linux-kernel - [PATCH v1] pinctrl: generic: Add output-enable property

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Date:   Fri, 16 Jun 2017 10:59:41 +0200
From:   Jacopo Mondi <jacopo+renesas@...ndi.org>
To:     linus.walleij@...aro.org, andy.shevchenko@...il.com,
        dongas86@...il.com, geert+renesas@...der.be,
        Chris.Brandt@...esas.com, laurent.pinchart@...asonboard.com,
        robh+dt@...nel.org, mark.rutland@....com
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] pinctrl: generic: Add output-enable property

Add output-enable generic pin configuration property.
This properties allows enabling/disabling pin's output capabilities
without actually driving any value on the line.

Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
---

So, after that many discussions I'm now sending this, that only adds a new
flag used to enable or disable a pin's output capabilities.
I intentionally avoided naming the output buffer explicitly because if and how
it has to be enabled/disabled is a platform specific details each driver
has to take care of.

Dong: this is similar to what you recently proposed, without mentioning the
output buffer directly. Can I have your Reviewed-by or your Acked-by here?

Linus, Andy: I initially proposed to add "output-buffer-enable" in place of this
one, so not to confuse the property's semantic with its real world effect.
While I'm still partially convinced output-enable is not the most accurate choice
possible, it certainly is the best balance with bindings clearness, and the one
where more consensus has been collected on. Hope this flies for you too and we
can have this merged so me and Dong can send our updated series on top of this.

Thanks
   j

 Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt | 2 ++
 drivers/pinctrl/pinconf-generic.c                              | 3 +++
 include/linux/pinctrl/pinconf-generic.h                        | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
index f01d154..f8af190 100644
--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
@@ -259,6 +259,8 @@ input-debounce		- debounce mode with debound time X
 power-source		- select between different power supplies
 low-power-enable	- enable low power mode
 low-power-disable	- disable low power mode
+output-disable		- disable output on a pin
+output-enable		- enable output on a pin
 output-low		- set the pin to output mode with low level
 output-high		- set the pin to output mode with high level
 slew-rate		- set the slew rate
diff --git a/drivers/pinctrl/pinconf-generic.c b/drivers/pinctrl/pinconf-generic.c
index 720a19f..fc0c230 100644
--- a/drivers/pinctrl/pinconf-generic.c
+++ b/drivers/pinctrl/pinconf-generic.c
@@ -44,6 +44,7 @@ static const struct pin_config_item conf_items[] = {
 	PCONFDUMP(PIN_CONFIG_INPUT_SCHMITT, "input schmitt trigger", NULL, false),
 	PCONFDUMP(PIN_CONFIG_INPUT_SCHMITT_ENABLE, "input schmitt enabled", NULL, false),
 	PCONFDUMP(PIN_CONFIG_LOW_POWER_MODE, "pin low power", "mode", true),
+	PCONFDUMP(PIN_CONFIG_OUTPUT_ENABLE, "output enabled", NULL, false),
 	PCONFDUMP(PIN_CONFIG_OUTPUT, "pin output", "level", true),
 	PCONFDUMP(PIN_CONFIG_POWER_SOURCE, "pin power source", "selector", true),
 	PCONFDUMP(PIN_CONFIG_SLEW_RATE, "slew rate", NULL, true),
@@ -172,6 +173,8 @@ static const struct pinconf_generic_params dt_params[] = {
 	{ "input-schmitt-enable", PIN_CONFIG_INPUT_SCHMITT_ENABLE, 1 },
 	{ "low-power-disable", PIN_CONFIG_LOW_POWER_MODE, 0 },
 	{ "low-power-enable", PIN_CONFIG_LOW_POWER_MODE, 1 },
+	{ "output-disable", PIN_CONFIG_OUTPUT_ENABLE, 0 },
+	{ "output-enable", PIN_CONFIG_OUTPUT_ENABLE, 1 },
 	{ "output-high", PIN_CONFIG_OUTPUT, 1, },
 	{ "output-low", PIN_CONFIG_OUTPUT, 0, },
 	{ "power-source", PIN_CONFIG_POWER_SOURCE, 0 },
diff --git a/include/linux/pinctrl/pinconf-generic.h b/include/linux/pinctrl/pinconf-generic.h
index 7620eb1..5761958 100644
--- a/include/linux/pinctrl/pinconf-generic.h
+++ b/include/linux/pinctrl/pinconf-generic.h
@@ -73,6 +73,8 @@
  *	operation, if several modes of operation are supported these can be
  *	passed in the argument on a custom form, else just use argument 1
  *	to indicate low power mode, argument 0 turns low power mode off.
+ * @PIN_CONFIG_OUTPUT_ENABLE: this will enable the pin's output mode
+ * 	without driving a value there. 1 enables output mode, 0 disables it.
  * @PIN_CONFIG_OUTPUT: this will configure the pin as an output. Use argument
  *	1 to indicate high level, argument 0 to indicate low level. (Please
  *	see Documentation/pinctrl.txt, section "GPIO mode pitfalls" for a
@@ -105,6 +107,7 @@ enum pin_config_param {
 	PIN_CONFIG_INPUT_SCHMITT,
 	PIN_CONFIG_INPUT_SCHMITT_ENABLE,
 	PIN_CONFIG_LOW_POWER_MODE,
+	PIN_CONFIG_OUTPUT_ENABLE,
 	PIN_CONFIG_OUTPUT,
 	PIN_CONFIG_POWER_SOURCE,
 	PIN_CONFIG_SLEW_RATE,
--
2.7.4