On Sat, 29 Jul 2017 20:27:13 -0500
David Lechner <david@xxxxxxxxxxxxxx> wrote:
> On 07/28/2017 05:20 PM, Andy Shevchenko wrote:
> > ACPI enabled platforms do not have a mean of regulators. Instead we use
> > hard coded voltage value for reference pin. When value is 0 (default) we
> > fall back to request a regulator.
> >
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > ---
> > drivers/iio/adc/ti-ads7950.c | 24 ++++++++++++++++++++----
> > 1 file changed, 20 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
> > index 16a06633332c..ab669af291b7 100644
> > --- a/drivers/iio/adc/ti-ads7950.c
> > +++ b/drivers/iio/adc/ti-ads7950.c
> > @@ -21,6 +21,7 @@
> > * GNU General Public License for more details.
> > */
> >
> > +#include <linux/acpi.h>
> > #include <linux/bitops.h>
> > #include <linux/device.h>
> > #include <linux/err.h>
> > @@ -37,6 +38,12 @@
> > #include <linux/iio/trigger_consumer.h>
> > #include <linux/iio/triggered_buffer.h>
> >
> > +/*
> > + * In case of ACPI, we use the 5000 mV as default for the reference pin.
> > + * Device tree users encode that via the vref-supply regulator.
> > + */
> > +#define TI_ADS7950_VA_MV_ACPI_DEFAULT 5000
>
> Now that I've thought about it a bit, you don't need to call this the
> ACPI default, just call it the default. Then it will be obvious that
> this is used when you don't have a regulator.
>
> > +
> > #define TI_ADS7950_CR_MANUAL BIT(12)
> > #define TI_ADS7950_CR_WRITE BIT(11)
> > #define TI_ADS7950_CR_CHAN(ch) ((ch) << 7)
> > @@ -58,6 +65,7 @@ struct ti_ads7950_state {
> > struct spi_message scan_single_msg;
> >
> > struct regulator *reg;
> > + unsigned int vref_mv;
> >
> > unsigned int settings;
> >
> > @@ -305,11 +313,15 @@ static int ti_ads7950_get_range(struct ti_ads7950_state *st)
> > {
> > int vref;
> >
> > - vref = regulator_get_voltage(st->reg);
> > - if (vref < 0)
> > - return vref;
> > + if (st->vref_mv) {
> > + vref = st->vref_mv;
> > + } else {
> > + vref = regulator_get_voltage(st->reg);
> > + if (vref < 0)
> > + return vref;
> >
> > - vref /= 1000;
> > + vref /= 1000;
> > + }
> >
> > if (st->settings & TI_ADS7950_CR_RANGE_5V)
> > vref *= 2;
> > @@ -411,6 +423,10 @@ static int ti_ads7950_probe(struct spi_device *spi)
> > spi_message_init_with_transfers(&st->scan_single_msg,
> > st->scan_single_xfer, 3);
> >
> > + /* Use hard coded value for reference voltage in ACPI case */
> > + if (ACPI_COMPANION(&spi->dev))
> > + st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT;
>
> Instead of checking or ACPI, you could just say "if we have a dummy
> regulator, then use the default value".
>
Agreed. Sounds sensible to me. Hopefully in DT people will
provide the right regulator, but chances are this won't
always happen.
Jonathan
> > +
> > st->reg = devm_regulator_get(&spi->dev, "vref");
> > if (IS_ERR(st->reg)) {
> > dev_err(&spi->dev, "Failed get get regulator \"vref\"\n");
> >
>
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