iio: pressure: bmp280: Use char instead of s32 for data buffer

As it was reported and discussed here [1], storing the sensor data in an
endian aware s32 buffer is not optimal. Advertising the timestamp as an
addition of 2 s32 variables which is also implied is again not the best
practice. For that reason, change the s32 sensor_data buffer to a u8
buffer and align it properly.

[1]: https://lore.kernel.org/linux-iio/73d13cc0-afb9-4306-b498-5d821728c3ba@stanley.mountain/

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://patch.msgid.link/20240930202353.38203-3-vassilisamir@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 472a6696303b7ef41150af36cc4bf6625609ec39..6811619c6f1125fab343e05b070e7cf6e3db96bf 100644 (file)
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -1023,8 +1023,9 @@ static irqreturn_t bmp280_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct bmp280_data *data = iio_priv(indio_dev);
-       u32 adc_temp, adc_press;
-       s32 t_fine;
+       u32 adc_temp, adc_press, comp_press;
+       s32 t_fine, comp_temp;
+       s32 *chans = (s32 *)data->sensor_data;
        int ret;
 
        guard(mutex)(&data->lock);
@@ -1044,7 +1045,7 @@ static irqreturn_t bmp280_trigger_handler(int irq, void *p)
                goto out;
        }
 
-       data->sensor_data[1] = bmp280_compensate_temp(data, adc_temp);
+       comp_temp = bmp280_compensate_temp(data, adc_temp);
 
        /* Pressure calculations */
        adc_press = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(&data->buf[0]));
@@ -1054,10 +1055,12 @@ static irqreturn_t bmp280_trigger_handler(int irq, void *p)
        }
 
        t_fine = bmp280_calc_t_fine(data, adc_temp);
+       comp_press = bmp280_compensate_press(data, adc_press, t_fine);
 
-       data->sensor_data[0] = bmp280_compensate_press(data, adc_press, t_fine);
+       chans[0] = comp_press;
+       chans[1] = comp_temp;
 
-       iio_push_to_buffers_with_timestamp(indio_dev, &data->sensor_data,
+       iio_push_to_buffers_with_timestamp(indio_dev, data->sensor_data,
                                           iio_get_time_ns(indio_dev));
 
 out:
@@ -1138,8 +1141,9 @@ static irqreturn_t bme280_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct bmp280_data *data = iio_priv(indio_dev);
-       u32 adc_temp, adc_press, adc_humidity;
-       s32 t_fine;
+       u32 adc_temp, adc_press, adc_humidity, comp_press, comp_humidity;
+       s32 t_fine, comp_temp;
+       s32 *chans = (s32 *)data->sensor_data;
        int ret;
 
        guard(mutex)(&data->lock);
@@ -1159,7 +1163,7 @@ static irqreturn_t bme280_trigger_handler(int irq, void *p)
                goto out;
        }
 
-       data->sensor_data[1] = bmp280_compensate_temp(data, adc_temp);
+       comp_temp = bmp280_compensate_temp(data, adc_temp);
 
        /* Pressure calculations */
        adc_press = FIELD_GET(BMP280_MEAS_TRIM_MASK, get_unaligned_be24(&data->buf[0]));
@@ -1169,8 +1173,7 @@ static irqreturn_t bme280_trigger_handler(int irq, void *p)
        }
 
        t_fine = bmp280_calc_t_fine(data, adc_temp);
-
-       data->sensor_data[0] = bmp280_compensate_press(data, adc_press, t_fine);
+       comp_press = bmp280_compensate_press(data, adc_press, t_fine);
 
        /* Humidity calculations */
        adc_humidity = get_unaligned_be16(&data->buf[6]);
@@ -1179,9 +1182,14 @@ static irqreturn_t bme280_trigger_handler(int irq, void *p)
                dev_err(data->dev, "reading humidity skipped\n");
                goto out;
        }
-       data->sensor_data[2] = bme280_compensate_humidity(data, adc_humidity, t_fine);
 
-       iio_push_to_buffers_with_timestamp(indio_dev, &data->sensor_data,
+       comp_humidity = bme280_compensate_humidity(data, adc_humidity, t_fine);
+
+       chans[0] = comp_press;
+       chans[1] = comp_temp;
+       chans[2] = comp_humidity;
+
+       iio_push_to_buffers_with_timestamp(indio_dev, data->sensor_data,
                                           iio_get_time_ns(indio_dev));
 
 out:
@@ -1618,8 +1626,9 @@ static irqreturn_t bmp380_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct bmp280_data *data = iio_priv(indio_dev);
-       u32 adc_temp, adc_press;
-       s32 t_fine;
+       u32 adc_temp, adc_press, comp_press;
+       s32 t_fine, comp_temp;
+       s32 *chans = (s32 *)data->sensor_data;
        int ret;
 
        guard(mutex)(&data->lock);
@@ -1639,7 +1648,7 @@ static irqreturn_t bmp380_trigger_handler(int irq, void *p)
                goto out;
        }
 
-       data->sensor_data[1] = bmp380_compensate_temp(data, adc_temp);
+       comp_temp = bmp380_compensate_temp(data, adc_temp);
 
        /* Pressure calculations */
        adc_press = get_unaligned_le24(&data->buf[0]);
@@ -1649,10 +1658,12 @@ static irqreturn_t bmp380_trigger_handler(int irq, void *p)
        }
 
        t_fine = bmp380_calc_t_fine(data, adc_temp);
+       comp_press = bmp380_compensate_press(data, adc_press, t_fine);
 
-       data->sensor_data[0] = bmp380_compensate_press(data, adc_press, t_fine);
+       chans[0] = comp_press;
+       chans[1] = comp_temp;
 
-       iio_push_to_buffers_with_timestamp(indio_dev, &data->sensor_data,
+       iio_push_to_buffers_with_timestamp(indio_dev, data->sensor_data,
                                           iio_get_time_ns(indio_dev));
 
 out:
@@ -2199,7 +2210,7 @@ static irqreturn_t bmp580_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct bmp280_data *data = iio_priv(indio_dev);
-       int ret;
+       int ret, offset;
 
        guard(mutex)(&data->lock);
 
@@ -2211,13 +2222,15 @@ static irqreturn_t bmp580_trigger_handler(int irq, void *p)
                goto out;
        }
 
-       /* Temperature calculations */
-       memcpy(&data->sensor_data[1], &data->buf[0], 3);
-
        /* Pressure calculations */
-       memcpy(&data->sensor_data[0], &data->buf[3], 3);
+       memcpy(&data->sensor_data[offset], &data->buf[3], 3);
+
+       offset += sizeof(s32);
+
+       /* Temperature calculations */
+       memcpy(&data->sensor_data[offset], &data->buf[0], 3);
 
-       iio_push_to_buffers_with_timestamp(indio_dev, &data->sensor_data,
+       iio_push_to_buffers_with_timestamp(indio_dev, data->sensor_data,
                                           iio_get_time_ns(indio_dev));
 
 out:
@@ -2523,23 +2536,24 @@ static irqreturn_t bmp180_trigger_handler(int irq, void *p)
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct bmp280_data *data = iio_priv(indio_dev);
-       int ret, chan_value;
+       int ret, comp_temp, comp_press;
+       s32 *chans = (s32 *)data->sensor_data;
 
        guard(mutex)(&data->lock);
 
-       ret = bmp180_read_temp(data, &chan_value);
+       ret = bmp180_read_temp(data, &comp_temp);
        if (ret)
                goto out;
 
-       data->sensor_data[1] = chan_value;
 
-       ret = bmp180_read_press(data, &chan_value);
+       ret = bmp180_read_press(data, &comp_press);
        if (ret)
                goto out;
 
-       data->sensor_data[0] = chan_value;
+       chans[0] = comp_press;
+       chans[1] = comp_temp;
 
-       iio_push_to_buffers_with_timestamp(indio_dev, &data->sensor_data,
+       iio_push_to_buffers_with_timestamp(indio_dev, data->sensor_data,
                                           iio_get_time_ns(indio_dev));
 
 out:

diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
index a9f220c1f77a700d1ccf1bad9d9e54501ae38c4f..dc1bf04cb0b5d4cc58bfea36ef6884f1cc1a5fc9 100644 (file)
--- a/drivers/iio/pressure/bmp280.h
+++ b/drivers/iio/pressure/bmp280.h
@@ -322,6 +322,7 @@
                                         BMP280_NUM_TEMP_BYTES + \
                                         BME280_NUM_HUMIDITY_BYTES)
 
+#define BME280_NUM_MAX_CHANNELS                3
 /* Core exported structs */
 
 static const char *const bmp280_supply_names[] = {
@@ -419,7 +420,8 @@ struct bmp280_data {
         * Data to push to userspace triggered buffer. Up to 3 channels and
         * s64 timestamp, aligned.
         */
-       s32 sensor_data[6] __aligned(8);
+       u8 sensor_data[ALIGN(sizeof(s32) * BME280_NUM_MAX_CHANNELS, sizeof(s64))
+                      + sizeof(s64)] __aligned(sizeof(s64));
 
        /*
         * DMA (thus cache coherency maintenance) may require the