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

[PATCH 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.

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 | 753 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 770 insertions(+)
 create mode 100644 drivers/iio/pressure/dps310.c

-- 
2.7.4

[PATCH 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 | 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@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..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 °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_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[] = {
+	 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};
+	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);
+	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};
+	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");
+		return -EAGAIN;
+	}
+
+	r = regmap_bulk_read(regmap, DPS310_TMP_BASE, val, 3);
+	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;
+}
+
+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;
+		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;
+}
+
+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);
+
+	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@jms.id.au>");
+MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

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

[Peter Meerwald-Stadler]

[-- Attachment #1: Type: text/plain, Size: 13810 bytes --]

On Mon, 6 May 2019, Eddie James wrote:

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

some comments below
 
> 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 | 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@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..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 °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_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

> +		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

> +		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@jms.id.au>");
> +MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
> +MODULE_LICENSE("GPL v2");
> 

-- 

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

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

[Eddie James]

On 5/6/19 4:18 PM, Peter Meerwald-Stadler wrote:
> On Mon, 6 May 2019, Eddie James wrote:
>
>> From: Joel Stanley <joel@jms.id.au>
> 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@linux.ibm.com>
>> ---
>>   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@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..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 °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_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?


>
>> +		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...


>
>> +		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@jms.id.au>");
>> +MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
>> +MODULE_LICENSE("GPL v2");
>>

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

[Jonathan Cameron]

On Tue, 7 May 2019 11:01:36 -0500
Eddie James <eajames@linux.vnet.ibm.com> wrote:

> On 5/6/19 4:18 PM, Peter Meerwald-Stadler wrote:
> > On Mon, 6 May 2019, Eddie James wrote:
> >  
> >> From: Joel Stanley <joel@jms.id.au>  
> > 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@linux.ibm.com>
> >> ---
> >>   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@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..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 °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_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@jms.id.au>");
> >> +MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
> >> +MODULE_LICENSE("GPL v2");
> >>  
> 

[PATCH 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 | 51 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index 21d5dcb..3e03685 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -214,6 +214,9 @@ static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
 	case DPS310_MEAS_CFG:
 	case DPS310_CFG_REG:
 	case DPS310_RESET:
+	case 0x0e:
+	case 0x0f:
+	case 0x62:
 		return true;
 	default:
 		return false;
@@ -230,6 +233,7 @@ 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:
 		return true;
 	default:
 		return false;
@@ -311,7 +315,7 @@ static const struct regmap_config dps310_regmap_config = {
 	.writeable_reg = dps310_is_writeable_reg,
 	.volatile_reg = dps310_is_volatile_reg,
 	.cache_type = REGCACHE_RBTREE,
-	.max_register = 0x29,
+	.max_register = 0x62,
 };
 
 static const struct iio_info dps310_info = {
@@ -319,6 +323,47 @@ static const struct iio_info dps310_info = {
 	.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.
+ */
+static int dps310_temp_workaround(struct dps310_data *data)
+{
+	int r, reg;
+
+	r = regmap_read(data->regmap, 0x32, &reg);
+	if (r < 0)
+		return r;
+
+	/*
+	 * 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;
+
+	r = regmap_write(data->regmap, 0x0e, 0xA5);
+	if (r < 0)
+		return r;
+
+	r = regmap_write(data->regmap, 0x0f, 0x96);
+	if (r < 0)
+		return r;
+
+	r = regmap_write(data->regmap, 0x62, 0x02);
+	if (r < 0)
+		return r;
+
+	r = regmap_write(data->regmap, 0x0e, 0x00);
+	if (r < 0)
+		return r;
+
+	r = regmap_write(data->regmap, 0x0f, 0x00);
+
+	return r;
+}
+
 static int dps310_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -380,6 +425,10 @@ static int dps310_probe(struct i2c_client *client,
 	if (r < 0)
 		goto err;
 
+	r = dps310_temp_workaround(data);
+	if (r < 0)
+		return r;
+
 	r = devm_iio_device_register(&client->dev, iio);
 	if (r)
 		goto err;
-- 
2.7.4

[PATCH 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 | 327 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 301 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index 3e03685..fe88480 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/i2c.h>
+#include <linux/math64.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 
@@ -29,6 +30,8 @@
 #define DPS310_TMP_B1		0x04
 #define DPS310_TMP_B2		0x05
 #define DPS310_PRS_CFG		0x06
+#define  DPS310_PRS_RATE_BITS	GENMASK(6, 4)
+#define  DPS310_PRS_PRC_BITS	GENMASK(3, 0)
 #define DPS310_TMP_CFG		0x07
 #define  DPS310_TMP_RATE_BITS	GENMASK(6, 4)
 #define  DPS310_TMP_PRC_BITS	GENMASK(3, 0)
@@ -51,6 +54,7 @@
 #define DPS310_RESET		0x0c
 #define  DPS310_RESET_MAGIC	(BIT(0) | BIT(3))
 #define DPS310_COEF_BASE	0x10
+#define DPS310_NUM_COEF_REGS	0x12
 
 #define DPS310_PRS_BASE		DPS310_PRS_B0
 #define DPS310_TMP_BASE		DPS310_TMP_B0
@@ -58,7 +62,7 @@
 #define DPS310_CALC_RATE(_n)	ilog2(_n)
 #define DPS310_CALC_PRC(_n)	ilog2(_n)
 
-const int scale_factor[] = {
+static const int scale_factor[] = {
 	 524288,
 	1572864,
 	3670016,
@@ -74,6 +78,8 @@ struct dps310_data {
 	struct regmap *regmap;
 
 	s32 c0, c1;
+	s32 c00, c10, c20, c30, c01, c11, c21;
+	s32 pressure_raw;
 	s32 temp_raw;
 };
 
@@ -86,33 +92,81 @@ static const struct iio_chan_spec dps310_channels[] = {
 			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
 			BIT(IIO_CHAN_INFO_RAW),
 	},
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+			BIT(IIO_CHAN_INFO_RAW),
+	},
 };
 
-/* To be called after checking the TMP_RDY bit in MEAS_CFG */
-static int dps310_get_temp_coef(struct dps310_data *data)
+/* To be called after checking the COEF_RDY bit in MEAS_CFG */
+static int dps310_get_coefs(struct dps310_data *data)
 {
 	struct regmap *regmap = data->regmap;
-	u8 coef[3] = {0};
+
 	int r;
+	u8 coef[DPS310_NUM_COEF_REGS] = {0};
 	u32 c0, c1;
+	u32 c00, c10, c20, c30, c01, c11, c21;
 
-	/*
-	 * Read temperature calibration coefficients c0 and c1 from the
-	 * COEF register. The numbers are 12-bit 2's compliment numbers
-	 */
-	r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef, 3);
+	/* Read all sensor calibration coefficients from the COEF registers. */
+	r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef,
+			     DPS310_NUM_COEF_REGS);
 	if (r < 0)
 		return r;
 
+	/*
+	 * Calculate temperature calibration coefficients c0 and c1. The numbers
+	 * are 12-bit 2's complement numbers.
+	 */
 	c0 = (coef[0] << 4) | (coef[1] >> 4);
 	data->c0 = sign_extend32(c0, 11);
 
 	c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
 	data->c1 = sign_extend32(c1, 11);
 
+	/*
+	 * Calculate pressure calibration coefficients. c00 and c10 are 20 bit
+	 * 2's complement numbers, while the rest are 16 bit 2's complement
+	 * numbers.
+	 */
+	c00 = (coef[3] << 12) | (coef[4] << 4) | (coef[5] >> 4);
+	data->c00 = sign_extend32(c00, 19);
+
+	c10 = ((coef[5] & GENMASK(3, 0)) << 16) | (coef[6] << 8) | coef[7];
+	data->c10 = sign_extend32(c10, 19);
+
+	c01 = (coef[8] << 8) | coef[9];
+	data->c01 = sign_extend32(c01, 15);
+
+	c11 = (coef[10] << 8) | coef[11];
+	data->c11 = sign_extend32(c11, 15);
+
+	c20 = (coef[12] << 8) | coef[13];
+	data->c20 = sign_extend32(c20, 15);
+
+	c21 = (coef[14] << 8) | coef[15];
+	data->c21 = sign_extend32(c21, 15);
+
+	c30 = (coef[16] << 8) | coef[17];
+	data->c30 = sign_extend32(c30, 15);
+
 	return 0;
 }
 
+static int dps310_get_pres_precision(struct dps310_data *data)
+{
+	int val, r;
+
+	r = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+	if (r < 0)
+		return r;
+
+	return BIT(val & GENMASK(2, 0));
+}
+
 static int dps310_get_temp_precision(struct dps310_data *data)
 {
 	int val, r;
@@ -128,6 +182,24 @@ static int dps310_get_temp_precision(struct dps310_data *data)
 	return BIT(val & GENMASK(2, 0));
 }
 
+static int dps310_set_pres_precision(struct dps310_data *data, int val)
+{
+	int ret;
+	u8 shift_en;
+
+	if (val < 0 || val > 128)
+		return -EINVAL;
+
+	shift_en = val >= 16 ? DPS310_PRS_SHIFT_EN : 0;
+	ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+				DPS310_PRS_SHIFT_EN, shift_en);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
+				  DPS310_PRS_PRC_BITS, DPS310_CALC_PRC(val));
+}
+
 static int dps310_set_temp_precision(struct dps310_data *data, int val)
 {
 	int ret;
@@ -146,6 +218,19 @@ static int dps310_set_temp_precision(struct dps310_data *data, int val)
 				  DPS310_TMP_PRC_BITS, DPS310_CALC_PRC(val));
 }
 
+static int dps310_set_pres_samp_freq(struct dps310_data *data, int freq)
+{
+	u8 val;
+
+	if (freq < 0 || freq > 128)
+		return -EINVAL;
+
+	val = DPS310_CALC_RATE(freq) << 4;
+
+	return regmap_update_bits(data->regmap, DPS310_PRS_CFG,
+				  DPS310_PRS_RATE_BITS, val);
+}
+
 static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
 {
 	u8 val;
@@ -159,6 +244,17 @@ static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
 				  DPS310_TMP_RATE_BITS, val);
 }
 
+static int dps310_get_pres_samp_freq(struct dps310_data *data)
+{
+	int val, r;
+
+	r = regmap_read(data->regmap, DPS310_PRS_CFG, &val);
+	if (r < 0)
+		return r;
+
+	return BIT((val & DPS310_PRS_RATE_BITS) >> 4);
+}
+
 static int dps310_get_temp_samp_freq(struct dps310_data *data)
 {
 	int val, r;
@@ -170,6 +266,16 @@ static int dps310_get_temp_samp_freq(struct dps310_data *data)
 	return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
 }
 
+static int dps310_get_pres_k(struct dps310_data *data)
+{
+	int r = dps310_get_pres_precision(data);
+
+	if (r < 0)
+		return r;
+
+	return scale_factor[DPS310_CALC_PRC(r)];
+}
+
 static int dps310_get_temp_k(struct dps310_data *data)
 {
 	int r = dps310_get_temp_precision(data);
@@ -180,7 +286,33 @@ static int dps310_get_temp_k(struct dps310_data *data)
 	return scale_factor[DPS310_CALC_PRC(r)];
 }
 
-static int dps310_read_temp(struct dps310_data *data)
+static int dps310_read_pres_raw(struct dps310_data *data)
+{
+	struct device *dev = &data->client->dev;
+	int r, ready;
+	u8 val[3];
+	s32 raw;
+
+	r = regmap_read(data->regmap, DPS310_MEAS_CFG, &ready);
+	if (r < 0)
+		return r;
+
+	if (!(ready & DPS310_PRS_RDY)) {
+		dev_dbg(dev, "pressure not ready\n");
+		return -EAGAIN;
+	}
+
+	r = regmap_bulk_read(data->regmap, DPS310_PRS_BASE, val, 3);
+	if (r < 0)
+		return r;
+
+	raw = (val[0] << 16) | (val[1] << 8) | val[2];
+	data->pressure_raw = sign_extend32(raw, 23);
+
+	return 0;
+}
+
+static int dps310_read_temp_raw(struct dps310_data *data)
 {
 	struct device *dev = &data->client->dev;
 	struct regmap *regmap = data->regmap;
@@ -246,26 +378,139 @@ static int dps310_write_raw(struct iio_dev *iio,
 {
 	struct dps310_data *data = iio_priv(iio);
 
-	if (chan->type != IIO_TEMP)
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			return dps310_set_pres_samp_freq(data, val);
+
+		case IIO_TEMP:
+			return dps310_set_temp_samp_freq(data, val);
+
+		default:
+			return -EINVAL;
+		}
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			return dps310_set_pres_precision(data, val);
+
+		case IIO_TEMP:
+			return dps310_set_temp_precision(data, val);
+
+		default:
+			return -EINVAL;
+		}
+
+	default:
 		return -EINVAL;
+	}
+}
+
+static int dps310_calculate_pressure(struct dps310_data *data)
+{
+	int i;
+	int kpi = dps310_get_pres_k(data);
+	int kti = dps310_get_temp_k(data);
+	s64 rem = 0ULL;
+	s64 pressure = 0ULL;
+	s64 p;
+	s64 t;
+	s64 denoms[7];
+	s64 nums[7];
+	s64 rems[7];
+	s64 kp;
+	s64 kt;
+
+	if (kpi < 0)
+		return kpi;
+
+	if (kti < 0)
+		return kti;
+
+	kp = (s64)kpi;
+	kt = (s64)kti;
+
+	/* Ignore errors and use the latest temperature */
+	dps310_read_temp_raw(data);
+
+	p = (s64)data->pressure_raw;
+	t = (s64)data->temp_raw;
+
+	/* Section 4.9.1 of the DPS310 spec; algebra'd to avoid underflow */
+	nums[0] = (s64)data->c00;
+	denoms[0] = 1LL;
+	nums[1] = p * (s64)data->c10;
+	denoms[1] = kp;
+	nums[2] = p * p * (s64)data->c20;
+	denoms[2] = kp * kp;
+	nums[3] = p * p * p * (s64)data->c30;
+	denoms[3] = kp * kp * kp;
+	nums[4] = t * (s64)data->c01;
+	denoms[4] = kt;
+	nums[5] = t * p * (s64)data->c11;
+	denoms[5] = kp * kt;
+	nums[6] = t * p * p * (s64)data->c21;
+	denoms[6] = kp * kp * kt;
+
+	/* Kernel lacks a div64_s64_rem function; denoms are all positive */
+	for (i = 0; i < 7; ++i) {
+		u64 rem;
+
+		if (nums[i] < 0LL) {
+			pressure -= div64_u64_rem(-nums[i], denoms[i], &rem);
+			rems[i] = -rem;
+		} else {
+			pressure += div64_u64_rem(nums[i], denoms[i], &rem);
+			rems[i] = (s64)rem;
+		}
+	}
+
+	/* Increase precision and calculate the remainder sum */
+	for (i = 0; i < 7; ++i)
+		rem += div64_s64((s64)rems[i] * 1000000000LL, denoms[i]);
+
+	pressure += div_s64(rem, 1000000000LL);
+
+	return (int)pressure;
+}
+
+static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
+				long mask)
+{
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		return dps310_set_temp_samp_freq(data, val);
+		*val = dps310_get_pres_samp_freq(data);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_RAW:
+		ret = dps310_read_pres_raw(data);
+		if (ret)
+			return ret;
+
+		*val = dps310_calculate_pressure(data);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1;
+		*val2 = 1000; /* Convert Pa to KPa per IIO ABI */
+		return IIO_VAL_FRACTIONAL;
+
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
-		return dps310_set_temp_precision(data, val);
+		*val = dps310_get_pres_precision(data);
+		return IIO_VAL_INT;
+
 	default:
 		return -EINVAL;
 	}
-
-	return -EINVAL;
 }
 
-static int dps310_read_raw(struct iio_dev *iio,
-			   struct iio_chan_spec const *chan,
-			   int *val, int *val2, long mask)
+static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
+			    long mask)
 {
-	struct dps310_data *data = iio_priv(iio);
 	int ret;
 
 	switch (mask) {
@@ -274,7 +519,7 @@ static int dps310_read_raw(struct iio_dev *iio,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_RAW:
-		ret = dps310_read_temp(data);
+		ret = dps310_read_temp_raw(data);
 		if (ret)
 			return ret;
 
@@ -305,8 +550,24 @@ static int dps310_read_raw(struct iio_dev *iio,
 	default:
 		return -EINVAL;
 	}
+}
 
-	return -EINVAL;
+static int dps310_read_raw(struct iio_dev *iio,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct dps310_data *data = iio_priv(iio);
+
+	switch (chan->type) {
+	case IIO_PRESSURE:
+		return dps310_read_pressure(data, val, val2, mask);
+
+	case IIO_TEMP:
+		return dps310_read_temp(data, val, val2, mask);
+
+	default:
+		return -EINVAL;
+	}
 }
 
 static const struct regmap_config dps310_regmap_config = {
@@ -390,6 +651,13 @@ static int dps310_probe(struct i2c_client *client,
 		return PTR_ERR(data->regmap);
 
 	/*
+	 * Set up pressure sensor in single sample, one measurement per second
+	 * mode
+	 */
+	r = regmap_write(data->regmap, DPS310_PRS_CFG,
+			 DPS310_CALC_RATE(1) | DPS310_CALC_PRC(1));
+
+	/*
 	 * Set up external (MEMS) temperature sensor in single sample, one
 	 * measurement per second mode
 	 */
@@ -399,16 +667,23 @@ static int dps310_probe(struct i2c_client *client,
 	if (r < 0)
 		goto err;
 
-	/* Temp shift is disabled when PRC <= 8 */
+	/* Temp and pressure shifts are disabled when PRC <= 8 */
 	r = regmap_write_bits(data->regmap, DPS310_CFG_REG,
-			      DPS310_TMP_SHIFT_EN, 0);
+			      DPS310_TMP_SHIFT_EN | DPS310_PRS_SHIFT_EN, 0);
+	if (r < 0)
+		goto err;
+
+	/* MEAS_CFG doesn't seem to update unless first written with 0 */
+	r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+			      DPS310_MEAS_CTRL_BITS, 0);
 	if (r < 0)
 		goto err;
 
-	/* Turn on temperature measurement in the background */
+	/* Turn on temperature and pressure measurement in the background */
 	r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
 			      DPS310_MEAS_CTRL_BITS,
-			      DPS310_TEMP_EN | DPS310_BACKGROUND);
+			      DPS310_PRS_EN | DPS310_TEMP_EN |
+			      DPS310_BACKGROUND);
 	if (r < 0)
 		goto err;
 
@@ -421,7 +696,7 @@ static int dps310_probe(struct i2c_client *client,
 	if (r < 0)
 		goto err;
 
-	r = dps310_get_temp_coef(data);
+	r = dps310_get_coefs(data);
 	if (r < 0)
 		goto err;
 
-- 
2.7.4

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

[Peter Meerwald-Stadler]

On Mon, 6 May 2019, Eddie James wrote:

some comments below

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

this should update the TODO, right? it implements pressure

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

this change should be in the previous/initial patch

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

-- 

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