[PATCH v4 0/4] Add sysfs interface to switchtec-dma

[Logan Gunthorpe]

This is mostly a resend of my series last week. I'm really hoping to
get this in this cycle as this is the work I actually need to get done
and the bug fixes are something of a side project.

This patch set adds a handful of sysfs attributes to the switchtec-dma
driver. This is the 4th version which I'm hoping to get it in now
that my bug fixes and cleanup branch from Sashiko feedback was merged.

The first two patches clean up and generalize the technique that
ioat used to add sysfs attributes to a dma channel. The other two
patches add a couple different sets of sysfs attributes that are useful
in configuring and monitoring the hardware.

This patch set is based on v7.4-rc2.

Logan

[v3] https://lore.kernel.org/all/20261103154022.459620-1-logang@xxxxxxxxxxxx/

--

Changes since v3:
 - Added Dave Jiang's Reviewed-by tag
 - Rebased on v7.4-rc2

Changes since v2:
 - Renamed the new channel lookup helpers to use the dmaengine_ prefix:
   dma_chan_from_dev_lock() and dma_chan_from_dev_unlock() are now
   dmaengine_chan_from_dev_lock() and dmaengine_chan_from_dev_unlock(),
   and the dma_chan_from_dev CLASS is now dmaengine_chan_from_dev.
   (Per Frank Li)
 - Rebased on v7.4-rc1

Changes since v1:
 - Replaced the per-channel embedded-kobject approach entirely with a
   new dma_device.chan_groups mechanism that attaches driver sysfs
   attributes directly to the channel's existing struct device
   instead of a second, separately-managed kobject. (Per Sashiko)
 - Fixed the busy-channel check in perf_cfg_store(): it now returns
   -EBUSY instead of falsely reporting success, and the racy lockless
   chan->client_count check has been replaced with a hw_cfg_locked
   flag that's set/cleared under hw_ctrl_lock from
   alloc/free_chan_resources(), closing a TOCTOU window against
   concurrent channel allocation. (Per Sashiko)
 - Took the hw_ctrl_lock around the perf_cfg read-modify-write
   so concurrent sysfs writes to different config attributes can't
   interleave and lose an update. (Per Sashiko)
 - Converted latency_selector_show() from strcat() to
   sysfs_emit()/sysfs_emit_at(). (Per Sashiko)
 - The PCI1008 device ID patch has been removed from this
   series, expanded and sent separately.

Logan Gunthorpe (4):
  dmaengine: add per-channel sysfs attribute groups via chan_groups
  dmaengine: ioatdma: convert per-channel sysfs to chan_groups
  dmaengine: switchtec-dma: add config sysfs attributes
  dmaengine: switchtec-dma: add pmon sysfs attributes

 drivers/dma/dmaengine.c     |  27 +++
 drivers/dma/dmaengine.h     |  19 ++
 drivers/dma/ioat/dma.h      |   6 +-
 drivers/dma/ioat/init.c     |   5 +-
 drivers/dma/ioat/sysfs.c    | 166 ++++++-------
 drivers/dma/switchtec_dma.c | 452 ++++++++++++++++++++++++++++++++++++
 include/linux/dmaengine.h   |   4 +
 7 files changed, 569 insertions(+), 110 deletions(-)


base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb
-- 
2.47.3