pinctrl: generic: add slew rate config parameter

Add PIN_CONFIG_SLEW_RATE parameter into pinconf-generic driver.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/include/linux/pinctrl/pinconf-generic.h b/include/linux/pinctrl/pinconf-generic.h
index 40d7bb9..3e7909a 100644
--- a/include/linux/pinctrl/pinconf-generic.h
+++ b/include/linux/pinctrl/pinconf-generic.h
@@ -60,6 +60,9 @@
  * @PIN_CONFIG_POWER_SOURCE: if the pin can select between different power
  *	supplies, the argument to this parameter (on a custom format) tells
  *	the driver which alternative power source to use.
+ * @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_LOW_POWER_MODE: this will configure the pin for low power
  *	operation, if several modes of operation are supported these can be
  *	passed in the argument on a custom form, else just use argument 1
@@ -83,6 +86,7 @@
 	PIN_CONFIG_INPUT_SCHMITT,
 	PIN_CONFIG_INPUT_DEBOUNCE,
 	PIN_CONFIG_POWER_SOURCE,
+	PIN_CONFIG_SLEW_RATE,
 	PIN_CONFIG_LOW_POWER_MODE,
 	PIN_CONFIG_OUTPUT,
 	PIN_CONFIG_END = 0x7FFF,