[PATCH] iio: pressure: dps310: support negative pressure and temperature values

From: Thomas Haemmerle
Date: Wed Mar 27 2024 - 04:50:11 EST

The current implementation interprets negative values returned from
function invocation as error codes, even those that report actual data.
This has a side effect that when temperature values are calculated -
they also converted by error code, which leads to false interpretation
of results.

Fix this by using the return values only for error handling and passing
a pointer for the values.

Signed-off-by: Thomas Haemmerle <thomas.haemmerle@xxxxxxxxxxxxxxxxxxxx>
---
drivers/iio/pressure/dps310.c | 122 +++++++++++++++++++---------------
1 file changed, 69 insertions(+), 53 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index 1ff091b2f764..373d1c063b05 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -171,7 +171,7 @@ static int dps310_temp_workaround(struct dps310_data *data)
int reg;

rc = regmap_read(data->regmap, 0x32, &reg);
- if (rc)
+ if (rc < 0)
return rc;

/*
@@ -256,24 +256,24 @@ static int dps310_startup(struct dps310_data *data)
return dps310_temp_workaround(data);
}

-static int dps310_get_pres_precision(struct dps310_data *data)
+static int dps310_get_pres_precision(struct dps310_data *data, int *val)
{
int rc;
- int val;

- rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+ rc = regmap_read(data->regmap, DPS310_PRS_CFG, val);
if (rc < 0)
return rc;

- return BIT(val & GENMASK(2, 0));
+ *val = BIT(*val & GENMASK(2, 0));
+
+ return 0;
}

-static int dps310_get_temp_precision(struct dps310_data *data)
+static int dps310_get_temp_precision(struct dps310_data *data, int *val)
{
int rc;
- int val;

- rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ rc = regmap_read(data->regmap, DPS310_TMP_CFG, val);
if (rc < 0)
return rc;

@@ -281,7 +281,9 @@ static int dps310_get_temp_precision(struct dps310_data *data)
* Scale factor is bottom 4 bits of the register, but 1111 is
* reserved so just grab bottom three
*/
- return BIT(val & GENMASK(2, 0));
+ *val = BIT(*val & GENMASK(2, 0));
+
+ return 0;
}

/* Called with lock held */
@@ -350,48 +352,56 @@ static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
DPS310_TMP_RATE_BITS, val);
}

-static int dps310_get_pres_samp_freq(struct dps310_data *data)
+static int dps310_get_pres_samp_freq(struct dps310_data *data, int *val)
{
int rc;
- int val;

- rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+ rc = regmap_read(data->regmap, DPS310_PRS_CFG, val);
if (rc < 0)
return rc;

- return BIT((val & DPS310_PRS_RATE_BITS) >> 4);
+ *val = BIT((*val & DPS310_PRS_RATE_BITS) >> 4);
+
+ return 0;
}

-static int dps310_get_temp_samp_freq(struct dps310_data *data)
+static int dps310_get_temp_samp_freq(struct dps310_data *data, int *val)
{
int rc;
- int val;

- rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ rc = regmap_read(data->regmap, DPS310_TMP_CFG, val);
if (rc < 0)
return rc;

- return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
+ *val = BIT((*val & DPS310_TMP_RATE_BITS) >> 4);
+
+ return 0;
}

-static int dps310_get_pres_k(struct dps310_data *data)
+static int dps310_get_pres_k(struct dps310_data *data, int *val)
{
- int rc = dps310_get_pres_precision(data);
+ int rc;

- if (rc < 0)
+ rc = dps310_get_pres_precision(data, val);
+ if (rc)
return rc;

- return scale_factors[ilog2(rc)];
+ *val = scale_factors[ilog2(*val)];
+
+ return 0;
}

-static int dps310_get_temp_k(struct dps310_data *data)
+static int dps310_get_temp_k(struct dps310_data *data, int *val)
{
- int rc = dps310_get_temp_precision(data);
+ int rc;

- if (rc < 0)
+ rc = dps310_get_temp_precision(data, val);
+ if (rc)
return rc;

- return scale_factors[ilog2(rc)];
+ *val = scale_factors[ilog2(*val)];
+
+ return 0;
}

static int dps310_reset_wait(struct dps310_data *data)
@@ -464,7 +474,10 @@ 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);
+ rc = dps310_get_pres_samp_freq(data, &rate);
+ if (rc)
+ return rc;
+
timeout = DPS310_POLL_TIMEOUT_US(rate);

/* Poll for sensor readiness; base the timeout upon the sample rate. */
@@ -510,7 +523,10 @@ 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);
+ rc = dps310_get_temp_samp_freq(data, &rate);
+ if (rc)
+ return rc;
+
timeout = DPS310_POLL_TIMEOUT_US(rate);

/* Poll for sensor readiness; base the timeout upon the sample rate. */
@@ -612,13 +628,13 @@ static int dps310_write_raw(struct iio_dev *iio,
return rc;
}

-static int dps310_calculate_pressure(struct dps310_data *data)
+static int dps310_calculate_pressure(struct dps310_data *data, int *val)
{
int i;
int rc;
int t_ready;
- int kpi = dps310_get_pres_k(data);
- int kti = dps310_get_temp_k(data);
+ int kpi;
+ int kti;
s64 rem = 0ULL;
s64 pressure = 0ULL;
s64 p;
@@ -629,11 +645,13 @@ static int dps310_calculate_pressure(struct dps310_data *data)
s64 kp;
s64 kt;

- if (kpi < 0)
- return kpi;
+ rc = dps310_get_pres_k(data, &kpi);
+ if (rc < 0)
+ return rc;

- if (kti < 0)
- return kti;
+ rc = dps310_get_temp_k(data, &kti);
+ if (rc < 0)
+ return rc;

kp = (s64)kpi;
kt = (s64)kti;
@@ -687,7 +705,9 @@ static int dps310_calculate_pressure(struct dps310_data *data)
if (pressure < 0LL)
return -ERANGE;

- return (int)min_t(s64, pressure, INT_MAX);
+ *val = (int)min_t(s64, pressure, INT_MAX);
+
+ return 0;
}

static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
@@ -697,11 +717,10 @@ static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,

switch (mask) {
case IIO_CHAN_INFO_SAMP_FREQ:
- rc = dps310_get_pres_samp_freq(data);
+ rc = dps310_get_pres_samp_freq(data, val);
if (rc < 0)
return rc;

- *val = rc;
return IIO_VAL_INT;

case IIO_CHAN_INFO_PROCESSED:
@@ -709,20 +728,17 @@ static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
if (rc)
return rc;

- rc = dps310_calculate_pressure(data);
+ rc = dps310_calculate_pressure(data, val);
if (rc < 0)
return rc;

- *val = rc;
*val2 = 1000; /* Convert Pa to KPa per IIO ABI */
return IIO_VAL_FRACTIONAL;

case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
- rc = dps310_get_pres_precision(data);
+ rc = dps310_get_pres_precision(data, val);
if (rc < 0)
return rc;
-
- *val = rc;
return IIO_VAL_INT;

default:
@@ -730,14 +746,15 @@ static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
}
}

-static int dps310_calculate_temp(struct dps310_data *data)
+static int dps310_calculate_temp(struct dps310_data *data, int *val)
{
s64 c0;
s64 t;
- int kt = dps310_get_temp_k(data);
+ int kt, rc;

- if (kt < 0)
- return kt;
+ rc = dps310_get_temp_k(data, &kt);
+ if (rc < 0)
+ return rc;

/* Obtain inverse-scaled offset */
c0 = div_s64((s64)kt * (s64)data->c0, 2);
@@ -746,7 +763,9 @@ static int dps310_calculate_temp(struct dps310_data *data)
t = c0 + ((s64)data->temp_raw * (s64)data->c1);

/* Convert to milliCelsius and scale the temperature */
- return (int)div_s64(t * 1000LL, kt);
+ *val = (int)div_s64(t * 1000LL, kt);
+
+ return 0;
}

static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
@@ -756,11 +775,10 @@ static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,

switch (mask) {
case IIO_CHAN_INFO_SAMP_FREQ:
- rc = dps310_get_temp_samp_freq(data);
+ rc = dps310_get_temp_samp_freq(data, val);
if (rc < 0)
return rc;

- *val = rc;
return IIO_VAL_INT;

case IIO_CHAN_INFO_PROCESSED:
@@ -768,19 +786,17 @@ static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
if (rc)
return rc;

- rc = dps310_calculate_temp(data);
+ rc = dps310_calculate_temp(data, val);
if (rc < 0)
return rc;

- *val = rc;
return IIO_VAL_INT;

case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
- rc = dps310_get_temp_precision(data);
+ rc = dps310_get_temp_precision(data, val);
if (rc < 0)
return rc;

- *val = rc;
return IIO_VAL_INT;

default:
--
2.34.1