iio: hi8435: cleanup reset gpio

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>

diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c
index d09cb6ff8044d5f783e5d00715e4a91dd1d2d643..ab59969b7c497b0fd846fb5b02461bbfc352b4ed 100644 (file)
--- a/drivers/iio/adc/hi8435.c
+++ b/drivers/iio/adc/hi8435.c
@@ -476,13 +476,15 @@ 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);