From: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Date: Fri, 19 May 2017 14:48:02 +0000 (+0300)
Subject: iio: hi8435: cleanup reset gpio
X-Git-Tag: v4.9.94~228
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e187c0c9104db9271afa0c2b63c403ace286b93d;p=platform%2Fkernel%2Flinux-amlogic.git

iio: hi8435: cleanup reset gpio


[ Upstream commit 61305664a542f874283f74bf0b27ddb31f5045d7 ]

Reset GPIO is active low.

Currently driver uses gpiod_set_value(1) to clean reset, which depends
on device tree to contain GPIO_ACTIVE_HIGH - that does not match reality.

This fixes driver to use _raw version of gpiod_set_value() to enforce
active-low semantics despite of what's written in device tree. Allowing
device tree to override that only opens possibility for errors and does
not add any value.

Additionally, use _cansleep version to make things work with i2c-gpio
and other sleeping gpio drivers.

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c
index 52b2dcf..fec696e 100644
--- a/drivers/iio/adc/hi8435.c
+++ b/drivers/iio/adc/hi8435.c
@@ -453,13 +453,15 @@ static int hi8435_probe(struct spi_device *spi)
 	priv->spi = spi;
 
 	reset_gpio = devm_gpiod_get(&spi->dev, NULL, GPIOD_OUT_LOW);
-	if (IS_ERR(reset_gpio)) {
-		/* chip s/w reset if h/w reset failed */
+	if (!IS_ERR(reset_gpio)) {
+		/* need >=100ns low pulse to reset chip */
+		gpiod_set_raw_value_cansleep(reset_gpio, 0);
+		udelay(1);
+		gpiod_set_raw_value_cansleep(reset_gpio, 1);
+	} else {
+		/* s/w reset chip if h/w reset is not available */
 		hi8435_writeb(priv, HI8435_CTRL_REG, HI8435_CTRL_SRST);
 		hi8435_writeb(priv, HI8435_CTRL_REG, 0);
-	} else {
-		udelay(5);
-		gpiod_set_value(reset_gpio, 1);
 	}
 
 	spi_set_drvdata(spi, idev);