Re: [PATCH v3 4/5] iio: pressure: bmp280: Add support for BMP380 sensor family

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 10 Jul 2022 11:18:31 +0200
Angel Iglesias <ang.iglesiasg@gmail.com> wrote:

> Adds compatibility with the new generation of this sensor, the BMP380
> 
> Includes basic sensor initialization to do pressure and temp
> measurements and allows tuning oversampling settings for each channel.
> 
> The compensation algorithms are adapted from the device datasheet and
> the repository https://github.com/BoschSensortec/BMP3-Sensor-API
> 
> Signed-off-by: Angel Iglesias <ang.iglesiasg@gmail.com>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> 
Say what was reported with # whatever
, or drop these tags.  The message asking you to add them is applicable to
patches that are fixing things upstream.  Adding them here implies that the
whole patch is a fix that was reported by the bots.

One thing I'd previously missed in here is you are doing regmap_bulk_*
accesses.  Those should be using dma safe buffer. Look for IIO_DMA_MINALIGN
in the current IIO togreg branch.
You can't safely use buffers on the stack.

Otherwise, looks pretty good to me.

Thanks,

Jonathan


> ---
>  drivers/iio/pressure/bmp280-core.c   | 356 +++++++++++++++++++++++++++
>  drivers/iio/pressure/bmp280-i2c.c    |   5 +
>  drivers/iio/pressure/bmp280-regmap.c |  55 +++++
>  drivers/iio/pressure/bmp280-spi.c    |   5 +
>  drivers/iio/pressure/bmp280.h        | 101 ++++++++
>  5 files changed, 522 insertions(+)
> 
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 59e9c5fb4ab4..5d5d20d97cf6 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -12,10 +12,13 @@
>   * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP180-DS000-121.pdf
>   * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf
>   * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf
> + * https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmp388-ds001.pdf
>   */
>  
>  #define pr_fmt(fmt) "bmp280: " fmt
>  
> +#include <linux/bitops.h>
> +#include <linux/bitfield.h>
>  #include <linux/device.h>
>  #include <linux/module.h>
>  #include <linux/regmap.h>
> @@ -29,6 +32,7 @@
>  #include <linux/completion.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/random.h>
> +#include <asm/unaligned.h>
>  
>  #include "bmp280.h"
>  
> @@ -74,6 +78,24 @@ struct bmp280_calib {
>  	s8  H6;
>  };
>  
> +/* See datasheet Section 3.11.1. */
> +struct bmp380_calib {
> +	u16 T1;
> +	u16 T2;
> +	s8  T3;
> +	s16 P1;
> +	s16 P2;
> +	s8  P3;
> +	s8  P4;
> +	u16 P5;
> +	u16 P6;
> +	s8  P7;
> +	s8  P8;
> +	s16 P9;
> +	s8  P10;
> +	s8  P11;
> +};
> +
>  static const char *const bmp280_supply_names[] = {
>  	"vddd", "vdda"
>  };
> @@ -90,6 +112,7 @@ struct bmp280_data {
>  	union {
>  		struct bmp180_calib bmp180;
>  		struct bmp280_calib bmp280;
> +		struct bmp380_calib bmp380;
>  	} calib;
>  	struct regulator_bulk_data supplies[BMP280_NUM_SUPPLIES];
>  	unsigned int start_up_time; /* in microseconds */
> @@ -138,6 +161,25 @@ struct bmp280_chip_info {
>  enum { T1, T2, T3 };
>  enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };
>  
> +enum {
> +	/* Temperature calib indexes */
> +	BMP380_T1 = 0,
> +	BMP380_T2 = 2,
> +	BMP380_T3 = 4,
> +	/* Pressure calib indexes */
> +	BMP380_P1 = 5,
> +	BMP380_P2 = 7,
> +	BMP380_P3 = 9,
> +	BMP380_P4 = 10,
> +	BMP380_P5 = 11,
> +	BMP380_P6 = 13,
> +	BMP380_P7 = 15,
> +	BMP380_P8 = 16,
> +	BMP380_P9 = 17,
> +	BMP380_P10 = 19,
> +	BMP380_P11 = 20
> +};
> +
>  static const struct iio_chan_spec bmp280_channels[] = {
>  	{
>  		.type = IIO_PRESSURE,
> @@ -708,6 +750,310 @@ static const struct bmp280_chip_info bme280_chip_info = {
>  	.read_calib = bmp280_read_calib,
>  };
>  
> +/* Send a command to BMP3XX sensors */
> +static int bmp380_cmd(struct bmp280_data *data, u8 cmd)
> +{
> +	int ret;
> +	unsigned int reg;
> +
> +	/* check if device is ready to process a command */
> +	ret = regmap_read(data->regmap, BMP380_REG_STATUS, &reg);
> +	if (ret) {
> +		dev_err(data->dev, "failed to read error register\n");
> +		return ret;
> +	}
> +	if (!(reg & BMP380_STATUS_CMD_RDY_MASK)) {
> +		dev_err(data->dev, "device is not ready to accept commands\n");
> +		return -EBUSY;
> +	}
> +
> +	/* send command to process */
> +	ret = regmap_write(data->regmap, BMP380_REG_CMD, cmd);
> +	if (ret) {
> +		dev_err(data->dev, "failed to send command to device\n");
> +		return ret;
> +	}
> +	/* wait for 2ms for command to be proccessed */
> +	usleep_range(data->start_up_time, data->start_up_time + 100);
> +	/* check for command processing error */
> +	ret = regmap_read(data->regmap, BMP380_REG_ERROR, &reg);
> +	if (ret) {
> +		dev_err(data->dev, "error reading ERROR reg\n");
> +		return ret;
> +	}
> +	if (reg & BMP380_ERR_CMD_MASK) {
> +		dev_err(data->dev, "error processing command 0x%X\n", cmd);
> +		return -EINVAL;
> +	}
> +	dev_dbg(data->dev, "Command 0x%X proccessed successfully\n", cmd);
> +
> +	return 0;
> +}
> +
> +/*
> + * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
> + * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
> + * value.
> + *
> + * Taken from datasheet, Section Appendix 9, "Compensation formula" and repo
> + * https://github.com/BoschSensortec/BMP3-Sensor-API
> + */
> +static s32 bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
> +{
> +	s64 var1, var2, var3, var4, var5, var6, comp_temp;
> +	struct bmp380_calib *calib = &data->calib.bmp380;
> +
> +	var1 = ((s64) adc_temp) - (((s64) calib->T1) << 8);
> +	var2 = var1 * ((s64) calib->T2);
> +	var3 = var1 * var1;
> +	var4 = var3 * ((s64) calib->T3);
> +	var5 = (var2 << 18) + var4;
> +	var6 = var5 >> 32;
> +	data->t_fine = (s32) var6;
> +	comp_temp = (var6 * 25) >> 14;
> +
> +	comp_temp = clamp_val(comp_temp, BMP380_MIN_TEMP, BMP380_MAX_TEMP);
> +	return (s32) comp_temp;
> +}
> +
> +/*
> + * Returns pressure in Pa as unsigned 32 bit integer in fractional Pascal.
> + * Output value of "9528709" represents 9528709/100 = 95287.09 Pa = 952.8709 hPa
> + *
> + * Taken from datasheet, Section 9.3. "Pressure compensation" and repository
> + * https://github.com/BoschSensortec/BMP3-Sensor-API
> + */
> +static u32 bmp380_compensate_press(struct bmp280_data *data, u32 adc_press)
> +{
> +	s64 var1, var2, var3, var4, var5, var6, offset, sensitivity;
> +	u64 comp_press;
> +	struct bmp380_calib *calib = &data->calib.bmp380;
> +
> +	var1 = ((s64)data->t_fine) * ((s64)data->t_fine);
> +	var2 = var1 >> 6;
> +	var3 = (var2 * ((s64) data->t_fine)) >> 8;
> +	var4 = (((s64)calib->P8) * var3) >> 5;
> +	var5 = (((s64) calib->P7) * var1) << 4;
> +	var6 = (((s64) calib->P6) * ((s64)data->t_fine)) << 22;
> +	offset = (((s64)calib->P5) << 47) + var4 + var5 + var6;
> +	var2 = (((s64)calib->P4) * var3) >> 5;
> +	var4 = (((s64) calib->P3) * var1) << 2;
> +	var5 = (((s64) calib->P2) - ((s64) 1<<14)) *
> +		(((s64)data->t_fine) << 21);
> +	sensitivity = ((((s64) calib->P1) - ((s64) 1 << 14)) << 46) +
> +			var2 + var4 + var5;
> +	var1 = (sensitivity >> 24) * ((s64)adc_press);
> +	var2 = ((s64)calib->P10) * ((s64) data->t_fine);
> +	var3 = var2 + (((s64) calib->P9) << 16);
> +	var4 = (var3 * ((s64)adc_press)) >> 13;
> +
> +	/*
> +	 * Dividing by 10 followed by multiplying by 10 to avoid
> +	 * possible overflow caused by (uncomp_data->pressure * partial_data4)
> +	 */
> +	var5 = (((s64)adc_press) * (var4 / 10)) >> 9;
> +	var5 *= 10;
> +	var6 = ((s64)adc_press) * ((s64)adc_press);
> +	var2 = (((s64)calib->P11) * var6) >> 16;
> +	var3 = (var2 * ((s64)adc_press)) >> 7;
> +	var4 = (offset >> 2) + var1 + var5 + var3;
> +	comp_press = ((u64)var4 * 25) >> 40;
> +
> +	comp_press = clamp_val(comp_press, BMP380_MIN_PRES, BMP380_MAX_PRES);
> +	return (u32)comp_press;
> +}
> +
> +static int bmp380_read_temp(struct bmp280_data *data, int *val)
> +{
> +	int ret;
> +	u8 tmp[3];
> +	u32 adc_temp;
> +	s32 comp_temp;
> +
> +	ret = regmap_bulk_read(data->regmap, BMP380_REG_TEMP_XLSB, tmp, 3);
As below.
> +	if (ret < 0) {
> +		dev_err(data->dev, "failed to read temperature\n");
> +		return ret;
> +	}
> +
> +	adc_temp = get_unaligned_le24(tmp);
> +	if (adc_temp == BMP380_TEMP_SKIPPED) {
> +		/* reading was skipped */
> +		dev_err(data->dev, "reading temperature skipped\n");
> +		return -EIO;
> +	}
> +	comp_temp = bmp380_compensate_temp(data, adc_temp);
> +
> +	/*
> +	 * val might be NULL if we're called by the read_press routine,
> +	 * who only cares about the carry over t_fine value.
> +	 */
> +	if (val) {
> +		/* IIO reports temperatures in mC */
> +		*val = comp_temp * 10;
> +		return IIO_VAL_INT;
> +	}
> +
> +	return 0;
> +}
> +
> +static int bmp380_read_press(struct bmp280_data *data, int *val, int *val2)
> +{
> +	int ret;
> +	u8 tmp[3];
> +	u32 adc_press;
> +	s32 comp_press;
> +
> +	/* Read and compensate temperature so we get a reading of t_fine. */
> +	ret = bmp380_read_temp(data, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_bulk_read(data->regmap, BMP380_REG_PRESS_XLSB, tmp, 3);

As below, buffer should be DMA safe.

> +	if (ret < 0) {
> +		dev_err(data->dev, "failed to read pressure\n");
> +		return ret;
> +	}
> +
> +	adc_press = get_unaligned_le24(tmp);
> +	if (adc_press == BMP380_PRESS_SKIPPED) {
> +		/* reading was skipped */
> +		dev_err(data->dev, "reading pressure skipped\n");
> +		return -EIO;
> +	}
> +	comp_press = bmp380_compensate_press(data, adc_press);
> +
> +	*val = comp_press;
> +	/* Compensated pressure is in cPa (centipascals) */
> +	*val2 = 100000;
> +
> +	return IIO_VAL_FRACTIONAL;
> +}
> +
> +static int bmp380_read_calib(struct bmp280_data *data, unsigned int chip)
> +{
> +	int ret;
> +	struct bmp380_calib *calib = &data->calib.bmp380;
> +	u8 buf[BMP380_CALIB_REG_COUNT];

I'd missed this previously but for SPI drivers, we should be providing
regmap_bulk accesses with DMA safe buffers.  That means they can't be on the
stack and need to be appropriately aligned IIO_DMA_MINALIGN as part of
the *data structure.

Last time I checked the SPI regmap implementation doesn't currently use
the buffers directly but it has in the past and may do again in the future 
- hence we should be careful to allow for that.

> +
> +	/* Read temperature calibration values. */
> +	ret = regmap_bulk_read(data->regmap, BMP380_REG_CALIB_TEMP_START, buf,
> +			       BMP380_CALIB_REG_COUNT);
> +	if (ret < 0) {
> +		dev_err(data->dev,
> +			"failed to read temperature calibration parameters\n");
> +		return ret;
> +	}
> +
> +	/* Toss the temperature calibration data into the entropy pool */
> +	add_device_randomness(buf, sizeof(buf));
> +
> +	/* Parse calibration data */
> +	calib->T1 = get_unaligned_le16(&buf[BMP380_T1]);
> +	calib->T2 = get_unaligned_le16(&buf[BMP380_T2]);
> +	calib->T3 = buf[BMP380_T3];
> +	calib->P1 = get_unaligned_le16(&buf[BMP380_P1]);
> +	calib->P2 = get_unaligned_le16(&buf[BMP380_P2]);
> +	calib->P3 = buf[BMP380_P3];
> +	calib->P4 = buf[BMP380_P4];
> +	calib->P5 = get_unaligned_le16(&buf[BMP380_P5]);
> +	calib->P6 = get_unaligned_le16(&buf[BMP380_P6]);
> +	calib->P7 = buf[BMP380_P7];
> +	calib->P8 = buf[BMP380_P8];
> +	calib->P9 = get_unaligned_le16(&buf[BMP380_P9]);
> +	calib->P10 = buf[BMP380_P10];
> +	calib->P11 = buf[BMP380_P11];
> +
> +	return 0;
> +}