linux-kernel - [PATCH] gpio: tegra: Implement gpio_get

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Message-ID: <1461933078-20366-1-git-send-email-ldewangan@nvidia.com>
Date:	Fri, 29 Apr 2016 18:01:18 +0530
From:	Laxman Dewangan <ldewangan@...dia.com>
To:	<linus.walleij@...aro.org>, <swarren@...dotorg.org>,
	<thierry.reding@...il.com>
CC:	<linux-gpio@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	Laxman Dewangan <ldewangan@...dia.com>
Subject: [PATCH] gpio: tegra: Implement gpio_get_direction callback

Implement gpio_get_direction() callback for Tegra GPIO.
The direction is only valid if the pin is configured as
GPIO. If pin is not configured in GPIO mode then this
function return error.

This makes debugfs and initial reading of the state of
the lines more accurate.

Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
---
This patch is based on discussion on series 
Re: [PATCH V5 0/4] gpio: tegra: Cleanups and support for debounce
>From Linus W:
It would be nice if you also implement .get_direction() which makes
debugfs and initial reading of the state of the lines more accurate.

 drivers/gpio/gpio-tegra.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
index b3ddd92..6f2292b 100644
--- a/drivers/gpio/gpio-tegra.c
+++ b/drivers/gpio/gpio-tegra.c
@@ -191,6 +191,24 @@ static int tegra_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 	return 0;
 }
 
+static int tegra_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+	struct tegra_gpio_info *tgi = gpiochip_get_data(chip);
+	u32 pin_mask = BIT(GPIO_BIT(offset));
+	u32 cnf, oe;
+
+	cnf = tegra_gpio_readl(tgi, GPIO_CNF(tgi, offset));
+	oe = tegra_gpio_readl(tgi, GPIO_OE(tgi, offset));
+	if (cnf & pin_mask) {
+		if (oe & pin_mask)
+			return GPIOF_DIR_OUT;
+
+		return GPIOF_DIR_IN;
+	}
+
+	return -EINVAL;
+}
+
 static int tegra_gpio_set_debounce(struct gpio_chip *chip, unsigned int offset,
 				   unsigned int debounce)
 {
@@ -575,6 +593,7 @@ static int tegra_gpio_probe(struct platform_device *pdev)
 	tgi->gc.get			= tegra_gpio_get;
 	tgi->gc.direction_output	= tegra_gpio_direction_output;
 	tgi->gc.set			= tegra_gpio_set;
+	tgi->gc.get_direction		= tegra_gpio_get_direction;
 	tgi->gc.to_irq			= tegra_gpio_to_irq;
 	tgi->gc.base			= 0;
 	tgi->gc.ngpio			= tgi->bank_count * 32;
-- 
2.1.4