[v2,0/2] i2c-designware: Add support for AMD PSP semaphore

This patchset comprises support for new i2c-designware controller setup on some
AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
controller and acts as an i2c arbitrator there (x86 is leasing bus from it).

First commit aims to improve generic i2c-designware code by adding extra locking
on probe() and disable() paths. I would like to ask someone with access to
boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
behavior of my changes on such setup.

Second commit adds support for new PSP semaphore arbitration mechanism.
Implementation is similar to the one from i2c-designware-baytrail.c however
there are two main differences:
1) Add new ACPI ID in order to protect against silent binding of the old driver
to the setup with PSP semaphore. Extra flag ARBITRATION_SEMAPHORE added to this
new _HID allows to recognize setup with PSP.
2) Beside acquire_lock() and release_lock() methods we are also applying quirks
to the lock_bus() and unlock_bus() global adapter methods. With this in place
all i2c clients drivers may lock i2c bus for a desired number of i2c
transactions (e.g. write-wait-read) without being aware of that such bus is
shared with another entity.

This patchset is a follow-up to the RFC sent earlier on LKML [1], with review
comments applied.

Looking forward to some feedback.

[1] https://lkml.org/lkml/2021/12/22/219

v1 -> v2:
* Remove usage of unions
* Get rid of unnecessary __packed attributes
* Switch to use iopoll.h and bitfields.h APIs were applicable
* Follow the convention to check for the error first
* Reorder entries (includes, table entries) alphabetically
* Add necessary includes
* Add Kconfig dependency on X86_64
(above two fixes for "kernel test robot <lkp@intel.com>" issues)
* Modify probe() to use terminating entry for traversing through table
  instead of ARRAY_SIZE
* Fix typos in comments
* Rebase patchset

Jan Dabros (2):
  i2c: designware: Add missing locks
  i2c: designware: Add AMD PSP I2C bus support

 MAINTAINERS                                  |   1 +
 drivers/acpi/acpi_apd.c                      |   7 +-
 drivers/i2c/busses/Kconfig                   |  11 +
 drivers/i2c/busses/Makefile                  |   1 +
 drivers/i2c/busses/i2c-designware-amdpsp.c   | 373 +++++++++++++++++++
 drivers/i2c/busses/i2c-designware-baytrail.c |  10 +-
 drivers/i2c/busses/i2c-designware-common.c   |  12 +
 drivers/i2c/busses/i2c-designware-core.h     |  18 +-
 drivers/i2c/busses/i2c-designware-master.c   |   6 +
 drivers/i2c/busses/i2c-designware-platdrv.c  |  61 +++
 10 files changed, 489 insertions(+), 11 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-designware-amdpsp.c

Hi,

Adding proper Andy's email address (and removing wrong one) in the
whole patchset. Sorry for noise!

Best Regards,
Jan


pt., 28 sty 2022 o 15:48 Jan Dabros <jsd@semihalf.com> napisał(a):
>
> This patchset comprises support for new i2c-designware controller setup on some
> AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
> controller and acts as an i2c arbitrator there (x86 is leasing bus from it).
>
> First commit aims to improve generic i2c-designware code by adding extra locking
> on probe() and disable() paths. I would like to ask someone with access to
> boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
> behavior of my changes on such setup.
>
> Second commit adds support for new PSP semaphore arbitration mechanism.
> Implementation is similar to the one from i2c-designware-baytrail.c however
> there are two main differences:
> 1) Add new ACPI ID in order to protect against silent binding of the old driver
> to the setup with PSP semaphore. Extra flag ARBITRATION_SEMAPHORE added to this
> new _HID allows to recognize setup with PSP.
> 2) Beside acquire_lock() and release_lock() methods we are also applying quirks
> to the lock_bus() and unlock_bus() global adapter methods. With this in place
> all i2c clients drivers may lock i2c bus for a desired number of i2c
> transactions (e.g. write-wait-read) without being aware of that such bus is
> shared with another entity.
>
> This patchset is a follow-up to the RFC sent earlier on LKML [1], with review
> comments applied.
>
> Looking forward to some feedback.
>
> [1] https://lkml.org/lkml/2021/12/22/219
>
> v1 -> v2:
> * Remove usage of unions
> * Get rid of unnecessary __packed attributes
> * Switch to use iopoll.h and bitfields.h APIs were applicable
> * Follow the convention to check for the error first
> * Reorder entries (includes, table entries) alphabetically
> * Add necessary includes
> * Add Kconfig dependency on X86_64
> (above two fixes for "kernel test robot <lkp@intel.com>" issues)
> * Modify probe() to use terminating entry for traversing through table
>   instead of ARRAY_SIZE
> * Fix typos in comments
> * Rebase patchset
>
> Jan Dabros (2):
>   i2c: designware: Add missing locks
>   i2c: designware: Add AMD PSP I2C bus support
>
>  MAINTAINERS                                  |   1 +
>  drivers/acpi/acpi_apd.c                      |   7 +-
>  drivers/i2c/busses/Kconfig                   |  11 +
>  drivers/i2c/busses/Makefile                  |   1 +
>  drivers/i2c/busses/i2c-designware-amdpsp.c   | 373 +++++++++++++++++++
>  drivers/i2c/busses/i2c-designware-baytrail.c |  10 +-
>  drivers/i2c/busses/i2c-designware-common.c   |  12 +
>  drivers/i2c/busses/i2c-designware-core.h     |  18 +-
>  drivers/i2c/busses/i2c-designware-master.c   |   6 +
>  drivers/i2c/busses/i2c-designware-platdrv.c  |  61 +++
>  10 files changed, 489 insertions(+), 11 deletions(-)
>  create mode 100644 drivers/i2c/busses/i2c-designware-amdpsp.c
>
> --
> 2.35.0.rc0.227.g00780c9af4-goog
>