--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright IBM Corp 2019
+/*
+ * The DPS310 is a barometric pressure and temperature sensor.
+ * Currently only reading a single temperature is supported by
+ * this driver.
+ *
+ * https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
+ *
+ * Temperature calculation:
+ * c0 * 0.5 + c1 * T_raw / kT °C
+ *
+ * TODO:
+ * - Pressure sensor readings
+ * - Optionally support the FIFO
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define DPS310_DEV_NAME "dps310"
+
+#define DPS310_PRS_B0 0x00
+#define DPS310_PRS_B1 0x01
+#define DPS310_PRS_B2 0x02
+#define DPS310_TMP_B0 0x03
+#define DPS310_TMP_B1 0x04
+#define DPS310_TMP_B2 0x05
+#define DPS310_PRS_CFG 0x06
+#define DPS310_TMP_CFG 0x07
+#define DPS310_TMP_RATE_BITS GENMASK(6, 4)
+#define DPS310_TMP_PRC_BITS GENMASK(3, 0)
+#define DPS310_TMP_EXT BIT(7)
+#define DPS310_MEAS_CFG 0x08
+#define DPS310_MEAS_CTRL_BITS GENMASK(2, 0)
+#define DPS310_PRS_EN BIT(0)
+#define DPS310_TEMP_EN BIT(1)
+#define DPS310_BACKGROUND BIT(2)
+#define DPS310_PRS_RDY BIT(4)
+#define DPS310_TMP_RDY BIT(5)
+#define DPS310_SENSOR_RDY BIT(6)
+#define DPS310_COEF_RDY BIT(7)
+#define DPS310_CFG_REG 0x09
+#define DPS310_INT_HL BIT(7)
+#define DPS310_TMP_SHIFT_EN BIT(3)
+#define DPS310_PRS_SHIFT_EN BIT(4)
+#define DPS310_FIFO_EN BIT(5)
+#define DPS310_SPI_EN BIT(6)
+#define DPS310_RESET 0x0c
+#define DPS310_RESET_MAGIC 0x09
+#define DPS310_COEF_BASE 0x10
+#define DPS310_COEF_SRC 0x28
+
+/* Make sure sleep time is <= 20ms for usleep_range */
+#define DPS310_POLL_SLEEP_US(t) min(20000, (t) / 8)
+/* Silently handle error in rate value here */
+#define DPS310_POLL_TIMEOUT_US(rc) ((rc) <= 0 ? 1000000 : 1000000 / (rc))
+
+#define DPS310_PRS_BASE DPS310_PRS_B0
+#define DPS310_TMP_BASE DPS310_TMP_B0
+
+/*
+ * These values (defined in the spec) indicate how to scale the raw register
+ * values for each level of precision available.
+ */
+static const int scale_factors[] = {
+ 524288,
+ 1572864,
+ 3670016,
+ 7864320,
+ 253952,
+ 516096,
+ 1040384,
+ 2088960,
+};
+
+struct dps310_data {
+ struct i2c_client *client;
+ struct regmap *regmap;
+ struct mutex lock; /* Lock for sequential HW access functions */
+
+ s32 c0, c1;
+ s32 temp_raw;
+};
+
+static const struct iio_chan_spec dps310_channels[] = {
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+ BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+ BIT(IIO_CHAN_INFO_PROCESSED),
+ },
+};
+
+/* To be called after checking the COEF_RDY bit in MEAS_CFG */
+static int dps310_get_temp_coef(struct dps310_data *data)
+{
+ int rc;
+ u8 coef[3];
+ u32 c0, c1;
+
+ /*
+ * Read temperature calibration coefficients c0 and c1 from the
+ * COEF register. The numbers are 12-bit 2's compliment numbers
+ */
+ rc = regmap_bulk_read(data->regmap, DPS310_COEF_BASE, coef,
+ sizeof(coef));
+ if (rc < 0)
+ return rc;
+
+ c0 = (coef[0] << 4) | (coef[1] >> 4);
+ data->c0 = sign_extend32(c0, 11);
+
+ c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
+ data->c1 = sign_extend32(c1, 11);
+
+ return 0;
+}
+
+static int dps310_get_temp_precision(struct dps310_data *data)
+{
+ int rc;
+ int val;
+
+ rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ if (rc < 0)
+ return rc;
+
+ /*
+ * Scale factor is bottom 4 bits of the register, but 1111 is
+ * reserved so just grab bottom three
+ */
+ return BIT(val & GENMASK(2, 0));
+}
+
+/* Called with lock held */
+static int dps310_set_temp_precision(struct dps310_data *data, int val)
+{
+ int rc;
+ u8 shift_en;
+
+ if (val < 0 || val > 128)
+ return -EINVAL;
+
+ shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
+ rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+ DPS310_TMP_SHIFT_EN, shift_en);
+ if (rc)
+ return rc;
+
+ return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+ DPS310_TMP_PRC_BITS, ilog2(val));
+}
+
+/* Called with lock held */
+static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
+{
+ u8 val;
+
+ if (freq < 0 || freq > 128)
+ return -EINVAL;
+
+ val = ilog2(freq) << 4;
+
+ return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
+ DPS310_TMP_RATE_BITS, val);
+}
+
+static int dps310_get_temp_samp_freq(struct dps310_data *data)
+{
+ int rc;
+ int val;
+
+ rc = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
+ if (rc < 0)
+ return rc;
+
+ return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
+}
+
+static int dps310_get_temp_k(struct dps310_data *data)
+{
+ int rc = dps310_get_temp_precision(data);
+
+ if (rc < 0)
+ return rc;
+
+ return scale_factors[ilog2(rc)];
+}
+
+static int dps310_read_temp(struct dps310_data *data)
+{
+ int rc;
+ int rate;
+ int ready;
+ int timeout;
+ s32 raw;
+ u8 val[3];
+
+ if (mutex_lock_interruptible(&data->lock))
+ return -EINTR;
+
+ rate = dps310_get_temp_samp_freq(data);
+ timeout = DPS310_POLL_TIMEOUT_US(rate);
+
+ /* Poll for sensor readiness; base the timeout upon the sample rate. */
+ rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+ ready & DPS310_TMP_RDY,
+ DPS310_POLL_SLEEP_US(timeout), timeout);
+ if (rc < 0)
+ goto done;
+
+ rc = regmap_bulk_read(data->regmap, DPS310_TMP_BASE, val, sizeof(val));
+ if (rc < 0)
+ goto done;
+
+ raw = (val[0] << 16) | (val[1] << 8) | val[2];
+ data->temp_raw = sign_extend32(raw, 23);
+
+done:
+ mutex_unlock(&data->lock);
+ return rc;
+}
+
+static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case DPS310_PRS_CFG:
+ case DPS310_TMP_CFG:
+ case DPS310_MEAS_CFG:
+ case DPS310_CFG_REG:
+ case DPS310_RESET:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case DPS310_PRS_B0:
+ case DPS310_PRS_B1:
+ case DPS310_PRS_B2:
+ case DPS310_TMP_B0:
+ case DPS310_TMP_B1:
+ case DPS310_TMP_B2:
+ case DPS310_MEAS_CFG:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static int dps310_write_raw(struct iio_dev *iio,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ int rc;
+ struct dps310_data *data = iio_priv(iio);
+
+ if (chan->type != IIO_TEMP)
+ return -EINVAL;
+
+ if (mutex_lock_interruptible(&data->lock))
+ return -EINTR;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ rc = dps310_set_temp_samp_freq(data, val);
+ break;
+
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ rc = dps310_set_temp_precision(data, val);
+ break;
+
+ default:
+ rc = -EINVAL;
+ break;
+ }
+
+ mutex_unlock(&data->lock);
+ return rc;
+}
+
+static int dps310_calculate_temp(struct dps310_data *data)
+{
+ s64 c0;
+ s64 t;
+ int kt = dps310_get_temp_k(data);
+
+ if (kt < 0)
+ return kt;
+
+ /* Obtain inverse-scaled offset */
+ c0 = div_s64((s64)kt * (s64)data->c0, 2);
+
+ /* Add the offset to the unscaled temperature */
+ t = c0 + ((s64)data->temp_raw * (s64)data->c1);
+
+ /* Convert to milliCelsius and scale the temperature */
+ return (int)div_s64(t * 1000LL, kt);
+}
+
+static int dps310_read_raw(struct iio_dev *iio,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct dps310_data *data = iio_priv(iio);
+ int rc;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ rc = dps310_get_temp_samp_freq(data);
+ if (rc < 0)
+ return rc;
+
+ *val = rc;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_PROCESSED:
+ rc = dps310_read_temp(data);
+ if (rc)
+ return rc;
+
+ rc = dps310_calculate_temp(data);
+ if (rc < 0)
+ return rc;
+
+ *val = rc;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ rc = dps310_get_temp_precision(data);
+ if (rc < 0)
+ return rc;
+
+ *val = rc;
+ return IIO_VAL_INT;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static void dps310_reset(void *action_data)
+{
+ struct dps310_data *data = action_data;
+
+ regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
+}
+
+static const struct regmap_config dps310_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .writeable_reg = dps310_is_writeable_reg,
+ .volatile_reg = dps310_is_volatile_reg,
+ .cache_type = REGCACHE_RBTREE,
+ .max_register = DPS310_COEF_SRC,
+};
+
+static const struct iio_info dps310_info = {
+ .read_raw = dps310_read_raw,
+ .write_raw = dps310_write_raw,
+};
+
+static int dps310_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct dps310_data *data;
+ struct iio_dev *iio;
+ int rc, ready;
+
+ iio = devm_iio_device_alloc(&client->dev, sizeof(*data));
+ if (!iio)
+ return -ENOMEM;
+
+ data = iio_priv(iio);
+ data->client = client;
+ mutex_init(&data->lock);
+
+ iio->dev.parent = &client->dev;
+ iio->name = id->name;
+ iio->channels = dps310_channels;
+ iio->num_channels = ARRAY_SIZE(dps310_channels);
+ iio->info = &dps310_info;
+ iio->modes = INDIO_DIRECT_MODE;
+
+ data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
+ if (IS_ERR(data->regmap))
+ return PTR_ERR(data->regmap);
+
+ /* Register to run the device reset when the device is removed */
+ rc = devm_add_action_or_reset(&client->dev, dps310_reset, data);
+ if (rc)
+ return rc;
+
+ /*
+ * Set up external (MEMS) temperature sensor in single sample, one
+ * measurement per second mode
+ */
+ rc = regmap_write(data->regmap, DPS310_TMP_CFG, DPS310_TMP_EXT);
+ if (rc < 0)
+ return rc;
+
+ /* Temp shift is disabled when PRC <= 8 */
+ rc = regmap_write_bits(data->regmap, DPS310_CFG_REG,
+ DPS310_TMP_SHIFT_EN, 0);
+ if (rc < 0)
+ return rc;
+
+ /* MEAS_CFG doesn't update correctly unless first written with 0 */
+ rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+ DPS310_MEAS_CTRL_BITS, 0);
+ if (rc < 0)
+ return rc;
+
+ /* Turn on temperature measurement in the background */
+ rc = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
+ DPS310_MEAS_CTRL_BITS,
+ DPS310_TEMP_EN | DPS310_BACKGROUND);
+ if (rc < 0)
+ return rc;
+
+ /*
+ * Calibration coefficients required for reporting temperature.
+ * They are available 40ms after the device has started
+ */
+ rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
+ ready & DPS310_COEF_RDY, 10000, 40000);
+ if (rc < 0)
+ return rc;
+
+ rc = dps310_get_temp_coef(data);
+ if (rc < 0)
+ return rc;
+
+ rc = devm_iio_device_register(&client->dev, iio);
+ if (rc)
+ return rc;
+
+ i2c_set_clientdata(client, iio);
+
+ return 0;
+}
+
+static const struct i2c_device_id dps310_id[] = {
+ { DPS310_DEV_NAME, 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, dps310_id);
+
+static struct i2c_driver dps310_driver = {
+ .driver = {
+ .name = DPS310_DEV_NAME,
+ },
+ .probe = dps310_probe,
+ .id_table = dps310_id,
+};
+module_i2c_driver(dps310_driver);
+
+MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
+MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");
OSDN Git Service
