[v2,0/5] gpio: add support for pull-up/pull-down configuration

Hello,

As we started discussing in [1], it would be useful to have a way to
configure pull-up/pull-down resistors for simple GPIO controllers that
don't have any pinmuxing capability, and therefore no interaction with
the pinctrl subsystem.

This is a second iteration of the patches (the v1 was posted at
https://patchwork.ozlabs.org/cover/1020392/).

Changes since v1:

 - Add a comment in the binding that explicitly states that the new
   bit 4 and 5 should only be used for HW with a simple on/off
   pull-up/pull-down configuration. More complex HW should use a pin
   control binding. Suggested by Linus Walleij.

 - Change gpiod_set_debounce() and gpiod_set_transitory() to use the
   new gpio_set_config() helper. This is done in a new, separate
   patch. Suggested by Linus Walleij.

 - Add error checking in gpiod_configure_flags() to make sure pull-up
   and pull-down are not both enabled on the same GPIO. Suggested by
   Jan Kundrát. Jan suggested to put this in the code converting from
   DT properties to internal flags, but it actually makes more sense
   to do it in gpiod_configure_flags(), independently from DT parsing.

 - Add a check in gpio-pca953x driver that pull-up/pull-down is indeed
   supported by the underlying HW in the
   pca953x_gpio_set_pull_up_down() function. Noticed by Linus Walleij.

 - Move the changes in include/dt-bindings/gpio/gpio.h to the
   dt-bindings patch, as suggested by Rob Herring.

Rob: due to the changes in the dt-bindings patch, I have not kept your
Acked-by.

Thomas

[1] https://marc.info/?l=linux-gpio&m=154491873506701&w=2

Thomas Petazzoni (5):
  dt-bindings: gpio: document the new pull-up/pull-down flags
  gpio: rename gpio_set_drive_single_ended() to gpio_set_config()
  gpio: use new gpio_set_config() helper in more places
  gpio: add core support for pull-up/pull-down configuration
  gpio: pca953x: add ->set_config implementation

 .../devicetree/bindings/gpio/gpio.txt         | 12 ++++
 drivers/gpio/gpio-pca953x.c                   | 66 ++++++++++++++++++-
 drivers/gpio/gpiolib-of.c                     |  5 ++
 drivers/gpio/gpiolib.c                        | 50 +++++++++-----
 drivers/gpio/gpiolib.h                        |  2 +
 include/dt-bindings/gpio/gpio.h               |  6 ++
 include/linux/gpio/machine.h                  |  2 +
 include/linux/of_gpio.h                       |  2 +
 8 files changed, 127 insertions(+), 18 deletions(-)

On Thu, Feb 7, 2019 at 5:29 PM Thomas Petazzoni
<thomas.petazzoni@bootlin.com> wrote:

> As we started discussing in [1], it would be useful to have a way to
> configure pull-up/pull-down resistors for simple GPIO controllers that
> don't have any pinmuxing capability, and therefore no interaction with
> the pinctrl subsystem.
>
> This is a second iteration of the patches (the v1 was posted at
> https://patchwork.ozlabs.org/cover/1020392/).

I don't see any problem with this patch set so I have merged it
into an immutable branch in my GPIO tree, and if it builds fine
I will merge it for devel (for-v5.1).

Notably we do not add a userspace ABI in this patch series.

I guess that is fine for now, but I think we might see userspace
support requests soon. But that can be a different patch
and should be driven by actual need for that.

Yours,
Linus Walleij