event-channel
> + * Values: <uint32_t>
> + *
> + * The identifier of the Xen camera's control event channel
> + * used to signal activity in the ring buffer.
> + *
> + * req-ring-ref
> + * Values: <uint32_t>
> + *
> + * The Xen grant reference granting permission for the backend to map
> + * a sole page of camera's control ring buffer.
> + *
> + *-------------------- Camera Event Transport Parameters
> ----------------------
> + *
> + * This communication path is used to deliver asynchronous events from
> backend
> + * to frontend, set up per virtual camera device.
> + *
> + * evt-event-channel
> + * Values: <uint32_t>
> + *
> + * The identifier of the Xen camera's event channel
> + * used to signal activity in the ring buffer.
> + *
> + * evt-ring-ref
> + * Values: <uint32_t>
> + *
> + * The Xen grant reference granting permission for the backend to map
> + * a sole page of camera's event ring buffer.
> + */
> +
> +/*
> +
> ******************************************************************************
> + * STATE DIAGRAMS
> +
> ******************************************************************************
> + *
> + * Tool stack creates front and back state nodes with initial state
> + * XenbusStateInitialising.
> + * Tool stack creates and sets up frontend camera configuration
> + * nodes per domain.
> + *
> + *-------------------------------- Normal flow
> --------------------------------
> + *
> + * Front Back
> + * ================================= =====================================
> + * XenbusStateInitialising XenbusStateInitialising
> + * o Query backend device
> identification
> + * data.
> + * o Open and validate backend device.
> + * |
> + * |
> + * V
> + * XenbusStateInitWait
> + *
> + * o Query frontend configuration
> + * o Allocate and initialize
> + * event channels per configured
> + * camera.
> + * o Publish transport parameters
> + * that will be in effect during
> + * this connection.
> + * |
> + * |
> + * V
> + * XenbusStateInitialised
> + *
> + * o Query frontend transport
> parameters.
> + * o Connect to the event channels.
> + * |
> + * |
> + * V
> + * XenbusStateConnected
> + *
> + * o Create and initialize OS
> + * virtual camera as per
> + * configuration.
> + * |
> + * |
> + * V
> + * XenbusStateConnected
> + *
> + * XenbusStateUnknown
> + * XenbusStateClosed
> + * XenbusStateClosing
> + * o Remove virtual camera device
> + * o Remove event channels
> + * |
> + * |
> + * V
> + * XenbusStateClosed
> + *
> + *------------------------------- Recovery flow
> -------------------------------
> + *
> + * In case of frontend unrecoverable errors backend handles that as
> + * if frontend goes into the XenbusStateClosed state.
> + *
> + * In case of backend unrecoverable errors frontend tries removing
> + * the virtualized device. If this is possible at the moment of error,
> + * then frontend goes into the XenbusStateInitialising state and is ready for
> + * new connection with backend. If the virtualized device is still in use and
> + * cannot be removed, then frontend goes into the XenbusStateReconfiguring
> state
> + * until either the virtualized device is removed or backend initiates a new
> + * connection. On the virtualized device removal frontend goes into the
> + * XenbusStateInitialising state.
> + *
> + * Note on XenbusStateReconfiguring state of the frontend: if backend has
> + * unrecoverable errors then frontend cannot send requests to the backend
> + * and thus cannot provide functionality of the virtualized device anymore.
> + * After backend is back to normal the virtualized device may still hold some
> + * state: configuration in use, allocated buffers, client application state
> etc.
> + * In most cases, this will require frontend to implement complex recovery
> + * reconnect logic. Instead, by going into XenbusStateReconfiguring state,
> + * frontend will make sure no new clients of the virtualized device are
> + * accepted, allow existing client(s) to exit gracefully by signaling error
> + * state etc.
> + * Once all the clients are gone frontend can reinitialize the virtualized
> + * device and get into XenbusStateInitialising state again signaling the
> + * backend that a new connection can be made.
> + *
> + * There are multiple conditions possible under which frontend will go from
> + * XenbusStateReconfiguring into XenbusStateInitialising, some of them are OS
> + * specific. For example:
> + * 1. The underlying OS framework may provide callbacks to signal that the
> last
> + * client of the virtualized device has gone and the device can be removed
> + * 2. Frontend can schedule a deferred work (timer/tasklet/workqueue)
> + * to periodically check if this is the right time to re-try removal of
> + * the virtualized device.
> + * 3. By any other means.
> + *
> +
> ******************************************************************************
> + * REQUEST CODES
> +
> ******************************************************************************
> + */
> +#define XENCAMERA_OP_CONFIG_SET 0x00
> +#define XENCAMERA_OP_CONFIG_GET 0x01
> +#define XENCAMERA_OP_CONFIG_VALIDATE 0x02
> +#define XENCAMERA_OP_FRAME_RATE_SET 0x03
> +#define XENCAMERA_OP_BUF_GET_LAYOUT 0x04
> +#define XENCAMERA_OP_BUF_REQUEST 0x05
> +#define XENCAMERA_OP_BUF_CREATE 0x06
> +#define XENCAMERA_OP_BUF_DESTROY 0x07
> +#define XENCAMERA_OP_BUF_QUEUE 0x08
> +#define XENCAMERA_OP_BUF_DEQUEUE 0x09
> +#define XENCAMERA_OP_CTRL_ENUM 0x0a
> +#define XENCAMERA_OP_CTRL_SET 0x0b
> +#define XENCAMERA_OP_CTRL_GET 0x0c
> +#define XENCAMERA_OP_STREAM_START 0x0d
> +#define XENCAMERA_OP_STREAM_STOP 0x0e
> +
> +#define XENCAMERA_CTRL_BRIGHTNESS 0
> +#define XENCAMERA_CTRL_CONTRAST 1
> +#define XENCAMERA_CTRL_SATURATION 2
> +#define XENCAMERA_CTRL_HUE 3
> +
> +/* Number of supported controls. */
> +#define XENCAMERA_MAX_CTRL 4
> +
> +/* Control is read-only. */
> +#define XENCAMERA_CTRL_FLG_RO (1 << 0)
> +/* Control is write-only. */
> +#define XENCAMERA_CTRL_FLG_WO (1 << 1)
> +/* Control's value is volatile. */
> +#define XENCAMERA_CTRL_FLG_VOLATILE (1 << 2)
> +
> +/* Supported color spaces. */
> +#define XENCAMERA_COLORSPACE_DEFAULT 0
> +#define XENCAMERA_COLORSPACE_SMPTE170M 1
> +#define XENCAMERA_COLORSPACE_REC709 2
> +#define XENCAMERA_COLORSPACE_SRGB 3
> +#define XENCAMERA_COLORSPACE_OPRGB 4
> +#define XENCAMERA_COLORSPACE_BT2020 5
> +#define XENCAMERA_COLORSPACE_DCI_P3 6
> +
> +/* Color space transfer function. */
> +#define XENCAMERA_XFER_FUNC_DEFAULT 0
> +#define XENCAMERA_XFER_FUNC_709 1
> +#define XENCAMERA_XFER_FUNC_SRGB 2
> +#define XENCAMERA_XFER_FUNC_OPRGB 3
> +#define XENCAMERA_XFER_FUNC_NONE 4
> +#define XENCAMERA_XFER_FUNC_DCI_P3 5
> +#define XENCAMERA_XFER_FUNC_SMPTE2084 6
> +
> +/* Color space Y’CbCr encoding. */
> +#define XENCAMERA_YCBCR_ENC_IGNORE 0
> +#define XENCAMERA_YCBCR_ENC_601 1
> +#define XENCAMERA_YCBCR_ENC_709 2
> +#define XENCAMERA_YCBCR_ENC_XV601 3
> +#define XENCAMERA_YCBCR_ENC_XV709 4
> +#define XENCAMERA_YCBCR_ENC_BT2020 5
> +#define XENCAMERA_YCBCR_ENC_BT2020_CONST_LUM 6
> +
> +/* Quantization range. */
> +#define XENCAMERA_QUANTIZATION_DEFAULT 0
> +#define XENCAMERA_QUANTIZATION_FULL_RANGE 1
> +#define XENCAMERA_QUANTIZATION_LIM_RANGE 2
> +
> +/*
> +
> ******************************************************************************
> + * EVENT CODES
> +
> ******************************************************************************
> + */
> +#define XENCAMERA_EVT_FRAME_AVAIL 0x00
> +#define XENCAMERA_EVT_CTRL_CHANGE 0x01
> +
> +/*
> +
> ******************************************************************************
> + * XENSTORE FIELD AND PATH NAME STRINGS, HELPERS
> +
> ******************************************************************************
> + */
> +#define XENCAMERA_DRIVER_NAME "vcamera"
> +
> +#define XENCAMERA_LIST_SEPARATOR ","
> +#define XENCAMERA_RESOLUTION_SEPARATOR "x"
> +#define XENCAMERA_FRACTION_SEPARATOR "/"
> +
> +#define XENCAMERA_FIELD_BE_VERSIONS "versions"
> +#define XENCAMERA_FIELD_FE_VERSION "version"
> +#define XENCAMERA_FIELD_REQ_RING_REF "req-ring-ref"
> +#define XENCAMERA_FIELD_REQ_CHANNEL "req-event-channel"
> +#define XENCAMERA_FIELD_EVT_RING_REF "evt-ring-ref"
> +#define XENCAMERA_FIELD_EVT_CHANNEL "evt-event-channel"
> +#define XENCAMERA_FIELD_MAX_BUFFERS "max-buffers"
> +#define XENCAMERA_FIELD_CONTROLS "controls"
> +#define XENCAMERA_FIELD_FORMATS "formats"
> +#define XENCAMERA_FIELD_FRAME_RATES "frame-rates"
> +#define XENCAMERA_FIELD_BE_ALLOC "be-alloc"
> +#define XENCAMERA_FIELD_UNIQUE_ID "unique-id"
> +
> +#define XENCAMERA_CTRL_BRIGHTNESS_STR "brightness"
> +#define XENCAMERA_CTRL_CONTRAST_STR "contrast"
> +#define XENCAMERA_CTRL_SATURATION_STR "saturation"
> +#define XENCAMERA_CTRL_HUE_STR "hue"
> +
> +#define XENCAMERA_FOURCC_BIGENDIAN_STR "-BE"
> +
> +/* Maximum number of buffer planes supported. */
> +#define XENCAMERA_MAX_PLANE 4
> +
> +/*
> +
> ******************************************************************************
> + * STATUS RETURN CODES
> +
> ******************************************************************************
> + *
> + * Status return code is zero on success and -XEN_EXX on failure.
> + *
> +
> ******************************************************************************
> + * Assumptions
> +
> ******************************************************************************
> + *
> + * - usage of grant reference 0 as invalid grant reference:
> + * grant reference 0 is valid, but never exposed to a PV driver,
> + * because of the fact it is already in use/reserved by the PV console.
> + * - all references in this document to page sizes must be treated
> + * as pages of size XEN_PAGE_SIZE unless otherwise noted.
> + * - all FOURCC mappings used for configuration and messaging are
> + * Linux V4L2 ones:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/videodev2.h
> + * with the following exceptions:
> + * - characters are allowed in [0x20; 0x7f] range
> + * - when used for XenStore configuration entries the following
> + * are not allowed:
> + * - '/', '\', ' ' (space), '<', '>', ':', '"', '|', '?', '*'
> + * - if trailing spaces are part of the FOURCC code then those must be
> + * trimmed
> + *
> + *
> +
> ******************************************************************************
> + * Description of the protocol between frontend and backend driver
> +
> ******************************************************************************
> + *
> + * The two halves of a Para-virtual camera driver communicate with
> + * each other using shared pages and event channels.
> + * Shared page contains a ring with request/response packets.
> + *
> + * All reserved fields in the structures below must be 0.
> + *
> + * For all request/response/event packets:
> + * - frame rate parameter is represented as a pair of 4 octet long
> + * numerator and denominator:
> + * - frame_rate_numer - uint32_t, numerator of the frame rate
> + * - frame_rate_denom - uint32_t, denominator of the frame rate
> + * The corresponding frame rate (Hz) is calculated as:
> + * frame_rate = frame_rate_numer / frame_rate_denom
> + * - buffer index is a zero based index of the buffer. Must be less than
> + * the value of XENCAMERA_OP_CONFIG_SET.num_bufs response:
> + * - index - uint8_t, index of the buffer.
> + *
> + *
> + *---------------------------------- Requests
> ---------------------------------
> + *
> + * All request packets have the same length (64 octets).
> + * All request packets have common header:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | operation | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * id - uint16_t, private guest value, echoed in response.
> + * operation - uint8_t, operation code, XENCAMERA_OP_XXX.
> + *
> + *
> + * Request to set/validate the configuration - request to set the
> + * configuration/mode of the camera (XENCAMERA_OP_CONFIG_SET) or to
> + * check if the configuration is valid and can be used
> + * (XENCAMERA_OP_CONFIG_VALIDATE):
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CONFIG_XXX | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | pixel format | 12
> + * +----------------+----------------+----------------+----------------+
> + * | width | 16
> + * +----------------+----------------+----------------+----------------+
> + * | height | 20
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 24
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * pixel_format - uint32_t, pixel format to be used, FOURCC code.
> + * width - uint32_t, width in pixels.
> + * height - uint32_t, height in pixels.
> + *
> + * See response format for this request.
> + *
> + * Notes:
> + * - the only difference between XENCAMERA_OP_CONFIG_VALIDATE and
> + * XENCAMERA_OP_CONFIG_SET is that the former doesn't actually change
> + * camera configuration, but queries if the configuration is valid.
> + * This can be used while stream is active and/or buffers allocated.
> + * - frontend must check the corresponding response in order to see
> + * if the values reported back by the backend do match the desired ones
> + * and can be accepted.
> + * - frontend may send multiple XENCAMERA_OP_CONFIG_SET requests before
> + * sending XENCAMERA_OP_STREAM_START request to update or tune the
> + * final stream configuration.
> + * - configuration cannot be changed during active streaming, e.g.
> + * after XENCAMERA_OP_STREAM_START and before XENCAMERA_OP_STREAM_STOP
> + * requests.
> + */
> +struct xencamera_config_req {
> + uint32_t pixel_format;
> + uint32_t width;
> + uint32_t height;
> +};
> +
> +/*
> + * Request current configuration of the camera:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CONFIG_GET | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * See response format for this request.
> + *
> + *
> + * Request to set the frame rate of the stream:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _FRAME_RATE_SET| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | frame_rate_numer | 12
> + * +----------------+----------------+----------------+----------------+
> + * | frame_rate_denom | 16
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 20
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * frame_rate_numer - uint32_t, numerator of the frame rate.
> + * frame_rate_denom - uint32_t, denominator of the frame rate.
> + *
> + * Notes:
> + * - to query the current (actual) frame rate use XENCAMERA_OP_CONFIG_GET
> + * request.
> + * - this request can be used with camera buffers allocated, but stream
> + * stopped, e.g. frontend is allowed to stop the stream with
> + * XENCAMERA_OP_STREAM_STOP, hold the buffers allocated (e.g. keep the
> + * configuration set with XENCAMERA_OP_CONFIG_SET), change the
> + * frame rate of the stream and (re)start the stream again with
> + * XENCAMERA_OP_STREAM_START.
> + * - frame rate cannot be changed during active streaming, e.g.
> + * after XENCAMERA_OP_STREAM_START and before XENCAMERA_OP_STREAM_STOP
> + * commands.
> + */
> +struct xencamera_frame_rate_req {
> + uint32_t frame_rate_numer;
> + uint32_t frame_rate_denom;
> +};
> +
> +/*
> + * Request camera buffer's layout:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _BUF_GET_LAYOUT| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * See response format for this request.
> + *
> + *
> + * Request number of buffers to be used:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_BUF_REQUEST| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | num_bufs | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * num_bufs - uint8_t, desired number of buffers to be used.
> + *
> + * If num_bufs is not zero then the backend validates the requested number of
> + * buffers and responds with the number of buffers allowed for this frontend.
> + * Frontend is responsible for checking the corresponding response in order
> to
> + * see if the values reported back by the backend do match the desired ones
> + * and can be accepted.
> + * Frontend is allowed to send multiple XENCAMERA_OP_BUF_REQUEST requests
> + * before sending XENCAMERA_OP_STREAM_START request to update or tune the
> + * final configuration.
> + * Frontend is not allowed to change the camera configuration after this call
> + * with a non-zero value of num_bufs. If camera reconfiguration is required
> + * then this request must be sent with num_bufs set to zero and any created
> + * buffers must be destroyed first.
> + * Frontend is not allowed to change the number of buffers after the
> + * streaming has started.
> + *
> + * If num_bufs is 0 and streaming has not started yet, then the backend will
> + * free all previously allocated buffers (if any).
> + * Trying to call this if streaming is in progress will result in an error.
> + *
> + * If camera reconfiguration is required then the streaming must be stopped
> + * and this request must be sent with num_bufs set to zero and any
> + * created buffers must be destroyed.
> + *
> + * Please note, that the number of buffers in this request must not exceed
> + * the value configured in XenStore.max-buffers.
> + *
> + * See response format for this request.
> + */
> +struct xencamera_buf_request {
> + uint8_t num_bufs;
> +};
> +
> +/*
> + * Request camera buffer creation:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_BUF_CREATE | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | plane_offset[0] | 16
> + * +----------------+----------------+----------------+----------------+
> + * | plane_offset[1] | 20
> + * +----------------+----------------+----------------+----------------+
> + * | plane_offset[2] | 24
> + * +----------------+----------------+----------------+----------------+
> + * | plane_offset[3] | 28
> + * +----------------+----------------+----------------+----------------+
> + * | gref_directory | 32
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 36
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * An attempt to create multiple buffers with the same index is an error.
> + * index can be re-used after destroying the corresponding camera buffer.
> + *
> + * index - uint8_t, index of the buffer to be created in the range
> + * from 0 to the num_bufs field returned in response for
> + * XENCAMERA_OP_BUF_REQUEST request
> + * plane_offset - array of uint32_t, offset of the corresponding plane
> + * in octets from the buffer start. Number of offsets returned is
> + * equal to the value returned in XENCAMERA_OP_BUF_GET_LAYOUT.num_planes.
> + * gref_directory - grant_ref_t, a reference to the first shared page
> + * describing shared buffer references. The size of the buffer is equal to
> + * XENCAMERA_OP_BUF_GET_LAYOUT.size response. At least one page exists. If
> + * shared buffer size exceeds what can be addressed by this single page,
> + * then reference to the next shared page must be supplied (see
> + * gref_dir_next_page below).
> + *
> + * If XENCAMERA_FIELD_BE_ALLOC configuration entry is set, then backend will
> + * allocate the buffer with the parameters provided in this request and page
> + * directory is handled as follows:
> + * Frontend on request:
> + * - allocates pages for the directory (gref_directory,
> + * gref_dir_next_page(s)
> + * - grants permissions for the pages of the directory to the backend
> + * - sets gref_dir_next_page fields
> + * Backend on response:
> + * - grants permissions for the pages of the buffer allocated to
> + * the frontend
> + * - fills in page directory with grant references
> + * (gref[] in struct xencamera_page_directory)
> + */
> +struct xencamera_buf_create_req {
> + uint8_t index;
> + uint8_t reserved[3];
> + uint32_t plane_offset[XENCAMERA_MAX_PLANE];
> + grant_ref_t gref_directory;
> +};
> +
> +/*
> + * Shared page for XENCAMERA_OP_BUF_CREATE buffer descriptor (gref_directory
> in
> + * the request) employs a list of pages, describing all pages of the shared
> + * data buffer:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | gref_dir_next_page | 4
> + * +----------------+----------------+----------------+----------------+
> + * | gref[0] | 8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | gref[i] |
> i*4+8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | gref[N - 1] |
> N*4+8
> + * +----------------+----------------+----------------+----------------+
> + *
> + * gref_dir_next_page - grant_ref_t, reference to the next page describing
> + * page directory. Must be 0 if there are no more pages in the list.
> + * gref[i] - grant_ref_t, reference to a shared page of the buffer
> + * allocated at XENCAMERA_OP_BUF_CREATE.
> + *
> + * Number of grant_ref_t entries in the whole page directory is not
> + * passed, but instead can be calculated as:
> + * num_grefs_total = (XENCAMERA_OP_BUF_REQUEST.size + XEN_PAGE_SIZE - 1) /
> + * XEN_PAGE_SIZE
> + */
> +struct xencamera_page_directory {
> + grant_ref_t gref_dir_next_page;
> + grant_ref_t gref[1]; /* Variable length */
> +};
> +
> +/*
> + * Request buffer destruction - destroy a previously allocated camera buffer:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_BUF_DESTROY| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * index - uint8_t, index of the buffer to be destroyed.
> + *
> + *
> + * Request queueing of the buffer for backend use:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_BUF_QUEUE | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * Notes:
> + * - frontends must not access the buffer content after this request until
> + * response to XENCAMERA_OP_BUF_DEQUEUE has been received.
> + * - buffers must be queued to the backend before destroying them with
> + * XENCAMERA_OP_BUF_DESTROY.
> + *
> + * index - uint8_t, index of the buffer to be queued.
> + *
> + *
> + * Request dequeueing of the buffer for frontend use:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_OP_BUF_DEQUEUE | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * Notes:
> + * - frontend is allowed to access the buffer content after the
> corresponding
> + * response to this request.
> + *
> + * index - uint8_t, index of the buffer to be queued.
> + *
> + *
> + * Request camera control details:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CTRL_ENUM | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * See response format for this request.
> + *
> + * index - uint8_t, index of the control to be queried.
> + */
> +struct xencamera_index {
> + uint8_t index;
> +};
> +
> +/*
> + * Request camera control change:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_SET_CTRL | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | type | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * | value low 32-bit | 20
> + * +----------------+----------------+----------------+----------------+
> + * | value high 32-bit | 24
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 28
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * type - uint8_t, type of the control, one of the XENCAMERA_CTRL_XXX.
> + * value - int64_t, new value of the control.
> + */
> +struct xencamera_ctrl_value {
> + uint8_t type;
> + uint8_t reserved[7];
> + int64_t value;
> +};
> +
> +/*
> + * Request camera control state:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_GET_CTRL | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | type | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * See response format for this request.
> + *
> + * type - uint8_t, type of the control, one of the XENCAMERA_CTRL_XXX.
> + */
> +struct xencamera_get_ctrl_req {
> + uint8_t type;
> +};
> +
> +/*
> + * Request camera capture stream start:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_OP_STREAM_START| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + *
> + * Request camera capture stream stop:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_OP_STREAM_STOP | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + *
> + *---------------------------------- Responses
> --------------------------------
> + *
> + * All response packets have the same length (64 octets).
> + *
> + * All response packets have common header:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | operation | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + *
> + * id - uint16_t, copied from the request.
> + * operation - uint8_t, XENCAMERA_OP_* - copied from request.
> + * status - int32_t, response status, zero on success and -XEN_EXX on
> failure.
> + *
> + *
> + * Configuration response - response for XENCAMERA_OP_CONFIG_SET,
> + * XENCAMERA_OP_CONFIG_GET and XENCAMERA_OP_CONFIG_VALIDATE requests:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CONFIG_XXX | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + * | pixel format | 12
> + * +----------------+----------------+----------------+----------------+
> + * | width | 16
> + * +----------------+----------------+----------------+----------------+
> + * | height | 20
> + * +----------------+----------------+----------------+----------------+
> + * | colorspace | 24
> + * +----------------+----------------+----------------+----------------+
> + * | xfer_func | 28
> + * +----------------+----------------+----------------+----------------+
> + * | ycbcr_enc | 32
> + * +----------------+----------------+----------------+----------------+
> + * | quantization | 36
> + * +----------------+----------------+----------------+----------------+
> + * | displ_asp_ratio_numer | 40
> + * +----------------+----------------+----------------+----------------+
> + * | displ_asp_ratio_denom | 44
> + * +----------------+----------------+----------------+----------------+
> + * | frame_rate_numer | 48
> + * +----------------+----------------+----------------+----------------+
> + * | frame_rate_denom | 52
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 56
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * Meaning of the corresponding values in this response is the same as for
> + * XENCAMERA_OP_CONFIG_SET and XENCAMERA_OP_FRAME_RATE_SET requests.
> + *
> + * colorspace - uint32_t, this supplements pixel_format parameter,
> + * one of the XENCAMERA_COLORSPACE_XXX.
> + * xfer_func - uint32_t, this supplements colorspace parameter,
> + * one of the XENCAMERA_XFER_FUNC_XXX.
> + * ycbcr_enc - uint32_t, this supplements colorspace parameter,
> + * one of the XENCAMERA_YCBCR_ENC_XXX. Please note, that ycbcr_enc is only
> + * valid for YCbCr pixelformats and should be ignored otherwise.
> + * quantization - uint32_t, this supplements colorspace parameter,
> + * one of the XENCAMERA_QUANTIZATION_XXX.
> + * displ_asp_ratio_numer - uint32_t, numerator of the display aspect ratio.
> + * displ_asp_ratio_denom - uint32_t, denominator of the display aspect ratio.
> + */
> +struct xencamera_config_resp {
> + uint32_t pixel_format;
> + uint32_t width;
> + uint32_t height;
> + uint32_t colorspace;
> + uint32_t xfer_func;
> + uint32_t ycbcr_enc;
> + uint32_t quantization;
> + uint32_t displ_asp_ratio_numer;
> + uint32_t displ_asp_ratio_denom;
> + uint32_t frame_rate_numer;
> + uint32_t frame_rate_denom;
> +};
> +
> +/*
> + * Request buffer response - response for XENCAMERA_OP_BUF_GET_LAYOUT
> + * request:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_BUF_GET_LAYOUT | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + * | num_planes | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | size | 16
> + * +----------------+----------------+----------------+----------------+
> + * | plane_size[0] | 20
> + * +----------------+----------------+----------------+----------------+
> + * | plane_size[1] | 24
> + * +----------------+----------------+----------------+----------------+
> + * | plane_size[2] | 28
> + * +----------------+----------------+----------------+----------------+
> + * | plane_size[3] | 32
> + * +----------------+----------------+----------------+----------------+
> + * | plane_stride[0] | 36
> + * +----------------+----------------+----------------+----------------+
> + * | plane_stride[1] | 40
> + * +----------------+----------------+----------------+----------------+
> + * | plane_stride[2] | 44
> + * +----------------+----------------+----------------+----------------+
> + * | plane_stride[3] | 48
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * num_planes - uint8_t, number of planes of the buffer.
> + * size - uint32_t, overall size of the buffer including sizes of the
> + * individual planes and padding if applicable.
> + * plane_size - array of uint32_t, size in octets of the corresponding plane
> + * including padding.
> + * plane_stride - array of uint32_t, size in octets occupied by the
> + * corresponding single image line including padding if applicable.
> + *
> + * Note! The sizes and strides in this response apply to all buffers created
> + * with XENCAMERA_OP_BUF_CREATE command, but individual buffers may have
> + * different plane offsets, see XENCAMERA_OP_BUF_REQUEST.plane_offset.
> + */
> +struct xencamera_buf_get_layout_resp {
> + uint8_t num_planes;
> + uint8_t reserved[3];
> + uint32_t size;
> + uint32_t plane_size[XENCAMERA_MAX_PLANE];
> + uint32_t plane_stride[XENCAMERA_MAX_PLANE];
> +};
> +
> +/*
> + * Request buffer response - response for XENCAMERA_OP_BUF_REQUEST
> + * request:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_OP_BUF_REQUEST | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + * | num_buffers | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * num_buffers - uint8_t, number of buffers to be used.
> + *
> + *
> + * Control enumerate response - response for XENCAMERA_OP_CTRL_ENUM:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CTRL_ENUM | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | type | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | flags | 16
> + * +----------------+----------------+----------------+----------------+
> + * | min low 32-bits | 20
> + * +----------------+----------------+----------------+----------------+
> + * | min high 32-bits | 24
> + * +----------------+----------------+----------------+----------------+
> + * | max low 32-bits | 28
> + * +----------------+----------------+----------------+----------------+
> + * | max high 32-bits | 32
> + * +----------------+----------------+----------------+----------------+
> + * | step low 32-bits | 36
> + * +----------------+----------------+----------------+----------------+
> + * | step high 32-bits | 40
> + * +----------------+----------------+----------------+----------------+
> + * | def_val low 32-bits | 44
> + * +----------------+----------------+----------------+----------------+
> + * | def_val high 32-bits | 48
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 52
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * index - uint8_t, index of the camera control in response.
> + * type - uint8_t, type of the control, one of the XENCAMERA_CTRL_XXX.
> + * flags - uint32_t, flags of the control, one of the XENCAMERA_CTRL_FLG_XXX.
> + * min - int64_t, minimum value of the control.
> + * max - int64_t, maximum value of the control.
> + * step - int64_t, minimum size in which control value can be changed.
> + * def_val - int64_t, default value of the control.
> + */
> +struct xencamera_ctrl_enum_resp {
> + uint8_t index;
> + uint8_t type;
> + uint8_t reserved[2];
> + uint32_t flags;
> + int64_t min;
> + int64_t max;
> + int64_t step;
> + int64_t def_val;
> +};
> +
> +/*
> + * Get control response - response for XENCAMERA_OP_CTRL_GET:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | _OP_CTRL_GET | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | status | 8
> + * +----------------+----------------+----------------+----------------+
> + * | type | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 20
> + * +----------------+----------------+----------------+----------------+
> + * | value low 32-bit | 24
> + * +----------------+----------------+----------------+----------------+
> + * | value high 32-bit | 28
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 32
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * type - uint8_t, type of the control, one of the XENCAMERA_CTRL_XXX.
> + * value - int64_t, new value of the control.
> + */
> +
> +/*
> + *----------------------------------- Events
> ----------------------------------
> + *
> + * Events are sent via a shared page allocated by the front and propagated by
> + * evt-event-channel/evt-ring-ref XenStore entries.
> + *
> + * All event packets have the same length (64 octets).
> + * All event packets have common header:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id | type | reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + *
> + * id - uint16_t, event id, may be used by front.
> + * type - uint8_t, type of the event.
> + *
> + *
> + * Frame captured event - event from back to front when a new captured
> + * frame is available:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_EVT_FRAME_AVAIL| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | index | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | used_sz | 16
> + * +----------------+----------------+----------------+----------------+
> + * | seq_num | 20
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 24
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * index - uint8_t, index of the buffer that contains new captured frame,
> + * see XENCAMERA_OP_BUF_CREATE description on the range
> + * used_sz - uint32_t, number of octets this frame has. This can be less
> + * than the XENCAMERA_OP_BUF_REQUEST.size (response) for compressed formats.
> + * seq_num - uint32_t, sequential number of the frame. Must be
> + * monotonically increasing. If skips are detected in seq_num then that
> + * means that the frames in-between were dropped. Note however that not
> + * all video capture hardware is capable of detecting dropped frames.
> + * In that case there will be no skips in the sequence counter.
> + */
> +struct xencamera_frame_avail_evt {
> + uint8_t index;
> + uint8_t reserved[3];
> + uint32_t used_sz;
> + uint32_t seq_num;
> +};
> +
> +/*
> + * Control change event- event from back to front when camera control
> + * has changed:
> + * 0 1 2 3 octet
> + * +----------------+----------------+----------------+----------------+
> + * | id |_EVT_CTRL_CHANGE| reserved | 4
> + * +----------------+----------------+----------------+----------------+
> + * | type | reserved | 8
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 12
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 16
> + * +----------------+----------------+----------------+----------------+
> + * | value low 32-bit | 20
> + * +----------------+----------------+----------------+----------------+
> + * | value high 32-bit | 24
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 28
> + * +----------------+----------------+----------------+----------------+
> + * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
> + * +----------------+----------------+----------------+----------------+
> + * | reserved | 64
> + * +----------------+----------------+----------------+----------------+
> + *
> + * type - uint8_t, type of the control, one of the XENCAMERA_CTRL_XXX.
> + * value - int64_t, new value of the control.
> + *
> + * Notes:
> + * - this event is not sent for write-only controls
> + * - this event is not sent to the originator of the control change
> + * - this event is not sent when frontend first connects, e.g. initial
> + * control state must be explicitly queried
> + */
> +
> +struct xencamera_req {
> + uint16_t id;
> + uint8_t operation;
> + uint8_t reserved[5];
> + union {
> + struct xencamera_config_req config;
> + struct xencamera_frame_rate_req frame_rate;
> + struct xencamera_buf_request buf_request;
> + struct xencamera_buf_create_req buf_create;
> + struct xencamera_index index;
> + struct xencamera_ctrl_value ctrl_value;
> + struct xencamera_get_ctrl_req get_ctrl;
> + uint8_t reserved[56];
> + } req;
> +};
> +
> +struct xencamera_resp {
> + uint16_t id;
> + uint8_t operation;
> + uint8_t reserved;
> + int32_t status;
> + union {
> + struct xencamera_config_resp config;
> + struct xencamera_buf_get_layout_resp buf_layout;
> + struct xencamera_buf_request buf_request;
> + struct xencamera_ctrl_enum_resp ctrl_enum;
> + struct xencamera_ctrl_value ctrl_value;
> + uint8_t reserved1[56];
> + } resp;
> +};
> +
> +struct xencamera_evt {
> + uint16_t id;
> + uint8_t type;
> + uint8_t reserved[5];
> + union {
> + struct xencamera_frame_avail_evt frame_avail;
> + struct xencamera_ctrl_value ctrl_value;
> + uint8_t reserved[56];
> + } evt;
> +};
> +
> +DEFINE_RING_TYPES(xen_cameraif, struct xencamera_req, struct xencamera_resp);
> +
> +/*
> +
> ******************************************************************************
> + * Back to front events delivery
> +
> ******************************************************************************
> + * In order to deliver asynchronous events from back to front a shared page
> is
> + * allocated by front and its granted reference propagated to back via
> + * XenStore entries (evt-ring-ref/evt-event-channel).
> + * This page has a common header used by both front and back to synchronize
> + * access and control event's ring buffer, while back being a producer of the
> + * events and front being a consumer. The rest of the page after the header
> + * is used for event packets.
> + *
> + * Upon reception of an event(s) front may confirm its reception
> + * for either each event, group of events or none.
> + */
> +
> +struct xencamera_event_page {
> + uint32_t in_cons;
> + uint32_t in_prod;
> + uint8_t reserved[56];
> +};
> +
> +#define XENCAMERA_EVENT_PAGE_SIZE 4096
> +#define XENCAMERA_IN_RING_OFFS (sizeof(struct xencamera_event_page))
> +#define XENCAMERA_IN_RING_SIZE (XENCAMERA_EVENT_PAGE_SIZE -
> XENCAMERA_IN_RING_OFFS)
> +#define XENCAMERA_IN_RING_LEN (XENCAMERA_IN_RING_SIZE / sizeof(struct
> xencamera_evt))
> +#define XENCAMERA_IN_RING(page) \
> + ((struct xencamera_evt *)((char *)(page) + XENCAMERA_IN_RING_OFFS))
> +#define XENCAMERA_IN_RING_REF(page, idx) \
> + (XENCAMERA_IN_RING((page))[(idx) % XENCAMERA_IN_RING_LEN])
> +
> +#endif /* __XEN_PUBLIC_IO_CAMERAIF_H__ */
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
>
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