From cc8baffe176197645ed674b38cef1d8548769a69 Mon Sep 17 00:00:00 2001 From: Christopher Bostic Date: Mon, 20 May 2019 21:13:33 -0500 Subject: iio: dps310: Temperature measurement errata 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 Signed-off-by: Joel Stanley Signed-off-by: Eddie James Signed-off-by: Jonathan Cameron --- drivers/iio/pressure/dps310.c | 52 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 50 insertions(+), 2 deletions(-) diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c index 9acfccba1d50..a093e3a15665 100644 --- a/drivers/iio/pressure/dps310.c +++ b/drivers/iio/pressure/dps310.c @@ -53,7 +53,6 @@ #define DPS310_RESET 0x0c #define DPS310_RESET_MAGIC 0x09 #define DPS310_COEF_BASE 0x10 -#define DPS310_COEF_SRC 0x28 /* Make sure sleep time is <= 20ms for usleep_range */ #define DPS310_POLL_SLEEP_US(t) min(20000, (t) / 8) @@ -234,6 +233,10 @@ static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg) case DPS310_MEAS_CFG: case DPS310_CFG_REG: case DPS310_RESET: + /* No documentation available on the registers below */ + case 0x0e: + case 0x0f: + case 0x62: return true; default: return false; @@ -250,6 +253,7 @@ static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg) case DPS310_TMP_B1: case DPS310_TMP_B2: case DPS310_MEAS_CFG: + case 0x32: /* No documentation available on this register */ return true; default: return false; @@ -360,7 +364,7 @@ static 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 = DPS310_COEF_SRC, + .max_register = 0x62, /* No documentation available on this register */ }; static const struct iio_info dps310_info = { @@ -368,6 +372,46 @@ 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. The registers used below are undocumented. + */ +static int dps310_temp_workaround(struct dps310_data *data) +{ + int rc; + int reg; + + rc = regmap_read(data->regmap, 0x32, ®); + if (rc < 0) + return rc; + + /* + * If bit 1 is set then the device is okay, and the workaround does not + * need to be applied + */ + if (reg & BIT(1)) + return 0; + + rc = regmap_write(data->regmap, 0x0e, 0xA5); + if (rc < 0) + return rc; + + rc = regmap_write(data->regmap, 0x0f, 0x96); + if (rc < 0) + return rc; + + rc = regmap_write(data->regmap, 0x62, 0x02); + if (rc < 0) + return rc; + + rc = regmap_write(data->regmap, 0x0e, 0x00); + if (rc < 0) + return rc; + + return regmap_write(data->regmap, 0x0f, 0x00); +} + static int dps310_probe(struct i2c_client *client, const struct i2c_device_id *id) { @@ -439,6 +483,10 @@ static int dps310_probe(struct i2c_client *client, if (rc < 0) return rc; + rc = dps310_temp_workaround(data); + if (rc < 0) + return rc; + rc = devm_iio_device_register(&client->dev, iio); if (rc) return rc; -- cgit v1.2.3