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

From: Eddie James
Date: Tue May 07 2019 - 12:02:37 EST


On 5/6/19 4:18 PM, Peter Meerwald-Stadler wrote:
On Mon, 6 May 2019, Eddie James wrote:

From: Joel Stanley <joel@xxxxxxxxx>
some comments below


Thanks for the quick review! Will get these in for v2, I did have a couple of questions below though.

Eddie


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

Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx>
---
MAINTAINERS | 6 +
drivers/iio/pressure/Kconfig | 10 +
drivers/iio/pressure/Makefile | 1 +
drivers/iio/pressure/dps310.c | 429 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 446 insertions(+)
create mode 100644 drivers/iio/pressure/dps310.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c61c49d..a91dfa9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7743,6 +7743,12 @@ W: http://industrypack.sourceforge.net
S: Maintained
F: drivers/ipack/
+INFINEON DPS310 Driver
+M: Eddie James <eajames@xxxxxxxxxxxxx>
+L: linux-iio@xxxxxxxxxxxxxxx
+F: drivers/iio/pressure/dps310.c
+S: Maintained
+
INFINIBAND SUBSYSTEM
M: Doug Ledford <dledford@xxxxxxxxxx>
M: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index efeb89f..681a1cc 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -52,6 +52,16 @@ config IIO_CROS_EC_BARO
To compile this driver as a module, choose M here: the module
will be called cros_ec_baro.
+config DPS310
+ tristate "Infineon DPS310 pressure and temperature sensor"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ Support for the Infineon DPS310 digital barometric pressure sensor.
+
+ This driver can also be built as a module. If so, the module will be
+ called dps310.
+
config HID_SENSOR_PRESS
depends on HID_SENSOR_HUB
select IIO_BUFFER
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index c2058d7..d8f5ace 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_BMP280) += bmp280.o
bmp280-objs := bmp280-core.o bmp280-regmap.o
obj-$(CONFIG_BMP280_I2C) += bmp280-i2c.o
obj-$(CONFIG_BMP280_SPI) += bmp280-spi.o
+obj-$(CONFIG_DPS310) += dps310.o
obj-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
obj-$(CONFIG_HID_SENSOR_PRESS) += hid-sensor-press.o
obj-$(CONFIG_HP03) += hp03.o
diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
new file mode 100644
index 0000000..21d5dcb
--- /dev/null
+++ b/drivers/iio/pressure/dps310.c
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright IBM Corp 2019
+/*
+ * The DPS310 is a barometric pressure and temperature sensor.
+ * Currently only reading a single temperature is supported by
+ * this driver.
+ *
+ * https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
+ *
+ * Temperature calculation:
+ * c0 * 0.5 + c1 * T_raw / kT ÂC
+ *
+ * TODO:
+ * - Pressure sensor readings
+ * - Optionally support the FIFO
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define DPS310_PRS_B0 0x00
+#define DPS310_PRS_B1 0x01
+#define DPS310_PRS_B2 0x02
+#define DPS310_TMP_B0 0x03
+#define DPS310_TMP_B1 0x04
+#define DPS310_TMP_B2 0x05
+#define DPS310_PRS_CFG 0x06
+#define DPS310_TMP_CFG 0x07
+#define DPS310_TMP_RATE_BITS GENMASK(6, 4)
+#define DPS310_TMP_PRC_BITS GENMASK(3, 0)
+#define DPS310_TMP_EXT BIT(7)
+#define DPS310_MEAS_CFG 0x08
+#define DPS310_MEAS_CTRL_BITS GENMASK(2, 0)
+#define DPS310_PRS_EN BIT(0)
+#define DPS310_TEMP_EN BIT(1)
+#define DPS310_BACKGROUND BIT(2)
+#define DPS310_PRS_RDY BIT(4)
+#define DPS310_TMP_RDY BIT(5)
+#define DPS310_SENSOR_RDY BIT(6)
+#define DPS310_COEF_RDY BIT(7)
+#define DPS310_CFG_REG 0x09
+#define DPS310_INT_HL BIT(7)
+#define DPS310_TMP_SHIFT_EN BIT(3)
+#define DPS310_PRS_SHIFT_EN BIT(4)
+#define DPS310_FIFO_EN BIT(5)
+#define DPS310_SPI_EN BIT(6)
+#define DPS310_RESET 0x0c
+#define DPS310_RESET_MAGIC (BIT(0) | BIT(3))
+#define DPS310_COEF_BASE 0x10
+
+#define DPS310_PRS_BASE DPS310_PRS_B0
+#define DPS310_TMP_BASE DPS310_TMP_B0
+
+#define DPS310_CALC_RATE(_n) ilog2(_n)
+#define DPS310_CALC_PRC(_n) ilog2(_n)
+
+const int scale_factor[] = {
static
maybe plural, scale_factors?
maybe some comment would be good what these values relate to

+ 524288,
+ 1572864,
+ 3670016,
+ 7864320,
+ 253952,
+ 516096,
+ 1040384,
+ 2088960,
+};
+
+struct dps310_data {
+ struct i2c_client *client;
+ struct regmap *regmap;
+
+ s32 c0, c1;
+ s32 temp_raw;
+};
+
+static const struct iio_chan_spec dps310_channels[] = {
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
+ BIT(IIO_CHAN_INFO_SCALE) |
+ BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+ BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+ BIT(IIO_CHAN_INFO_RAW),
+ },
+};
+
+/* To be called after checking the TMP_RDY bit in MEAS_CFG */
+static int dps310_get_temp_coef(struct dps310_data *data)
+{
+ struct regmap *regmap = data->regmap;
+ u8 coef[3] = {0};
initialization needed?

+ int r;
+ u32 c0, c1;
+
+ /*
+ * Read temperature calibration coefficients c0 and c1 from the
+ * COEF register. The numbers are 12-bit 2's compliment numbers
+ */
+ r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef, 3);
sizeof(coef) instead of 3

+ if (r < 0)
+ return r;
+
+ c0 = (coef[0] << 4) | (coef[1] >> 4);
+ data->c0 = sign_extend32(c0, 11);
+
+ c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
+ data->c1 = sign_extend32(c1, 11);
+
+ return 0;
+}
+
+static int dps310_get_temp_precision(struct dps310_data *data)
+{
+ int val, r;
+
+ r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ if (r < 0)
+ return r;
+
+ /*
+ * Scale factor is bottom 4 bits of the register, but 1111 is
+ * reserved so just grab bottom three
+ */
+ return BIT(val & GENMASK(2, 0));
+}
+
+static int dps310_set_temp_precision(struct dps310_data *data, int val)
+{
+ int ret;
+ u8 shift_en;
+
+ if (val < 0 || val > 128)
+ return -EINVAL;
+
+ shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
+ ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+ DPS310_TMP_SHIFT_EN, shift_en);
+ if (ret)
+ return ret;
+
+ return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+ DPS310_TMP_PRC_BITS, DPS310_CALC_PRC(val));
+}
+
+static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
+{
+ u8 val;
+
+ if (freq < 0 || freq > 128)
+ return -EINVAL;
+
+ val = DPS310_CALC_RATE(freq) << 4;
+
+ return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+ DPS310_TMP_RATE_BITS, val);
+}
+
+static int dps310_get_temp_samp_freq(struct dps310_data *data)
+{
+ int val, r;
+
+ r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ if (r < 0)
+ return r;
+
+ return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
+}
+
+static int dps310_get_temp_k(struct dps310_data *data)
+{
+ int r = dps310_get_temp_precision(data);
+
+ if (r < 0)
+ return r;
+
+ return scale_factor[DPS310_CALC_PRC(r)];
+}
+
+static int dps310_read_temp(struct dps310_data *data)
+{
+ struct device *dev = &data->client->dev;
+ struct regmap *regmap = data->regmap;
+ u8 val[3] = {0};
initialization needed?

+ int r, ready;
+ int T_raw;
+
+ r = regmap_read(regmap, DPS310_MEAS_CFG, &ready);
+ if (r < 0)
+ return r;
+ if (!(ready & DPS310_TMP_RDY)) {
+ dev_dbg(dev, "temperature not ready\n");
most drivers wait for the results to become ready\


OK, this may have to wait up to a second then, since the background measurement rate can be as low as 1 HZ... I can base the timeout on the sample rate. Would that be OK?



+ 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@xxxxxxxxx>");
+MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");