Re: [PATCH 1/3] iio: Add driver for Infineon DPS310

From: Jonathan Cameron
Date: Sat May 11 2019 - 05:54:03 EST

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On Tue, 7 May 2019 11:01:36 -0500
Eddie James <eajames@xxxxxxxxxxxxxxxxxx> wrote:

> On 5/6/19 4:18 PM, Peter Meerwald-Stadler wrote:
> > On Mon, 6 May 2019, Eddie James wrote:
> >
> >> From: Joel Stanley <joel@xxxxxxxxx>
> > some comments below
>
>
> Thanks for the quick review! Will get these in for v2, I did have a
> couple of questions below though.
>
> Eddie
>
>
> >
> >> The DPS310 is a temperature and pressure sensor. It can be accessed over
> >> i2c and SPI.
> >>
> >> Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
> >> ---
> >> MAINTAINERS | 6 +
> >> drivers/iio/pressure/Kconfig | 10 +
> >> drivers/iio/pressure/Makefile | 1 +
> >> drivers/iio/pressure/dps310.c | 429 ++++++++++++++++++++++++++++++++++++++++++
> >> 4 files changed, 446 insertions(+)
> >> create mode 100644 drivers/iio/pressure/dps310.c
> >>
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index c61c49d..a91dfa9 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -7743,6 +7743,12 @@ W: http://industrypack.sourceforge.net
> >> S: Maintained
> >> F: drivers/ipack/
> >>
> >> +INFINEON DPS310 Driver
> >> +M: Eddie James <eajames@xxxxxxxxxxxxx>
> >> +L: linux-iio@xxxxxxxxxxxxxxx
> >> +F: drivers/iio/pressure/dps310.c
> >> +S: Maintained
> >> +
> >> INFINIBAND SUBSYSTEM
> >> M: Doug Ledford <dledford@xxxxxxxxxx>
> >> M: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> >> diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
> >> index efeb89f..681a1cc 100644
> >> --- a/drivers/iio/pressure/Kconfig
> >> +++ b/drivers/iio/pressure/Kconfig
> >> @@ -52,6 +52,16 @@ config IIO_CROS_EC_BARO
> >> To compile this driver as a module, choose M here: the module
> >> will be called cros_ec_baro.
> >>
> >> +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 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 c2058d7..d8f5ace 100644
> >> --- a/drivers/iio/pressure/Makefile
> >> +++ b/drivers/iio/pressure/Makefile
> >> @@ -9,6 +9,7 @@ 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-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
> >> obj-$(CONFIG_HID_SENSOR_PRESS) += hid-sensor-press.o
> >> obj-$(CONFIG_HP03) += hp03.o
> >> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> >> new file mode 100644
> >> index 0000000..21d5dcb
> >> --- /dev/null
> >> +++ b/drivers/iio/pressure/dps310.c
> >> @@ -0,0 +1,429 @@
> >> +// SPDX-License-Identifier: GPL-2.0+
> >> +// Copyright IBM Corp 2019
> >> +/*
> >> + * The DPS310 is a barometric pressure and temperature sensor.
> >> + * Currently only reading a single temperature is supported by
> >> + * this driver.
> >> + *
> >> + * https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
> >> + *
> >> + * Temperature calculation:
> >> + * c0 * 0.5 + c1 * T_raw / kT ÂC
> >> + *
> >> + * TODO:
> >> + * - Pressure sensor readings
> >> + * - Optionally support the FIFO
> >> + */
> >> +
> >> +#include <linux/i2c.h>
> >> +#include <linux/module.h>
> >> +#include <linux/regmap.h>
> >> +
> >> +#include <linux/iio/iio.h>
> >> +#include <linux/iio/sysfs.h>
> >> +
> >> +#define DPS310_PRS_B0 0x00
> >> +#define DPS310_PRS_B1 0x01
> >> +#define DPS310_PRS_B2 0x02
> >> +#define DPS310_TMP_B0 0x03
> >> +#define DPS310_TMP_B1 0x04
> >> +#define DPS310_TMP_B2 0x05
> >> +#define DPS310_PRS_CFG 0x06
> >> +#define DPS310_TMP_CFG 0x07
> >> +#define DPS310_TMP_RATE_BITS GENMASK(6, 4)
> >> +#define DPS310_TMP_PRC_BITS GENMASK(3, 0)
> >> +#define DPS310_TMP_EXT BIT(7)
> >> +#define DPS310_MEAS_CFG 0x08
> >> +#define DPS310_MEAS_CTRL_BITS GENMASK(2, 0)
> >> +#define DPS310_PRS_EN BIT(0)
> >> +#define DPS310_TEMP_EN BIT(1)
> >> +#define DPS310_BACKGROUND BIT(2)
> >> +#define DPS310_PRS_RDY BIT(4)
> >> +#define DPS310_TMP_RDY BIT(5)
> >> +#define DPS310_SENSOR_RDY BIT(6)
> >> +#define DPS310_COEF_RDY BIT(7)
> >> +#define DPS310_CFG_REG 0x09
> >> +#define DPS310_INT_HL BIT(7)
> >> +#define DPS310_TMP_SHIFT_EN BIT(3)
> >> +#define DPS310_PRS_SHIFT_EN BIT(4)
> >> +#define DPS310_FIFO_EN BIT(5)
> >> +#define DPS310_SPI_EN BIT(6)
> >> +#define DPS310_RESET 0x0c
> >> +#define DPS310_RESET_MAGIC (BIT(0) | BIT(3))
> >> +#define DPS310_COEF_BASE 0x10
> >> +
> >> +#define DPS310_PRS_BASE DPS310_PRS_B0
> >> +#define DPS310_TMP_BASE DPS310_TMP_B0
> >> +
> >> +#define DPS310_CALC_RATE(_n) ilog2(_n)
> >> +#define DPS310_CALC_PRC(_n) ilog2(_n)
> >> +
> >> +const int scale_factor[] = {
> > static
> > maybe plural, scale_factors?
> > maybe some comment would be good what these values relate to
> >
> >> + 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),
> >> + },
> >> +};
> >> +
> >> +/* To be called after checking the TMP_RDY bit in MEAS_CFG */
> >> +static int dps310_get_temp_coef(struct dps310_data *data)
> >> +{
> >> + struct regmap *regmap = data->regmap;
> >> + u8 coef[3] = {0};
> > initialization needed?
> >
> >> + int r;
> >> + u32 c0, c1;
> >> +
> >> + /*
> >> + * 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);
> > sizeof(coef) instead of 3
> >
> >> + if (r < 0)
> >> + return r;
> >> +
> >> + 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);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int dps310_get_temp_precision(struct dps310_data *data)
> >> +{
> >> + int val, r;
> >> +
> >> + r = regmap_read(data->regmap, DPS310_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 ? DPS310_TMP_SHIFT_EN : 0;
> >> + ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> >> + DPS310_TMP_SHIFT_EN, shift_en);
> >> + if (ret)
> >> + return ret;
> >> +
> >> + return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
> >> + DPS310_TMP_PRC_BITS, DPS310_CALC_PRC(val));
> >> +}
> >> +
> >> +static int dps310_set_temp_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_TMP_CFG,
> >> + DPS310_TMP_RATE_BITS, val);
> >> +}
> >> +
> >> +static int dps310_get_temp_samp_freq(struct dps310_data *data)
> >> +{
> >> + int val, r;
> >> +
> >> + r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
> >> + if (r < 0)
> >> + return r;
> >> +
> >> + return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
> >> +}
> >> +
> >> +static int dps310_get_temp_k(struct dps310_data *data)
> >> +{
> >> + int r = dps310_get_temp_precision(data);
> >> +
> >> + if (r < 0)
> >> + return r;
> >> +
> >> + return scale_factor[DPS310_CALC_PRC(r)];
> >> +}
> >> +
> >> +static int dps310_read_temp(struct dps310_data *data)
> >> +{
> >> + struct device *dev = &data->client->dev;
> >> + struct regmap *regmap = data->regmap;
> >> + u8 val[3] = {0};
> > initialization needed?
> >
> >> + int r, ready;
> >> + int T_raw;
> >> +
> >> + r = regmap_read(regmap, DPS310_MEAS_CFG, &ready);
> >> + if (r < 0)
> >> + return r;
> >> + if (!(ready & DPS310_TMP_RDY)) {
> >> + dev_dbg(dev, "temperature not ready\n");
> > most drivers wait for the results to become ready\
>
>
> OK, this may have to wait up to a second then, since the background
> measurement rate can be as low as 1 HZ... I can base the timeout on the
> sample rate. Would that be OK?
Yes. I may be that we actually want to pick a my power hungry and faster
default to avoid any stupid userspace programs wondering why they
don't get an answer for 1 second.

>
>
> >
> >> + return -EAGAIN;
> >> + }
> >> +
> >> + r = regmap_bulk_read(regmap, DPS310_TMP_BASE, val, 3);
> > sizeof(val)
> >
> >> + if (r < 0)
> >> + return r;
> >> +
> >> + T_raw = (val[0] << 16) | (val[1] << 8) | val[2];
> >> + data->temp_raw = sign_extend32(T_raw, 23);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
> >> +{
> >> + switch (reg) {
> >> + case DPS310_PRS_CFG:
> >> + case DPS310_TMP_CFG:
> >> + case DPS310_MEAS_CFG:
> >> + case DPS310_CFG_REG:
> >> + case DPS310_RESET:
> >> + return true;
> >> + default:
> >> + return false;
> >> + }
> >> +}
> >> +
> >> +static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
> >> +{
> >> + switch (reg) {
> >> + case DPS310_PRS_B0:
> >> + case DPS310_PRS_B1:
> >> + case DPS310_PRS_B2:
> >> + case DPS310_TMP_B0:
> >> + case DPS310_TMP_B1:
> >> + case DPS310_TMP_B2:
> >> + case DPS310_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;
> > not needed, dead code
> >
> >> +}
> >> +
> >> +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;
> >> +
> >> + 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;
> > one could try to avoid the multipliation here and somehow mangle it into
> > _SCALE/_OFFSET
>
>
> Don't think it's worth it? Would have to divide the offset by c1 and
> then multiply by c1 again in the scale...

I think you are actually better just reporting as PROCESSED.

>
>
> >
> >> + return IIO_VAL_INT;
> >> +
> >> + case IIO_CHAN_INFO_OFFSET:
> >> + ret = dps310_get_temp_k(data);
> >> + if (ret < 0)
> >> + return ret;
> >> +
> >> + *val = (data->c0 >> 1) * ret;
> >> + return IIO_VAL_INT;
> >> +
> >> + case IIO_CHAN_INFO_SCALE:
> >> + ret = dps310_get_temp_k(data);
> >> + if (ret < 0)
> >> + return ret;
> >> +
> >> + *val = 1000; /* milliCelsius per Celsius */
> >> + *val2 = ret;
> >> + 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;
> > not needed, dead code
> >
> >> +}
> >> +
> >> +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 = {
> >> + .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, ready;
> >> +
> >> + 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);
> >> +
> >> + /*
> >> + * Set up external (MEMS) temperature sensor in single sample, one
> >> + * measurement per second mode
> >> + */
> >> + r = regmap_write(data->regmap, DPS310_TMP_CFG,
> >> + DPS310_TMP_EXT | DPS310_CALC_RATE(1) |
> >> + DPS310_CALC_PRC(1));
> >> + if (r < 0)
> >> + goto err;
> >> +
> >> + /* Temp shift is disabled when PRC <= 8 */
> >> + r = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> >> + DPS310_TMP_SHIFT_EN, 0);
> >> + if (r < 0)
> >> + goto err;
> >> +
> >> + /* Turn on temperature measurement in the background */
> >> + r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> >> + DPS310_MEAS_CTRL_BITS,
> >> + DPS310_TEMP_EN | DPS310_BACKGROUND);
> >> + if (r < 0)
> >> + goto err;
> >> +
> >> + /*
> >> + * Calibration coefficients required for reporting temperature.
> >> + * They are available 40ms after the device has started
> >> + */
> >> + r = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
> >> + ready & DPS310_COEF_RDY, 10000, 40000);
> >> + if (r < 0)
> >> + goto err;
> >> +
> >> + r = dps310_get_temp_coef(data);
> >> + if (r < 0)
> >> + goto err;
> >> +
> >> + r = devm_iio_device_register(&client->dev, iio);
> >> + if (r)
> >> + goto err;
> >> +
> >> + i2c_set_clientdata(client, iio);
> >> +
> >> + dev_info(&client->dev, "%s: sensor '%s'\n", dev_name(&iio->dev),
> >> + client->name);
> > don't clutter the log
> >
> >> +
> >> + return 0;
> >> +
> >> +err:
> >> + regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
> >> + return r;
> >> +}
> >> +
> >> +static int dps310_remove(struct i2c_client *client)
> >> +{
> >> + struct dps310_data *data = i2c_get_clientdata(client);
> >> +
> >> + return regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
> >> +}
> >> +
> >> +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,
> >> + .remove = dps310_remove,
> >> + .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 v2");
> >>
>

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