[PATCH v2 0/4] Add sysfs interface to switchtec-dma

[Logan Gunthorpe]

This patch set adds a handful of sysfs attributes to the switchtec-dma
driver.

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 the miscellaneous fixes series I sent
earlier[1].

Logan

[1] https://lore.kernel.org/all/20260727181526.9672-1-logang@xxxxxxxxxxxx/

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: 0428de2e30c4690e119db5ee4b27725216b61de8
--
2.47.3