Message-Id: <20251106-qcom-qce-cmd-descr-v8-0-ecddca23ca26@linaro.org>
Date: Thu, 06 Nov 2025 12:33:56 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Vinod Koul <vkoul@...nel.org>, Jonathan Corbet <corbet@....net>, 
 Thara Gopinath <thara.gopinath@...il.com>, 
 Herbert Xu <herbert@...dor.apana.org.au>, 
 "David S. Miller" <davem@...emloft.net>, 
 Udit Tiwari <quic_utiwari@...cinc.com>, 
 Daniel Perez-Zoghbi <dperezzo@...cinc.com>, 
 Md Sadre Alam <mdalam@....qualcomm.com>
Cc: dmaengine@...r.kernel.org, linux-doc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-crypto@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
 Dmitry Baryshkov <lumag@...nel.org>
Subject: [PATCH v8 00/11] crypto/dmaengine: qce: introduce BAM locking and
 use DMA for register I/O

Currently the QCE crypto driver accesses the crypto engine registers
directly via CPU. Trust Zone may perform crypto operations simultaneously
resulting in a race condition. To remedy that, let's introduce generic
LOCK/UNLOCK flags in the dma engine API that allow linux to request a
DMA controller lock for the duration of the transaction.

In the specific case of the BAM DMA this translates to sending command
descriptors performing dummy writes with the relevant flags set. The BAM
will then lock all other pipes not related to the current pipe group, and
keep handling the current pipe only until it sees the the unlock bit.

In order for the locking to work correctly, we also need to switch to
using DMA for all register I/O.

On top of this, the series contains some additional tweaks and
refactoring.

The goal of this is not to improve the performance but to prepare the
driver for supporting decryption into secure buffers in the future.

Tested with tcrypt.ko, kcapi and cryptsetup.

Shout out to Daniel and Udit from Qualcomm for helping me out with some
DMA issues we encountered.

Merging strategy: either an Ack from Vinod or an immutable branch with
the DMA changes for the crypto subsystem will work.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
Changes in v8:
- Rework the command descriptor logic and drop a lot of unneeded code
- Use the physical address for BAM command descriptor access, not the
  mapped DMA address
- Fix the problems with iommu faults on newer platforms
- Generalize the LOCK/UNLOCK flags in dmaengine and reword the docs and
  commit messages
- Make the BAM locking logic stricter in the DMA engine driver
- Add some additional minor QCE driver refactoring changes to the series
- Lots of small reworks and tweaks to rebase on current mainline and fix
  previous issues
- Link to v7: https://lore.kernel.org/all/20250311-qce-cmd-descr-v7-0-db613f5d9c9f@linaro.org/

Changes in v7:
- remove unused code: writing to multiple registers was not used in v6,
  neither were the functions for reading registers over BAM DMA-
- remove
- don't read the SW_VERSION register needlessly in the BAM driver,
  instead: encode the information on whether the IP supports BAM locking
  in device match data
- shrink code where possible with logic modifications (for instance:
  change the implementation of qce_write() instead of replacing it
  everywhere with a new symbol)
- remove duplicated error messages
- rework commit messages
- a lot of shuffling code around for easier review and a more
  streamlined series
- Link to v6: https://lore.kernel.org/all/20250115103004.3350561-1-quic_mdalam@quicinc.com/

Changes in v6:
- change "BAM" to "DMA"
- Ensured this series is compilable with the current Linux-next tip of
  the tree (TOT).

Changes in v5:
- Added DMA_PREP_LOCK and DMA_PREP_UNLOCK flag support in separate patch
- Removed DMA_PREP_LOCK & DMA_PREP_UNLOCK flag
- Added FIELD_GET and GENMASK macro to extract major and minor version

Changes in v4:
- Added feature description and test hardware
  with test command
- Fixed patch version numbering
- Dropped dt-binding patch
- Dropped device tree changes
- Added BAM_SW_VERSION register read
- Handled the error path for the api dma_map_resource()
  in probe
- updated the commit messages for batter redability
- Squash the change where qce_bam_acquire_lock() and
  qce_bam_release_lock() api got introduce to the change where
  the lock/unlock flag get introced
- changed cover letter subject heading to
  "dmaengine: qcom: bam_dma: add cmd descriptor support"
- Added the very initial post for BAM lock/unlock patch link
  as v1 to track this feature

Changes in v3:
- https://lore.kernel.org/lkml/183d4f5e-e00a-8ef6-a589-f5704bc83d4a@quicinc.com/
- Addressed all the comments from v2
- Added the dt-binding
- Fix alignment issue
- Removed type casting from qce_write_reg_dma()
  and qce_read_reg_dma()
- Removed qce_bam_txn = dma->qce_bam_txn; line from
  qce_alloc_bam_txn() api and directly returning
  dma->qce_bam_txn

Changes in v2:
- https://lore.kernel.org/lkml/20231214114239.2635325-1-quic_mdalam@quicinc.com/
- Initial set of patches for cmd descriptor support
- Add client driver to use BAM lock/unlock feature
- Added register read/write via BAM in QCE Crypto driver
  to use BAM lock/unlock feature

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

---
Bartosz Golaszewski (11):
      dmaengine: Add DMA_PREP_LOCK/DMA_PREP_UNLOCK flags
      dmaengine: qcom: bam_dma: Extend the driver's device match data
      dmaengine: qcom: bam_dma: Add bam_pipe_lock flag support
      crypto: qce - Include algapi.h in the core.h header
      crypto: qce - Remove unused ignore_buf
      crypto: qce - Simplify arguments of devm_qce_dma_request()
      crypto: qce - Use existing devres APIs in devm_qce_dma_request()
      crypto: qce - Map crypto memory for DMA
      crypto: qce - Add BAM DMA support for crypto register I/O
      crypto: qce - Add support for BAM locking
      crypto: qce - Switch to using BAM DMA for crypto I/O

 Documentation/driver-api/dmaengine/provider.rst |   9 ++
 drivers/crypto/qce/aead.c                       |  10 ++
 drivers/crypto/qce/common.c                     |  39 ++++--
 drivers/crypto/qce/core.c                       |  28 ++++-
 drivers/crypto/qce/core.h                       |  11 ++
 drivers/crypto/qce/dma.c                        | 158 ++++++++++++++++++++----
 drivers/crypto/qce/dma.h                        |  15 ++-
 drivers/crypto/qce/sha.c                        |   8 ++
 drivers/crypto/qce/skcipher.c                   |   7 ++
 drivers/dma/qcom/bam_dma.c                      |  64 ++++++++--
 include/linux/dmaengine.h                       |   6 +
 11 files changed, 304 insertions(+), 51 deletions(-)
---
base-commit: f3dfcffe2756f05cbae80ffdaa0ddf951e08431a
change-id: 20251103-qcom-qce-cmd-descr-c5e9b11fe609

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

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