iio: addac: ad74413r: fix Current Input, Loop Powered Mode
Commit Message
Currently, the driver handles CH_FUNC_CURRENT_INPUT_LOOP_POWER and
CH_FUNC_CURRENT_INPUT_EXT_POWER completely identically. But that's not
correct. In order for CH_FUNC_CURRENT_INPUT_LOOP_POWER to work, two
changes must be made:
(1) expose access to the DAC_CODE_x register so that the intended
output current can be set, i.e. expose the channel as both current
output and current input, and
(2) per the data sheet
When selecting the current input loop powered function, tie the
VIOUTN_x pin to ground via the on-chip 200 kΩ resistor by enabling
the CH_200K_TO_GND bit in the ADC_CONFIGx registers.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
There's of course also CH_FUNC_CURRENT_INPUT_LOOP_POWER_HART which is
likely to require a similar fix, but as I don't have a ad74413r I
can't test that.
drivers/iio/addac/ad74413r.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
Comments
On Wed, 1 Mar 2023 12:55:11 +0100
Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
> Currently, the driver handles CH_FUNC_CURRENT_INPUT_LOOP_POWER and
> CH_FUNC_CURRENT_INPUT_EXT_POWER completely identically. But that's not
> correct. In order for CH_FUNC_CURRENT_INPUT_LOOP_POWER to work, two
> changes must be made:
>
> (1) expose access to the DAC_CODE_x register so that the intended
> output current can be set, i.e. expose the channel as both current
> output and current input, and
>
> (2) per the data sheet
>
> When selecting the current input loop powered function, tie the
> VIOUTN_x pin to ground via the on-chip 200 kΩ resistor by enabling
> the CH_200K_TO_GND bit in the ADC_CONFIGx registers.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> There's of course also CH_FUNC_CURRENT_INPUT_LOOP_POWER_HART which is
> likely to require a similar fix, but as I don't have a ad74413r I
> can't test that.
Looks correct to me based on the "current input, loop powered" section
of the datasheet, but want to leave a little more time for someone
familiar with the part to comment.
Given me a poke if I seem to have lost this in 2 weeks. (That happens
less now I track with patchwork, but you never know ;)
Thanks,
Jonathan
>
> drivers/iio/addac/ad74413r.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
> index f32c8c2fb26d..f5d072092709 100644
> --- a/drivers/iio/addac/ad74413r.c
> +++ b/drivers/iio/addac/ad74413r.c
> @@ -99,6 +99,7 @@ struct ad74413r_state {
> #define AD74413R_REG_ADC_CONFIG_X(x) (0x05 + (x))
> #define AD74413R_ADC_CONFIG_RANGE_MASK GENMASK(7, 5)
> #define AD74413R_ADC_CONFIG_REJECTION_MASK GENMASK(4, 3)
> +#define AD74413R_ADC_CONFIG_CH_200K_TO_GND BIT(2)
> #define AD74413R_ADC_RANGE_10V 0b000
> #define AD74413R_ADC_RANGE_2P5V_EXT_POW 0b001
> #define AD74413R_ADC_RANGE_2P5V_INT_POW 0b010
> @@ -424,9 +425,20 @@ static int ad74413r_set_channel_dac_code(struct ad74413r_state *st,
> static int ad74413r_set_channel_function(struct ad74413r_state *st,
> unsigned int channel, u8 func)
> {
> - return regmap_update_bits(st->regmap,
> + int ret;
> +
> + ret = regmap_update_bits(st->regmap,
> AD74413R_REG_CH_FUNC_SETUP_X(channel),
> AD74413R_CH_FUNC_SETUP_MASK, func);
> + if (ret)
> + return ret;
> +
> + if (func == CH_FUNC_CURRENT_INPUT_LOOP_POWER)
> + ret = regmap_set_bits(st->regmap,
> + AD74413R_REG_ADC_CONFIG_X(channel),
> + AD74413R_ADC_CONFIG_CH_200K_TO_GND);
> +
> + return ret;
> }
>
> static int ad74413r_set_adc_conv_seq(struct ad74413r_state *st,
> @@ -1112,6 +1124,11 @@ static struct iio_chan_spec ad74413r_current_input_channels[] = {
> AD74413R_ADC_CURRENT_CHANNEL,
> };
>
> +static struct iio_chan_spec ad74413r_current_input_loop_channels[] = {
> + AD74413R_DAC_CHANNEL(IIO_CURRENT, BIT(IIO_CHAN_INFO_SCALE)),
> + AD74413R_ADC_CURRENT_CHANNEL,
> +};
> +
> static struct iio_chan_spec ad74413r_resistance_input_channels[] = {
> AD74413R_ADC_CHANNEL(IIO_RESISTANCE, BIT(IIO_CHAN_INFO_PROCESSED)),
> };
> @@ -1135,7 +1152,7 @@ static const struct ad74413r_channels ad74413r_channels_map[] = {
> [CH_FUNC_CURRENT_OUTPUT] = AD74413R_CHANNELS(current_output),
> [CH_FUNC_VOLTAGE_INPUT] = AD74413R_CHANNELS(voltage_input),
> [CH_FUNC_CURRENT_INPUT_EXT_POWER] = AD74413R_CHANNELS(current_input),
> - [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input),
> + [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input_loop),
> [CH_FUNC_RESISTANCE_INPUT] = AD74413R_CHANNELS(resistance_input),
> [CH_FUNC_DIGITAL_INPUT_LOGIC] = AD74413R_CHANNELS(digital_input),
> [CH_FUNC_DIGITAL_INPUT_LOOP_POWER] = AD74413R_CHANNELS(digital_input),
On Sat, 4 Mar 2023 17:15:42 +0000
Jonathan Cameron <jic23@kernel.org> wrote:
> On Wed, 1 Mar 2023 12:55:11 +0100
> Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
>
> > Currently, the driver handles CH_FUNC_CURRENT_INPUT_LOOP_POWER and
> > CH_FUNC_CURRENT_INPUT_EXT_POWER completely identically. But that's not
> > correct. In order for CH_FUNC_CURRENT_INPUT_LOOP_POWER to work, two
> > changes must be made:
> >
> > (1) expose access to the DAC_CODE_x register so that the intended
> > output current can be set, i.e. expose the channel as both current
> > output and current input, and
> >
> > (2) per the data sheet
> >
> > When selecting the current input loop powered function, tie the
> > VIOUTN_x pin to ground via the on-chip 200 kΩ resistor by enabling
> > the CH_200K_TO_GND bit in the ADC_CONFIGx registers.
> >
> > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> > ---
> > There's of course also CH_FUNC_CURRENT_INPUT_LOOP_POWER_HART which is
> > likely to require a similar fix, but as I don't have a ad74413r I
> > can't test that.
>
> Looks correct to me based on the "current input, loop powered" section
> of the datasheet, but want to leave a little more time for someone
> familiar with the part to comment.
>
> Given me a poke if I seem to have lost this in 2 weeks. (That happens
> less now I track with patchwork, but you never know ;)
>
> Thanks,
>
> Jonathan
Applied, Thanks
Jonathan
>
> >
> > drivers/iio/addac/ad74413r.c | 21 +++++++++++++++++++--
> > 1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
> > index f32c8c2fb26d..f5d072092709 100644
> > --- a/drivers/iio/addac/ad74413r.c
> > +++ b/drivers/iio/addac/ad74413r.c
> > @@ -99,6 +99,7 @@ struct ad74413r_state {
> > #define AD74413R_REG_ADC_CONFIG_X(x) (0x05 + (x))
> > #define AD74413R_ADC_CONFIG_RANGE_MASK GENMASK(7, 5)
> > #define AD74413R_ADC_CONFIG_REJECTION_MASK GENMASK(4, 3)
> > +#define AD74413R_ADC_CONFIG_CH_200K_TO_GND BIT(2)
> > #define AD74413R_ADC_RANGE_10V 0b000
> > #define AD74413R_ADC_RANGE_2P5V_EXT_POW 0b001
> > #define AD74413R_ADC_RANGE_2P5V_INT_POW 0b010
> > @@ -424,9 +425,20 @@ static int ad74413r_set_channel_dac_code(struct ad74413r_state *st,
> > static int ad74413r_set_channel_function(struct ad74413r_state *st,
> > unsigned int channel, u8 func)
> > {
> > - return regmap_update_bits(st->regmap,
> > + int ret;
> > +
> > + ret = regmap_update_bits(st->regmap,
> > AD74413R_REG_CH_FUNC_SETUP_X(channel),
> > AD74413R_CH_FUNC_SETUP_MASK, func);
> > + if (ret)
> > + return ret;
> > +
> > + if (func == CH_FUNC_CURRENT_INPUT_LOOP_POWER)
> > + ret = regmap_set_bits(st->regmap,
> > + AD74413R_REG_ADC_CONFIG_X(channel),
> > + AD74413R_ADC_CONFIG_CH_200K_TO_GND);
> > +
> > + return ret;
> > }
> >
> > static int ad74413r_set_adc_conv_seq(struct ad74413r_state *st,
> > @@ -1112,6 +1124,11 @@ static struct iio_chan_spec ad74413r_current_input_channels[] = {
> > AD74413R_ADC_CURRENT_CHANNEL,
> > };
> >
> > +static struct iio_chan_spec ad74413r_current_input_loop_channels[] = {
> > + AD74413R_DAC_CHANNEL(IIO_CURRENT, BIT(IIO_CHAN_INFO_SCALE)),
> > + AD74413R_ADC_CURRENT_CHANNEL,
> > +};
> > +
> > static struct iio_chan_spec ad74413r_resistance_input_channels[] = {
> > AD74413R_ADC_CHANNEL(IIO_RESISTANCE, BIT(IIO_CHAN_INFO_PROCESSED)),
> > };
> > @@ -1135,7 +1152,7 @@ static const struct ad74413r_channels ad74413r_channels_map[] = {
> > [CH_FUNC_CURRENT_OUTPUT] = AD74413R_CHANNELS(current_output),
> > [CH_FUNC_VOLTAGE_INPUT] = AD74413R_CHANNELS(voltage_input),
> > [CH_FUNC_CURRENT_INPUT_EXT_POWER] = AD74413R_CHANNELS(current_input),
> > - [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input),
> > + [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input_loop),
> > [CH_FUNC_RESISTANCE_INPUT] = AD74413R_CHANNELS(resistance_input),
> > [CH_FUNC_DIGITAL_INPUT_LOGIC] = AD74413R_CHANNELS(digital_input),
> > [CH_FUNC_DIGITAL_INPUT_LOOP_POWER] = AD74413R_CHANNELS(digital_input),
>
@@ -99,6 +99,7 @@ struct ad74413r_state {
#define AD74413R_REG_ADC_CONFIG_X(x) (0x05 + (x))
#define AD74413R_ADC_CONFIG_RANGE_MASK GENMASK(7, 5)
#define AD74413R_ADC_CONFIG_REJECTION_MASK GENMASK(4, 3)
+#define AD74413R_ADC_CONFIG_CH_200K_TO_GND BIT(2)
#define AD74413R_ADC_RANGE_10V 0b000
#define AD74413R_ADC_RANGE_2P5V_EXT_POW 0b001
#define AD74413R_ADC_RANGE_2P5V_INT_POW 0b010
@@ -424,9 +425,20 @@ static int ad74413r_set_channel_dac_code(struct ad74413r_state *st,
static int ad74413r_set_channel_function(struct ad74413r_state *st,
unsigned int channel, u8 func)
{
- return regmap_update_bits(st->regmap,
+ int ret;
+
+ ret = regmap_update_bits(st->regmap,
AD74413R_REG_CH_FUNC_SETUP_X(channel),
AD74413R_CH_FUNC_SETUP_MASK, func);
+ if (ret)
+ return ret;
+
+ if (func == CH_FUNC_CURRENT_INPUT_LOOP_POWER)
+ ret = regmap_set_bits(st->regmap,
+ AD74413R_REG_ADC_CONFIG_X(channel),
+ AD74413R_ADC_CONFIG_CH_200K_TO_GND);
+
+ return ret;
}
static int ad74413r_set_adc_conv_seq(struct ad74413r_state *st,
@@ -1112,6 +1124,11 @@ static struct iio_chan_spec ad74413r_current_input_channels[] = {
AD74413R_ADC_CURRENT_CHANNEL,
};
+static struct iio_chan_spec ad74413r_current_input_loop_channels[] = {
+ AD74413R_DAC_CHANNEL(IIO_CURRENT, BIT(IIO_CHAN_INFO_SCALE)),
+ AD74413R_ADC_CURRENT_CHANNEL,
+};
+
static struct iio_chan_spec ad74413r_resistance_input_channels[] = {
AD74413R_ADC_CHANNEL(IIO_RESISTANCE, BIT(IIO_CHAN_INFO_PROCESSED)),
};
@@ -1135,7 +1152,7 @@ static const struct ad74413r_channels ad74413r_channels_map[] = {
[CH_FUNC_CURRENT_OUTPUT] = AD74413R_CHANNELS(current_output),
[CH_FUNC_VOLTAGE_INPUT] = AD74413R_CHANNELS(voltage_input),
[CH_FUNC_CURRENT_INPUT_EXT_POWER] = AD74413R_CHANNELS(current_input),
- [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input),
+ [CH_FUNC_CURRENT_INPUT_LOOP_POWER] = AD74413R_CHANNELS(current_input_loop),
[CH_FUNC_RESISTANCE_INPUT] = AD74413R_CHANNELS(resistance_input),
[CH_FUNC_DIGITAL_INPUT_LOGIC] = AD74413R_CHANNELS(digital_input),
[CH_FUNC_DIGITAL_INPUT_LOOP_POWER] = AD74413R_CHANNELS(digital_input),