This is a version 2 of the V4L2 API bits to support Software Digital Radio (SDR). The changes from version 1 are: - fix compilation; - add a new capture type for SDR (V4L2_BUF_TYPE_SDR_CAPTURE), with the corresponding documentation; - remove legacy V4L1 buffer types from videobuf2.h. With regards to VIDIOC_S_TUNER, what's currently defined there is that, in contrary to what a radio device does, this ioctl would set the input. This patch adds the very basic stuff for SDR: - a separate devnode; - an VIDIOC_QUERYCAP caps for SDR; - a fourcc group for SDR; - a few DocBook bits. What's missing: - SDR specific controls; - Sample rate config; ... As discussing DocBook changes inside the patch is hard, I'm adding here the DocBook formatted changes. The DocBook changes add the following bits: At Chapter 1. Common API Elements, it adds: <text> Software Digital Radio (SDR) Tuners and Modulators ================================================== Those devices are special types of Radio devices that don't have any analog demodulator. Instead, it samples the radio IF or baseband and sends the samples for userspace to demodulate. Tuners ====== SDR receivers can have one or more tuners sampling RF signals. Each tuner is associated with one or more inputs, depending on the number of RF connectors on the tuner. The type field of the respective struct v4l2_input returned by the VIDIOC_ENUMINPUT ioctl is set to V4L2_INPUT_TYPE_TUNER and its tuner field contains the index number of the tuner input. To query and change tuner properties applications use the VIDIOC_G_TUNER and VIDIOC_S_TUNER ioctl, respectively. The struct v4l2_tuner returned by VIDIOC_G_TUNER also contains signal status information applicable when the tuner of the current SDR input is queried. In order to change the SDR input, VIDIOC_S_TUNER with a new SDR index should be called. Drivers must support both ioctls and set the V4L2_CAP_SDR and V4L2_CAP_TUNER flags in the struct v4l2_capability returned by the VIDIOC_QUERYCAP ioctl. Modulators ========== To be defined. </text> At the end of Chapter 2. Image Formats, it adds: <text> SDR format struture =================== Table 2.4. struct v4l2_sdr_format ================================= __u32 sampleformat The format of the samples used by the SDR device. This is a little endian four character code. Table 2.5. SDR formats ====================== V4L2_SDR_FMT_I8Q8 Samples are given by a sequence of 8 bits in-phase(I) and 8 bits quadrature (Q) samples taken from a signal(t) represented by the following expression: signal(t) = I * cos(2π fc t) - Q * sin(2π fc t) </text> Of course, other formats will be needed at Table 2.5, as SDR could also be taken baseband samples, being, for example, a simple sequence of equally time-spaced digitalized samples of the signal in time. SDR samples could also use other resolutions, use a non-linear (A-law, u-law) ADC, or even compress the samples (with ADPCM, for example). So, this table will grow as newer devices get added, and an userspace library may be required to convert them into some common format. At "Chapter 4. Interfaces", it adds the following text: <text> Software Digital Radio(SDR) Interface ===================================== This interface is intended for Software Digital Radio (SDR) receivers and transmitters. Conventionally V4L2 SDR devices are accessed through character device special files named /dev/sdr0 to/dev/radio255 and uses a dynamically allocated major/minor number. Querying Capabilities ===================== Devices supporting the radio interface set the V4L2_CAP_SDR and V4L2_CAP_TUNER or V4L2_CAP_MODULATOR flag in the capabilities field of struct v4l2_capability returned by the VIDIOC_QUERYCAP ioctl. Other combinations of capability flags are reserved for future extensions. Supplemental Functions ====================== SDR receivers should support tuner ioctls. SDR transmitter ioctl's will be defined in the future. SDR devices should also support one or more of the following I/O ioctls: read or write, memory mapped IO, user memory IO and/or DMA buffers. SDR devices can also support controls ioctls. The SDR Input/Output are A/D or D/A samples taken from a modulated signal, and can eventually be packed by the hardware. They are generally encoded using cartesian in-phase/quadrature (I/Q) samples, to make demodulation easier. The format of the samples should be according with SDR format. </text> Note: "SDR format" on the last paragraph is an hyperlink to Chapter 2. Image Formats. At "Appendix A. Function Reference - ioctl VIDIOC_QUERYCAP", it adds: <text> Table A.93. Device Capabilities Flags ... V4L2_CAP_SDR 0x00100000 The device is a Software Digital Radio. For more information about SDR programming see the section called “Software Digital Radio (SDR) Tuners and Modulators”. </text> Mauro Carvalho Chehab (3): [media] Add SDR at V4L2 API videodev2.h: Remove the unused old V4L1 buffer types [media] V4L2 api: Add a buffer capture type for SDR Documentation/DocBook/media/v4l/common.xml | 35 ++++++++++++++++++ Documentation/DocBook/media/v4l/dev-capture.xml | 26 ++++++++------ Documentation/DocBook/media/v4l/io.xml | 6 ++++ Documentation/DocBook/media/v4l/pixfmt.xml | 41 ++++++++++++++++++++++ Documentation/DocBook/media/v4l/v4l2.xml | 1 + .../DocBook/media/v4l/vidioc-querycap.xml | 7 ++++ drivers/media/v4l2-core/v4l2-dev.c | 3 ++ drivers/media/v4l2-core/v4l2-ioctl.c | 32 +++++++++++++++++ include/media/v4l2-dev.h | 3 +- include/media/v4l2-ioctl.h | 8 +++++ include/uapi/linux/videodev2.h | 33 +++++++---------- 11 files changed, 163 insertions(+), 32 deletions(-) -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
