[PATCH v6 0/4] New Microsemi PCI Switch Management Driver

[Logan Gunthorpe]

Hi,

Hopefully this is the last change necessary. The new code to handle
unbind follows Jason's suggestions and is a lot easier to reason about.
It's also been tested interrupting a number of operations.

Thanks,

Logan

--

Changes since v5:

* Reworked cleanup during unbind again. This time we follow the pattern
  roughly suggested by Jason Gunthorpe: we use an alive flag
  that's checked with a rw semaphore held by the cdev ops. Except
  instead of using the rwsem we just use the already existing
  mrpc_mutex. (Seeing the vast majority of locations that would use the
  semaphore overlap with the existing mutex.)
* Added a small performance enhancement so the code reads less io memory
  if the user is quick in submitting their read request.

Changes since v4:

* Turns out pushing the pci release code into the device release
  function didn't work as I would have liked. If you try to unbind the
  device with an instance open, then you hit a kernel bug at
  drivers/pci/msi.c:371. (This didn't occur in v3.)

  To solve this, we've moved the pci release code back into the
  unregister function and reintroduced an alive flag. This time,
  however, the alive flag is protected by mrpc_mutex and we're very
  careful about what happens to devices still in use (they should
  all be released through the timeout path and an ENODEV error
  returned to userspace; while new commands are blocked with the
  same error).

Changes since v3:

* Removed stdev_is_alive and moved pci deinit functions
  into the device release function which only occurs after all
  cdev instances are closed. (per Bjorn)
* Reduced locking in read/write functions (per Bjorn)
* Use pci_alloc_irq_vectors to vastly improve ISR initialization (Bjorn)
* A few other minor nits and cleanup as noticed by Bjorn

Changes since v2:

* Collected reviewed and tested tags
* Very minor fix to the error path in the create function

Changes since v1:

* Rebased onto 4.10-rc6 (cleanly)
* Split the patch into a few more easily digestible patches (as
  suggested by Greg Kroah-Hartman)
* Folded switchtec.c into switchtec.h (per Greg)
* Fixed a bunch of 32bit build warnings caught by the kbuild test robot
* Fixed some issues in the documentation so it has a proper
  reStructredText format (as noted by Jonathan Corbet)
* Fixed padding and sizes in the IOCTL structures as noticed by Emil
  Velikov and used pahole to verify their consistency across 32 and 64
  bit builds
* Reworked one of the IOCTL interfaces to be more future proof (per
  Emil).

Changes since RFC:

* Fixed incorrect use of the drive model as pointed out by Greg
  Kroah-Hartman
* Used devm functions as suggested by Keith Busch
* Added a handful of sysfs attributes to the switchtec class
* Added a handful of IOCTLs to the switchtec device
* A number of miscellaneous bug fixes

--

Hi,

This is a continuation of the RFC we posted lasted month [1] which
proposes a management driver for Microsemi's Switchtec line of PCI
switches. This hardware is still looking to be used in the Open
Compute Platform

To make this entirely clear: the Switchtec products are compliant
with the PCI specifications and are supported today with the standard
in-kernel driver. However, these devices also expose a management endpoint
on a separate PCI function address which can be used to perform some
advanced operations. This is a driver for that function. See the patch
for more information.

Since the RFC, we've made the changes requested by Greg Kroah-Hartman
and Keith Busch, and we've also fleshed out a number of features. We've
added a couple of IOCTLs and sysfs attributes which are documented in
the patch. Significant work has also been done on the userspace tool
which is available under a GPL license at [2]. We've also had testing
done by some of the interested parties.

We hope to see this work included in either 4.11 or 4.12 assuming a
smooth review process.

The patch is based off of the v4.10-rc6 release.

Thanks for your review,

Logan

[1] https://www.spinics.net/lists/linux-pci/msg56897.html
[2] https://github.com/sbates130272/switchtec-user

Logan Gunthorpe (4):
  MicroSemi Switchtec management interface driver
  switchtec: Add user interface documentation
  switchtec: Add sysfs attributes to the Switchtec driver
  switchtec: Add IOCTLs to the Switchtec driver

 Documentation/ABI/testing/sysfs-class-switchtec |   96 ++
 Documentation/ioctl/ioctl-number.txt            |    1 +
 Documentation/switchtec.txt                     |   80 ++
 MAINTAINERS                                     |   11 +
 drivers/pci/Kconfig                             |    1 +
 drivers/pci/Makefile                            |    1 +
 drivers/pci/switch/Kconfig                      |   13 +
 drivers/pci/switch/Makefile                     |    1 +
 drivers/pci/switch/switchtec.c                  | 1599 +++++++++++++++++++++++
 include/uapi/linux/switchtec_ioctl.h            |  132 ++
 10 files changed, 1935 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-switchtec
 create mode 100644 Documentation/switchtec.txt
 create mode 100644 drivers/pci/switch/Kconfig
 create mode 100644 drivers/pci/switch/Makefile
 create mode 100644 drivers/pci/switch/switchtec.c
 create mode 100644 include/uapi/linux/switchtec_ioctl.h

--
2.1.4