[PATCH v2 0/6] i2c: qcom-cci: Runtime capability detection and improved read/write

[Loic Poulain]

Improves the Qualcomm CCI I2C driver read/write in different ways:

- Capabilities (queue sizes, max transfer lengths, supported I2C mode)
  are currently hardcoded per DT compatible string in a handful of
  cci_data instances. Patch 4 replaces the static per-compatible
  structs with a single version-sorted capability catalog resolved
  at runtime from CCI_HW_VERSION.

- The driver only supported single-command writes, capped at 11 bytes
  regardless of how much space the command queue actually has. Patches
  2 and 5 factor out the write-command queueing into a reusable helper
  and then add burst-write support, chunking longer writes
  across the whole queue instead of a single command's payload.

- The FIFO read path hardcoded a fixed 12-byte limit unrelated to the
  actual per-revision FIFO size, with a special-cased drain loop.
  Patch 6 simplify the FIFO read/drain-loop and derive the read-side
  limits from each revision's FIFO size

- Add burst-read support using threshold interrupts, allowing reads of
  arbitrary size by draining the FIFO incrementally during the transfer.

Also add overflow and underflow IRQ reporting, as queue/fifo limits are
now derived from the hardware capabilities and exercised more
aggressively.

Support for unbounded write transfers using the threshold IRQ
mechanism is planned as a follow-up and not part of this series.

Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- Split the HALT_ACK reset fix out into its own patch (Andi)
- Fix a typo in the "Detect capabilities from CCI_HW_VERSION" commit
  message (Andi)
- Use GENMASK()/FIELD_GET() to decode the CCI_HW_VERSION fields (Konrad)
- Derive the number of masters from the DT i2c-bus subnodes instead of
  encoding it per compatible string (Konrad)
- Add burst read support via RD_THRESHOLD/RD_PAUSE IRQs
- Link to v1: https://lore.kernel.org/r/20261004-cci-imp-v1-0-227d12cb4829@xxxxxxxxxxxxxxxx

---
Loic Poulain (6):
      i2c: qcom-cci: Factor out write command queue programming
      i2c: qcom-cci: Handle and report queue overflow/underflow interrupts
      i2c: qcom-cci: Detect capabilities from CCI_HW_VERSION at runtime
      i2c: qcom-cci: Add burst write support
      i2c: qcom-cci: Extend i2c read limits based on CCI revision
      i2c: qcom-cci: Add burst read support

 drivers/i2c/busses/i2c-qcom-cci.c | 429 +++++++++++++++++++++++++++++---------
 1 file changed, 325 insertions(+), 104 deletions(-)
---
base-commit: d6dc536a4c8bb99dd822bc349a9e801be7ea81c9
change-id: 20260929-cci-imp-8ba384309942

Best regards,
-- 
Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>