linux-kernel - [PATCH] of/gpio: Define OF_GPIO_OPEN_DRAIN flag for Open Drain outputs.

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Date:	Mon, 10 Feb 2014 14:05:08 -0800
From:	David Daney <ddaney.cavm@...il.com>
To:	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	linux-gpio@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, David Daney <david.daney@...ium.com>
Subject: [PATCH] of/gpio: Define OF_GPIO_OPEN_DRAIN flag for Open Drain outputs.

From: David Daney <david.daney@...ium.com>

When we have a GPIO pin connected to an open-drain network, we want a
standard way of specifying this in the device tree.  So we choose bit
1 of the flag field to indicate open drain.

A typical use case would be something like:

	enum of_gpio_flags f;
	.
	.
	.
	reset_gpio = of_get_named_gpio_flags(node, "reset", 0, &f);
	.
	.
	.
	ret = gpio_request_one(reset_gpio,
		(f & OF_GPIO_OPEN_DRAIN) ? GPIOF_OPEN_DRAIN : 0,
		 "reset");
	.
	.
	.
	gpio_direction_output(reset_gpio, 1);
	gpio_set_value(reset_gpio, 0);
	msleep(20);
	gpio_set_value(reset_gpio, 1);
	.
	.
	.

Signed-off-by: David Daney <david.daney@...ium.com>
---
 include/linux/of_gpio.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
index f14123a..0e374774 100644
--- a/include/linux/of_gpio.h
+++ b/include/linux/of_gpio.h
@@ -30,6 +30,7 @@ struct device_node;
  */
 enum of_gpio_flags {
 	OF_GPIO_ACTIVE_LOW = 0x1,
+	OF_GPIO_OPEN_DRAIN = 0x2,
 };
 
 #ifdef CONFIG_OF_GPIO
-- 
1.7.11.7

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