We basically use the same for formating the DACs scale in almost all DAC
drivers. So put this into a common helper function which does the job for us.
The helper function uses 64-bit math to be as accurate as possible to minimize
the error we get when multiplying out_voltage_scale with out_voltage_raw.
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
---
drivers/staging/iio/dac/ad5064.c | 15 ++++++---------
drivers/staging/iio/dac/ad5360.c | 15 ++++++---------
drivers/staging/iio/dac/ad5446.c | 7 +------
drivers/staging/iio/dac/ad5504.c | 7 +------
drivers/staging/iio/dac/ad5624r_spi.c | 7 +------
drivers/staging/iio/dac/ad5686.c | 8 +-------
drivers/staging/iio/dac/ad5791.c | 4 +---
drivers/staging/iio/dac/dac.h | 24 ++++++++++++++++++++++++
8 files changed, 41 insertions(+), 46 deletions(-)
diff --git a/drivers/staging/iio/dac/ad5064.c b/drivers/staging/iio/dac/ad5064.c
index 867e4ab..a3ffb4f 100644
--- a/drivers/staging/iio/dac/ad5064.c
+++ b/drivers/staging/iio/dac/ad5064.c
@@ -281,7 +281,7 @@ static int ad5064_read_raw(struct iio_dev *indio_dev,
{
struct ad5064_state *st = iio_priv(indio_dev);
unsigned int vref;
- int scale_uv;
+ int vref_uv;
switch (m) {
case 0:
@@ -289,14 +289,11 @@ static int ad5064_read_raw(struct iio_dev *indio_dev,
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
vref = st->chip_info->shared_vref ? 0 : chan->channel;
- scale_uv = regulator_get_voltage(st->vref_reg[vref].consumer);
- if (scale_uv < 0)
- return scale_uv;
-
- scale_uv = (scale_uv * 100) >> chan->scan_type.realbits;
- *val = scale_uv / 100000;
- *val2 = (scale_uv % 100000) * 10;
- return IIO_VAL_INT_PLUS_MICRO;
+ vref_uv = regulator_get_voltage(st->vref_reg[vref].consumer);
+ if (vref_uv < 0)
+ return vref_uv;
+
+ return iio_dac_format_scale(vref_uv, chan, val, val2);
default:
break;
}
diff --git a/drivers/staging/iio/dac/ad5360.c b/drivers/staging/iio/dac/ad5360.c
index 012d714..8fbd68b 100644
--- a/drivers/staging/iio/dac/ad5360.c
+++ b/drivers/staging/iio/dac/ad5360.c
@@ -372,7 +372,7 @@ static int ad5360_read_raw(struct iio_dev *indio_dev,
{
struct ad5360_state *st = iio_priv(indio_dev);
unsigned int ofs_index;
- int scale_uv;
+ int vref_uv;
int ret;
switch (m) {
@@ -385,14 +385,11 @@ static int ad5360_read_raw(struct iio_dev *indio_dev,
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/* vout = 4 * vref * dac_code */
- scale_uv = ad5360_get_channel_vref(st, chan->channel) * 4 * 100;
- if (scale_uv < 0)
- return scale_uv;
-
- scale_uv >>= (chan->scan_type.realbits);
- *val = scale_uv / 100000;
- *val2 = (scale_uv % 100000) * 10;
- return IIO_VAL_INT_PLUS_MICRO;
+ vref_uv = ad5360_get_channel_vref(st, chan->channel) * 4 * 100;
+ if (vref_uv < 0)
+ return vref_uv;
+
+ return iio_dac_format_scale(vref_uv, chan, val, val2);
case IIO_CHAN_INFO_CALIBBIAS:
ret = ad5360_read(indio_dev, AD5360_READBACK_OFFSET,
chan->address);
diff --git a/drivers/staging/iio/dac/ad5446.c b/drivers/staging/iio/dac/ad5446.c
index ef1ad11..6b0fe7f 100644
--- a/drivers/staging/iio/dac/ad5446.c
+++ b/drivers/staging/iio/dac/ad5446.c
@@ -278,15 +278,10 @@ static int ad5446_read_raw(struct iio_dev *indio_dev,
long m)
{
struct ad5446_state *st = iio_priv(indio_dev);
- unsigned long scale_uv;
switch (m) {
case IIO_CHAN_INFO_SCALE:
- scale_uv = (st->vref_mv * 1000) >> chan->scan_type.realbits;
- *val = scale_uv / 1000;
- *val2 = (scale_uv % 1000) * 1000;
- return IIO_VAL_INT_PLUS_MICRO;
-
+ return iio_dac_format_scale(st->vref_mv * 1000, chan, val, val2);
}
return -EINVAL;
}
diff --git a/drivers/staging/iio/dac/ad5504.c b/drivers/staging/iio/dac/ad5504.c
index f20a5dc..7021e83 100644
--- a/drivers/staging/iio/dac/ad5504.c
+++ b/drivers/staging/iio/dac/ad5504.c
@@ -77,7 +77,6 @@ static int ad5504_read_raw(struct iio_dev *indio_dev,
long m)
{
struct ad5504_state *st = iio_priv(indio_dev);
- unsigned long scale_uv;
int ret;
switch (m) {
@@ -90,11 +89,7 @@ static int ad5504_read_raw(struct iio_dev *indio_dev,
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
- scale_uv = (st->vref_mv * 1000) >> chan->scan_type.realbits;
- *val = scale_uv / 1000;
- *val2 = (scale_uv % 1000) * 1000;
- return IIO_VAL_INT_PLUS_MICRO;
-
+ return iio_dac_format_scale(st->vref_mv * 1000, chan, val, val2);
}
return -EINVAL;
}
diff --git a/drivers/staging/iio/dac/ad5624r_spi.c b/drivers/staging/iio/dac/ad5624r_spi.c
index 6cb00e1..76d6a34 100644
--- a/drivers/staging/iio/dac/ad5624r_spi.c
+++ b/drivers/staging/iio/dac/ad5624r_spi.c
@@ -99,15 +99,10 @@ static int ad5624r_read_raw(struct iio_dev *indio_dev,
long m)
{
struct ad5624r_state *st = iio_priv(indio_dev);
- unsigned long scale_uv;
switch (m) {
case IIO_CHAN_INFO_SCALE:
- scale_uv = (st->vref_mv * 1000) >> chan->scan_type.realbits;
- *val = scale_uv / 1000;
- *val2 = (scale_uv % 1000) * 1000;
- return IIO_VAL_INT_PLUS_MICRO;
-
+ return iio_dac_format_scale(st->vref_mv * 1000, chan, val, val2);
}
return -EINVAL;
}
diff --git a/drivers/staging/iio/dac/ad5686.c b/drivers/staging/iio/dac/ad5686.c
index bbaa928..845f79d 100644
--- a/drivers/staging/iio/dac/ad5686.c
+++ b/drivers/staging/iio/dac/ad5686.c
@@ -293,7 +293,6 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
long m)
{
struct ad5686_state *st = iio_priv(indio_dev);
- unsigned long scale_uv;
int ret;
switch (m) {
@@ -307,12 +306,7 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
return IIO_VAL_INT;
break;
case IIO_CHAN_INFO_SCALE:
- scale_uv = (st->vref_mv * 100000)
- >> (chan->scan_type.realbits);
- *val = scale_uv / 100000;
- *val2 = (scale_uv % 100000) * 10;
- return IIO_VAL_INT_PLUS_MICRO;
-
+ return iio_dac_format_scale(st->vref_mv * 1000, chan, val, val2);
}
return -EINVAL;
}
diff --git a/drivers/staging/iio/dac/ad5791.c b/drivers/staging/iio/dac/ad5791.c
index 79c4821..462c423 100644
--- a/drivers/staging/iio/dac/ad5791.c
+++ b/drivers/staging/iio/dac/ad5791.c
@@ -238,9 +238,7 @@ static int ad5791_read_raw(struct iio_dev *indio_dev,
*val >>= chan->scan_type.shift;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
- *val = 0;
- *val2 = (((u64)st->vref_mv) * 1000000ULL) >> chan->scan_type.realbits;
- return IIO_VAL_INT_PLUS_MICRO;
+ return iio_dac_format_scale(st->vref_mv * 1000, chan, val, val2);
case IIO_CHAN_INFO_OFFSET:
val64 = (((u64)st->vref_neg_mv) << chan->scan_type.realbits);
do_div(val64, st->vref_mv);
diff --git a/drivers/staging/iio/dac/dac.h b/drivers/staging/iio/dac/dac.h
index 0754d71..ad43e2f 100644
--- a/drivers/staging/iio/dac/dac.h
+++ b/drivers/staging/iio/dac/dac.h
@@ -2,5 +2,29 @@
* dac.h - sysfs attributes associated with DACs
*/
+#include <linux/math64.h>
+
#define IIO_DEV_ATTR_OUT_RAW(_num, _store, _addr) \
IIO_DEVICE_ATTR(out_voltage##_num##_raw, S_IWUSR, NULL, _store, _addr)
+
+/* iio_dac_format_scale: Helper function for formating the scale attribute for a
+ * DAC.
+ *
+ * @vref_span_uv: span of the reference voltage in microvolts
+ * @chan: channel to format for
+ * @val: val of iio raw_write callback
+ * @val2: val2 of the iio raw_write callback
+ */
+static inline int iio_dac_format_scale(unsigned long vref_span_uv,
+ const struct iio_chan_spec *chan, unsigned int *val, unsigned int *val2)
+{
+ u64 result;
+ u32 _val2;
+
+ result = (((u64)vref_span_uv) * 1000) >> chan->scan_type.realbits;
+
+ *val = div_u64_rem(result, 1000000, &_val2);
+ *val2 = _val2;
+
+ return IIO_VAL_INT_PLUS_MICRO;
+}
--
1.7.7.1
--
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