pinctrl: Add skew-delay pin config and bindings

Some pin controllers (such as the Gemini) can control the
expected clock skew and output delay on certain pins with a
sub-nanosecond granularity. This is typically done by shunting
in a number of double inverters in front of or behind the pin.
Make it possible to configure this with a generic binding.

Cc: devicetree@vger.kernel.org
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/pinctrl/pinconf-generic.h b/include/linux/pinctrl/pinconf-generic.h
index 5d8bc7f21c2a..ec6dadcc1fde 100644
--- a/include/linux/pinctrl/pinconf-generic.h
+++ b/include/linux/pinctrl/pinconf-generic.h
@@ -90,6 +90,10 @@
  * @PIN_CONFIG_SLEW_RATE: if the pin can select slew rate, the argument to
  *      this parameter (on a custom format) tells the driver which alternative
  *      slew rate to use.
+ * @PIN_CONFIG_SKEW_DELAY: if the pin has programmable skew rate (on inputs)
+ *      or latch delay (on outputs) this parameter (in a custom format)
+ *      specifies the clock skew or latch delay. It typically controls how
+ *      many double inverters are put in front of the line.
  * @PIN_CONFIG_END: this is the last enumerator for pin configurations, if
  *      you need to pass in custom configurations to the pin controller, use
  *      PIN_CONFIG_END+1 as the base offset.
@@ -117,6 +121,7 @@ enum pin_config_param {
         PIN_CONFIG_POWER_SOURCE,
         PIN_CONFIG_SLEEP_HARDWARE_STATE,
         PIN_CONFIG_SLEW_RATE,
+        PIN_CONFIG_SKEW_DELAY,
         PIN_CONFIG_END = 0x7F,
         PIN_CONFIG_MAX = 0xFF,
 };