From eb3742c4250c6a79e7080bdb6286e5df50c7f26a Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sat, 28 Oct 2017 15:37:17 +0200 Subject: [PATCH 04/31] 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 Acked-by: Hans Ulli Kroll Signed-off-by: Linus Walleij --- Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt | 4 ++++ drivers/pinctrl/pinconf-generic.c | 2 ++ include/linux/pinctrl/pinconf-generic.h | 5 +++++ 3 files changed, 11 insertions(+) --- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt @@ -271,6 +271,10 @@ output-high - set the pin to output mod sleep-hardware-state - indicate this is sleep related state which will be programmed into the registers for the sleep state. slew-rate - set the slew rate +skew-delay - this affects the expected clock skew on input pins + and the delay before latching a value to an output + pin. Typically indicates how many double-inverters are + used to delay the signal. For example: --- a/drivers/pinctrl/pinconf-generic.c +++ b/drivers/pinctrl/pinconf-generic.c @@ -49,6 +49,7 @@ static const struct pin_config_item conf PCONFDUMP(PIN_CONFIG_POWER_SOURCE, "pin power source", "selector", true), PCONFDUMP(PIN_CONFIG_SLEEP_HARDWARE_STATE, "sleep hardware state", NULL, false), PCONFDUMP(PIN_CONFIG_SLEW_RATE, "slew rate", NULL, true), + PCONFDUMP(PIN_CONFIG_SKEW_DELAY, "skew delay", NULL, true), }; static void pinconf_generic_dump_one(struct pinctrl_dev *pctldev, @@ -181,6 +182,7 @@ static const struct pinconf_generic_para { "power-source", PIN_CONFIG_POWER_SOURCE, 0 }, { "sleep-hardware-state", PIN_CONFIG_SLEEP_HARDWARE_STATE, 0 }, { "slew-rate", PIN_CONFIG_SLEW_RATE, 0 }, + { "skew-delay", PIN_CONFIG_SKEW_DELAY, 0 }, }; /** --- 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, };