[PATCH net-next v4 0/5] Enable PTP timestamping/PPS for AM65x SR1.0 devices

[Diogo Ivo <diogo.ivo@siemens.com>]

This patch series enables support for PTP in AM65x SR1.0 devices.

This feature relies heavily on the Industrial Ethernet Peripheral
(IEP) hardware module, which implements a hardware counter through
which time is kept. This hardware block is the basis for exposing
a PTP hardware clock to userspace and for issuing timestamps for
incoming/outgoing packets, allowing for time synchronization.

The IEP also has compare registers that fire an interrupt when the
counter reaches the value stored in a compare register. This feature
allows us to support PPS events in the kernel.

The changes are separated into five patches:
 - PATCH 01/05: Register SR1.0 devices with the IEP infrastructure to
		expose a PHC clock to userspace, allowing time to be
		adjusted using standard PTP tools. The code for issuing/
		collecting packet timestamps is already present in the
		current state of the driver, so only this needs to be
		done.
 - PATCH 02/05: Remove unnecessary spinlock synchronization.
 - PATCH 03/05: Document IEP interrupt in DT binding.
 - PATCH 04/05: Add support for IEP compare event/interrupt handling
		to enable PPS events.
 - PATCH 05/05: Add the interrupts to the IOT2050 device tree.

Currently every compare event generates two interrupts, the first
corresponding to the actual event and the second being a spurious
but otherwise harmless interrupt. The root cause of this has been
identified and has been solved in the platform's SDK. A forward port
of the SDK's patches also fixes the problem in upstream but is not
included here since it's upstreaming is out of the scope of this
series. If someone from TI would be willing to chime in and help
get the interrupt changes upstream that would be great!

Signed-off-by: Diogo Ivo <diogo.ivo@siemens.com>
---
Changes in v4:
- Remove unused 'flags' variables in patch 02/05
- Add patch 03/05 describing IEP interrupt in DT binding
- Link to v3: https://lore.kernel.org/r/20240607-iep-v3-0-4824224105bc@siemens.com

Changes in v3:
- Collect Reviewed-by tags
- Add patch 02/04 removing spinlocks from IEP driver
- Use mutex-based synchronization when accessing HW registers
- Link to v2: https://lore.kernel.org/r/20240604-iep-v2-0-ea8e1c0a5686@siemens.com

Changes in v2:
- Collect Reviewed-by tags
- PATCH 01/03: Limit line length to 80 characters
- PATCH 02/03: Proceed with limited functionality if getting IRQ fails,
	       limit line length to 80 characters
- Link to v1: https://lore.kernel.org/r/20240529-iep-v1-0-7273c07592d3@siemens.com

---
Diogo Ivo (5):
      net: ti: icssg-prueth: Enable PTP timestamping support for SR1.0 devices
      net: ti: icss-iep: Remove spinlock-based synchronization
      dt-bindings: net: Add IEP interrupt
      net: ti: icss-iep: Enable compare events
      arm64: dts: ti: iot2050: Add IEP interrupts for SR1.0 devices

 .../devicetree/bindings/net/ti,icss-iep.yaml       |  9 +++
 .../boot/dts/ti/k3-am65-iot2050-common-pg1.dtsi    | 12 +++
 drivers/net/ethernet/ti/icssg/icss_iep.c           | 88 ++++++++++++++++++----
 drivers/net/ethernet/ti/icssg/icssg_prueth_sr1.c   | 51 ++++++++++++-
 4 files changed, 145 insertions(+), 15 deletions(-)
---
base-commit: 2f0e3f6a6824dfda2759225326d9c69203c06bc8
change-id: 20240529-iep-8bb4a3cb9068

Best regards,
-- 
Diogo Ivo <diogo.ivo@siemens.com>