[PATCH v3 0/3] driver core: Add device link related sysfs files

[Saravana Kannan <saravanak@google.com>]

With fw_devlink and with sync_state() callback features, there's a lot
of device/device link related information that's not available in sysfs.

Exposing these details to user space can be very useful in understanding
suspend/resume issues, runtime pm issues, probing issues, figuring out
the modules that'd be needed for first stage init, etc. In fact, an
earlier verion of this series was very helpful in debugging and
validating the recent memory leak fix[1].

This series is based on driver-core-next and [1] cherry-picked on top of
it.

[1] - https://lore.kernel.org/lkml/20200519063000.128819-1-saravanak@google.com/

v1->v2:
Patch 1/4
- New patch
Patch 2/4
- Fixed the warnings I saw before that were related to incorrect
  sysfs removal code when a device link is deleted.
- Fixed error handling in device_link_add()
- Split up flags into more meaningful files.
- Added status file.
Patch 3/4
- Fixed error handling that Greg pointed out before.
Patch 4/4
- New patch

v2->v3:
- Dropped patch 1/4 from v2 since it was already picked up. So numbering
  has shifted.
Patch 1/3
- Added documentation

Saravana Kannan (3):
  driver core: Expose device link details in sysfs
  driver core: Add state_synced sysfs file for devices that support it
  driver core: Add waiting_for_supplier sysfs file for devices

 Documentation/ABI/testing/sysfs-class-devlink | 126 ++++++++++
 .../ABI/testing/sysfs-devices-consumer        |   8 +
 .../ABI/testing/sysfs-devices-state_synced    |  24 ++
 .../ABI/testing/sysfs-devices-supplier        |   8 +
 .../sysfs-devices-waiting_for_supplier        |  17 ++
 drivers/base/core.c                           | 237 +++++++++++++++++-
 drivers/base/dd.c                             |  22 ++
 include/linux/device.h                        |  58 ++---
 8 files changed, 464 insertions(+), 36 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-devlink
 create mode 100644 Documentation/ABI/testing/sysfs-devices-consumer
 create mode 100644 Documentation/ABI/testing/sysfs-devices-state_synced
 create mode 100644 Documentation/ABI/testing/sysfs-devices-supplier
 create mode 100644 Documentation/ABI/testing/sysfs-devices-waiting_for_supplier

-- 
2.27.0.rc0.183.gde8f92d652-goog