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Subject[PATCH v2 6/9] iio: imu: adis: Refactor adis_initial_startup
Date
From: Nuno Sá <nuno.sa@analog.com>

All the ADIS devices perform, at the beginning, a self test to make sure
the device is in a sane state. Previously, the logic was that the self-test
was performed in adis_initial_startup() and if that failed a reset was done
and then a self-test was attempted again.

This change unifies the reset mechanism under the adis_initial_startup()
call. A HW reset will be done if GPIO is configured, or a SW reset
otherwise. This should make sure that the chip is in a sane state for
self-test. Once the reset is done, the self-test operation will be
performed. If anything goes wrong with self-test, the driver should just
bail/error-out (i.e. no second attempt). The chip would likely not be a in
a sane state state if the self-test fails after a reset.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/iio/imu/Kconfig | 1 +
drivers/iio/imu/adis.c | 29 ++++++++++++++++++++++-------
2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/imu/Kconfig b/drivers/iio/imu/Kconfig
index 60bb1029e759..63036cf473c7 100644
--- a/drivers/iio/imu/Kconfig
+++ b/drivers/iio/imu/Kconfig
@@ -85,6 +85,7 @@ endmenu

config IIO_ADIS_LIB
tristate
+ depends on GPIOLIB
help
A set of IO helper functions for the Analog Devices ADIS* device family.

diff --git a/drivers/iio/imu/adis.c b/drivers/iio/imu/adis.c
index f7845a90f376..0bd6e32cf577 100644
--- a/drivers/iio/imu/adis.c
+++ b/drivers/iio/imu/adis.c
@@ -7,6 +7,7 @@
*/

#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/kernel.h>
@@ -368,6 +369,10 @@ static int adis_self_test(struct adis *adis)
* __adis_initial_startup() - Device initial setup
* @adis: The adis device
*
+ * The function performs a HW reset via a reset pin that should be specified
+ * via GPIOLIB. If no pin is configured a SW reset will be performed.
+ * The RST pin for the ADIS devices should be configured as ACTIVE_LOW.
+ *
* Returns 0 if the device is operational, a negative error code otherwise.
*
* This function should be called early on in the device initialization sequence
@@ -375,18 +380,28 @@ static int adis_self_test(struct adis *adis)
*/
int __adis_initial_startup(struct adis *adis)
{
+ const struct adis_timeout *timeouts = adis->data->timeouts;
+ struct gpio_desc *gpio;
int ret;

- ret = adis_self_test(adis);
- if (ret) {
- dev_err(&adis->spi->dev, "Self-test failed, trying reset.\n");
- __adis_reset(adis);
- ret = adis_self_test(adis);
+ /* check if the device has rst pin low */
+ gpio = devm_gpiod_get_optional(&adis->spi->dev, "reset", GPIOD_ASIS);
+ if (IS_ERR(gpio))
+ return PTR_ERR(gpio);
+
+ if (gpio) {
+ gpiod_set_value_cansleep(gpio, 1);
+ msleep(10);
+ /* bring device out of reset */
+ gpiod_set_value_cansleep(gpio, 0);
+ msleep(timeouts->reset_ms);
+ } else {
+ ret = __adis_reset(adis);
if (ret)
- dev_err(&adis->spi->dev, "Second self-test failed, giving up.\n");
+ return ret;
}

- return ret;
+ return adis_self_test(adis);
}
EXPORT_SYMBOL_GPL(__adis_initial_startup);

--
2.20.1
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