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staging:iio:magnetometer:ak8975 convert to iio_chan_spec + cleanups.
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iio_chan_spec conversion is straight forward.

Other changes:
* use i2c_smbus_write_byte_data in write_data
* c99 isms to setup various structures.
* move the comment about the scale factor and kill off trivial access func.
* make mode setting code use a bool rather than a ulong.

Ultimately I'd like to get rid of that mode bit entirely and handle it through
core pm routines, but have left it for now.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Jonathan Cameron authored and Greg Kroah-Hartman committed Aug 23, 2011
1 parent 7991029 commit 694e1b5
Showing 1 changed file with 103 additions and 111 deletions.
214 changes: 103 additions & 111 deletions drivers/staging/iio/magnetometer/ak8975.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@
#include <linux/gpio.h>

#include "../iio.h"
#include "magnet.h"

/*
* Register definitions, as well as various shifts and masks to get at the
Expand Down Expand Up @@ -93,38 +92,28 @@ struct ak8975_data {
struct mutex lock;
u8 asa[3];
long raw_to_gauss[3];
unsigned long mode;
bool mode;
u8 reg_cache[AK8975_MAX_REGS];
int eoc_gpio;
int eoc_irq;
};

static const int ak8975_index_to_reg[] = {
AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
};

/*
* Helper function to write to the I2C device's registers.
*/
static int ak8975_write_data(struct i2c_client *client,
u8 reg, u8 val, u8 mask, u8 shift)
{
u8 regval;
struct i2c_msg msg;
u8 w_data[2];
int ret = 0;

struct ak8975_data *data = i2c_get_clientdata(client);
u8 regval;
int ret;

regval = data->reg_cache[reg];
regval &= ~mask;
regval |= val << shift;

w_data[0] = reg;
w_data[1] = regval;

msg.addr = client->addr;
msg.flags = 0;
msg.len = 2;
msg.buf = w_data;

ret = i2c_transfer(client->adapter, &msg, 1);
regval = (data->reg_cache[reg] & ~mask) | (val << shift);
ret = i2c_smbus_write_byte_data(client, reg, regval);
if (ret < 0) {
dev_err(&client->dev, "Write to device fails status %x\n", ret);
return ret;
Expand All @@ -140,21 +129,20 @@ static int ak8975_write_data(struct i2c_client *client,
static int ak8975_read_data(struct i2c_client *client,
u8 reg, u8 length, u8 *buffer)
{
struct i2c_msg msg[2];
u8 w_data[2];
int ret;

w_data[0] = reg;

msg[0].addr = client->addr;
msg[0].flags = I2C_M_NOSTART; /* set repeated start and write */
msg[0].len = 1;
msg[0].buf = w_data;

msg[1].addr = client->addr;
msg[1].flags = I2C_M_RD;
msg[1].len = length;
msg[1].buf = buffer;
struct i2c_msg msg[2] = {
{
.addr = client->addr,
.flags = I2C_M_NOSTART,
.len = 1,
.buf = &reg,
}, {
.addr = client->addr,
.flags = I2C_M_RD,
.len = length,
.buf = buffer,
}
};

ret = i2c_transfer(client->adapter, msg, 2);
if (ret < 0) {
Expand Down Expand Up @@ -204,8 +192,41 @@ static int ak8975_setup(struct i2c_client *client)
return ret;
}

/* Precalculate scale factor for each axis and
store in the device data. */
/*
* 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;
Expand All @@ -222,7 +243,7 @@ static ssize_t show_mode(struct device *dev, struct device_attribute *devattr,
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = iio_priv(indio_dev);

return sprintf(buf, "%lu\n", data->mode);
return sprintf(buf, "%u\n", data->mode);
}

/*
Expand All @@ -235,26 +256,22 @@ static ssize_t store_mode(struct device *dev, struct device_attribute *devattr,
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = iio_priv(indio_dev);
struct i2c_client *client = data->client;
unsigned long oval;
bool value;
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;
}
ret = strtobool(buf, &value);
if (ret < 0)
return ret;

mutex_lock(&data->lock);

/* Write the mode to the device. */
if (data->mode != oval) {
if (data->mode != value) {
ret = ak8975_write_data(client,
AK8975_REG_CNTL,
(u8)oval,
(u8)value,
AK8975_REG_CNTL_MODE_MASK,
AK8975_REG_CNTL_MODE_SHIFT);

Expand All @@ -263,58 +280,14 @@ static ssize_t store_mode(struct device *dev, struct device_attribute *devattr,
mutex_unlock(&data->lock);
return ret;
}
data->mode = oval;
data->mode = value;
}

mutex_unlock(&data->lock);

return count;
}

/*
* Emits the scale factor to bring the raw value into Gauss units.
*
* 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().
*/
static ssize_t show_scale(struct device *dev, struct device_attribute *devattr,
char *buf)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = iio_priv(indio_dev);
struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr);

return sprintf(buf, "%ld\n", data->raw_to_gauss[this_attr->address]);
}

static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
struct i2c_client *client = data->client;
Expand Down Expand Up @@ -371,13 +344,10 @@ static int wait_conversion_complete_polled(struct ak8975_data *data)
/*
* 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)
static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct ak8975_data *data = iio_priv(indio_dev);
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;
Expand Down Expand Up @@ -429,7 +399,8 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,

/* 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);
ret = ak8975_read_data(client, ak8975_index_to_reg[index],
2, (u8 *)&meas_reg);
if (ret < 0) {
dev_err(&client->dev, "Read axis data fails\n");
goto exit;
Expand All @@ -442,30 +413,48 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,

/* Clamp to valid range. */
raw = clamp_t(s16, raw, -4096, 4095);

return sprintf(buf, "%d\n", raw);
*val = raw;
return IIO_VAL_INT;

exit:
mutex_unlock(&data->lock);
return ret;
}

static int ak8975_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2,
long mask)
{
struct ak8975_data *data = iio_priv(indio_dev);

switch (mask) {
case 0:
return ak8975_read_axis(indio_dev, chan->address, val);
case (1 << IIO_CHAN_INFO_SCALE_SEPARATE):
*val = data->raw_to_gauss[chan->address];
return IIO_VAL_INT;
}
return -EINVAL;
}

#define AK8975_CHANNEL(axis, index) \
{ \
.type = IIO_MAGN, \
.modified = 1, \
.channel2 = IIO_MOD_##axis, \
.info_mask = (1 << IIO_CHAN_INFO_SCALE_SEPARATE), \
.address = index, \
}

static const struct iio_chan_spec ak8975_channels[] = {
AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
};

static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, show_mode, store_mode, 0);
static IIO_DEV_ATTR_MAGN_X_SCALE(S_IRUGO, show_scale, NULL, 0);
static IIO_DEV_ATTR_MAGN_Y_SCALE(S_IRUGO, show_scale, NULL, 1);
static IIO_DEV_ATTR_MAGN_Z_SCALE(S_IRUGO, show_scale, NULL, 2);
static IIO_DEV_ATTR_MAGN_X(show_raw, AK8975_REG_HXL);
static IIO_DEV_ATTR_MAGN_Y(show_raw, AK8975_REG_HYL);
static IIO_DEV_ATTR_MAGN_Z(show_raw, AK8975_REG_HZL);

static struct attribute *ak8975_attr[] = {
&iio_dev_attr_mode.dev_attr.attr,
&iio_dev_attr_magn_x_scale.dev_attr.attr,
&iio_dev_attr_magn_y_scale.dev_attr.attr,
&iio_dev_attr_magn_z_scale.dev_attr.attr,
&iio_dev_attr_magn_x_raw.dev_attr.attr,
&iio_dev_attr_magn_y_raw.dev_attr.attr,
&iio_dev_attr_magn_z_raw.dev_attr.attr,
NULL
};

Expand All @@ -475,6 +464,7 @@ static struct attribute_group ak8975_attr_group = {

static const struct iio_info ak8975_info = {
.attrs = &ak8975_attr_group,
.read_raw = &ak8975_read_raw,
.driver_module = THIS_MODULE,
};

Expand Down Expand Up @@ -530,6 +520,8 @@ static int ak8975_probe(struct i2c_client *client,
data->eoc_irq = client->irq;
data->eoc_gpio = eoc_gpio;
indio_dev->dev.parent = &client->dev;
indio_dev->channels = ak8975_channels;
indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
indio_dev->info = &ak8975_info;
indio_dev->modes = INDIO_DIRECT_MODE;

Expand Down

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