[PATCH v3 0/3] iio: Add driver for Infineon DPS310

[PATCH v3 0/3] iio: Add driver for Infineon DPS310

[Eddie James]

The DPS310 is a temperature and pressure sensor. It can be accessed over i2c
and SPI.

The driver supports polled measurement of temperature and pressure over i2c
only.

Changes since v2:
 - Switch to processed rather than raw for both pressure and temperature
 - Add locking around writing frequency/sampling rates and sensor reads
 - Further cleanup

Changes since v1:
 - Switch to wait for temperature/pressure sensor ready
 - Various cleanup

Christopher Bostic (1):
  iio: dps310: Temperature measurement errata

Eddie James (1):
  iio: dps310: Add pressure sensing capability

Joel Stanley (1):
  iio: Add driver for Infineon DPS310

 MAINTAINERS                   |   6 +
 drivers/iio/pressure/Kconfig  |  10 +
 drivers/iio/pressure/Makefile |   1 +
 drivers/iio/pressure/dps310.c | 824 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 841 insertions(+)
 create mode 100644 drivers/iio/pressure/dps310.c

-- 
1.8.3.1

[PATCH v3 1/3] iio: Add driver for Infineon DPS310

[Eddie James]

From: Joel Stanley <joel@jms.id.au>

The DPS310 is a temperature and pressure sensor. It can be accessed over
i2c and SPI.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 MAINTAINERS                   |   6 +
 drivers/iio/pressure/Kconfig  |  10 +
 drivers/iio/pressure/Makefile |   1 +
 drivers/iio/pressure/dps310.c | 468 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 485 insertions(+)
 create mode 100644 drivers/iio/pressure/dps310.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 7345e45..ea31027 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7760,6 +7760,12 @@ W:	http://industrypack.sourceforge.net
 S:	Maintained
 F:	drivers/ipack/
 
+INFINEON DPS310 Driver
+M:	Eddie James <eajames@linux.ibm.com>
+L:	linux-iio@vger.kernel.org
+F:	drivers/iio/pressure/dps310.c
+S:	Maintained
+
 INFINIBAND SUBSYSTEM
 M:	Doug Ledford <dledford@redhat.com>
 M:	Jason Gunthorpe <jgg@mellanox.com>
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..9acfccb
--- /dev/null
+++ b/drivers/iio/pressure/dps310.c
@@ -0,0 +1,468 @@
+// 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:
+ *  - 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_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_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
+#define DPS310_COEF_SRC		0x28
+
+/* 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 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),
+	},
+};
+
+/* To be called after checking the COEF_RDY bit in MEAS_CFG */
+static int dps310_get_temp_coef(struct dps310_data *data)
+{
+	int rc;
+	u8 coef[3];
+	u32 c0, c1;
+
+	/*
+	 * Read temperature calibration coefficients c0 and c1 from the
+	 * COEF register. The numbers are 12-bit 2's compliment numbers
+	 */
+	rc = regmap_bulk_read(data->regmap, DPS310_COEF_BASE, coef,
+			      sizeof(coef));
+	if (rc < 0)
+		return rc;
+
+	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 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_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_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_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_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_temp(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_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 = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
+	if (rc < 0)
+		goto done;
+
+	raw = (val[0] << 16) | (val[1] << 8) | val[2];
+	data->temp_raw = sign_extend32(raw, 23);
+
+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:
+		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)
+{
+	int rc;
+	struct dps310_data *data = iio_priv(iio);
+
+	if (chan->type != IIO_TEMP)
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&data->lock))
+		return -EINTR;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		rc = dps310_set_temp_samp_freq(data, val);
+		break;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		rc = dps310_set_temp_precision(data, val);
+		break;
+
+	default:
+		rc = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&data->lock);
+	return rc;
+}
+
+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_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 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(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 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 = DPS310_COEF_SRC,
+};
+
+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 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 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 shift is disabled when PRC <= 8 */
+	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+			       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 measurement in the background */
+	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+			       DPS310_MEAS_CTRL_BITS,
+			       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_temp_coef(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");
-- 
1.8.3.1

[PATCH v3 2/3] iio: dps310: Temperature measurement errata

[Eddie James]

From: Christopher Bostic <cbostic@linux.vnet.ibm.com>

Add a manufacturer's suggested workaround to deal with early revisions
of chip that don't indicate correct temperature. Readings can be in the
~60C range when they should be in the ~20's.

Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/iio/pressure/dps310.c | 52 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 50 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index 9acfccb..a093e3a 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -53,7 +53,6 @@
 #define DPS310_RESET		0x0c
 #define  DPS310_RESET_MAGIC	0x09
 #define DPS310_COEF_BASE	0x10
-#define DPS310_COEF_SRC		0x28
 
 /* Make sure sleep time is <= 20ms for usleep_range */
 #define DPS310_POLL_SLEEP_US(t)		min(20000, (t) / 8)
@@ -234,6 +233,10 @@ static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
 	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;
@@ -250,6 +253,7 @@ static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
 	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;
@@ -360,7 +364,7 @@ static void dps310_reset(void *action_data)
 	.writeable_reg = dps310_is_writeable_reg,
 	.volatile_reg = dps310_is_volatile_reg,
 	.cache_type = REGCACHE_RBTREE,
-	.max_register = DPS310_COEF_SRC,
+	.max_register = 0x62, /* No documentation available on this register */
 };
 
 static const struct iio_info dps310_info = {
@@ -368,6 +372,46 @@ static void dps310_reset(void *action_data)
 	.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)
 {
@@ -439,6 +483,10 @@ static int dps310_probe(struct i2c_client *client,
 	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;
-- 
1.8.3.1

[PATCH v3 3/3] iio: dps310: Add pressure sensing capability

[Eddie James]

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@linux.ibm.com>
---
 drivers/iio/pressure/dps310.c | 360 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 334 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index a093e3a..8a96d9d 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -11,11 +11,11 @@
  *   c0 * 0.5 + c1 * T_raw / kT °C
  *
  * TODO:
- *  - Pressure sensor readings
  *  - Optionally support the FIFO
  */
 
 #include <linux/i2c.h>
+#include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 
@@ -31,6 +31,8 @@
 #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)
@@ -83,6 +85,8 @@ struct dps310_data {
 	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;
 };
 
@@ -93,33 +97,79 @@ struct dps310_data {
 			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_temp_coef(struct dps310_data *data)
+static int dps310_get_coefs(struct dps310_data *data)
 {
 	int rc;
-	u8 coef[3];
+	u8 coef[18];
 	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
-	 */
+	/* 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;
@@ -137,6 +187,25 @@ static int dps310_get_temp_precision(struct dps310_data *data)
 }
 
 /* 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;
@@ -156,6 +225,20 @@ static int dps310_set_temp_precision(struct dps310_data *data, int 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;
@@ -169,6 +252,18 @@ 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 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;
@@ -181,6 +276,16 @@ 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 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);
@@ -191,7 +296,7 @@ static int dps310_get_temp_k(struct dps310_data *data)
 	return scale_factors[ilog2(rc)];
 }
 
-static int dps310_read_temp(struct dps310_data *data)
+static int dps310_read_pres_raw(struct dps310_data *data)
 {
 	int rc;
 	int rate;
@@ -203,23 +308,67 @@ static int dps310_read_temp(struct dps310_data *data)
 	if (mutex_lock_interruptible(&data->lock))
 		return -EINTR;
 
-	rate = dps310_get_temp_samp_freq(data);
+	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_TMP_RDY,
+				      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)
-		goto done;
+		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;
@@ -267,19 +416,40 @@ static int dps310_write_raw(struct iio_dev *iio,
 	int rc;
 	struct dps310_data *data = iio_priv(iio);
 
-	if (chan->type != IIO_TEMP)
-		return -EINVAL;
-
 	if (mutex_lock_interruptible(&data->lock))
 		return -EINTR;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		rc = dps310_set_temp_samp_freq(data, val);
+		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:
-		rc = dps310_set_temp_precision(data, val);
+		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:
@@ -291,6 +461,122 @@ static int dps310_write_raw(struct iio_dev *iio,
 	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);
+
+	return (int)pressure;
+}
+
+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;
@@ -310,11 +596,9 @@ static int dps310_calculate_temp(struct dps310_data *data)
 	return (int)div_s64(t * 1000LL, kt);
 }
 
-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 rc;
 
 	switch (mask) {
@@ -327,7 +611,7 @@ static int dps310_read_raw(struct iio_dev *iio,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_PROCESSED:
-		rc = dps310_read_temp(data);
+		rc = dps310_read_temp_raw(data);
 		if (rc)
 			return rc;
 
@@ -351,6 +635,24 @@ static int dps310_read_raw(struct iio_dev *iio,
 	}
 }
 
+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;
@@ -444,6 +746,12 @@ static int dps310_probe(struct i2c_client *client,
 		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
 	 */
@@ -451,9 +759,9 @@ static int dps310_probe(struct i2c_client *client,
 	if (rc < 0)
 		return rc;
 
-	/* Temp shift is disabled when PRC <= 8 */
+	/* Temp and pressure shifts are disabled when PRC <= 8 */
 	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
-			       DPS310_TMP_SHIFT_EN, 0);
+			       DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
 	if (rc < 0)
 		return rc;
 
@@ -463,9 +771,9 @@ static int dps310_probe(struct i2c_client *client,
 	if (rc < 0)
 		return rc;
 
-	/* Turn on temperature measurement in the background */
+	/* Turn on temperature and pressure measurement in the background */
 	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
-			       DPS310_MEAS_CTRL_BITS,
+			       DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
 			       DPS310_TEMP_EN | DPS310_BACKGROUND);
 	if (rc < 0)
 		return rc;
@@ -479,7 +787,7 @@ static int dps310_probe(struct i2c_client *client,
 	if (rc < 0)
 		return rc;
 
-	rc = dps310_get_temp_coef(data);
+	rc = dps310_get_coefs(data);
 	if (rc < 0)
 		return rc;
 
-- 
1.8.3.1

Re: [PATCH v3 1/3] iio: Add driver for Infineon DPS310

[Jonathan Cameron]

On Wed, 15 May 2019 13:41:15 -0500
Eddie James <eajames@linux.ibm.com> wrote:

> From: Joel Stanley <joel@jms.id.au>
> 
> The DPS310 is a temperature and pressure sensor. It can be accessed over
> i2c and SPI.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
Hi Eddie,

One spacing issue in the Kconfig file otherwise I think this looks good.

However, Joel, I would definitely prefer it if you took a look and ideally
provided a Signed-off-by as we need the Developer Certificate of Origin
stuff to be clearly correct.

Thanks,

Jonathan
> ---
>  MAINTAINERS                   |   6 +
>  drivers/iio/pressure/Kconfig  |  10 +
>  drivers/iio/pressure/Makefile |   1 +
>  drivers/iio/pressure/dps310.c | 468 ++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 485 insertions(+)
>  create mode 100644 drivers/iio/pressure/dps310.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7345e45..ea31027 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7760,6 +7760,12 @@ W:	http://industrypack.sourceforge.net
>  S:	Maintained
>  F:	drivers/ipack/
>  
> +INFINEON DPS310 Driver
> +M:	Eddie James <eajames@linux.ibm.com>
> +L:	linux-iio@vger.kernel.org
> +F:	drivers/iio/pressure/dps310.c
> +S:	Maintained
> +
>  INFINIBAND SUBSYSTEM
>  M:	Doug Ledford <dledford@redhat.com>
>  M:	Jason Gunthorpe <jgg@mellanox.com>
> 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
Mixture of spaces and tabs here it seems. Please match the rest of the file
(which is hopefully consistent!).
> +	 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..9acfccb
> --- /dev/null
> +++ b/drivers/iio/pressure/dps310.c
> @@ -0,0 +1,468 @@
> +// 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:
> + *  - 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_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_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
> +#define DPS310_COEF_SRC		0x28
> +
> +/* 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 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),
> +	},
> +};
> +
> +/* To be called after checking the COEF_RDY bit in MEAS_CFG */
> +static int dps310_get_temp_coef(struct dps310_data *data)
> +{
> +	int rc;
> +	u8 coef[3];
> +	u32 c0, c1;
> +
> +	/*
> +	 * Read temperature calibration coefficients c0 and c1 from the
> +	 * COEF register. The numbers are 12-bit 2's compliment numbers
> +	 */
> +	rc = regmap_bulk_read(data->regmap, DPS310_COEF_BASE, coef,
> +			      sizeof(coef));
> +	if (rc < 0)
> +		return rc;
> +
> +	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 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_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_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_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_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_temp(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_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 = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
> +	if (rc < 0)
> +		goto done;
> +
> +	raw = (val[0] << 16) | (val[1] << 8) | val[2];
> +	data->temp_raw = sign_extend32(raw, 23);
> +
> +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:
> +		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)
> +{
> +	int rc;
> +	struct dps310_data *data = iio_priv(iio);
> +
> +	if (chan->type != IIO_TEMP)
> +		return -EINVAL;
> +
> +	if (mutex_lock_interruptible(&data->lock))
> +		return -EINTR;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		rc = dps310_set_temp_samp_freq(data, val);
> +		break;
> +
> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> +		rc = dps310_set_temp_precision(data, val);
> +		break;
> +
> +	default:
> +		rc = -EINVAL;
> +		break;
> +	}
> +
> +	mutex_unlock(&data->lock);
> +	return rc;
> +}
> +
> +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_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 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(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 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 = DPS310_COEF_SRC,
> +};
> +
> +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 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 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 shift is disabled when PRC <= 8 */
> +	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> +			       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 measurement in the background */
> +	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> +			       DPS310_MEAS_CTRL_BITS,
> +			       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_temp_coef(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");

Re: [PATCH v3 2/3] iio: dps310: Temperature measurement errata

[Jonathan Cameron]

On Wed, 15 May 2019 13:41:16 -0500
Eddie James <eajames@linux.ibm.com> wrote:

> From: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> 
> Add a manufacturer's suggested workaround to deal with early revisions
> of chip that don't indicate correct temperature. Readings can be in the
> ~60C range when they should be in the ~20's.
> 
> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
Looks fine to me.

For reference:

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/iio/pressure/dps310.c | 52 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 50 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index 9acfccb..a093e3a 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c
> @@ -53,7 +53,6 @@
>  #define DPS310_RESET		0x0c
>  #define  DPS310_RESET_MAGIC	0x09
>  #define DPS310_COEF_BASE	0x10
> -#define DPS310_COEF_SRC		0x28
>  
>  /* Make sure sleep time is <= 20ms for usleep_range */
>  #define DPS310_POLL_SLEEP_US(t)		min(20000, (t) / 8)
> @@ -234,6 +233,10 @@ static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
>  	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;
> @@ -250,6 +253,7 @@ static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
>  	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;
> @@ -360,7 +364,7 @@ static void dps310_reset(void *action_data)
>  	.writeable_reg = dps310_is_writeable_reg,
>  	.volatile_reg = dps310_is_volatile_reg,
>  	.cache_type = REGCACHE_RBTREE,
> -	.max_register = DPS310_COEF_SRC,
> +	.max_register = 0x62, /* No documentation available on this register */
>  };
>  
>  static const struct iio_info dps310_info = {
> @@ -368,6 +372,46 @@ static void dps310_reset(void *action_data)
>  	.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)
>  {
> @@ -439,6 +483,10 @@ static int dps310_probe(struct i2c_client *client,
>  	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;

Re: [PATCH v3 3/3] iio: dps310: Add pressure sensing capability

[Jonathan Cameron]

On Wed, 15 May 2019 13:41:17 -0500
Eddie James <eajames@linux.ibm.com> wrote:

> 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@linux.ibm.com>
One really minor comment inline.

Otherwise looks good to me. For reference

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/iio/pressure/dps310.c | 360 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 334 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> index a093e3a..8a96d9d 100644
> --- a/drivers/iio/pressure/dps310.c
> +++ b/drivers/iio/pressure/dps310.c
> @@ -11,11 +11,11 @@
>   *   c0 * 0.5 + c1 * T_raw / kT °C
>   *
>   * TODO:
> - *  - Pressure sensor readings
>   *  - Optionally support the FIFO
>   */
>  
>  #include <linux/i2c.h>
> +#include <linux/math64.h>
>  #include <linux/module.h>
>  #include <linux/regmap.h>
>  
> @@ -31,6 +31,8 @@
>  #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)
> @@ -83,6 +85,8 @@ struct dps310_data {
>  	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;
>  };
>  
> @@ -93,33 +97,79 @@ struct dps310_data {
>  			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_temp_coef(struct dps310_data *data)
> +static int dps310_get_coefs(struct dps310_data *data)
>  {
>  	int rc;
> -	u8 coef[3];
> +	u8 coef[18];
>  	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
> -	 */
> +	/* 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;
> @@ -137,6 +187,25 @@ static int dps310_get_temp_precision(struct dps310_data *data)
>  }
>  
>  /* 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;
> @@ -156,6 +225,20 @@ static int dps310_set_temp_precision(struct dps310_data *data, int 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;
> @@ -169,6 +252,18 @@ 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 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;
> @@ -181,6 +276,16 @@ 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 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);
> @@ -191,7 +296,7 @@ static int dps310_get_temp_k(struct dps310_data *data)
>  	return scale_factors[ilog2(rc)];
>  }
>  
> -static int dps310_read_temp(struct dps310_data *data)
> +static int dps310_read_pres_raw(struct dps310_data *data)
>  {
>  	int rc;
>  	int rate;
> @@ -203,23 +308,67 @@ static int dps310_read_temp(struct dps310_data *data)
>  	if (mutex_lock_interruptible(&data->lock))
>  		return -EINTR;
>  
> -	rate = dps310_get_temp_samp_freq(data);
> +	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_TMP_RDY,
> +				      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)
> -		goto done;
> +		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;
> @@ -267,19 +416,40 @@ static int dps310_write_raw(struct iio_dev *iio,
>  	int rc;
>  	struct dps310_data *data = iio_priv(iio);
>  
> -	if (chan->type != IIO_TEMP)
> -		return -EINVAL;
> -
>  	if (mutex_lock_interruptible(&data->lock))
>  		return -EINTR;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_SAMP_FREQ:
> -		rc = dps310_set_temp_samp_freq(data, val);
> +		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:
> -		rc = dps310_set_temp_precision(data, val);
> +		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:
> @@ -291,6 +461,122 @@ static int dps310_write_raw(struct iio_dev *iio,
>  	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);
> +
> +	return (int)pressure;
I have a vague feeling that one of the static checkers will moan about this.
It may be worth an explicit masking or min to ensure that it can tell we
are definitely within range.


> +}
> +
> +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;
> @@ -310,11 +596,9 @@ static int dps310_calculate_temp(struct dps310_data *data)
>  	return (int)div_s64(t * 1000LL, kt);
>  }
>  
> -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 rc;
>  
>  	switch (mask) {
> @@ -327,7 +611,7 @@ static int dps310_read_raw(struct iio_dev *iio,
>  		return IIO_VAL_INT;
>  
>  	case IIO_CHAN_INFO_PROCESSED:
> -		rc = dps310_read_temp(data);
> +		rc = dps310_read_temp_raw(data);
>  		if (rc)
>  			return rc;
>  
> @@ -351,6 +635,24 @@ static int dps310_read_raw(struct iio_dev *iio,
>  	}
>  }
>  
> +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;
> @@ -444,6 +746,12 @@ static int dps310_probe(struct i2c_client *client,
>  		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
>  	 */
> @@ -451,9 +759,9 @@ static int dps310_probe(struct i2c_client *client,
>  	if (rc < 0)
>  		return rc;
>  
> -	/* Temp shift is disabled when PRC <= 8 */
> +	/* Temp and pressure shifts are disabled when PRC <= 8 */
>  	rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
> -			       DPS310_TMP_SHIFT_EN, 0);
> +			       DPS310_PRS_SHIFT_EN | DPS310_TMP_SHIFT_EN, 0);
>  	if (rc < 0)
>  		return rc;
>  
> @@ -463,9 +771,9 @@ static int dps310_probe(struct i2c_client *client,
>  	if (rc < 0)
>  		return rc;
>  
> -	/* Turn on temperature measurement in the background */
> +	/* Turn on temperature and pressure measurement in the background */
>  	rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
> -			       DPS310_MEAS_CTRL_BITS,
> +			       DPS310_MEAS_CTRL_BITS, DPS310_PRS_EN |
>  			       DPS310_TEMP_EN | DPS310_BACKGROUND);
>  	if (rc < 0)
>  		return rc;
> @@ -479,7 +787,7 @@ static int dps310_probe(struct i2c_client *client,
>  	if (rc < 0)
>  		return rc;
>  
> -	rc = dps310_get_temp_coef(data);
> +	rc = dps310_get_coefs(data);
>  	if (rc < 0)
>  		return rc;
>