iio: pressure: dps310: Reset chip if MEAS_CFG is corrupt

Move the startup procedure into a function, and correct a missing check on the return code for writing the PRS_CFG register.

Signed-off-by Eddie James <[email protected]>

---
 drivers/iio/pressure/dps310.c | 192 ++++++++++++++++++----------------
 1 file changed, 103 insertions(+), 89 deletions(-)

drivers/iio/pressure/dps310.c +103 -90

index 36fb7ae0d0a9..f79b274bb38d 100644
@@ -159,6 +159,106 @@ static int dps310_get_coefs(struct dps310_data *data)
        return 0;
 }
 
+/*
+ * Some verions of chip will read temperatures in the ~60C range when
+ * its actually ~20C. This is the manufacturer recommended workaround
+ * to correct the issue. The registers used below are undocumented.
+ */
+static int dps310_temp_workaround(struct dps310_data *data)
+{
+       int rc;
+       int reg;
+
+       rc = regmap_read(data->regmap, 0x32, &reg);
+       if (rc < 0)
+               return rc;
+
+       /*
+        * If bit 1 is set then the device is okay, and the workaround does not
+        * need to be applied
+        */
+       if (reg & BIT(1))
+               return 0;
+
+       rc = regmap_write(data->regmap, 0x0e, 0xA5);
+       if (rc < 0)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x0f, 0x96);
+       if (rc < 0)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x62, 0x02);
+       if (rc < 0)
+               return rc;
+
+       rc = regmap_write(data->regmap, 0x0e, 0x00);
+       if (rc < 0)
+               return rc;
+
+       return regmap_write(data->regmap, 0x0f, 0x00);
+}
+
+static int dps310_startup(struct dps310_data *data)
+{
+       int rc;
+       int ready;
+
+       /*
+        * Set up pressure sensor in single sample, one measurement per second
+        * mode
+        */
+       rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
+       if (rc < 0)
+               return rc;
+
+       /*
+        * Set up external (MEMS) temperature sensor in single sample, one
+        * measurement per second mode
+        */
+       rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
+       if (rc < 0)
+               return rc;
+
+       /* Temp and pressure shifts are disabled when PRC <= 8 */
+       rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+                              DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
+       if (rc < 0)
+               return rc;
+
+       /* MEAS_CFG doesn't update correctly unless first written with 0 */
+       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+                              DPS310_MEAS_CTRL_BITS, 0);
+       if (rc < 0)
+               return rc;
+
+       /* Turn on temperature and pressure measurement in the background */
+       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+                              DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
+                              DPS310_TEMP_EN | DPS310_BACKGROUND);
+       if (rc < 0)
+               return rc;
+
+       /*
+        * Calibration coefficients required for reporting temperature.
+        * They are available 40ms after the device has started
+        */
+       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+                                     ready & DPS310_COEF_RDY, 10000, 40000);
+       if (rc < 0)
+               return rc;
+
+       rc = dps310_get_coefs(data);
+       if (rc < 0)
+               return rc;
+
+       rc = dps310_temp_workaround(data);
+       if (rc < 0)
+               return rc;
+
+       return 0;
+}
+
 static int dps310_get_pres_precision(struct dps310_data *data)
 {
        int rc;

@@ -677,52 +777,12 @@ static const struct iio_info dps310_info = {
        .write_raw = dps310_write_raw,
 };
 
-/*
- * Some verions of chip will read temperatures in the ~60C range when
- * its actually ~20C. This is the manufacturer recommended workaround
- * to correct the issue. The registers used below are undocumented.
- */
-static int dps310_temp_workaround(struct dps310_data *data)
-{
-       int rc;
-       int reg;
-
-       rc = regmap_read(data->regmap, 0x32, &reg);
-       if (rc < 0)
-               return rc;
-
-       /*
-        * If bit 1 is set then the device is okay, and the workaround does not
-        * need to be applied
-        */
-       if (reg & BIT(1))
-               return 0;
-
-       rc = regmap_write(data->regmap, 0x0e, 0xA5);
-       if (rc < 0)
-               return rc;
-
-       rc = regmap_write(data->regmap, 0x0f, 0x96);
-       if (rc < 0)
-               return rc;
-
-       rc = regmap_write(data->regmap, 0x62, 0x02);
-       if (rc < 0)
-               return rc;
-
-       rc = regmap_write(data->regmap, 0x0e, 0x00);
-       if (rc < 0)
-               return rc;
-
-       return regmap_write(data->regmap, 0x0f, 0x00);
-}
-
 static int dps310_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
 {
        struct dps310_data *data;
        struct iio_dev *iio;
-       int rc, ready;
+       int rc;
 
        iio = devm_iio_device_alloc(&client->dev,  sizeof(*data));
        if (!iio)

@@ -747,54 +807,8 @@ static int dps310_probe(struct i2c_client *client,
        if (rc)
                return rc;
 
-       /*
-        * Set up pressure sensor in single sample, one measurement per second
-        * mode
-        */
-       rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
-
-       /*
-        * Set up external (MEMS) temperature sensor in single sample, one
-        * measurement per second mode
-        */
-       rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
-       if (rc < 0)
-               return rc;
-
-       /* Temp and pressure shifts are disabled when PRC <= 8 */
-       rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
-                              DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
-       if (rc < 0)
-               return rc;
-
-       /* MEAS_CFG doesn't update correctly unless first written with 0 */
-       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
-                              DPS310_MEAS_CTRL_BITS, 0);
-       if (rc < 0)
-               return rc;
-
-       /* Turn on temperature and pressure measurement in the background */
-       rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
-                              DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
-                              DPS310_TEMP_EN | DPS310_BACKGROUND);
-       if (rc < 0)
-               return rc;
-
-       /*
-        * Calibration coefficients required for reporting temperature.
-        * They are available 40ms after the device has started
-        */
-       rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
-                                     ready & DPS310_COEF_RDY, 10000, 40000);
-       if (rc < 0)
-               return rc;
-
-       rc = dps310_get_coefs(data);
-       if (rc < 0)
-               return rc;
-
-       rc = dps310_temp_workaround(data);
-       if (rc < 0)
+       rc = dps310_startup(data);
+       if (rc)
                return rc;
 
        rc = devm_iio_device_register(&client->dev, iio);
--

2.27.0

Move the startup procedure into a function, and correct a missing check on the return code for writing the PRS_CFG register.

+/*
+ * Some verions of chip will read temperatures in the ~60C range when

+ * its actually ~20C. This is the manufacturer recommended workaround

+ * to correct the issue. The registers used below are undocumented.
+ */

Corruption of the MEAS_CFG register has been observed soon after system boot. In order to recover this scenario, check MEAS_CFG if measurement isn't ready, and if it's incorrect, reset the DPS310 and execute the startup procedure.

Signed-off-by Eddie James <[email protected]>

---
 drivers/iio/pressure/dps310.c | 88 +++++++++++++++++++++++++++++------
 1 file changed, 73 insertions(+), 15 deletions(-)

drivers/iio/pressure/dps310.c +73 -16

index f79b274bb38d..fbceaa2cd71c 100644
@@ -397,6 +397,44 @@ static int dps310_get_temp_k(struct dps310_data *data)
        return scale_factors[ilog2(rc)];
 }
 
+/*
+ * Called with lock held. Returns a negative value on error, a positive value
+ * when the device is not ready, and zero when the device is ready.
+ */
+static int dps310_check_reset_meas_cfg(struct dps310_data *data, int ready_bit)
+{
+       int meas_cfg;
+       int rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &meas_cfg);
+
+       if (rc < 0)
+               return rc;
+
+       /* Device is ready, proceed to measurement */
+       if (meas_cfg & ready_bit)
+               return 0;
+
+       /* Device is OK, just not ready */
+       if (meas_cfg & (DPS310_PRS_EN | DPS310_TEMP_EN | DPS310_BACKGROUND))
+               return 1;
+
+       /* DPS310 register state corrupt, better start from scratch */
+       rc = regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+       if (rc < 0)
+               return rc;
+
+       /* Wait for device chip access: 2.5ms in specification */
+       usleep_range(2500, 12000);
+
+       /* Reinitialize the chip */
+       rc = dps310_startup(data);
+       if (rc)
+               return rc;
+
+       dev_info(&data->client->dev,
+                "recovered from corrupted MEAS_CFG=%02x\n", meas_cfg);
+       return 1;
+}
+
 static int dps310_read_pres_raw(struct dps310_data *data)
 {
        int rc;

@@ -409,16 +447,26 @@ static int dps310_read_pres_raw(struct dps310_data *data)
        if (mutex_lock_interruptible(&data->lock))
                return -EINTR;
 
-       rate = dps310_get_pres_samp_freq(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);
-       if (rc)
+       rc = dps310_check_reset_meas_cfg(data, DPS310_PRS_RDY);
+       if (rc < 0)
                goto done;
 
+       if (rc > 0) {
+               rate = dps310_get_pres_samp_freq(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);
+               if (rc)
+                       goto done;
+       }
+
        rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
        if (rc < 0)
                goto done;

@@ -458,16 +506,26 @@ static int dps310_read_temp_raw(struct dps310_data *data)
        if (mutex_lock_interruptible(&data->lock))
                return -EINTR;
 
-       rate = dps310_get_temp_samp_freq(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);
+       rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
        if (rc < 0)
                goto done;
 
+       if (rc > 0) {
+               rate = dps310_get_temp_samp_freq(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)
+                       goto done;
+       }
+
        rc = dps310_read_temp_ready(data);
 
 done:
--

2.27.0