Re: [PATCH 3/3] iio: dps310: Add pressure sensing capability

From: Peter Meerwald-Stadler
Date: Mon May 06 2019 - 17:25:55 EST

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On Mon, 6 May 2019, Eddie James wrote:

some comments below

> The DPS310 supports measurement of pressure, so support that in the
> driver. Use background measurement like the temperature sensing and
> default to lowest precision and lowest measurement rate.
>
> Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
> ---
> drivers/iio/pressure/dps310.c | 327 ++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 301 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index 3e03685..fe88480 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c
> @@ -16,6 +16,7 @@
> */

this should update the TODO, right? it implements pressure

>
> #include <linux/i2c.h>
> +#include <linux/math64.h>
> #include <linux/module.h>
> #include <linux/regmap.h>
>
> @@ -29,6 +30,8 @@
> #define DPS310_TMP_B1 0x04
> #define DPS310_TMP_B2 0x05
> #define DPS310_PRS_CFG 0x06
> +#define DPS310_PRS_RATE_BITS GENMASK(6, 4)
> +#define DPS310_PRS_PRC_BITS GENMASK(3, 0)
> #define DPS310_TMP_CFG 0x07
> #define DPS310_TMP_RATE_BITS GENMASK(6, 4)
> #define DPS310_TMP_PRC_BITS GENMASK(3, 0)
> @@ -51,6 +54,7 @@
> #define DPS310_RESET 0x0c
> #define DPS310_RESET_MAGIC (BIT(0) | BIT(3))
> #define DPS310_COEF_BASE 0x10
> +#define DPS310_NUM_COEF_REGS 0x12
>
> #define DPS310_PRS_BASE DPS310_PRS_B0
> #define DPS310_TMP_BASE DPS310_TMP_B0
> @@ -58,7 +62,7 @@
> #define DPS310_CALC_RATE(_n) ilog2(_n)
> #define DPS310_CALC_PRC(_n) ilog2(_n)
>
> -const int scale_factor[] = {
> +static const int scale_factor[] = {

this change should be in the previous/initial patch

> 524288,
> 1572864,
> 3670016,
> @@ -74,6 +78,8 @@ struct dps310_data {
> struct regmap *regmap;
>
> s32 c0, c1;
> + s32 c00, c10, c20, c30, c01, c11, c21;
> + s32 pressure_raw;
> s32 temp_raw;
> };
>
> @@ -86,33 +92,81 @@ static const struct iio_chan_spec dps310_channels[] = {
> BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> BIT(IIO_CHAN_INFO_RAW),
> },
> + {
> + .type = IIO_PRESSURE,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
> + BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> + BIT(IIO_CHAN_INFO_RAW),
> + },
> };
>
> -/* To be called after checking the TMP_RDY bit in MEAS_CFG */
> -static int dps310_get_temp_coef(struct dps310_data *data)
> +/* To be called after checking the COEF_RDY bit in MEAS_CFG */
> +static int dps310_get_coefs(struct dps310_data *data)
> {
> struct regmap *regmap = data->regmap;
> - u8 coef[3] = {0};
> +
> int r;
> + u8 coef[DPS310_NUM_COEF_REGS] = {0};
> u32 c0, c1;
> + u32 c00, c10, c20, c30, c01, c11, c21;
>
> - /*
> - * Read temperature calibration coefficients c0 and c1 from the
> - * COEF register. The numbers are 12-bit 2's compliment numbers
> - */
> - r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef, 3);
> + /* Read all sensor calibration coefficients from the COEF registers. */
> + r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef,
> + DPS310_NUM_COEF_REGS);
> if (r < 0)
> return r;
>
> + /*
> + * Calculate temperature calibration coefficients c0 and c1. The numbers
> + * are 12-bit 2's complement numbers.
> + */
> c0 = (coef[0] << 4) | (coef[1] >> 4);
> data->c0 = sign_extend32(c0, 11);
>
> c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
> data->c1 = sign_extend32(c1, 11);
>
> + /*
> + * Calculate pressure calibration coefficients. c00 and c10 are 20 bit
> + * 2's complement numbers, while the rest are 16 bit 2's complement
> + * numbers.
> + */
> + c00 = (coef[3] << 12) | (coef[4] << 4) | (coef[5] >> 4);
> + data->c00 = sign_extend32(c00, 19);
> +
> + c10 = ((coef[5] & GENMASK(3, 0)) << 16) | (coef[6] << 8) | coef[7];
> + data->c10 = sign_extend32(c10, 19);
> +
> + c01 = (coef[8] << 8) | coef[9];
> + data->c01 = sign_extend32(c01, 15);
> +
> + c11 = (coef[10] << 8) | coef[11];
> + data->c11 = sign_extend32(c11, 15);
> +
> + c20 = (coef[12] << 8) | coef[13];
> + data->c20 = sign_extend32(c20, 15);
> +
> + c21 = (coef[14] << 8) | coef[15];
> + data->c21 = sign_extend32(c21, 15);
> +
> + c30 = (coef[16] << 8) | coef[17];
> + data->c30 = sign_extend32(c30, 15);
> +
> return 0;
> }
>
> +static int dps310_get_pres_precision(struct dps310_data *data)
> +{
> + int val, r;
> +
> + r = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
> + if (r < 0)
> + return r;
> +
> + return BIT(val & GENMASK(2, 0));
> +}
> +
> static int dps310_get_temp_precision(struct dps310_data *data)
> {
> int val, r;
> @@ -128,6 +182,24 @@ static int dps310_get_temp_precision(struct dps310_data *data)
> return BIT(val & GENMASK(2, 0));
> }
>
> +static int dps310_set_pres_precision(struct dps310_data *data, int val)
> +{
> + int ret;
> + u8 shift_en;
> +
> + if (val < 0 || val > 128)
> + return -EINVAL;
> +
> + shift_en = val >= 16 ? DPS310_PRS_SHIFT_EN : 0;
> + ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> + DPS310_PRS_SHIFT_EN, shift_en);
> + if (ret)
> + return ret;
> +
> + return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
> + DPS310_PRS_PRC_BITS, DPS310_CALC_PRC(val));
> +}
> +
> static int dps310_set_temp_precision(struct dps310_data *data, int val)
> {
> int ret;
> @@ -146,6 +218,19 @@ static int dps310_set_temp_precision(struct dps310_data *data, int val)
> DPS310_TMP_PRC_BITS, DPS310_CALC_PRC(val));
> }
>
> +static int dps310_set_pres_samp_freq(struct dps310_data *data, int freq)
> +{
> + u8 val;
> +
> + if (freq < 0 || freq > 128)
> + return -EINVAL;
> +
> + val = DPS310_CALC_RATE(freq) << 4;
> +
> + return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
> + DPS310_PRS_RATE_BITS, val);
> +}
> +
> static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
> {
> u8 val;
> @@ -159,6 +244,17 @@ 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)
> +{
> + int val, r;
> +
> + r = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
> + if (r < 0)
> + return r;
> +
> + return BIT((val & DPS310_PRS_RATE_BITS) >> 4);
> +}
> +
> static int dps310_get_temp_samp_freq(struct dps310_data *data)
> {
> int val, r;
> @@ -170,6 +266,16 @@ static int dps310_get_temp_samp_freq(struct dps310_data *data)
> return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
> }
>
> +static int dps310_get_pres_k(struct dps310_data *data)
> +{
> + int r = dps310_get_pres_precision(data);
> +
> + if (r < 0)
> + return r;
> +
> + return scale_factor[DPS310_CALC_PRC(r)];
> +}
> +
> static int dps310_get_temp_k(struct dps310_data *data)
> {
> int r = dps310_get_temp_precision(data);
> @@ -180,7 +286,33 @@ static int dps310_get_temp_k(struct dps310_data *data)
> return scale_factor[DPS310_CALC_PRC(r)];
> }
>
> -static int dps310_read_temp(struct dps310_data *data)
> +static int dps310_read_pres_raw(struct dps310_data *data)
> +{
> + struct device *dev = &data->client->dev;
> + int r, ready;
> + u8 val[3];
> + s32 raw;
> +
> + r = regmap_read(data->regmap, DPS310_MEAS_CFG, &ready);
> + if (r < 0)
> + return r;
> +
> + if (!(ready & DPS310_PRS_RDY)) {
> + dev_dbg(dev, "pressure not ready\n");
> + return -EAGAIN;
> + }
> +
> + r = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, 3);
> + if (r < 0)
> + return r;
> +
> + raw = (val[0] << 16) | (val[1] << 8) | val[2];
> + data->pressure_raw = sign_extend32(raw, 23);
> +
> + return 0;
> +}
> +
> +static int dps310_read_temp_raw(struct dps310_data *data)
> {
> struct device *dev = &data->client->dev;
> struct regmap *regmap = data->regmap;
> @@ -246,26 +378,139 @@ static int dps310_write_raw(struct iio_dev *iio,
> {
> struct dps310_data *data = iio_priv(iio);
>
> - if (chan->type != IIO_TEMP)
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + switch (chan->type) {
> + case IIO_PRESSURE:
> + return dps310_set_pres_samp_freq(data, val);
> +
> + case IIO_TEMP:
> + return dps310_set_temp_samp_freq(data, val);
> +
> + default:
> + return -EINVAL;
> + }
> +
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + switch (chan->type) {
> + case IIO_PRESSURE:
> + return dps310_set_pres_precision(data, val);
> +
> + case IIO_TEMP:
> + return dps310_set_temp_precision(data, val);
> +
> + default:
> + return -EINVAL;
> + }
> +
> + default:
> return -EINVAL;
> + }
> +}
> +
> +static int dps310_calculate_pressure(struct dps310_data *data)
> +{
> + int i;
> + int kpi = dps310_get_pres_k(data);
> + int kti = dps310_get_temp_k(data);
> + s64 rem = 0ULL;
> + s64 pressure = 0ULL;
> + s64 p;
> + s64 t;
> + s64 denoms[7];
> + s64 nums[7];
> + s64 rems[7];
> + s64 kp;
> + s64 kt;
> +
> + if (kpi < 0)
> + return kpi;
> +
> + if (kti < 0)
> + return kti;
> +
> + kp = (s64)kpi;
> + kt = (s64)kti;
> +
> + /* Ignore errors and use the latest temperature */
> + dps310_read_temp_raw(data);
> +
> + p = (s64)data->pressure_raw;
> + t = (s64)data->temp_raw;
> +
> + /* Section 4.9.1 of the DPS310 spec; algebra'd to avoid underflow */
> + nums[0] = (s64)data->c00;
> + denoms[0] = 1LL;
> + nums[1] = p * (s64)data->c10;
> + denoms[1] = kp;
> + nums[2] = p * p * (s64)data->c20;
> + denoms[2] = kp * kp;
> + nums[3] = p * p * p * (s64)data->c30;
> + denoms[3] = kp * kp * kp;
> + nums[4] = t * (s64)data->c01;
> + denoms[4] = kt;
> + nums[5] = t * p * (s64)data->c11;
> + denoms[5] = kp * kt;
> + nums[6] = t * p * p * (s64)data->c21;
> + denoms[6] = kp * kp * kt;
> +
> + /* Kernel lacks a div64_s64_rem function; denoms are all positive */
> + for (i = 0; i < 7; ++i) {
> + u64 rem;
> +
> + if (nums[i] < 0LL) {
> + pressure -= div64_u64_rem(-nums[i], denoms[i], &rem);
> + rems[i] = -rem;
> + } else {
> + pressure += div64_u64_rem(nums[i], denoms[i], &rem);
> + rems[i] = (s64)rem;
> + }
> + }
> +
> + /* Increase precision and calculate the remainder sum */
> + for (i = 0; i < 7; ++i)
> + rem += div64_s64((s64)rems[i] * 1000000000LL, denoms[i]);
> +
> + pressure += div_s64(rem, 1000000000LL);
> +
> + return (int)pressure;
> +}
> +
> +static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
> + long mask)
> +{
> + int ret;
>
> switch (mask) {
> case IIO_CHAN_INFO_SAMP_FREQ:
> - return dps310_set_temp_samp_freq(data, val);
> + *val = dps310_get_pres_samp_freq(data);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_RAW:
> + ret = dps310_read_pres_raw(data);
> + if (ret)
> + return ret;
> +
> + *val = dps310_calculate_pressure(data);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + *val = 1;
> + *val2 = 1000; /* Convert Pa to KPa per IIO ABI */
> + return IIO_VAL_FRACTIONAL;
> +
> case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> - return dps310_set_temp_precision(data, val);
> + *val = dps310_get_pres_precision(data);
> + return IIO_VAL_INT;
> +
> default:
> return -EINVAL;
> }
> -
> - return -EINVAL;
> }
>
> -static int dps310_read_raw(struct iio_dev *iio,
> - struct iio_chan_spec const *chan,
> - int *val, int *val2, long mask)
> +static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
> + long mask)
> {
> - struct dps310_data *data = iio_priv(iio);
> int ret;
>
> switch (mask) {
> @@ -274,7 +519,7 @@ static int dps310_read_raw(struct iio_dev *iio,
> return IIO_VAL_INT;
>
> case IIO_CHAN_INFO_RAW:
> - ret = dps310_read_temp(data);
> + ret = dps310_read_temp_raw(data);
> if (ret)
> return ret;
>
> @@ -305,8 +550,24 @@ static int dps310_read_raw(struct iio_dev *iio,
> default:
> return -EINVAL;
> }
> +}
>
> - return -EINVAL;
> +static int dps310_read_raw(struct iio_dev *iio,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct dps310_data *data = iio_priv(iio);
> +
> + switch (chan->type) {
> + case IIO_PRESSURE:
> + return dps310_read_pressure(data, val, val2, mask);
> +
> + case IIO_TEMP:
> + return dps310_read_temp(data, val, val2, mask);
> +
> + default:
> + return -EINVAL;
> + }
> }
>
> static const struct regmap_config dps310_regmap_config = {
> @@ -390,6 +651,13 @@ static int dps310_probe(struct i2c_client *client,
> return PTR_ERR(data->regmap);
>
> /*
> + * Set up pressure sensor in single sample, one measurement per second
> + * mode
> + */
> + r = regmap_write(data->regmap, DPS310_PRS_CFG,
> + DPS310_CALC_RATE(1) | DPS310_CALC_PRC(1));
> +
> + /*
> * Set up external (MEMS) temperature sensor in single sample, one
> * measurement per second mode
> */
> @@ -399,16 +667,23 @@ static int dps310_probe(struct i2c_client *client,
> if (r < 0)
> goto err;
>
> - /* Temp shift is disabled when PRC <= 8 */
> + /* Temp and pressure shifts are disabled when PRC <= 8 */
> r = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> - DPS310_TMP_SHIFT_EN, 0);
> + DPS310_TMP_SHIFT_EN | DPS310_PRS_SHIFT_EN, 0);
> + if (r < 0)
> + goto err;
> +
> + /* MEAS_CFG doesn't seem to update unless first written with 0 */
> + r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> + DPS310_MEAS_CTRL_BITS, 0);
> if (r < 0)
> goto err;
>
> - /* Turn on temperature measurement in the background */
> + /* Turn on temperature and pressure measurement in the background */
> r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> DPS310_MEAS_CTRL_BITS,
> - DPS310_TEMP_EN | DPS310_BACKGROUND);
> + DPS310_PRS_EN | DPS310_TEMP_EN |
> + DPS310_BACKGROUND);
> if (r < 0)
> goto err;
>
> @@ -421,7 +696,7 @@ static int dps310_probe(struct i2c_client *client,
> if (r < 0)
> goto err;
>
> - r = dps310_get_temp_coef(data);
> + r = dps310_get_coefs(data);
> if (r < 0)
> goto err;
>
>

--

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418

Next message: Petr Åtetiar: "[PATCH net-next v2 0/4] of_get_mac_address ERR_PTR fixes"
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