| Message ID | 20240618160836.945242-9-olivier.moysan@foss.st.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | iio: adc: dfsdm: add scaling support | expand |
On Tue, 2024-06-18 at 18:08 +0200, Olivier Moysan wrote: > Add scaling support to STM32 DFSDM. > > Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com> > --- Just some general comments... Acked-by: Nuno Sa <nuno.sa@analog.com> > drivers/iio/adc/Kconfig | 1 + > drivers/iio/adc/stm32-dfsdm-adc.c | 94 ++++++++++++++++++++++++++++++- > 2 files changed, 92 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index f3dfdaa80678..858ae8161fa4 100644 > ... > @@ -1301,6 +1339,8 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, > ret = stm32_dfsdm_single_conv(indio_dev, chan, val); > if (adc->hwc) > iio_hw_consumer_disable(adc->hwc); > + if (adc->backend[idx]) > + iio_backend_disable(&indio_dev->dev, adc->backend[idx]); > if (ret < 0) { > dev_err(&indio_dev->dev, > "%s: Conversion failed (channel %d)\n", > @@ -1320,6 +1360,45 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, > *val = adc->sample_freq; > > return IIO_VAL_INT; > + > + case IIO_CHAN_INFO_SCALE: > + /* > + * Scale is expressed in mV. > + * When fast mode is disabled, actual resolution may be lower > + * than 2^n, where n=realbits-1. > + * This leads to underestimating input voltage. To > + * compensate this deviation, the voltage reference can be > + * corrected with a factor = realbits resolution / actual max > + */ > + if (adc->backend[idx]) { > + iio_backend_read_raw(adc->backend[idx], val, val2, mask); > + This is something that I've been thinking about since the beginning of backends support. Basically having the "catch all" read_raw()/write_raw() or more dedicated interfaces. For example, in your usecase I think it would make more sense to have dedicated API's like iio_backend_read_scale() and iio_backend_read_offset() as you're extending that functionality. Calling iio_backend_read_raw() seems a bit weird to me. OTOH, iio_backend_read_raw() could be useful in cases where frontends call iio_backend_extend_chan_spec() and may get some functionality they are not aware of. And so, in the default: statement this "catch all" API could be used. Anyways, this are really minor (likely pedantic) details and you kind of came first and made the decision for me. As I don't really have strong feelings about it, I'm fine with it as-is. > + *val = div_u64((u64)*val * (u64)BIT(DFSDM_DATA_RES - 1), > max); > + *val2 = chan->scan_type.realbits; > + if (chan->differential) > + *val *= 2; > + } > + return IIO_VAL_FRACTIONAL_LOG2; > + > + case IIO_CHAN_INFO_OFFSET: > + /* > + * DFSDM output data are in the range [-2^n,2^n], > + * with n=realbits-1. > + * - Differential modulator: > + * Offset correspond to SD modulator offset. > + * - Single ended modulator: > + * Input is in [0V,Vref] range, where 0V corresponds to -2^n, and > Vref to 2^n. > + * Add 2^n to offset. (i.e. middle of input range) > + * offset = offset(sd) * vref / res(sd) * max / vref. > + */ > + if (adc->backend[idx]) { > + iio_backend_read_raw(adc->backend[idx], val, val2, mask); > + > + *val = div_u64((u64)max * *val, BIT(*val2 - 1)); > + if (!chan->differential) > + *val += max; > + } > + return IIO_VAL_INT; > } > > return -EINVAL; > @@ -1449,7 +1528,15 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev > *indio_dev, struct iio_c > * IIO_CHAN_INFO_RAW: used to compute regular conversion > * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling > */ > - ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); > + if (child) { > + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > + BIT(IIO_CHAN_INFO_SCALE) | > + BIT(IIO_CHAN_INFO_OFFSET); Not sure if the above SCALE and OFFSET are solely properties if the backend. If so, you could maybe use iio_backend_extend_chan_spec(). - Nuno Sá
Hi Nuno, On 6/19/24 07:47, Nuno Sá wrote: > On Tue, 2024-06-18 at 18:08 +0200, Olivier Moysan wrote: >> Add scaling support to STM32 DFSDM. >> >> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com> >> --- > > Just some general comments... > > Acked-by: Nuno Sa <nuno.sa@analog.com> > >> drivers/iio/adc/Kconfig | 1 + >> drivers/iio/adc/stm32-dfsdm-adc.c | 94 ++++++++++++++++++++++++++++++- >> 2 files changed, 92 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig >> index f3dfdaa80678..858ae8161fa4 100644 >> > > ... > >> @@ -1301,6 +1339,8 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, >> ret = stm32_dfsdm_single_conv(indio_dev, chan, val); >> if (adc->hwc) >> iio_hw_consumer_disable(adc->hwc); >> + if (adc->backend[idx]) >> + iio_backend_disable(&indio_dev->dev, adc->backend[idx]); >> if (ret < 0) { >> dev_err(&indio_dev->dev, >> "%s: Conversion failed (channel %d)\n", >> @@ -1320,6 +1360,45 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, >> *val = adc->sample_freq; >> >> return IIO_VAL_INT; >> + >> + case IIO_CHAN_INFO_SCALE: >> + /* >> + * Scale is expressed in mV. >> + * When fast mode is disabled, actual resolution may be lower >> + * than 2^n, where n=realbits-1. >> + * This leads to underestimating input voltage. To >> + * compensate this deviation, the voltage reference can be >> + * corrected with a factor = realbits resolution / actual max >> + */ >> + if (adc->backend[idx]) { >> + iio_backend_read_raw(adc->backend[idx], val, val2, mask); >> + > > This is something that I've been thinking about since the beginning of backends > support. Basically having the "catch all" read_raw()/write_raw() or more dedicated > interfaces. For example, in your usecase I think it would make more sense to have > dedicated API's like iio_backend_read_scale() and iio_backend_read_offset() as you're > extending that functionality. Calling iio_backend_read_raw() seems a bit weird to me. > > OTOH, iio_backend_read_raw() could be useful in cases where frontends call > iio_backend_extend_chan_spec() and may get some functionality they are not aware of. > And so, in the default: statement this "catch all" API could be used. > > Anyways, this are really minor (likely pedantic) details and you kind of came first > and made the decision for me. As I don't really have strong feelings about it, I'm > fine with it as-is. > My first idea was to stick to IIO read_raw API ('struct iio_chan_spec const *chan' should at least be added to prototype as you pointed it out). But I agree that iio_backend_read_raw() is not explicit regarding the requested info. I consider using the existing API iio_backend_ext_info_get() for v2, as you suggested. BRs Olivier >> + *val = div_u64((u64)*val * (u64)BIT(DFSDM_DATA_RES - 1), >> max); >> + *val2 = chan->scan_type.realbits; >> + if (chan->differential) >> + *val *= 2; >> + } >> + return IIO_VAL_FRACTIONAL_LOG2; >> + >> + case IIO_CHAN_INFO_OFFSET: >> + /* >> + * DFSDM output data are in the range [-2^n,2^n], >> + * with n=realbits-1. >> + * - Differential modulator: >> + * Offset correspond to SD modulator offset. >> + * - Single ended modulator: >> + * Input is in [0V,Vref] range, where 0V corresponds to -2^n, and >> Vref to 2^n. >> + * Add 2^n to offset. (i.e. middle of input range) >> + * offset = offset(sd) * vref / res(sd) * max / vref. >> + */ >> + if (adc->backend[idx]) { >> + iio_backend_read_raw(adc->backend[idx], val, val2, mask); >> + >> + *val = div_u64((u64)max * *val, BIT(*val2 - 1)); >> + if (!chan->differential) >> + *val += max; >> + } >> + return IIO_VAL_INT; >> } >> >> return -EINVAL; >> @@ -1449,7 +1528,15 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev >> *indio_dev, struct iio_c >> * IIO_CHAN_INFO_RAW: used to compute regular conversion >> * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling >> */ >> - ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); >> + if (child) { >> + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | >> + BIT(IIO_CHAN_INFO_SCALE) | >> + BIT(IIO_CHAN_INFO_OFFSET); > > Not sure if the above SCALE and OFFSET are solely properties if the backend. If so, > you could maybe use iio_backend_extend_chan_spec(). > > - Nuno Sá >
On Tue, 18 Jun 2024 18:08:34 +0200 Olivier Moysan <olivier.moysan@foss.st.com> wrote: > Add scaling support to STM32 DFSDM. Perhaps a short description here of how this works? Where does the scale come from, what assumptions are made etc. > > Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com> Some minor stuff. > diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c > index 69b4764d7cba..93bf6035bd6d 100644 > --- a/drivers/iio/adc/stm32-dfsdm-adc.c > +++ b/drivers/iio/adc/stm32-dfsdm-adc.c urn 0; > } > > @@ -1060,7 +1072,7 @@ static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev, > static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) > { > struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); > - int ret; > + int i = 0, ret; Don't mix assigned and unassigned variable declarations. Just use a separate line as this can mean subtle assignment or lack of assignment issues sneak in. > > /* Reset adc buffer index */ > adc->bufi = 0; > @@ -1071,6 +1083,15 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) > return ret; > } > > + if (adc->backend) { > + while (adc->backend[i]) { Could do similar to the suggestion below. Mostly I don't like the index variable manipulation. > + ret = iio_backend_enable(&indio_dev->dev, adc->backend[i]); > + if (ret < 0) > + return ret; > + i++; > + } > + } > + > ret = stm32_dfsdm_start_dfsdm(adc->dfsdm); > if (ret < 0) > goto err_stop_hwc; > @@ -1103,6 +1124,7 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) > static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) > { > struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); > + int i = 0; > > stm32_dfsdm_stop_conv(indio_dev); > > @@ -1110,6 +1132,13 @@ static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) > > stm32_dfsdm_stop_dfsdm(adc->dfsdm); > > + if (adc->backend) { > + while (adc->backend[i]) { > + iio_backend_disable(&indio_dev->dev, adc->backend[i]); > + i++; > + } Something like struct iio_backend **be = &adc->backend[0]; do { iio_backend_disable(&indio-dev->dev, be); } while (be++); maybe. Up to you. > + } > @@ -1320,6 +1360,45 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, > *val = adc->sample_freq; > > return IIO_VAL_INT; > + > + case IIO_CHAN_INFO_SCALE: > + /* > + * Scale is expressed in mV. > + * When fast mode is disabled, actual resolution may be lower > + * than 2^n, where n=realbits-1. As below, use a few more spaces. > + * This leads to underestimating input voltage. To > + * compensate this deviation, the voltage reference can be > + * corrected with a factor = realbits resolution / actual max > + */ > + if (adc->backend[idx]) { > + iio_backend_read_raw(adc->backend[idx], val, val2, mask); > + > + *val = div_u64((u64)*val * (u64)BIT(DFSDM_DATA_RES - 1), max); > + *val2 = chan->scan_type.realbits; > + if (chan->differential) > + *val *= 2; > + } > + return IIO_VAL_FRACTIONAL_LOG2; > + > + case IIO_CHAN_INFO_OFFSET: > + /* > + * DFSDM output data are in the range [-2^n,2^n], Use a few more spaces. [-2^2, 2^n] > + * with n=realbits-1. n = realbits - 1 Just to keep it closer to the C coding style. > + * - Differential modulator: > + * Offset correspond to SD modulator offset. > + * - Single ended modulator: > + * Input is in [0V,Vref] range, where 0V corresponds to -2^n, and Vref to 2^n. Avoid that long line with a suitable line break. > + * Add 2^n to offset. (i.e. middle of input range) > + * offset = offset(sd) * vref / res(sd) * max / vref. > + */ > + if (adc->backend[idx]) { > + iio_backend_read_raw(adc->backend[idx], val, val2, mask); > + > + *val = div_u64((u64)max * *val, BIT(*val2 - 1)); > + if (!chan->differential) > + *val += max; > + } > + return IIO_VAL_INT; > } > > return -EINVAL; > @@ -1449,7 +1528,15 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev, struct iio_c > * IIO_CHAN_INFO_RAW: used to compute regular conversion > * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling > */ > - ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); > + if (child) { > + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > + BIT(IIO_CHAN_INFO_SCALE) | > + BIT(IIO_CHAN_INFO_OFFSET); Indent looks a little odd. Maybe one more space neede? > + } else { > + /* Legacy. Scaling not supported */ > + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); > + } > + > ch->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | > BIT(IIO_CHAN_INFO_SAMP_FREQ); > > @@ -1816,3 +1903,4 @@ module_platform_driver(stm32_dfsdm_adc_driver); > MODULE_DESCRIPTION("STM32 sigma delta ADC"); > MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>"); > MODULE_LICENSE("GPL v2"); > +MODULE_IMPORT_NS(IIO_BACKEND);
Hi Jonathan, On 6/23/24 17:21, Jonathan Cameron wrote: > On Tue, 18 Jun 2024 18:08:34 +0200 > Olivier Moysan <olivier.moysan@foss.st.com> wrote: > >> Add scaling support to STM32 DFSDM. > Perhaps a short description here of how this works? Where does the scale come > from, what assumptions are made etc. >> Sure. Requires more explanations. Done >> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com> > > Some minor stuff. > >> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c >> index 69b4764d7cba..93bf6035bd6d 100644 >> --- a/drivers/iio/adc/stm32-dfsdm-adc.c >> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c > urn 0; >> } >> >> @@ -1060,7 +1072,7 @@ static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev, >> static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) >> { >> struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); >> - int ret; >> + int i = 0, ret; > > Don't mix assigned and unassigned variable declarations. Just use a separate line > as this can mean subtle assignment or lack of assignment issues sneak in. > Ack >> >> /* Reset adc buffer index */ >> adc->bufi = 0; >> @@ -1071,6 +1083,15 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) >> return ret; >> } >> >> + if (adc->backend) { >> + while (adc->backend[i]) { > > Could do similar to the suggestion below. > Mostly I don't like the index variable manipulation. > >> + ret = iio_backend_enable(&indio_dev->dev, adc->backend[i]); >> + if (ret < 0) >> + return ret; >> + i++; >> + } >> + } >> + >> ret = stm32_dfsdm_start_dfsdm(adc->dfsdm); >> if (ret < 0) >> goto err_stop_hwc; >> @@ -1103,6 +1124,7 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) >> static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) >> { >> struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); >> + int i = 0; >> >> stm32_dfsdm_stop_conv(indio_dev); >> >> @@ -1110,6 +1132,13 @@ static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) >> >> stm32_dfsdm_stop_dfsdm(adc->dfsdm); >> >> + if (adc->backend) { >> + while (adc->backend[i]) { >> + iio_backend_disable(&indio_dev->dev, adc->backend[i]); >> + i++; >> + } > Something like > struct iio_backend **be = &adc->backend[0]; > do { > iio_backend_disable(&indio-dev->dev, be); > } while (be++); > > maybe. Up to you. > If you don't mind, I will keep indexes. Pointers here looks more difficult to read, and pre/post incrementation in the loop condition can easily introduce bugs, imho. > >> + } > >> @@ -1320,6 +1360,45 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, >> *val = adc->sample_freq; >> >> return IIO_VAL_INT; >> + >> + case IIO_CHAN_INFO_SCALE: >> + /* >> + * Scale is expressed in mV. >> + * When fast mode is disabled, actual resolution may be lower >> + * than 2^n, where n=realbits-1. > > As below, use a few more spaces. > >> + * This leads to underestimating input voltage. To >> + * compensate this deviation, the voltage reference can be >> + * corrected with a factor = realbits resolution / actual max >> + */ >> + if (adc->backend[idx]) { >> + iio_backend_read_raw(adc->backend[idx], val, val2, mask); >> + >> + *val = div_u64((u64)*val * (u64)BIT(DFSDM_DATA_RES - 1), max); >> + *val2 = chan->scan_type.realbits; >> + if (chan->differential) >> + *val *= 2; >> + } >> + return IIO_VAL_FRACTIONAL_LOG2; >> + >> + case IIO_CHAN_INFO_OFFSET: >> + /* >> + * DFSDM output data are in the range [-2^n,2^n], > Use a few more spaces. [-2^2, 2^n] >> + * with n=realbits-1. > n = realbits - 1 > > Just to keep it closer to the C coding style. > Done >> + * - Differential modulator: >> + * Offset correspond to SD modulator offset. >> + * - Single ended modulator: >> + * Input is in [0V,Vref] range, where 0V corresponds to -2^n, and Vref to 2^n. > > Avoid that long line with a suitable line break. > Ack >> + * Add 2^n to offset. (i.e. middle of input range) >> + * offset = offset(sd) * vref / res(sd) * max / vref. >> + */ >> + if (adc->backend[idx]) { >> + iio_backend_read_raw(adc->backend[idx], val, val2, mask); >> + >> + *val = div_u64((u64)max * *val, BIT(*val2 - 1)); >> + if (!chan->differential) >> + *val += max; >> + } >> + return IIO_VAL_INT; >> } >> >> return -EINVAL; >> @@ -1449,7 +1528,15 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev, struct iio_c >> * IIO_CHAN_INFO_RAW: used to compute regular conversion >> * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling >> */ >> - ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); >> + if (child) { >> + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | >> + BIT(IIO_CHAN_INFO_SCALE) | >> + BIT(IIO_CHAN_INFO_OFFSET); > > Indent looks a little odd. Maybe one more space neede? > Ack >> + } else { >> + /* Legacy. Scaling not supported */ >> + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); >> + } >> + >> ch->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | >> BIT(IIO_CHAN_INFO_SAMP_FREQ); >> >> @@ -1816,3 +1903,4 @@ module_platform_driver(stm32_dfsdm_adc_driver); >> MODULE_DESCRIPTION("STM32 sigma delta ADC"); >> MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>"); >> MODULE_LICENSE("GPL v2"); >> +MODULE_IMPORT_NS(IIO_BACKEND); > BRs Olivier
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index f3dfdaa80678..858ae8161fa4 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -1223,6 +1223,7 @@ config STM32_DFSDM_ADC select IIO_BUFFER select IIO_BUFFER_HW_CONSUMER select IIO_TRIGGERED_BUFFER + select IIO_BACKEND help Select this option to support ADCSigma delta modulator for STMicroelectronics STM32 digital filter for sigma delta converter. diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index 69b4764d7cba..93bf6035bd6d 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -9,6 +9,7 @@ #include <linux/dmaengine.h> #include <linux/dma-mapping.h> #include <linux/iio/adc/stm32-dfsdm-adc.h> +#include <linux/iio/backend.h> #include <linux/iio/buffer.h> #include <linux/iio/hw-consumer.h> #include <linux/iio/sysfs.h> @@ -78,6 +79,7 @@ struct stm32_dfsdm_adc { /* ADC specific */ unsigned int oversamp; struct iio_hw_consumer *hwc; + struct iio_backend **backend; struct completion completion; u32 *buffer; @@ -672,6 +674,8 @@ static int stm32_dfsdm_generic_channel_parse_of(struct stm32_dfsdm *dfsdm, struct fwnode_handle *node) { struct stm32_dfsdm_channel *df_ch; + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + struct iio_backend *backend; const char *of_str; int ret, val; @@ -721,6 +725,14 @@ static int stm32_dfsdm_generic_channel_parse_of(struct stm32_dfsdm *dfsdm, if (ret != -EINVAL) df_ch->alt_si = 0; + if (adc->dev_data->type == DFSDM_IIO) { + backend = devm_iio_backend_subnode_get(&indio_dev->dev, NULL, node); + if (IS_ERR(backend)) + return dev_err_probe(&indio_dev->dev, PTR_ERR(backend), + "Failed to get backend\n"); + adc->backend[ch->scan_index] = backend; + } + return 0; } @@ -1060,7 +1072,7 @@ static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev, static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); - int ret; + int i = 0, ret; /* Reset adc buffer index */ adc->bufi = 0; @@ -1071,6 +1083,15 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) return ret; } + if (adc->backend) { + while (adc->backend[i]) { + ret = iio_backend_enable(&indio_dev->dev, adc->backend[i]); + if (ret < 0) + return ret; + i++; + } + } + ret = stm32_dfsdm_start_dfsdm(adc->dfsdm); if (ret < 0) goto err_stop_hwc; @@ -1103,6 +1124,7 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev) static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + int i = 0; stm32_dfsdm_stop_conv(indio_dev); @@ -1110,6 +1132,13 @@ static int stm32_dfsdm_predisable(struct iio_dev *indio_dev) stm32_dfsdm_stop_dfsdm(adc->dfsdm); + if (adc->backend) { + while (adc->backend[i]) { + iio_backend_disable(&indio_dev->dev, adc->backend[i]); + i++; + } + } + if (adc->hwc) iio_hw_consumer_disable(adc->hwc); @@ -1282,7 +1311,14 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, int *val2, long mask) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); - int ret; + + struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id]; + struct stm32_dfsdm_filter_osr *flo = &fl->flo[fl->fast]; + u32 max = flo->max << (flo->lshift - chan->scan_type.shift); + int ret, idx = chan->scan_index; + + if (flo->lshift < chan->scan_type.shift) + max = flo->max >> (chan->scan_type.shift - flo->lshift); switch (mask) { case IIO_CHAN_INFO_RAW: @@ -1291,6 +1327,8 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, return ret; if (adc->hwc) ret = iio_hw_consumer_enable(adc->hwc); + if (adc->backend[idx]) + ret = iio_backend_enable(&indio_dev->dev, adc->backend[idx]); if (ret < 0) { dev_err(&indio_dev->dev, "%s: IIO enable failed (channel %d)\n", @@ -1301,6 +1339,8 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, ret = stm32_dfsdm_single_conv(indio_dev, chan, val); if (adc->hwc) iio_hw_consumer_disable(adc->hwc); + if (adc->backend[idx]) + iio_backend_disable(&indio_dev->dev, adc->backend[idx]); if (ret < 0) { dev_err(&indio_dev->dev, "%s: Conversion failed (channel %d)\n", @@ -1320,6 +1360,45 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev, *val = adc->sample_freq; return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + /* + * Scale is expressed in mV. + * When fast mode is disabled, actual resolution may be lower + * than 2^n, where n=realbits-1. + * This leads to underestimating input voltage. To + * compensate this deviation, the voltage reference can be + * corrected with a factor = realbits resolution / actual max + */ + if (adc->backend[idx]) { + iio_backend_read_raw(adc->backend[idx], val, val2, mask); + + *val = div_u64((u64)*val * (u64)BIT(DFSDM_DATA_RES - 1), max); + *val2 = chan->scan_type.realbits; + if (chan->differential) + *val *= 2; + } + return IIO_VAL_FRACTIONAL_LOG2; + + case IIO_CHAN_INFO_OFFSET: + /* + * DFSDM output data are in the range [-2^n,2^n], + * with n=realbits-1. + * - Differential modulator: + * Offset correspond to SD modulator offset. + * - Single ended modulator: + * Input is in [0V,Vref] range, where 0V corresponds to -2^n, and Vref to 2^n. + * Add 2^n to offset. (i.e. middle of input range) + * offset = offset(sd) * vref / res(sd) * max / vref. + */ + if (adc->backend[idx]) { + iio_backend_read_raw(adc->backend[idx], val, val2, mask); + + *val = div_u64((u64)max * *val, BIT(*val2 - 1)); + if (!chan->differential) + *val += max; + } + return IIO_VAL_INT; } return -EINVAL; @@ -1449,7 +1528,15 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev, struct iio_c * IIO_CHAN_INFO_RAW: used to compute regular conversion * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling */ - ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); + if (child) { + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE) | + BIT(IIO_CHAN_INFO_OFFSET); + } else { + /* Legacy. Scaling not supported */ + ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); + } + ch->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | BIT(IIO_CHAN_INFO_SAMP_FREQ); @@ -1816,3 +1903,4 @@ module_platform_driver(stm32_dfsdm_adc_driver); MODULE_DESCRIPTION("STM32 sigma delta ADC"); MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>"); MODULE_LICENSE("GPL v2"); +MODULE_IMPORT_NS(IIO_BACKEND);
Add scaling support to STM32 DFSDM. Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com> --- drivers/iio/adc/Kconfig | 1 + drivers/iio/adc/stm32-dfsdm-adc.c | 94 ++++++++++++++++++++++++++++++- 2 files changed, 92 insertions(+), 3 deletions(-)