On Fri, Jun 29, 2018 at 10:15:33AM +0200, Ludovic Desroches wrote:

Add support for the drive strength configuration. Usually, this value is
expressed in mA. Since the numeric value depends on VDDIOP voltage, a
value we can't retrieve at runtime, the controller uses low, medium and
high to define the drive strength.

The PIO controller accepts two values for the low drive configuration: 0
and 1. Most of the time, we don't care about the drive strength. So we
keep the default value which is 0. The drive strength is advertised
through the sysfs only when it has been explicitly set in the device
tree i.e. if its value is different from 0.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
---

Changes:
- v2: use atmel,drive-strength property instead of drive-strengh one
since it is not expressend in mA and there is no way to retrieve this
value at runtime.
- v1: https://www.spinics.net/lists/linux-gpio/msg27789.html

 .../bindings/pinctrl/atmel,at91-pio4-pinctrl.txt   |  3 ++
 drivers/pinctrl/pinctrl-at91-pio4.c                | 42 ++++++++++++++++++++++
 include/dt-bindings/pinctrl/at91.h                 |  4 +++
 3 files changed, 49 insertions(+)

For the DT parts,

Acked-by: Rob Herring <robh@kernel.org>