Subject: [PATCH v7 0/5] Introduce the Counter character device interface

From: William Breathitt Gray <[email-masked]>
Date: Fri, 25 Dec 2020 19:15:33 -0500

Changes in v7:
 - Implemented u32 enums; enum types can now be used directly for
   callbacks and values
 - Fixed refcount underflow bug
 - Refactored all err check to check for err < 0; this should help
   prevent future oversights on valid positive return valids
 - Use mutex instead of raw_spin_lock in counter_chrdev_read();
   kifo_to_user() can now safely sleep
 - Renamed COUNTER_COMPONENT_DUMMY to COUNTER_COMPONENT_NONE to make
   purpose more obvious
 - Introduced a watch_validate() callback
 - Consolidated the functionality to clear the watches to the
   counter_clear_watches() function
 - Reimplemented counter_push_event() as a void function; on error,
   errno is returned via struct counter_event so that it can be handled
   by userspace (because interrupt handlers can't do much for this)
 - Renamed the events_config() callback to events_configure();
   "events_config" could be confused as a read callback when this is
   actually intended to configure the device for the requested events
 - Reimplemented 104-QUAD-8 driver to use events_configure() and
   watch_validate() callbacks; irq_trigger_enable sysfs attribute
   removed because events_configure() now serves this purpose

The changes for this revision were much simpler compared to the previous
revisions. I don't have any further questions for this patchset, so it's
really just a search for possible bugs or regressions now. Please test
and verify this patchset on your systems, and ACK appropriately.

To summarize the main points: there are no changes to the existing
Counter sysfs userspace interface; a Counter character device interface
is introduced that allows Counter events and associated data to be
read() by userspace; the events_configure() and watch_validate() driver
callbacks are introduced to support Counter events; and IRQ support is
added to the 104-QUAD-8 driver, serving as an example of how to support
the new Counter events functionality.

William Breathitt Gray (5):
  counter: Internalize sysfs interface code
  docs: counter: Update to reflect sysfs internalization
  counter: Add character device interface
  docs: counter: Document character device interface
  counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8

 Documentation/ABI/testing/sysfs-bus-counter   |   18 +-
 .../ABI/testing/sysfs-bus-counter-104-quad-8  |   25 +
 Documentation/driver-api/generic-counter.rst  |  416 ++++-
 .../userspace-api/ioctl/ioctl-number.rst      |    1 +
 MAINTAINERS                                   |    2 +-
 drivers/counter/104-quad-8.c                  |  799 +++++----
 drivers/counter/Kconfig                       |    6 +-
 drivers/counter/Makefile                      |    1 +
 drivers/counter/counter-chrdev.c              |  490 ++++++
 drivers/counter/counter-chrdev.h              |   16 +
 drivers/counter/counter-core.c                |  182 ++
 drivers/counter/counter-sysfs.c               |  868 ++++++++++
 drivers/counter/counter-sysfs.h               |   13 +
 drivers/counter/counter.c                     | 1496 -----------------
 drivers/counter/ftm-quaddec.c                 |   61 +-
 drivers/counter/microchip-tcb-capture.c       |  103 +-
 drivers/counter/stm32-lptimer-cnt.c           |  181 +-
 drivers/counter/stm32-timer-cnt.c             |  149 +-
 drivers/counter/ti-eqep.c                     |  224 +--
 include/linux/counter.h                       |  716 ++++----
 include/linux/counter_enum.h                  |   45 -
 include/uapi/linux/counter.h                  |  123 ++
 22 files changed, 3259 insertions(+), 2676 deletions(-)
 create mode 100644 drivers/counter/counter-chrdev.c
 create mode 100644 drivers/counter/counter-chrdev.h
 create mode 100644 drivers/counter/counter-core.c
 create mode 100644 drivers/counter/counter-sysfs.c
 create mode 100644 drivers/counter/counter-sysfs.h
 delete mode 100644 drivers/counter/counter.c
 delete mode 100644 include/linux/counter_enum.h
 create mode 100644 include/uapi/linux/counter.h

-- 
2.29.2

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