# Re: \[RFC 08/11\] gpiolib: cdev: Add hardware timestamp clock type

- From: Linus Walleij \<hidden\>
- Date: 2021-06-27 11:38:27 
- List: linux-doc
- Page: https://ratatoskr.run/linux-doc/2021/06/1426817
- Thread: https://ratatoskr.run/linux-tegra/2021/06/1426429/t.md

```text
On Sat, Jun 26, 2021 at 1:48 AM Dipen Patel [ref] wrote:

> This patch adds new clock type for the GPIO controller which can
> timestamp gpio lines using hardware means. To expose such
> functionalities to the userspace, code has been added in this patch
> where during line create call, it checks for new clock type and if
> requested, calls hardware timestamp related API from gpiolib.c.
> During line change event, it retrieves timestamp in nano seconds by
> calling gpiod_get_hw_timestamp API from gpiolib.c. At the line release,
> it disables this functionality by calling gpiod_hw_timestamp_control.
>
> Signed-off-by: Dipen Patel <dipenp@nvidia.com>

This looks good to me, pretty much exactly as I imagine it should be
done, and it is also nice that we only implement it
for the v2 UAPI.

Yours,
Linus Walleij
```