target/linux/gemini/patches-4.14/0004-pinctrl-Add-skew-delay-pin-config-and-bindings.patch

   1 From eb3742c4250c6a79e7080bdb6286e5df50c7f26a Mon Sep 17 00:00:00 2001
   2 From: Linus Walleij <linus.walleij@linaro.org>
   3 Date: Sat, 28 Oct 2017 15:37:17 +0200
   4 Subject: [PATCH 04/31] pinctrl: Add skew-delay pin config and bindings
   5
   6 Some pin controllers (such as the Gemini) can control the
   7 expected clock skew and output delay on certain pins with a
   8 sub-nanosecond granularity. This is typically done by shunting
   9 in a number of double inverters in front of or behind the pin.
  10 Make it possible to configure this with a generic binding.
  11
  12 Cc: devicetree@vger.kernel.org
  13 Acked-by: Rob Herring <robh@kernel.org>
  14 Acked-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
  15 Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
  16 ---
  17  Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt | 4 ++++
  18  drivers/pinctrl/pinconf-generic.c                              | 2 ++
  19  include/linux/pinctrl/pinconf-generic.h                        | 5 +++++
  20  3 files changed, 11 insertions(+)
  21
  22 --- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
  23 +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
  24 @@ -271,6 +271,10 @@ output-high                - set the pin to output mod
  25  sleep-hardware-state   - indicate this is sleep related state which will be programmed
  26                           into the registers for the sleep state.
  27  slew-rate              - set the slew rate
  28 +skew-delay             - this affects the expected clock skew on input pins
  29 +                         and the delay before latching a value to an output
  30 +                         pin. Typically indicates how many double-inverters are
  31 +                         used to delay the signal.
  32
  33  For example:
  34
  35 --- a/drivers/pinctrl/pinconf-generic.c
  36 +++ b/drivers/pinctrl/pinconf-generic.c
  37 @@ -49,6 +49,7 @@ static const struct pin_config_item conf
  38         PCONFDUMP(PIN_CONFIG_POWER_SOURCE, "pin power source", "selector", true),
  39         PCONFDUMP(PIN_CONFIG_SLEEP_HARDWARE_STATE, "sleep hardware state", NULL, false),
  40         PCONFDUMP(PIN_CONFIG_SLEW_RATE, "slew rate", NULL, true),
  41 +       PCONFDUMP(PIN_CONFIG_SKEW_DELAY, "skew delay", NULL, true),
  42  };
  43
  44  static void pinconf_generic_dump_one(struct pinctrl_dev *pctldev,
  45 @@ -181,6 +182,7 @@ static const struct pinconf_generic_para
  46         { "power-source", PIN_CONFIG_POWER_SOURCE, 0 },
  47         { "sleep-hardware-state", PIN_CONFIG_SLEEP_HARDWARE_STATE, 0 },
  48         { "slew-rate", PIN_CONFIG_SLEW_RATE, 0 },
  49 +       { "skew-delay", PIN_CONFIG_SKEW_DELAY, 0 },
  50  };
  51
  52  /**
  53 --- a/include/linux/pinctrl/pinconf-generic.h
  54 +++ b/include/linux/pinctrl/pinconf-generic.h
  55 @@ -90,6 +90,10 @@
  56   * @PIN_CONFIG_SLEW_RATE: if the pin can select slew rate, the argument to
  57   *     this parameter (on a custom format) tells the driver which alternative
  58   *     slew rate to use.
  59 + * @PIN_CONFIG_SKEW_DELAY: if the pin has programmable skew rate (on inputs)
  60 + *     or latch delay (on outputs) this parameter (in a custom format)
  61 + *     specifies the clock skew or latch delay. It typically controls how
  62 + *     many double inverters are put in front of the line.
  63   * @PIN_CONFIG_END: this is the last enumerator for pin configurations, if
  64   *     you need to pass in custom configurations to the pin controller, use
  65   *     PIN_CONFIG_END+1 as the base offset.
  66 @@ -117,6 +121,7 @@ enum pin_config_param {
  67         PIN_CONFIG_POWER_SOURCE,
  68         PIN_CONFIG_SLEEP_HARDWARE_STATE,
  69         PIN_CONFIG_SLEW_RATE,
  70 +       PIN_CONFIG_SKEW_DELAY,
  71         PIN_CONFIG_END = 0x7F,
  72         PIN_CONFIG_MAX = 0xFF,
  73  };