Re: [PATCH] iio: Add driver for Infineon DPS310

From: Peter Meerwald-Stadler
Date: Fri May 05 2017 - 07:43:51 EST

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In reply to: Joel Stanley: "[PATCH] iio: Add driver for Infineon DPS310"
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> The DPS310 is a temperature and pressure sensor. It can be accessed over
> i2c and SPI.

comments below

> This driver supports polled measurement of temperature over i2c only.
>
> Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
> ---
> drivers/iio/pressure/Kconfig | 11 ++
> drivers/iio/pressure/Makefile | 1 +
> drivers/iio/pressure/dps310.c | 401 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 413 insertions(+)
> create mode 100644 drivers/iio/pressure/dps310.c
>
> diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
> index bd8d96b96771..50caefc0cd7d 100644
> --- a/drivers/iio/pressure/Kconfig
> +++ b/drivers/iio/pressure/Kconfig
> @@ -42,6 +42,17 @@ config BMP280_SPI
> depends on SPI_MASTER
> select REGMAP
>
> +config DPS310
> + tristate "Infineon DPS310 pressure and temperature sensor"
> + depends on I2C
> + select REGMAP_I2C
> + help
> + Support for the Infineon DPS310 digital barometric pressure sensor.
> + This driver measures temperature only.

does it make sense to propose a driver for it then?
is there intention to add pressure soonish?

link to datasheet would be nice

> +
> + This driver can also be built as a module. If so, the module will be
> + called dps310.
> +
> config HID_SENSOR_PRESS
> depends on HID_SENSOR_HUB
> select IIO_BUFFER
> diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
> index de3dbc81dc5a..997bbaebfa34 100644
> --- a/drivers/iio/pressure/Makefile
> +++ b/drivers/iio/pressure/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_BMP280) += bmp280.o
> bmp280-objs := bmp280-core.o bmp280-regmap.o
> obj-$(CONFIG_BMP280_I2C) += bmp280-i2c.o
> obj-$(CONFIG_BMP280_SPI) += bmp280-spi.o
> +obj-$(CONFIG_DPS310) += dps310.o
> obj-$(CONFIG_HID_SENSOR_PRESS) += hid-sensor-press.o
> obj-$(CONFIG_HP03) += hp03.o
> obj-$(CONFIG_MPL115) += mpl115.o
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> new file mode 100644
> index 000000000000..5e8f91a5662b
> --- /dev/null
> +++ b/drivers/iio/pressure/dps310.c
> @@ -0,0 +1,401 @@
> +/*
> + * Copyright 2017 IBM Corporation
> + *
> + * Joel Stanley <joel@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + *
> + * The DPS310 is a barometric pressure and temperature sensor.
> + * Currently only reading a single temperature is supported by
> + * this driver.
> + *

maybe add a comment with I2C address

> + * TODO:
> + * - Pressure sensor readings
> + * - Optionally support the FIFO
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define PRS_BASE 0x00

prefix everything with DPS310_ or dps310_

> +#define TMP_BASE 0x03
> +#define PRS_CFG 0x06
> +#define TMP_CFG 0x07
> +#define TMP_RATE_BITS GENMASK(6, 4)
> +#define TMP_PRC_BITS GENMASK(3, 0)
> +#define TMP_EXT BIT(7)
> +#define MEAS_CFG 0x08
> +#define MEAS_CTRL_BITS GENMASK(2, 0)
> +#define PRESSURE_EN BIT(0)
> +#define TEMP_EN BIT(1)
> +#define BACKGROUND BIT(2)
> +#define PRS_RDY BIT(4)
> +#define TMP_RDY BIT(5)
> +#define SENSOR_RDY BIT(6)
> +#define COEF_RDY BIT(7)
> +#define CFG_REG 0x09
> +#define INT_HL BIT(7)
> +#define TMP_SHIFT_EN BIT(3)
> +#define PRS_SHIFT_EN BIT(4)
> +#define FIFO_EN BIT(5)
> +#define SPI_EN BIT(6)
> +#define RESET 0x0c
> +#define RESET_MAGIC (BIT(0) | BIT(3))
> +#define COEF_BASE 0x10
> +
> +#define TMP_RATE(_n) ilog2(_n)
> +#define TMP_PRC(_n) ilog2(_n)
> +
> +#define MCELSIUS_PER_CELSIUS 1000

indeed :)
questionable usefulness

> +
> +const int scale_factor[] = {
> + 524288,
> + 1572864,
> + 3670016,
> + 7864320,
> + 253952,
> + 516096,
> + 1040384,
> + 2088960,
> +};
> +
> +struct dps310_data {
> + struct i2c_client *client;
> + struct regmap *regmap;
> +
> + s32 c0, c1;
> + s32 temp_raw;
> +};
> +
> +static const struct iio_chan_spec dps310_channels[] = {
> + {
> + .type = IIO_TEMP,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
> + BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> + BIT(IIO_CHAN_INFO_RAW),
> + },
> +};
> +
> +static s32 dps310_twos_compliment(u32 raw, size_t num_bits)

use sign_extend32() instead?

> +{
> + s32 out = raw;
> +
> + if (raw & BIT(num_bits - 1))
> + out = raw - BIT(num_bits);
> +
> + return out;
> +}
> +
> +static int dps310_get_temp_coef(struct dps310_data *data)
> +{
> + struct regmap *regmap = data->regmap;
> + uint8_t coef[3] = {0};
> + int ready, r;
> + u32 c0, c1;
> +
> + r = regmap_read(regmap, MEAS_CFG, &ready);
> + if (r < 0)
> + return r;
> +
> + if (!(ready & COEF_RDY))
> + return -EAGAIN;
> +
> + /*
> + * 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, COEF_BASE, coef, 3);
> + if (r < 0)
> + return r;
> +
> + c0 = (coef[0] << 4) | (coef[1] >> 4);
> + data->c0 = dps310_twos_compliment(c0, 12);
> +
> + c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
> + data->c1 = dps310_twos_compliment(c1, 12);
> +
> + return 0;
> +}
> +
> +static int dps310_get_temp_precision(struct dps310_data *data)
> +{
> + int val, r;
> +
> + r = regmap_read(data->regmap, TMP_CFG, &val);
> + if (r < 0)
> + return r;
> +
> + /*
> + * Scale factor is bottom 4 bits of the register, but 1111 is
> + * reserved so just grab bottom three
> + */
> + return BIT(val & GENMASK(2, 0));
> +}
> +
> +static int dps310_set_temp_precision(struct dps310_data *data, int val)
> +{
> + int ret;
> + u8 shift_en;
> +
> + if (val < 0 || val > 128)
> + return -EINVAL;
> +
> + shift_en = val >= 16 ? TMP_SHIFT_EN : 0;
> + ret = regmap_write_bits(data->regmap, CFG_REG, TMP_SHIFT_EN, shift_en);
> + if (ret)
> + return ret;
> +
> + return regmap_update_bits(data->regmap, TMP_CFG, TMP_PRC_BITS,
> + TMP_PRC(val));
> +}
> +
> +static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
> +{
> + uint8_t val;
> +
> + if (freq < 0 || freq > 128)
> + return -EINVAL;
> +
> + val = ilog2(freq) << 4;
> +
> + return regmap_update_bits(data->regmap, TMP_CFG, TMP_RATE_BITS, val);
> +}
> +
> +static int dps310_get_temp_samp_freq(struct dps310_data *data)
> +{
> + int val, r;
> +
> + r = regmap_read(data->regmap, TMP_CFG, &val);
> + if (r < 0)
> + return r;
> +
> + return BIT((val & TMP_RATE_BITS) >> 4);
> +}
> +
> +static int dps310_get_temp_k(struct dps310_data *data)
> +{
> + int index = ilog2(dps310_get_temp_precision(data));
> +
> + return scale_factor[index];
> +}
> +
> +static int dps310_read_temp(struct dps310_data *data)
> +{
> + struct device *dev = &data->client->dev;
> + struct regmap *regmap = data->regmap;
> + uint8_t val[3] = {0};
> + int r, ready;
> + int T_raw;
> +
> + r = regmap_read(regmap, MEAS_CFG, &ready);
> + if (r < 0)
> + return r;
> + if (!(ready & TMP_RDY)) {
> + dev_dbg(dev, "temperature not ready\n");
> + return -EAGAIN;
> + }
> +
> + r = regmap_bulk_read(regmap, TMP_BASE, val, 3);

sizeof(val) maybe

> + if (r < 0)
> + return r;
> +
> + T_raw = (val[0] << 16) | (val[1] << 8) | val[2];
> + data->temp_raw = dps310_twos_compliment(T_raw, 24);
> +
> + return 0;
> +}
> +
> +static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case PRS_CFG:
> + case TMP_CFG:
> + case MEAS_CFG:
> + case CFG_REG:
> + case RESET:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case PRS_BASE ... (PRS_BASE + 2):
> + case TMP_BASE ... (TMP_BASE + 2):
> + case MEAS_CFG:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static int dps310_write_raw(struct iio_dev *iio,
> + struct iio_chan_spec const *chan, int val,
> + int val2, long mask)
> +{
> + struct dps310_data *data = iio_priv(iio);
> +
> + if (chan->type != IIO_TEMP)
> + return -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + return dps310_set_temp_samp_freq(data, val);
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + return dps310_set_temp_precision(data, val);
> + 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);
> + int ret;
> +
> + /* c0 * 0.5 + c1 * T_raw / kT °C */
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + *val = dps310_get_temp_samp_freq(data);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_RAW:
> + ret = dps310_read_temp(data);
> + if (ret)
> + return ret;
> +
> + *val = data->temp_raw * data->c1;
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_OFFSET:
> + *val = (data->c0 >> 1) * dps310_get_temp_k(data);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + *val = MCELSIUS_PER_CELSIUS;
> + *val2 = dps310_get_temp_k(data);
> + return IIO_VAL_FRACTIONAL;
> +
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + *val = dps310_get_temp_precision(data);
> + return IIO_VAL_INT;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct regmap_config dps310_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .writeable_reg = dps310_is_writeable_reg,
> + .volatile_reg = dps310_is_volatile_reg,
> + .cache_type = REGCACHE_RBTREE,
> + .max_register = 0x29,
> +};
> +
> +static const struct iio_info dps310_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = dps310_read_raw,
> + .write_raw = dps310_write_raw,
> +};
> +
> +static int dps310_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct dps310_data *data;
> + struct iio_dev *iio;
> + int r;
> +
> + iio = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!iio)
> + return -ENOMEM;
> +
> + data = iio_priv(iio);
> + data->client = client;
> +
> + iio->dev.parent = &client->dev;
> + iio->name = id->name;
> + iio->channels = dps310_channels;
> + iio->num_channels = ARRAY_SIZE(dps310_channels);
> + iio->info = &dps310_info;
> + iio->modes = INDIO_DIRECT_MODE;
> +
> + data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
> + if (IS_ERR(data->regmap))
> + return PTR_ERR(data->regmap);
> +
> + r = regmap_write(data->regmap, TMP_CFG, TMP_EXT | TMP_PRC(1));
> + if (r < 0)
> + return r;
> + r = regmap_write_bits(data->regmap, CFG_REG, TMP_SHIFT_EN, 0);
> + if (r < 0)
> + return r;
> +
> + /* Turn on temperature measurement in the background */
> + r = regmap_write_bits(data->regmap, MEAS_CFG, MEAS_CTRL_BITS,
> + TEMP_EN | BACKGROUND);

should be disabled again if _probe fails lateron

> + if (r < 0)
> + return r;
> +
> + /*
> + * Calibration coefficients required for reporting temperature.
> + * They are availalbe 40ms after the device has started

available

> + */
> + r = dps310_get_temp_coef(data);
> + if (r == -EAGAIN)
> + return -EPROBE_DEFER;

wouldn't it make more sense to wait for the data to become ready, maybe
with a timeout?

> + if (r < 0)
> + return r;
> +
> + r = devm_iio_device_register(&client->dev, iio);
> + if (r)
> + return r;
> +
> + i2c_set_clientdata(client, iio);
> +
> + dev_info(&client->dev, "%s: sensor '%s'\n", dev_name(&iio->dev),
> + client->name);

no extra logging, this adds little extra information

> + return 0;
> +}

turn off measurement in _remove()?

> +
> +static const struct i2c_device_id dps310_id[] = {
> + { "dps310", 0 },
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, dps310_id);
> +
> +static const unsigned short normal_i2c[] = {
> + 0x77, 0x76, I2C_CLIENT_END
> +};
> +
> +static struct i2c_driver dps310_driver = {
> + .driver = {
> + .name = "dps310",
> + },
> + .probe = dps310_probe,
> + .address_list = normal_i2c,
> + .id_table = dps310_id,
> +};
> +module_i2c_driver(dps310_driver);
> +
> +MODULE_AUTHOR("Joel Stanley <joel@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
> +MODULE_LICENSE("GPL");
>

--

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

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Previous message: Kalle Valo: "Re: [PATCHv3] wlcore: add wl1285 compatible"
In reply to: Joel Stanley: "[PATCH] iio: Add driver for Infineon DPS310"
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