[PATCH AUTOSEL for 4.4 057/167] iio: hi8435: cleanup reset gpio

Sasha Levin
2018-03-19T17:24:45Z

From: Nikita Yushchenko <nikita.yoush@cogentembedded.com>

[ 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>
---
drivers/iio/adc/hi8435.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c
index ba9e8fc747b8..7401f102dff4 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);
--
2.14.1