[PATCH v6 2/2] iio: pressure: dps310: Reset chip after timeout

[Eddie James <eajames@linux.ibm.com>]

The DPS310 chip has been observed to get "stuck" such that pressure
and temperature measurements are never indicated as "ready" in the
MEAS_CFG register. The only solution is to reset the device and try
again. In order to avoid continual failures, use a boolean flag to
only try the reset after timeout once if errors persist.

Fixes: ba6ec48e76bc ("iio: Add driver for Infineon DPS310")
Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/iio/pressure/dps310.c | 78 ++++++++++++++++++++++++++++++-----
 1 file changed, 68 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index c706a8b423b5..58571007a24f 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -89,6 +89,7 @@ struct dps310_data {
 	s32 c00, c10, c20, c30, c01, c11, c21;
 	s32 pressure_raw;
 	s32 temp_raw;
+	bool timeout_recovery_failed;
 };
 
 static const struct iio_chan_spec dps310_channels[] = {
@@ -393,11 +394,73 @@ static int dps310_get_temp_k(struct dps310_data *data)
 	return scale_factors[ilog2(rc)];
 }
 
+static int dps310_reset_wait(struct dps310_data *data)
+{
+	int rc;
+
+	rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+	if (rc)
+		return rc;
+
+	/* Wait for device chip access: 2.5ms in specification */
+	usleep_range(2500, 12000);
+	return 0;
+}
+
+static int dps310_reset_reinit(struct dps310_data *data)
+{
+	int rc;
+
+	rc = dps310_reset_wait(data);
+	if (rc)
+		return rc;
+
+	rc = dps310_startup(data);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int dps310_ready(struct dps310_data *data, int ready_bit, int timeout)
+{
+	int rc;
+	int ready;
+	int sleep = DPS310_POLL_SLEEP_US(timeout);
+
+	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready, ready & ready_bit,
+				      sleep, timeout);
+	if (rc) {
+		if (rc == -ETIMEDOUT && !data->timeout_recovery_failed) {
+			int rc2;
+
+			/* Reset and reinitialize the chip. */
+			rc2 = dps310_reset_reinit(data);
+			if (rc2) {
+				data->timeout_recovery_failed = true;
+			} else {
+				/* Try again to get sensor ready status. */
+				rc2 = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
+							       ready, ready & ready_bit, sleep,
+							       timeout);
+				if (rc2)
+					data->timeout_recovery_failed = true;
+				else
+					return 0;
+			}
+		}
+
+		return rc;
+	}
+
+	data->timeout_recovery_failed = false;
+	return 0;
+}
+
 static int dps310_read_pres_raw(struct dps310_data *data)
 {
 	int rc;
 	int rate;
-	int ready;
 	int timeout;
 	s32 raw;
 	u8 val[3];
@@ -409,9 +472,7 @@ static int dps310_read_pres_raw(struct dps310_data *data)
 	timeout = DPS310_POLL_TIMEOUT_US(rate);
 
 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
-	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
-				      ready & DPS310_PRS_RDY,
-				      DPS310_POLL_SLEEP_US(timeout), timeout);
+	rc = dps310_ready(data, DPS310_PRS_RDY, timeout);
 	if (rc)
 		goto done;
 
@@ -448,7 +509,6 @@ static int dps310_read_temp_raw(struct dps310_data *data)
 {
 	int rc;
 	int rate;
-	int ready;
 	int timeout;
 
 	if (mutex_lock_interruptible(&data->lock))
@@ -458,10 +518,8 @@ static int dps310_read_temp_raw(struct dps310_data *data)
 	timeout = DPS310_POLL_TIMEOUT_US(rate);
 
 	/* Poll for sensor readiness; base the timeout upon the sample rate. */
-	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
-				      ready & DPS310_TMP_RDY,
-				      DPS310_POLL_SLEEP_US(timeout), timeout);
-	if (rc < 0)
+	rc = dps310_ready(data, DPS310_TMP_RDY, timeout);
+	if (rc)
 		goto done;
 
 	rc = dps310_read_temp_ready(data);
@@ -756,7 +814,7 @@ static void dps310_reset(void *action_data)
 {
 	struct dps310_data *data = action_data;
 
-	regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+	dps310_reset_wait(data);
 }
 
 static const struct regmap_config dps310_regmap_config = {
-- 
2.31.1