media: i2c: add Sony IMX681 sensor support

[ooaklee]

Summary

• document the Sony IMX681 image sensor and its currently validated one-trio C-PHY profile
• add a standalone V4L2 sensor driver for 3840x2640 RAW10 at approximately 30 frames per second
• expose frame length, 24-bit exposure, analog-gain, and digital-gain controls
• enable the driver in the Ubuntu X1E kernel configuration and package policy

Dependency and status

This PR is intended to target jg/ubuntu-qcom-x1e-7.2.y directly. It is the first camera topic in the ordered release-line extraction after the Denali baseline in #82 and the QSPI/touch core in #83. It follows the staging correction merged through #81 but does not replay #81 or merge the broad -sp11 staging branch.

There is no camera-topic dependency: this branch is based directly on jg/ubuntu-qcom-x1e-7.2.y at 032e174490d2. The X1E80100 C-PHY receiver support and the Denali OLED camera graph will follow in separate stacked PRs.

This PR is a draft. The driver cannot be exercised end to end until those receiver and board-description topics are present, so the exact split stack still needs the hardware checks listed below.

Containment

• this topic adds the sensor binding, driver, register table, configuration, and maintainer entry only
• it adds no Denali device-tree node and changes no Qualcomm PHY or CAMSS driver
• the driver binds only to sony,imx681
• probe rejects any endpoint other than one CSI-2 C-PHY trio on lane/trio 0 at the 1.203 GHz V4L2 link frequency, and rejects any input clock other than 19.2 MHz
• only the validated 3840x2640 RAW10 mode is exposed
• none of the staging source's CCS changes, VFE write-mode changes, CSID crop/drop changes, diagnostic logging, or sensor-specific CAMSS format handling is included

Provenance

Both commits are authored by Leon Silcott and carry the authorized Signed-off-by: Leon Silcott <leon@boasi.io>. They are focused rewrites of the final integration state recorded in d915d679423e.

The register tables and initial standalone sensor work derive from @turbineBMW's public camera review patch at immutable revision 05e5335bc724. That contribution is credited in both commit messages, and @turbineBMW is listed as the binding and driver maintainer. No Signed-off-by or Co-authored-by trailer is attributed to @turbineBMW because the referenced source did not provide one for these rewritten commits.

Validation

• git diff --check 032e174490d2..HEAD
• strict checkpatch: no errors or checks; only the generic new-file/MAINTAINERS prompt for the driver/table commit, with both files covered by the new SONY IMX681 SENSOR DRIVER entry
• ARM64 ubuntu_x1e_defconfig W=1 build of drivers/media/i2c/imx681.o
• DT binding/schema validation for Documentation/devicetree/bindings/media/i2c/sony,imx681.yaml
• scripts/get_maintainer.pl resolves both new driver files to the new IMX681 maintainer entry
• source audit confirms this topic contains no board-DT, Qualcomm PHY, CAMSS, CCS, or userspace-ABI changes

Hardware checks still required

These checks apply once this branch is combined with the dependent C-PHY and Denali graph topics:

• boot the exact cumulative branch on an X1E Surface Pro 11 OLED
• verify IMX681 identification, media-graph enumeration, and runtime power transitions
• verify repeated and continuous 3840x2640 RAW10 capture at approximately 30 frames per second
• verify exposure, analog-gain, and digital-gain controls and repeated stream start/stop
• verify suspend/resume followed by a successful camera reopen
• verify that a system without a sony,imx681 firmware node gains no device and sees no probe regression when the module is present