On 30/03/15 09:35, Vianney le Clément de Saint-Marcq wrote:
> The mapping from the 16-bit EEPROM value to the decimal 0-1 range is
> approximate. A special case ensures 0xFFFF shows as 1.0 instead of
> 0.999998565.
>
> Writing to EEPROM requires an explicit erase by writing zero. In
> addition, it takes 20ms for the erase/write to complete. During this
> time no EEPROM register should be accessed. Therefore, two msleep()s
> are added to the write function and a mutex protects against concurrent
> access.
>
> Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@xxxxxxxxxxxxx>
> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@xxxxxxx>
>
Applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.
Thanks,
J
> ---
>
> v3: rename EMISSIVITY to CALIBEMISSIVITY
> v2: * remove iir, fir, and gain attributes
> * refactor emissivity to use IIO_CHAN_INFO_EMISSIVITY
> ---
> drivers/iio/temperature/mlx90614.c | 106 +++++++++++++++++++++++++++++++++++--
> 1 file changed, 103 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c
> index a112fc9..a307d8c 100644
> --- a/drivers/iio/temperature/mlx90614.c
> +++ b/drivers/iio/temperature/mlx90614.c
> @@ -12,12 +12,13 @@
> *
> * (7-bit I2C slave address 0x5a, 100KHz bus speed only!)
> *
> - * TODO: sleep mode, configuration EEPROM
> + * TODO: sleep mode, filter configuration
> */
>
> #include <linux/err.h>
> #include <linux/i2c.h>
> #include <linux/module.h>
> +#include <linux/delay.h>
>
> #include <linux/iio/iio.h>
>
> @@ -53,8 +54,47 @@
>
> struct mlx90614_data {
> struct i2c_client *client;
> + struct mutex lock; /* for EEPROM access only */
> };
>
> +/*
> + * Erase an address and write word.
> + * The mutex must be locked before calling.
> + */
> +static s32 mlx90614_write_word(const struct i2c_client *client, u8 command,
> + u16 value)
> +{
> + /*
> + * Note: The mlx90614 requires a PEC on writing but does not send us a
> + * valid PEC on reading. Hence, we cannot set I2C_CLIENT_PEC in
> + * i2c_client.flags. As a workaround, we use i2c_smbus_xfer here.
> + */
> + union i2c_smbus_data data;
> + s32 ret;
> +
> + dev_dbg(&client->dev, "Writing 0x%x to address 0x%x", value, command);
> +
> + data.word = 0x0000; /* erase command */
> + ret = i2c_smbus_xfer(client->adapter, client->addr,
> + client->flags | I2C_CLIENT_PEC,
> + I2C_SMBUS_WRITE, command,
> + I2C_SMBUS_WORD_DATA, &data);
> + if (ret < 0)
> + return ret;
> +
> + msleep(MLX90614_TIMING_EEPROM);
> +
> + data.word = value; /* actual write */
> + ret = i2c_smbus_xfer(client->adapter, client->addr,
> + client->flags | I2C_CLIENT_PEC,
> + I2C_SMBUS_WRITE, command,
> + I2C_SMBUS_WORD_DATA, &data);
> +
> + msleep(MLX90614_TIMING_EEPROM);
> +
> + return ret;
> +}
> +
> static int mlx90614_read_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *channel, int *val,
> int *val2, long mask)
> @@ -97,6 +137,61 @@ static int mlx90614_read_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_SCALE:
> *val = 20;
> return IIO_VAL_INT;
> + case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */
> + mutex_lock(&data->lock);
> + ret = i2c_smbus_read_word_data(data->client,
> + MLX90614_EMISSIVITY);
> + mutex_unlock(&data->lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (ret == 65535) {
> + *val = 1;
> + *val2 = 0;
> + } else {
> + *val = 0;
> + *val2 = ret * 15259; /* 1/65535 ~ 0.000015259 */
> + }
> + return IIO_VAL_INT_PLUS_NANO;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int mlx90614_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *channel, int val,
> + int val2, long mask)
> +{
> + struct mlx90614_data *data = iio_priv(indio_dev);
> + s32 ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_CALIBEMISSIVITY: /* 1/65535 / LSB */
> + if (val < 0 || val2 < 0 || val > 1 || (val == 1 && val2 != 0))
> + return -EINVAL;
> + val = val * 65535 + val2 / 15259; /* 1/65535 ~ 0.000015259 */
> +
> + mutex_lock(&data->lock);
> + ret = mlx90614_write_word(data->client, MLX90614_EMISSIVITY,
> + val);
> + mutex_unlock(&data->lock);
> +
> + if (ret < 0)
> + return ret;
> + return 0;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int mlx90614_write_raw_get_fmt(struct iio_dev *indio_dev,
> + const struct iio_chan_spec const *channel,
> + long mask)
> +{
> + switch (mask) {
> + case IIO_CHAN_INFO_CALIBEMISSIVITY:
> + return IIO_VAL_INT_PLUS_NANO;
> default:
> return -EINVAL;
> }
> @@ -115,7 +210,8 @@ static const struct iio_chan_spec mlx90614_channels[] = {
> .type = IIO_TEMP,
> .modified = 1,
> .channel2 = IIO_MOD_TEMP_OBJECT,
> - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
> BIT(IIO_CHAN_INFO_SCALE),
> },
> @@ -125,7 +221,8 @@ static const struct iio_chan_spec mlx90614_channels[] = {
> .modified = 1,
> .channel = 1,
> .channel2 = IIO_MOD_TEMP_OBJECT,
> - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_CALIBEMISSIVITY),
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
> BIT(IIO_CHAN_INFO_SCALE),
> },
> @@ -133,6 +230,8 @@ static const struct iio_chan_spec mlx90614_channels[] = {
>
> static const struct iio_info mlx90614_info = {
> .read_raw = mlx90614_read_raw,
> + .write_raw = mlx90614_write_raw,
> + .write_raw_get_fmt = mlx90614_write_raw_get_fmt,
> .driver_module = THIS_MODULE,
> };
>
> @@ -166,6 +265,7 @@ static int mlx90614_probe(struct i2c_client *client,
> data = iio_priv(indio_dev);
> i2c_set_clientdata(client, indio_dev);
> data->client = client;
> + mutex_init(&data->lock);
>
> indio_dev->dev.parent = &client->dev;
> indio_dev->name = id->name;
>
--
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