/*
* Perform some start-of-day setup, including reading the asa calibration
* values and caching them.
*/
static int ak8975_setup(struct i2c_client *client)
{
struct ak8975_data *data = i2c_get_clientdata(client);
u8 device_id;
int ret;
/* Confirm that the device we're talking to is really an AK8975. */
ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id);
if (ret < 0) {
dev_err(&client->dev, "Error reading WIA\n");
return ret;
}
if (device_id != AK8975_DEVICE_ID) {
dev_err(&client->dev, "Device ak8975 not found\n");
return -ENODEV;
}
/* Write the fused rom access mode. */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_FUSE_ROM,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting fuse access mode\n");
return ret;
}
/* Get asa data and store in the device data. */
ret = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa);
if (ret < 0) {
dev_err(&client->dev, "Not able to read asa data\n");
return ret;
}
/* Precalculate scale factor for each axis and
store in the device data. */
data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
return 0;
}
/*
* Sets the device's mode. 0 = off, 1 = on. The device's mode must be on
* for the magn raw attributes to be available.
*/
static ssize_t store_mode(struct device *dev, struct device_attribute *devattr,
const char *buf, size_t count)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = indio_dev->dev_data;
struct i2c_client *client = data->client;
unsigned long oval;
int ret;
/* Convert mode string and do some basic sanity checking on it.
only 0 or 1 are valid. */
if (strict_strtoul(buf, 10, &oval))
return -EINVAL;
if (oval > 1) {
dev_err(dev, "mode value is not supported\n");
return -EINVAL;
}
mutex_lock(&data->lock);
/* Write the mode to the device. */
if (data->mode != oval) {
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
(u8)oval,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting mode\n");
mutex_unlock(&data->lock);
return ret;
}
data->mode = oval;
}
mutex_unlock(&data->lock);
return count;
}
/*
* Emits the raw flux value for the x, y, or z axis.
*/
static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
struct ak8975_data *data = iio_priv(indio_dev);
struct i2c_client *client = data->client;
u16 meas_reg;
s16 raw;
int ret;
mutex_lock(&data->lock);
/* Set up the device for taking a sample. */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_ONCE,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting operating mode\n");
goto exit;
}
/* Wait for the conversion to complete. */
if (gpio_is_valid(data->eoc_gpio))
ret = wait_conversion_complete_gpio(data);
else
ret = wait_conversion_complete_polled(data);
if (ret < 0)
goto exit;
if (ret & AK8975_REG_ST1_DRDY_MASK) {
ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
if (ret < 0) {
dev_err(&client->dev, "Error in reading ST2\n");
goto exit;
}
if (ret & (AK8975_REG_ST2_DERR_MASK |
AK8975_REG_ST2_HOFL_MASK)) {
dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
ret = -EINVAL;
goto exit;
}
}
/* Read the flux value from the appropriate register
(the register is specified in the iio device attributes). */
ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
if (ret < 0) {
dev_err(&client->dev, "Read axis data fails\n");
goto exit;
}
meas_reg = ret;
mutex_unlock(&data->lock);
/* Endian conversion of the measured values. */
raw = (s16) (le16_to_cpu(meas_reg));
/* Clamp to valid range. */
raw = clamp_t(s16, raw, -4096, 4095);
*val = raw;
return IIO_VAL_INT;
exit:
mutex_unlock(&data->lock);
return ret;
}
/*
* Perform some start-of-day setup, including reading the asa calibration
* values and caching them.
*/
static int ak8975_setup(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
struct ak8975_data *data = iio_priv(indio_dev);
u8 device_id;
int ret;
/* Confirm that the device we're talking to is really an AK8975. */
ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
if (ret < 0) {
dev_err(&client->dev, "Error reading WIA\n");
return ret;
}
device_id = ret;
if (device_id != AK8975_DEVICE_ID) {
dev_err(&client->dev, "Device ak8975 not found\n");
return -ENODEV;
}
/* Write the fused rom access mode. */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_FUSE_ROM,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting fuse access mode\n");
return ret;
}
/* Get asa data and store in the device data. */
ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX,
3, data->asa);
if (ret < 0) {
dev_err(&client->dev, "Not able to read asa data\n");
return ret;
}
/* After reading fuse ROM data set power-down mode */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_POWER_DOWN,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting power-down mode\n");
return ret;
}
/*
* Precalculate scale factor (in Gauss units) for each axis and
* store in the device data.
*
* This scale factor is axis-dependent, and is derived from 3 calibration
* factors ASA(x), ASA(y), and ASA(z).
*
* These ASA values are read from the sensor device at start of day, and
* cached in the device context struct.
*
* Adjusting the flux value with the sensitivity adjustment value should be
* done via the following formula:
*
* Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
*
* where H is the raw value, ASA is the sensitivity adjustment, and Hadj
* is the resultant adjusted value.
*
* We reduce the formula to:
*
* Hadj = H * (ASA + 128) / 256
*
* H is in the range of -4096 to 4095. The magnetometer has a range of
* +-1229uT. To go from the raw value to uT is:
*
* HuT = H * 1229/4096, or roughly, 3/10.
*
* Since 1uT = 100 gauss, our final scale factor becomes:
*
* Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
* Hadj = H * ((ASA + 128) * 30 / 256
*
* Since ASA doesn't change, we cache the resultant scale factor into the
* device context in ak8975_setup().
*/
data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
return 0;
}
/*
* Emits the raw flux value for the x, y, or z axis.
*/
static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,
char *buf)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = indio_dev->dev_data;
struct i2c_client *client = data->client;
struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr);
u16 meas_reg;
s16 raw;
u8 read_status;
int ret;
mutex_lock(&data->lock);
if (data->mode == 0) {
dev_err(&client->dev, "Operating mode is in power down mode\n");
ret = -EBUSY;
goto exit;
}
/* Set up the device for taking a sample. */
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
AK8975_REG_CNTL_MODE_ONCE,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);
if (ret < 0) {
dev_err(&client->dev, "Error in setting operating mode\n");
goto exit;
}
/* Wait for the conversion to complete. */
if (data->eoc_gpio)
ret = wait_conversion_complete_gpio(data);
else
ret = wait_conversion_complete_polled(data);
if (ret < 0)
goto exit;
read_status = ret;
if (read_status & AK8975_REG_ST1_DRDY_MASK) {
ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
if (ret < 0) {
dev_err(&client->dev, "Error in reading ST2\n");
goto exit;
}
if (read_status & (AK8975_REG_ST2_DERR_MASK |
AK8975_REG_ST2_HOFL_MASK)) {
dev_err(&client->dev, "ST2 status error 0x%x\n",
read_status);
ret = -EINVAL;
goto exit;
}
}
/* Read the flux value from the appropriate register
(the register is specified in the iio device attributes). */
ret = ak8975_read_data(client, this_attr->address, 2, (u8 *)&meas_reg);
if (ret < 0) {
dev_err(&client->dev, "Read axis data fails\n");
goto exit;
}
mutex_unlock(&data->lock);
/* Endian conversion of the measured values. */
raw = (s16) (le16_to_cpu(meas_reg));
/* Clamp to valid range. */
raw = clamp_t(s16, raw, -4096, 4095);
return sprintf(buf, "%d\n", raw);
exit:
mutex_unlock(&data->lock);
return ret;
}
