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

From: William Breathitt Gray
Date: Fri Dec 25 2020 - 19:17:42 EST


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