[PATCH v4 00/11] counter: Add stm32 timer events support

[Fabrice Gasnier <fabrice.gasnier@foss.st.com>]

Improves the stm32 timer counter driver by introducing new signals,
e.g. counting frequency, and missing channels.

It also adds support for interrupt based events using the chrdev interface.
Two event types are added in this series: overflows and capture.

Up to now, stm32 timer counter driver focused mainly on quadrature
encoder feature on channel 1 & 2. It was limited to timers that has
the HW quadrature encoder.

With this series, all timer instances can be enabled for:
- Quadrature encoder on channel 1 and channel 2 (when supported in HW)
- Simple counting on internal clock
- Capture counter value when rising and falling edges are observed at
  channel 1 to channel 4 input (number of channels varies depending on
  the timer instance used)
- Push overflow and/or capture events through the chardev interface

Changes in v4:
- Introduce new COUNTER_COMP_FREQUENCY() macro
- Mainly update two last patchs, to address William's review comments
  (details in each patch)

Changes in V3:
- This series has been split [1] and renamed.
[1] https://lore.kernel.org/lkml/20230922143920.3144249-1-fabrice.gasnier@foss.st.com/
- Watch events tool patch applied, hence dropped from this series
- Refactor / split several patches
- Keep original signals order, to avoid breaking existing user space
- Don't adjust number of signals: adopt static configuration. rely on
  error mechanism to manage diversity across STM32 Timers instances.

Changes in v2:
- counter fix and improvement patch applied, hence dropped in v2 series
- mfd patch applied, hence dropped in v2 series
- revisit watch events tool (mainly command line interface)
- add one patch to rename STM32 Timer counter
- various review comments from v1

Fabrice Gasnier (11):
  counter: Introduce the COUNTER_COMP_FREQUENCY() macro
  counter: stm32-timer-cnt: rename quadrature signal
  counter: stm32-timer-cnt: rename counter
  counter: stm32-timer-cnt: adopt signal definitions
  counter: stm32-timer-cnt: introduce clock signal
  counter: stm32-timer-cnt: add counter prescaler extension
  counter: stm32-timer-cnt: add checks on quadrature encoder capability
  counter: stm32-timer-cnt: introduce channels
  counter: stm32-timer-cnt: probe number of channels from registers
  counter: stm32-timer-cnt: add support for overflow events
  counter: stm32-timer-cnt: add support for capture events

 drivers/counter/stm32-timer-cnt.c | 461 +++++++++++++++++++++++++++++-
 include/linux/counter.h           |   3 +
 include/linux/mfd/stm32-timers.h  |  13 +
 3 files changed, 463 insertions(+), 14 deletions(-)

-- 
2.25.1