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74 lines
3.2 KiB
Diff
74 lines
3.2 KiB
Diff
6 years ago
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From eb3742c4250c6a79e7080bdb6286e5df50c7f26a Mon Sep 17 00:00:00 2001
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From: Linus Walleij <linus.walleij@linaro.org>
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Date: Sat, 28 Oct 2017 15:37:17 +0200
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Subject: [PATCH 04/31] pinctrl: Add skew-delay pin config and bindings
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Some pin controllers (such as the Gemini) can control the
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expected clock skew and output delay on certain pins with a
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sub-nanosecond granularity. This is typically done by shunting
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in a number of double inverters in front of or behind the pin.
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Make it possible to configure this with a generic binding.
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Cc: devicetree@vger.kernel.org
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Acked-by: Rob Herring <robh@kernel.org>
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Acked-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
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Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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---
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Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt | 4 ++++
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drivers/pinctrl/pinconf-generic.c | 2 ++
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include/linux/pinctrl/pinconf-generic.h | 5 +++++
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3 files changed, 11 insertions(+)
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--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
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+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
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@@ -271,6 +271,10 @@ output-high - set the pin to output mod
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sleep-hardware-state - indicate this is sleep related state which will be programmed
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into the registers for the sleep state.
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slew-rate - set the slew rate
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+skew-delay - this affects the expected clock skew on input pins
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+ and the delay before latching a value to an output
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+ pin. Typically indicates how many double-inverters are
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+ used to delay the signal.
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For example:
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--- a/drivers/pinctrl/pinconf-generic.c
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+++ b/drivers/pinctrl/pinconf-generic.c
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@@ -49,6 +49,7 @@ static const struct pin_config_item conf
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PCONFDUMP(PIN_CONFIG_POWER_SOURCE, "pin power source", "selector", true),
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PCONFDUMP(PIN_CONFIG_SLEEP_HARDWARE_STATE, "sleep hardware state", NULL, false),
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PCONFDUMP(PIN_CONFIG_SLEW_RATE, "slew rate", NULL, true),
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+ PCONFDUMP(PIN_CONFIG_SKEW_DELAY, "skew delay", NULL, true),
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};
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static void pinconf_generic_dump_one(struct pinctrl_dev *pctldev,
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@@ -181,6 +182,7 @@ static const struct pinconf_generic_para
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{ "power-source", PIN_CONFIG_POWER_SOURCE, 0 },
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{ "sleep-hardware-state", PIN_CONFIG_SLEEP_HARDWARE_STATE, 0 },
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{ "slew-rate", PIN_CONFIG_SLEW_RATE, 0 },
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+ { "skew-delay", PIN_CONFIG_SKEW_DELAY, 0 },
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};
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/**
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--- a/include/linux/pinctrl/pinconf-generic.h
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+++ b/include/linux/pinctrl/pinconf-generic.h
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@@ -90,6 +90,10 @@
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* @PIN_CONFIG_SLEW_RATE: if the pin can select slew rate, the argument to
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* this parameter (on a custom format) tells the driver which alternative
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* slew rate to use.
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+ * @PIN_CONFIG_SKEW_DELAY: if the pin has programmable skew rate (on inputs)
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+ * or latch delay (on outputs) this parameter (in a custom format)
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+ * specifies the clock skew or latch delay. It typically controls how
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+ * many double inverters are put in front of the line.
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* @PIN_CONFIG_END: this is the last enumerator for pin configurations, if
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* you need to pass in custom configurations to the pin controller, use
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* PIN_CONFIG_END+1 as the base offset.
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@@ -117,6 +121,7 @@ enum pin_config_param {
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PIN_CONFIG_POWER_SOURCE,
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PIN_CONFIG_SLEEP_HARDWARE_STATE,
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PIN_CONFIG_SLEW_RATE,
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+ PIN_CONFIG_SKEW_DELAY,
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PIN_CONFIG_END = 0x7F,
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PIN_CONFIG_MAX = 0xFF,
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};
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