[RFC,v1,00/20] Review Request: Add support for Intel PMC

From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>

Starting with Intel(R) Tiger Lake and Elkhart Lake platforms the PMC
hardware adds the Timed I/O hardware interface.

The Timed I/O hardware implements some functionality similar to GPIO
with added timing logic that is driven by the Always Running Timer
(ART).

The Timed I/O Hardware implement 3 basic functions:
  * Input Timestamping
  * Single Shot Timed Output
  * Periodic Timed Output

 Please help to review the changes.

Thanks in advance,
Sowjanya 

Christopher Hall (9):
  gpio: Add basic GPIO driver for Intel PMC Timed I/O device
  arch: x86: Add ART support function to tsc code
  gpio: Add input code to Intel PMC Timed I/O Driver
  tools: gpio: Add additional polling support to gpio-event-mon
  kernel: time: Add system time to system counter translation
  tools: gpio: Add GPIO output generation user application
  arch/x86: Add ART nanosecond to ART conversion
  pwm: Add capability for PWM Driver managed state
  tools: gpio: Add PWM monitor application

Lakshmi Sowjanya D (11):
  gpio: Add GPIO polling interface to GPIO lib
  gpio: Add set_input and polling interface to GPIO lib code
  gpio: Add output event generation method to GPIOLIB and PMC Driver
  arch: x86: Add TSC to ART translation
  gpio: Add event count interface to gpiolib
  gpio: Add event count to Intel(R) PMC Timed I/O driver
  tools: gpio: Add event count capability to event monitor application
  gpio: Add PWM capabilities to Intel(R) PMC TIO driver
  pwm: Add second alignment to the core PWM interface
  gpio: Add PWM alignment support to the Intel(R) PMC Timed I/O driver
  gpio: Add GPIO monitor line to Intel(R) Timed I/O Driver

 MAINTAINERS                       |   7 +
 arch/x86/include/asm/tsc.h        |   5 +
 arch/x86/kernel/tsc.c             |  73 +++
 drivers/gpio/Kconfig              |  11 +
 drivers/gpio/Makefile             |   1 +
 drivers/gpio/gpio-intel-tio-pmc.c | 834 ++++++++++++++++++++++++++++++
 drivers/gpio/gpiolib-cdev.c       | 145 +++++-
 drivers/pwm/core.c                |  10 +-
 drivers/pwm/sysfs.c               |  37 ++
 include/linux/gpio/driver.h       |  29 ++
 include/linux/pwm.h               |   3 +
 include/linux/timekeeping.h       |   3 +
 include/uapi/linux/gpio.h         |  21 +
 kernel/time/timekeeping.c         |  63 +++
 tools/gpio/.gitignore             |   1 +
 tools/gpio/Build                  |   2 +
 tools/gpio/Makefile               |  21 +-
 tools/gpio/gpio-event-gen.c       | 191 +++++++
 tools/gpio/gpio-event-mon.c       |  58 ++-
 tools/gpio/gpio-pwm-mon.c         | 431 +++++++++++++++
 20 files changed, 1916 insertions(+), 30 deletions(-)
 create mode 100644 drivers/gpio/gpio-intel-tio-pmc.c
 create mode 100644 tools/gpio/gpio-event-gen.c
 create mode 100644 tools/gpio/gpio-pwm-mon.c

Hi Sowjanya,

thanks for your patches!

On Tue, Aug 24, 2021 at 6:48 PM <lakshmi.sowjanya.d@intel.com> wrote:

> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>

>

> Starting with Intel(R) Tiger Lake and Elkhart Lake platforms the PMC

> hardware adds the Timed I/O hardware interface.

>

> The Timed I/O hardware implements some functionality similar to GPIO

> with added timing logic that is driven by the Always Running Timer

> (ART).

>

> The Timed I/O Hardware implement 3 basic functions:

>   * Input Timestamping

>   * Single Shot Timed Output

>   * Periodic Timed Output

>

>  Please help to review the changes.


This looks very similar to the usecase proposed for the HTE
Hardware Timestamping Engine, proposed by Dipen Patel
for the nVidia 194 and which is currently in RFC:
https://lore.kernel.org/linux-gpio/20210625235532.19575-1-dipenp@nvidia.com/

Please review this new subsystem and see if you can just
make a slot-in driver using Dipen's patches instead.

Dipen: please have a look at Sowjanya's patches to see
if this hardware is similar to yours.

Sometimes several vendors come up with similar hardware
around the same time, because of industry trends, so I would
not be surprised if these two hardwares address the very
same usecase.

Yours,
Linus Walleij