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