Merge tag 'iio-for-5.3b' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

Second set of IIO device support, features, cleanups and minor fixes for 5.3.

A few bits for the counters subsystem mixed in here as well.
There are some late breaking fixes as well, which aren't so urgent
they can't wait for the merge window.

New Device Support
* adf4371
  - New driver + bindings.
  - Support the adf4372 PLL. Mostly ID and bindings.
* ad8366 (note includes rework of driver needed to allow support for these).
  - Support the ADL5240 variable gain amplifier (VGA).
  - Support the ADA4961 digital gain amplifier (DGA).
* dps310
  - New driver, in several parts from different authors for this temp
    and pressure sensor.
  - Includes errata workaround for a temperature reading issue.
* stk3310
  - Support the stk3335, mostly ID.

Features and cleanups
* core
  - drop error handling on debugfs registration.
  - harden by making sure we don't overrun iio_chan_info_postfix.
* docs
  - convert remaining docs to rst. At somepoint we'll fit these few
    into the main IIO docs.
  - improve sampling_frequency_available docs but explaining the
    range form.
* ad_sigma_delta
  - Drop a pointless goto.
* ad2s1210
  - Drop pointless platform data null check seeing as we don't actually
    use platform data anymore.
* ad7124
  - Relax limitation on channel numbers to allow pseudo different channels.
  - Support control of whether the input is buffered via DT.
  - Use dynamic allocation for channel configuration to make it easier
    to support new devices.
  - YAML binding conversion.
* ad7150
  - Comment tidy up.
  - Consistent and simple if (ret) handling of i2c errors.
  - FIELD_GET and GENMASK.
  - Ternary rather than !!(condition) for readability.
  - Use macros to avoid repetition of channel definitions.
* ad7606
  - Add software channel config (rather that pin controlled)
  - Refactor to simplify addition of new part in future.
* ad7746
  - of_deivce_id table.
* ad7780
  - MAINTAINERS entry
  - YAML DT bindings.
* ad8366
  - Stop using core mlock in favour of well scoped local lock.
  - SPDX + copyright date update.
* ad9834
  - of_device_id table
* adf4371
  - Add support for output stage muting before lock on has occured.
* adis library
  - MAINTAINERS entry to reflect that this now Alexandru's problem ;)
* adis162xx:
  - Fix a slightly incorrect set of comments and print statements on
    minimum supported voltage.
* adis16203
  - of_device_id table.
* adis16240
  - Add of_device_id table (in two parts as first patch only used it for
    MODULE_DEVICE_TABLE.)
* adt7316-spi
  - of_device_id table
* adxl372
  - YAML DT binding conversion.
  - Cleanup use of buffer callback functions (precursor to core rework).
* bh1710
  - Simplify getting the i2c adapter from the client.
* dht11
  - Mote to newer GPIO consumer interface.
* kxcjk-1013.c
  - Add binding for sensor in display of some ultrabooks after userspace
    tools updated for it not be a problem to report two similar sensors.
* imx7d
  - drop unused variables.
  - white space
  - define instead of variable for clock frequency that is fixed.
  - drop pointless error message.
* messon_saradc
  - SPDX
* sps30
  - MAINTAINERS entry
  - YAML binding conversion.
* st_accel
  - Tidy up ordering in various buffer related callbacks. This is
    part of a long running effort to simplify the core code.
* stm32-dfsdm:
  - Manage the resolution cleanly in triggerd modes.
  - Add fast mode support which allows more flexible filter choices.
  - Add a comment on the reason for a 16 bit record when technically
    not 'required'.
* st_lsm6dsx
  - Embed device name in the sensor_settings struct as i3c doesn't
    have a convenient name field to use for this.
* xilinx-adc
  - Relax constraints on supported platforms to reflect that this
    can used with FPGAs on PCIe cards and hence many architectures.
* counters/ftm-quaddec
  - Fix some formatting io MODULE_AUTHOR
  - MAINTAINERS entry

Fixes
* tools
  - fix incorrect handling of 32 bit channels.
* sca3000
  - Potential endian bug that is unlikely to bite anyone (be64 host
    seems unlikely for this old part).
* stm32-adc
  - Add vdda-supply. On some boards it needs to be turned on to supply
    the ADC.  DT bindings included.
* stm32-dfsdm
  - Fix output resolution to work with filter orders other than 3.
  - Fix output datatype as it's signed and previously claimed not to be.

* tag 'iio-for-5.3b' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio: (68 commits)
  iio: iio-utils: Fix possible incorrect mask calculation
  iio: frequency: adf4371: Add support for output stage mute
  dt-bindings: iio: frequency: Add ADF4372 PLL documentation
  iio: frequency: adf4371: Add support for ADF4372 PLL
  dt-bindings: iio: adc: Add buffered input property
  Convert AD7124 bindings documentation to YAML format.
  iio: adc: ad7124: Shift to dynamic allocation for channel configuration
  iio: adc: ad7124: Add buffered input support
  iio: adc: ad7124: Remove input number limitation
  MAINTAINERS: add ADIS IMU driver library entry
  iio: adis162xx: fix low-power docs & reports
  counter/ftm-quaddec: Add missing '>' in MODULE_AUTHOR
  iio: core: no need to check return value of debugfs_create functions
  docs: iio: convert to ReST
  iio: adc: stm32-adc: add missing vdda-supply
  dt-bindings: iio: adc: stm32: add missing vdda supply
  iio: adc: stm32-dfsdm: add comment for 16 bits record
  iio: adc: stm32-dfsdm: add fast mode support
  iio: adc: stm32-dfsdm: manage data resolution in trigger mode
  iio: adc: stm32-dfsdm: fix data type
  ...

3 files changed, 839 insertions, 0 deletions

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index b191811fd749..ba420e484787 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -53,6 +53,17 @@ 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.
+	  It can be accessed over I2C bus.
+
+	  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 c2058d7b2f93..d8f5ace1f25d 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 000000000000..2c1943bbc433
--- /dev/null
+++ b/drivers/iio/pressure/dps310.c
@@ -0,0 +1,827 @@
+// 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 °C
+ *
+ * TODO:
+ *  - Optionally support the FIFO
+ */
+
+#include <linux/i2c.h>
+#include <linux/limits.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define DPS310_DEV_NAME		"dps310"
+
+#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_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)
+#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	0x09
+#define DPS310_COEF_BASE	0x10
+
+/* Make sure sleep time is <= 20ms for usleep_range */
+#define DPS310_POLL_SLEEP_US(t)		min(20000, (t) / 8)
+/* Silently handle error in rate value here */
+#define DPS310_POLL_TIMEOUT_US(rc)	((rc) <= 0 ? 1000000 : 1000000 / (rc))
+
+#define DPS310_PRS_BASE		DPS310_PRS_B0
+#define DPS310_TMP_BASE		DPS310_TMP_B0
+
+/*
+ * These values (defined in the spec) indicate how to scale the raw register
+ * values for each level of precision available.
+ */
+static const int scale_factors[] = {
+	 524288,
+	1572864,
+	3670016,
+	7864320,
+	 253952,
+	 516096,
+	1040384,
+	2088960,
+};
+
+struct dps310_data {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct mutex lock;	/* Lock for sequential HW access functions */
+
+	s32 c0, c1;
+	s32 c00, c10, c20, c30, c01, c11, c21;
+	s32 pressure_raw;
+	s32 temp_raw;
+};
+
+static const struct iio_chan_spec dps310_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+			BIT(IIO_CHAN_INFO_PROCESSED),
+	},
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+			BIT(IIO_CHAN_INFO_PROCESSED),
+	},
+};
+
+/* To be called after checking the COEF_RDY bit in MEAS_CFG */
+static int dps310_get_coefs(struct dps310_data *data)
+{
+	int rc;
+	u8 coef[18];
+	u32 c0, c1;
+	u32 c00, c10, c20, c30, c01, c11, c21;
+
+	/* Read all sensor calibration coefficients from the COEF registers. */
+	rc = regmap_bulk_read(data->regmap, DPS310_COEF_BASE, coef,
+			      sizeof(coef));
+	if (rc < 0)
+		return rc;
+
+	/*
+	 * 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 rc;
+	int val;
+
+	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+	if (rc < 0)
+		return rc;
+
+	return BIT(val & GENMASK(2, 0));
+}
+
+static int dps310_get_temp_precision(struct dps310_data *data)
+{
+	int rc;
+	int val;
+
+	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+	if (rc < 0)
+		return rc;
+
+	/*
+	 * Scale factor is bottom 4 bits of the register, but 1111 is
+	 * reserved so just grab bottom three
+	 */
+	return BIT(val & GENMASK(2, 0));
+}
+
+/* Called with lock held */
+static int dps310_set_pres_precision(struct dps310_data *data, int val)
+{
+	int rc;
+	u8 shift_en;
+
+	if (val < 0 || val > 128)
+		return -EINVAL;
+
+	shift_en = val >= 16 ? DPS310_PRS_SHIFT_EN : 0;
+	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+			       DPS310_PRS_SHIFT_EN, shift_en);
+	if (rc)
+		return rc;
+
+	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
+				  DPS310_PRS_PRC_BITS, ilog2(val));
+}
+
+/* Called with lock held */
+static int dps310_set_temp_precision(struct dps310_data *data, int val)
+{
+	int rc;
+	u8 shift_en;
+
+	if (val < 0 || val > 128)
+		return -EINVAL;
+
+	shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
+	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+			       DPS310_TMP_SHIFT_EN, shift_en);
+	if (rc)
+		return rc;
+
+	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+				  DPS310_TMP_PRC_BITS, ilog2(val));
+}
+
+/* Called with lock held */
+static int dps310_set_pres_samp_freq(struct dps310_data *data, int freq)
+{
+	u8 val;
+
+	if (freq < 0 || freq > 128)
+		return -EINVAL;
+
+	val = ilog2(freq) << 4;
+
+	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
+				  DPS310_PRS_RATE_BITS, val);
+}
+
+/* Called with lock held */
+static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
+{
+	u8 val;
+
+	if (freq < 0 || freq > 128)
+		return -EINVAL;
+
+	val = ilog2(freq) << 4;
+
+	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+				  DPS310_TMP_RATE_BITS, val);
+}
+
+static int dps310_get_pres_samp_freq(struct dps310_data *data)
+{
+	int rc;
+	int val;
+
+	rc = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+	if (rc < 0)
+		return rc;
+
+	return BIT((val & DPS310_PRS_RATE_BITS) >> 4);
+}
+
+static int dps310_get_temp_samp_freq(struct dps310_data *data)
+{
+	int rc;
+	int val;
+
+	rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+	if (rc < 0)
+		return rc;
+
+	return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
+}
+
+static int dps310_get_pres_k(struct dps310_data *data)
+{
+	int rc = dps310_get_pres_precision(data);
+
+	if (rc < 0)
+		return rc;
+
+	return scale_factors[ilog2(rc)];
+}
+
+static int dps310_get_temp_k(struct dps310_data *data)
+{
+	int rc = dps310_get_temp_precision(data);
+
+	if (rc < 0)
+		return rc;
+
+	return scale_factors[ilog2(rc)];
+}
+
+static int dps310_read_pres_raw(struct dps310_data *data)
+{
+	int rc;
+	int rate;
+	int ready;
+	int timeout;
+	s32 raw;
+	u8 val[3];
+
+	if (mutex_lock_interruptible(&data->lock))
+		return -EINTR;
+
+	rate = dps310_get_pres_samp_freq(data);
+	timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+	/* Poll for sensor readiness; base the timeout upon the sample rate. */
+	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+				      ready & DPS310_PRS_RDY,
+				      DPS310_POLL_SLEEP_US(timeout), timeout);
+	if (rc)
+		goto done;
+
+	rc = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, sizeof(val));
+	if (rc < 0)
+		goto done;
+
+	raw = (val[0] << 16) | (val[1] << 8) | val[2];
+	data->pressure_raw = sign_extend32(raw, 23);
+
+done:
+	mutex_unlock(&data->lock);
+	return rc;
+}
+
+/* Called with lock held */
+static int dps310_read_temp_ready(struct dps310_data *data)
+{
+	int rc;
+	u8 val[3];
+	s32 raw;
+
+	rc = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
+	if (rc < 0)
+		return rc;
+
+	raw = (val[0] << 16) | (val[1] << 8) | val[2];
+	data->temp_raw = sign_extend32(raw, 23);
+
+	return 0;
+}
+
+static int dps310_read_temp_raw(struct dps310_data *data)
+{
+	int rc;
+	int rate;
+	int ready;
+	int timeout;
+
+	if (mutex_lock_interruptible(&data->lock))
+		return -EINTR;
+
+	rate = dps310_get_temp_samp_freq(data);
+	timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+	/* Poll for sensor readiness; base the timeout upon the sample rate. */
+	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+				      ready & DPS310_TMP_RDY,
+				      DPS310_POLL_SLEEP_US(timeout), timeout);
+	if (rc < 0)
+		goto done;
+
+	rc = dps310_read_temp_ready(data);
+
+done:
+	mutex_unlock(&data->lock);
+	return rc;
+}
+
+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:
+	/* No documentation available on the registers below */
+	case 0x0e:
+	case 0x0f:
+	case 0x62:
+		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:
+	case 0x32:	/* No documentation available on this register */
+		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)
+{
+	int rc;
+	struct dps310_data *data = iio_priv(iio);
+
+	if (mutex_lock_interruptible(&data->lock))
+		return -EINTR;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			rc = dps310_set_pres_samp_freq(data, val);
+			break;
+
+		case IIO_TEMP:
+			rc = dps310_set_temp_samp_freq(data, val);
+			break;
+
+		default:
+			rc = -EINVAL;
+			break;
+		}
+		break;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			rc = dps310_set_pres_precision(data, val);
+			break;
+
+		case IIO_TEMP:
+			rc = dps310_set_temp_precision(data, val);
+			break;
+
+		default:
+			rc = -EINVAL;
+			break;
+		}
+		break;
+
+	default:
+		rc = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&data->lock);
+	return rc;
+}
+
+static int dps310_calculate_pressure(struct dps310_data *data)
+{
+	int i;
+	int rc;
+	int t_ready;
+	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;
+
+	/* Refresh temp if it's ready, otherwise just use the latest value */
+	if (mutex_trylock(&data->lock)) {
+		rc = regmap_read(data->regmap, DPS310_MEAS_CFG, &t_ready);
+		if (rc >= 0 && t_ready & DPS310_TMP_RDY)
+			dps310_read_temp_ready(data);
+
+		mutex_unlock(&data->lock);
+	}
+
+	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 irem;
+
+		if (nums[i] < 0LL) {
+			pressure -= div64_u64_rem(-nums[i], denoms[i], &irem);
+			rems[i] = -irem;
+		} else {
+			pressure += div64_u64_rem(nums[i], denoms[i], &irem);
+			rems[i] = (s64)irem;
+		}
+	}
+
+	/* 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);
+	if (pressure < 0LL)
+		return -ERANGE;
+
+	return (int)min_t(s64, pressure, INT_MAX);
+}
+
+static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
+				long mask)
+{
+	int rc;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		rc = dps310_get_pres_samp_freq(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_PROCESSED:
+		rc = dps310_read_pres_raw(data);
+		if (rc)
+			return rc;
+
+		rc = dps310_calculate_pressure(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		*val2 = 1000; /* Convert Pa to KPa per IIO ABI */
+		return IIO_VAL_FRACTIONAL;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		rc = dps310_get_pres_precision(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int dps310_calculate_temp(struct dps310_data *data)
+{
+	s64 c0;
+	s64 t;
+	int kt = dps310_get_temp_k(data);
+
+	if (kt < 0)
+		return kt;
+
+	/* Obtain inverse-scaled offset */
+	c0 = div_s64((s64)kt * (s64)data->c0, 2);
+
+	/* Add the offset to the unscaled temperature */
+	t = c0 + ((s64)data->temp_raw * (s64)data->c1);
+
+	/* Convert to milliCelsius and scale the temperature */
+	return (int)div_s64(t * 1000LL, kt);
+}
+
+static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
+			    long mask)
+{
+	int rc;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		rc = dps310_get_temp_samp_freq(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_PROCESSED:
+		rc = dps310_read_temp_raw(data);
+		if (rc)
+			return rc;
+
+		rc = dps310_calculate_temp(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		rc = dps310_get_temp_precision(data);
+		if (rc < 0)
+			return rc;
+
+		*val = rc;
+		return IIO_VAL_INT;
+
+	default:
+		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 void dps310_reset(void *action_data)
+{
+	struct dps310_data *data = action_data;
+
+	regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+}
+
+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 = 0x62, /* No documentation available on this register */
+};
+
+static const struct iio_info dps310_info = {
+	.read_raw = dps310_read_raw,
+	.write_raw = dps310_write_raw,
+};
+
+/*
+ * Some verions of chip will read temperatures in the ~60C range when
+ * its actually ~20C. This is the manufacturer recommended workaround
+ * to correct the issue. The registers used below are undocumented.
+ */
+static int dps310_temp_workaround(struct dps310_data *data)
+{
+	int rc;
+	int reg;
+
+	rc = regmap_read(data->regmap, 0x32, &reg);
+	if (rc < 0)
+		return rc;
+
+	/*
+	 * If bit 1 is set then the device is okay, and the workaround does not
+	 * need to be applied
+	 */
+	if (reg & BIT(1))
+		return 0;
+
+	rc = regmap_write(data->regmap, 0x0e, 0xA5);
+	if (rc < 0)
+		return rc;
+
+	rc = regmap_write(data->regmap, 0x0f, 0x96);
+	if (rc < 0)
+		return rc;
+
+	rc = regmap_write(data->regmap, 0x62, 0x02);
+	if (rc < 0)
+		return rc;
+
+	rc = regmap_write(data->regmap, 0x0e, 0x00);
+	if (rc < 0)
+		return rc;
+
+	return regmap_write(data->regmap, 0x0f, 0x00);
+}
+
+static int dps310_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct dps310_data *data;
+	struct iio_dev *iio;
+	int rc, ready;
+
+	iio = devm_iio_device_alloc(&client->dev,  sizeof(*data));
+	if (!iio)
+		return -ENOMEM;
+
+	data = iio_priv(iio);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	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);
+
+	/* Register to run the device reset when the device is removed */
+	rc = devm_add_action_or_reset(&client->dev, dps310_reset, data);
+	if (rc)
+		return rc;
+
+	/*
+	 * Set up pressure sensor in single sample, one measurement per second
+	 * mode
+	 */
+	rc = regmap_write(data->regmap, DPS310_PRS_CFG, 0);
+
+	/*
+	 * Set up external (MEMS) temperature sensor in single sample, one
+	 * measurement per second mode
+	 */
+	rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
+	if (rc < 0)
+		return rc;
+
+	/* Temp and pressure shifts are disabled when PRC <= 8 */
+	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+			       DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
+	if (rc < 0)
+		return rc;
+
+	/* MEAS_CFG doesn't update correctly unless first written with 0 */
+	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+			       DPS310_MEAS_CTRL_BITS, 0);
+	if (rc < 0)
+		return rc;
+
+	/* Turn on temperature and pressure measurement in the background */
+	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+			       DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
+			       DPS310_TEMP_EN | DPS310_BACKGROUND);
+	if (rc < 0)
+		return rc;
+
+	/*
+	 * Calibration coefficients required for reporting temperature.
+	 * They are available 40ms after the device has started
+	 */
+	rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+				      ready & DPS310_COEF_RDY, 10000, 40000);
+	if (rc < 0)
+		return rc;
+
+	rc = dps310_get_coefs(data);
+	if (rc < 0)
+		return rc;
+
+	rc = dps310_temp_workaround(data);
+	if (rc < 0)
+		return rc;
+
+	rc = devm_iio_device_register(&client->dev, iio);
+	if (rc)
+		return rc;
+
+	i2c_set_clientdata(client, iio);
+
+	return 0;
+}
+
+static const struct i2c_device_id dps310_id[] = {
+	{ DPS310_DEV_NAME, 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, dps310_id);
+
+static struct i2c_driver dps310_driver = {
+	.driver = {
+		.name = DPS310_DEV_NAME,
+	},
+	.probe = dps310_probe,
+	.id_table = dps310_id,
+};
+module_i2c_driver(dps310_driver);
+
+MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
+MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");