On 10/19/11 14:21, Lars-Peter Clausen wrote:
> On 10/19/2011 03:01 PM, Jonathan Cameron wrote:
>> On 10/19/11 13:23, Lars-Peter Clausen wrote:
>>> The ad5791 currently assumes that the negative and positive supply have the
>>> same absolute value, which is not necessarily true. This patch introduces a
>>> offset attribute which will contain the negative supply voltage scaled
>>> according to the iio spec. The raw attribute now accepts values in the range
>>> of 0 to max instead of -max/2 to max/2.
>>>
>>> While we are at it also fix the vref span calculation. Since both positive and
>>> negative reference voltages are specificed as absolute values we need to add
>>> them and not subtract them to get the reference voltage span.
>> Everything commented here is fine, but one odd looking removal...
Got it now thanks.
>>> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxx>
>>> ---
>>> drivers/staging/iio/dac/ad5791.c | 24 ++++++++++++++++--------
>>> drivers/staging/iio/dac/ad5791.h | 2 ++
>>> 2 files changed, 18 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/staging/iio/dac/ad5791.c b/drivers/staging/iio/dac/ad5791.c
>>> index 9a76c43..c465fcf 100644
>>> --- a/drivers/staging/iio/dac/ad5791.c
>>> +++ b/drivers/staging/iio/dac/ad5791.c
>>> @@ -77,7 +77,8 @@ static int ad5791_spi_read(struct spi_device *spi, u8 addr, u32 *val)
>>> .indexed = 1, \
>>> .address = AD5791_ADDR_DAC0, \
>>> .channel = 0, \
>>> - .info_mask = (1 << IIO_CHAN_INFO_SCALE_SHARED), \
>>> + .info_mask = (1 << IIO_CHAN_INFO_SCALE_SHARED) | \
>>> + (1 << IIO_CHAN_INFO_OFFSET_SHARED), \
>>> .scan_type = IIO_ST('u', bits, 24, shift) \
>>> }
>>>
>>> @@ -225,6 +226,7 @@ static int ad5791_read_raw(struct iio_dev *indio_dev,
>>> long m)
>>> {
>>> struct ad5791_state *st = iio_priv(indio_dev);
>>> + u64 val64;
>>> int ret;
>>>
>>> switch (m) {
>>> @@ -234,12 +236,16 @@ static int ad5791_read_raw(struct iio_dev *indio_dev,
>>> return ret;
>>> *val &= AD5791_DAC_MASK;
>>> *val >>= chan->scan_type.shift;
>>> - *val -= (1 << (chan->scan_type.realbits - 1));
>>> return IIO_VAL_INT;
>>> case (1 << IIO_CHAN_INFO_SCALE_SHARED):
>>> *val = 0;
>>> *val2 = (st->vref_mv * 1000) >> chan->scan_type.realbits;
>>> return IIO_VAL_INT_PLUS_MICRO;
>>> + case (1 << IIO_CHAN_INFO_OFFSET_SHARED):
>>> + val64 = (((u64)st->vref_neg_mv) << chan->scan_type.realbits);
>>> + do_div(val64, st->vref_mv);
>>> + *val = -val64;
>>> + return IIO_VAL_INT;
>>> default:
>>> return -EINVAL;
>>> }
>>> @@ -257,7 +263,6 @@ static int ad5791_write_raw(struct iio_dev *indio_dev,
>>>
>>> switch (mask) {
>>> case 0:
>>> - val += (1 << (chan->scan_type.realbits - 1));
>> This line looks suspicious. What is it doing in this patch?
>> I'll be honest and say I'm not sure why it was there in the first place, but
>> I can't immediately see what it has to do with the rest of the patch.
>
> The driver would previously accept values from -(1 << realbits) / 2 to (1 <<
> realbits) / 2
> for the raw attribute. But this only really works if the the reference
> voltages are symmetrical.
> So what this patch does is to change the raw attribute to accept values from
> 0 to (1 << realbits) -1
> and add the offset attribute which contains the negative offset.
>
>>> val &= AD5791_RES_MASK(chan->scan_type.realbits);
>>> val <<= chan->scan_type.shift;
>>>
>>> @@ -309,12 +314,15 @@ static int __devinit ad5791_probe(struct spi_device *spi)
>>> st->pwr_down = true;
>>> st->spi = spi;
>>>
>>> - if (!IS_ERR(st->reg_vss) && !IS_ERR(st->reg_vdd))
>>> - st->vref_mv = (pos_voltage_uv - neg_voltage_uv) / 1000;
>>> - else if (pdata)
>>> - st->vref_mv = pdata->vref_pos_mv - pdata->vref_neg_mv;
>>> - else
>>> + if (!IS_ERR(st->reg_vss) && !IS_ERR(st->reg_vdd)) {
>>> + st->vref_mv = (pos_voltage_uv + neg_voltage_uv) / 1000;
>>> + st->vref_neg_mv = neg_voltage_uv / 1000;
>>> + } else if (pdata) {
>>> + st->vref_mv = pdata->vref_pos_mv + pdata->vref_neg_mv;
>>> + st->vref_neg_mv = pdata->vref_neg_mv;
>>> + } else {
>>> dev_warn(&spi->dev, "reference voltage unspecified\n");
>>> + }
>>>
>>> ret = ad5791_spi_write(spi, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
>>> if (ret)
>>> diff --git a/drivers/staging/iio/dac/ad5791.h b/drivers/staging/iio/dac/ad5791.h
>>> index 2a50a11..fd7edbd 100644
>>> --- a/drivers/staging/iio/dac/ad5791.h
>>> +++ b/drivers/staging/iio/dac/ad5791.h
>>> @@ -82,6 +82,7 @@ struct ad5791_chip_info {
>>> * @reg_vss: negative supply regulator
>>> * @chip_info: chip model specific constants
>>> * @vref_mv: actual reference voltage used
>>> + * @vref_neg_mv: voltage of the negative supply
>>> * @pwr_down_mode current power down mode
>>> */
>>>
>>> @@ -91,6 +92,7 @@ struct ad5791_state {
>>> struct regulator *reg_vss;
>>> const struct ad5791_chip_info *chip_info;
>>> unsigned short vref_mv;
>>> + unsigned int vref_neg_mv;
>>> unsigned ctrl;
>>> unsigned pwr_down_mode;
>>> bool pwr_down;
>>
>
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