Re: [PATCH v4 8/8] iio: adc: ad7606: add support for AD7606C-{16,18} parts

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On Fri, Sep 6, 2024 at 2:30 AM David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> On 9/5/24 3:24 AM, Alexandru Ardelean wrote:
> > The AD7606C-16 and AD7606C-18 are pretty similar with the AD7606B.
> > The main difference between AD7606C-16 & AD7606C-18 is the precision in
> > bits (16 vs 18).
> > Because of that, some scales need to be defined for the 18-bit variants, as
> > they need to be computed against 2**18 (vs 2**16 for the 16 bit-variants).
> >
> > Because the AD7606C-16,18 also supports bipolar & differential channels,
> > for SW-mode, the default range of 10 V or ±10V should be set at probe.
> > On reset, the default range (in the registers) is set to value 0x3 which
> > corresponds to '±10 V single-ended range', regardless of bipolar or
> > differential configuration.
> >
> > Aside from the scale/ranges, the AD7606C-16 is similar to the AD7606B.
> >
> > The AD7606C-18 variant offers 18-bit precision. Because of this, the
> > requirement to use this chip is that the SPI controller supports padding
> > of 18-bit sequences to 32-bit arrays.
> >
> > Datasheet links:
> >   https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606c-16.pdf
> >   https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606c-18.pdf
> >
> > Signed-off-by: Alexandru Ardelean <aardelean@xxxxxxxxxxxx>
> > ---
> >  drivers/iio/adc/ad7606.c     | 266 +++++++++++++++++++++++++++++++----
> >  drivers/iio/adc/ad7606.h     |  17 ++-
> >  drivers/iio/adc/ad7606_spi.c |  55 ++++++++
> >  3 files changed, 309 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
> > index 4c3fbb28f790..999c4411859e 100644
> > --- a/drivers/iio/adc/ad7606.c
> > +++ b/drivers/iio/adc/ad7606.c
> > @@ -28,14 +28,44 @@
> >
> >  #include "ad7606.h"
> >
> > +typedef void (*ad7606c_chan_setup_cb_t)(struct ad7606_state *st, int ch,
> > +                                     bool bipolar, bool differential);
> > +
> >  /*
> >   * Scales are computed as 5000/32768 and 10000/32768 respectively,
> >   * so that when applied to the raw values they provide mV values
> >   */
> > -static const unsigned int ad7606_scale_avail[2] = {
> > +static const unsigned int ad7606_16bit_hw_scale_avail[2] = {
> >       152588, 305176
> >  };
> >
> > +static const unsigned int ad7606_18bit_hw_scale_avail[2] = {
> > +     38147, 76294
> > +};
> > +
> > +static const unsigned int ad7606c_16_scale_single_ended_unipolar_avail[3] = {
> > +     76294, 152588, 190735,
> > +};
> > +
> > +static const unsigned int ad7606c_16_scale_single_ended_bipolar_avail[5] = {
> > +     76294, 152588, 190735, 305176, 381470
> > +};
> > +
> > +static const unsigned int ad7606c_16_scale_differential_bipolar_avail[4] = {
> > +     152588, 305176, 381470, 610352
> > +};
> > +
> > +static const unsigned int ad7606c_18_scale_single_ended_unipolar_avail[3] = {
> > +     19073, 38147, 47684
> > +};
> > +
> > +static const unsigned int ad7606c_18_scale_single_ended_bipolar_avail[5] = {
> > +     19073, 38147, 47684, 76294, 95367
> > +};
> > +
> > +static const unsigned int ad7606c_18_scale_differential_bipolar_avail[4] = {
> > +     38147, 76294, 95367, 152588
> > +};
> >
> >  static const unsigned int ad7616_sw_scale_avail[3] = {
> >       76293, 152588, 305176
> > @@ -82,11 +112,19 @@ static int ad7606_reg_access(struct iio_dev *indio_dev,
> >       }
> >  }
> >
> > -static int ad7606_read_samples(struct ad7606_state *st)
> > +static int ad7606_read_samples(struct ad7606_state *st, bool sign_extend_samples)
> >  {
> > +     unsigned int storagebits = st->chip_info->channels[1].scan_type.storagebits;
>
> Why [1]? Sure, they are all the same, but [0] would seem less arbitrary.

[0] is the timestamp channel.


>
> >       unsigned int num = st->chip_info->num_channels - 1;
> > -     u16 *data = st->data;
> > -     int ret;
> > +     u32 *data32 = st->data.d32;
> > +     u16 *data16 = st->data.d16;
> > +     void *data;
> > +     int i, ret;
> > +
> > +     if (storagebits > 16)
> > +             data = data32;
> > +     else
> > +             data = data16;
> >
> >       /*
> >        * The frstdata signal is set to high while and after reading the sample
> > @@ -108,11 +146,25 @@ static int ad7606_read_samples(struct ad7606_state *st)
> >                       return -EIO;
> >               }
> >
> > -             data++;
> > +             if (storagebits > 16)
> > +                     data32++;
> > +             else
> > +                     data16++;
> >               num--;
> >       }
> >
> > -     return st->bops->read_block(st->dev, num, data);
> > +     ret = st->bops->read_block(st->dev, num, data);
>
> Since data++ was removed, this looks broken now as well as the
> other read_block() not visible in the diff.
>
> Maybe better to drop data32 and data16, keep the change of data
> to void*, and change data++ to data += BITS_TO_BYTES(storagebits)?
>
> Although, all of this might be moot since it looks like this
> needs to be rebased on [1].
>
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?h=fixes-togreg&id=90826e08468ba7fb35d8b39645b22d9e80004afe

Oh.
Omitted that patch.
I forgot that fixes-togreg has a different cadence in another branch.

>
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (storagebits == 16 || !sign_extend_samples)
> > +             return 0;
> > +
> > +     /* For 18 bit samples, we need to sign-extend samples to 32 bits */
> > +     for (i = 0; i < num; i++)
> > +             data32[i] = sign_extend32(data32[i], 17);> +
> > +     return 0;
> >  }
> >
> >  static irqreturn_t ad7606_trigger_handler(int irq, void *p)
> > @@ -124,11 +176,11 @@ static irqreturn_t ad7606_trigger_handler(int irq, void *p)
> >
> >       guard(mutex)(&st->lock);
> >
> > -     ret = ad7606_read_samples(st);
> > +     ret = ad7606_read_samples(st, true);
>
> Shouldn't the sign_extend parameter depend on if the data is unipolar or bipolar?

[c1]
Sign-extension is only needed for 18-bit samples.
16-bit samples are already properly sign(ed), but to 16-bits.

It's a slight performance improvement, that may look quirky here.
The idea here, is that for ad7606_scan_direct() we only need to
sign-extend 1 sample of the 8 samples we get.
And we need to sign-extend it to 32 bits regardless of it being 16-bit
or 18-bit.

In ad7606_trigger_handler(), the 16-bit samples were pushed as-is.
Which means that we need to sign-extend the samples at least for
18-bits (as it is a new part)
The question now becomes if we should sign-extend to 32-bits, 16-bit
samples in ad7606_trigger_handler(), as that may break some ABI.

>
> >       if (ret)
> >               goto error_ret;
> >
> > -     iio_push_to_buffers_with_timestamp(indio_dev, st->data,
> > +     iio_push_to_buffers_with_timestamp(indio_dev, st->data.d16,
> >                                          iio_get_time_ns(indio_dev));
> >  error_ret:
> >       iio_trigger_notify_done(indio_dev->trig);
> > @@ -142,6 +194,7 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
> >                             int *val)
> >  {
> >       struct ad7606_state *st = iio_priv(indio_dev);
> > +     unsigned int storagebits = st->chip_info->channels[1].scan_type.storagebits;
> >       int ret;
> >
> >       gpiod_set_value(st->gpio_convst, 1);
> > @@ -152,9 +205,13 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
> >               goto error_ret;
> >       }
> >
> > -     ret = ad7606_read_samples(st);
> > -     if (ret == 0)
> > -             *val = sign_extend32(st->data[ch], 15);
> > +     ret = ad7606_read_samples(st, false);
>
> Why not let ad7606_read_samples() do the sign extending since
> it can do that now?

Related to comment [c1]

>
> > +     if (ret == 0) {
> > +             if (storagebits > 16)
> > +                     *val = sign_extend32(st->data.d32[ch], 17);
> > +             else
> > +                     *val = sign_extend32(st->data.d16[ch], 15);
> > +     }
> >
> >  error_ret:
> >       gpiod_set_value(st->gpio_convst, 0);
> > @@ -267,7 +324,7 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
> >                       ch = chan->address;
> >               cs = &st->chan_scales[ch];
> >               i = find_closest(val2, cs->scale_avail, cs->num_scales);
> > -             ret = st->write_scale(indio_dev, ch, i);
> > +             ret = st->write_scale(indio_dev, ch, i + cs->reg_offset);
> >               if (ret < 0)
> >                       return ret;
> >               cs->range = i;
> > @@ -350,6 +407,18 @@ static const struct iio_chan_spec ad7606_channels_16bit[] = {
> >       AD7606_CHANNEL(7, 16),
> >  };
> >
> > +static const struct iio_chan_spec ad7606_channels_18bit[] = {
> > +     IIO_CHAN_SOFT_TIMESTAMP(8),
> > +     AD7606_CHANNEL(0, 18),
> > +     AD7606_CHANNEL(1, 18),
> > +     AD7606_CHANNEL(2, 18),
> > +     AD7606_CHANNEL(3, 18),
> > +     AD7606_CHANNEL(4, 18),
> > +     AD7606_CHANNEL(5, 18),
> > +     AD7606_CHANNEL(6, 18),
> > +     AD7606_CHANNEL(7, 18),
> > +};
> > +
> >  /*
> >   * The current assumption that this driver makes for AD7616, is that it's
> >   * working in Hardware Mode with Serial, Burst and Sequencer modes activated.
> > @@ -410,6 +479,18 @@ static const struct ad7606_chip_info ad7606_chip_info_tbl[] = {
> >               .oversampling_avail = ad7606_oversampling_avail,
> >               .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
> >       },
> > +     [ID_AD7606C_16] = {
> > +             .channels = ad7606_channels_16bit,
> > +             .num_channels = 9,
>
> Could be nice to have a cleanup patch before this to convert others to
> use ARRAY_SIZE(), then use ARRAY_SIZE(ad7606_channels_16bit) here
> instead of 9.

Ack.

>
> > +             .oversampling_avail = ad7606_oversampling_avail,
> > +             .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
> > +     },
> > +     [ID_AD7606C_18] = {
> > +             .channels = ad7606_channels_18bit,
> > +             .num_channels = 9,
> > +             .oversampling_avail = ad7606_oversampling_avail,
> > +             .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
> > +     },
> >       [ID_AD7616] = {
> >               .channels = ad7616_channels,
> >               .num_channels = 17,
> > @@ -581,7 +662,122 @@ static const struct iio_trigger_ops ad7606_trigger_ops = {
> >       .validate_device = iio_trigger_validate_own_device,
> >  };
> >
> > -static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
> > +static void ad7606c_18_chan_setup(struct ad7606_state *st, int ch,
> > +                               bool bipolar, bool differential)
> > +{
> > +     struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> > +
> > +     if (differential) {
> > +             cs->scale_avail =
> > +                     ad7606c_18_scale_differential_bipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_18_scale_differential_bipolar_avail);
> > +             /* Bipolar differential ranges start at 8 (b1000) */
> > +             cs->reg_offset = 8;
> > +             cs->range = 1;
> > +     } else if (bipolar) {
> > +             cs->scale_avail =
> > +                     ad7606c_18_scale_single_ended_bipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_18_scale_single_ended_bipolar_avail);
>
> I guess cs->reg_offset is 0 for this one?

Yes.
I will make it explicit.

>
> > +             cs->range = 3;
> > +     } else {
> > +             cs->scale_avail =
> > +                     ad7606c_18_scale_single_ended_unipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_18_scale_single_ended_unipolar_avail);
> > +             /* Unipolar single-ended ranges start at 5 (b0101) */
> > +             cs->reg_offset = 5;
> > +             cs->range = 1;
> > +     }
> > +}
> > +
> > +static void ad7606c_16_chan_setup(struct ad7606_state *st, int ch,
> > +                               bool bipolar, bool differential)
> > +{
> > +     struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> > +
> > +     if (differential) {
> > +             cs->scale_avail =
> > +                     ad7606c_16_scale_differential_bipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_16_scale_differential_bipolar_avail);
> > +             /* Bipolar differential ranges start at 8 (b1000) */
> > +             cs->reg_offset = 8;
> > +             cs->range = 1;
> > +     } else if (bipolar) {
> > +             cs->scale_avail =
> > +                     ad7606c_16_scale_single_ended_bipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_16_scale_single_ended_bipolar_avail);
> > +             cs->range = 3;
> > +     } else {
> > +             cs->scale_avail =
> > +                     ad7606c_16_scale_single_ended_unipolar_avail;
> > +             cs->num_scales =
> > +                     ARRAY_SIZE(ad7606c_16_scale_single_ended_unipolar_avail);
> > +             /* Unipolar single-ended ranges start at 5 (b0101) */
> > +             cs->reg_offset = 5;
> > +             cs->range = 1;
> > +     }
> > +}
> > +
> > +static int ad7606c_sw_mode_setup_channels(struct iio_dev *indio_dev,
> > +                                       ad7606c_chan_setup_cb_t chan_setup_cb)
> > +{
> > +     unsigned int num_channels = indio_dev->num_channels - 1;
> > +     struct ad7606_state *st = iio_priv(indio_dev);
> > +     bool chan_configured[AD760X_MAX_CHANNELS] = {};
> > +     struct device *dev = st->dev;
> > +     int ret;
> > +     u32 ch;
> > +
> > +     /* We need to hook this first */
>
> Comment would be more useful if it said why.

Ack.
Will add.

>
> > +     ret = st->bops->sw_mode_config(indio_dev);
> > +     if (ret)
> > +             return ret;
> > +
> > +     device_for_each_child_node_scoped(dev, child) {
> > +             bool bipolar, differential;
> > +             u32 pins[2];
> > +
> > +             ret = fwnode_property_read_u32(child, "reg", &ch);
> > +             if (ret)
> > +                     continue;
> > +
> > +             /* channel number (here) is from 1 to num_channels */
> > +             if (ch == 0 || ch > num_channels) {
> > +                     dev_warn(st->dev,
> > +                              "Invalid channel number (ignoring): %d\n", ch);
> > +                     continue;
> > +             }
> > +
> > +             bipolar = fwnode_property_present(child, "bipolar");
>
> IIRC, fwnode_property_read_bool() is preferred for bool/flag properties.

Ack.

>
> > +
> > +             ret = fwnode_property_read_u32_array(child, "diff-channels",
> > +                                                  pins, ARRAY_SIZE(pins));
> > +             /* Channel is differential, if pins are the same as 'reg' */
> > +             if (ret == 0 && pins[0] == ch && pins[1] == ch)
> > +                     differential = true;
> > +             else
> > +                     differential = false;
>
> Would probably better to error on bad pin numbers rather than default to
> not differential.

No strong preference from my side.
Will implement failure/error case.

>
> > +
> > +             ch--;
> > +
> > +             chan_setup_cb(st, ch, bipolar, differential);
> > +             chan_configured[ch] = true;
> > +     }
> > +
> > +     /* Apply default configuration to unconfigured (via DT) channels */
> > +     for (ch = 0; ch < num_channels; ch++) {
> > +             if (!chan_configured[ch])
> > +                     chan_setup_cb(st, ch, false, false);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int ad7606_sw_mode_setup(struct iio_dev *indio_dev, unsigned int id)
> >  {
> >       unsigned int num_channels = indio_dev->num_channels - 1;
> >       struct ad7606_state *st = iio_priv(indio_dev);
> > @@ -596,17 +792,30 @@ static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
> >
> >       indio_dev->info = &ad7606_info_sw_mode;
> >
> > -     /* Scale of 0.076293 is only available in sw mode */
> > -     /* After reset, in software mode, ±10 V is set by default */
> > -     for (ch = 0; ch < num_channels; ch++) {
> > -             struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> > +     switch (id) {
> > +     case ID_AD7606C_18:
> > +             ret = ad7606c_sw_mode_setup_channels(indio_dev,
> > +                                                  ad7606c_18_chan_setup);
> > +             break;
> > +     case ID_AD7606C_16:
> > +             ret = ad7606c_sw_mode_setup_channels(indio_dev,
> > +                                                  ad7606c_16_chan_setup);
> > +             break;
> > +     default:
> > +             /* Scale of 0.076293 is only available in sw mode */
> > +             /* After reset, in software mode, ±10 V is set by default */
> > +             for (ch = 0; ch < num_channels; ch++) {
> > +                     struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> > +
> > +                     cs->scale_avail = ad7616_sw_scale_avail;
> > +                     cs->num_scales = ARRAY_SIZE(ad7616_sw_scale_avail);
> > +                     cs->range = 2;
> > +             }
> >
> > -             cs->scale_avail = ad7616_sw_scale_avail;
> > -             cs->num_scales = ARRAY_SIZE(ad7616_sw_scale_avail);
> > -             cs->range = 2;
> > +             ret = st->bops->sw_mode_config(indio_dev);
> > +             break;
> >       }
> >
> > -     ret = st->bops->sw_mode_config(indio_dev);
> >       if (ret)
> >               return ret;
> >
> > @@ -655,9 +864,16 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
> >       st->oversampling = 1;
> >
> >       cs = &st->chan_scales[0];
> > -     cs->range = 0;
> > -     cs->scale_avail = ad7606_scale_avail;
> > -     cs->num_scales = ARRAY_SIZE(ad7606_scale_avail);
> > +     switch (id) {
> > +     case ID_AD7606C_18:
> > +             cs->scale_avail = ad7606_18bit_hw_scale_avail;
> > +             cs->num_scales = ARRAY_SIZE(ad7606_18bit_hw_scale_avail);
> > +             break;
> > +     default:
> > +             cs->scale_avail = ad7606_16bit_hw_scale_avail;
> > +             cs->num_scales = ARRAY_SIZE(ad7606_16bit_hw_scale_avail);
> > +             break;
> > +     }
> >
> >       ret = devm_regulator_get_enable(dev, "avcc");
> >       if (ret)
> > @@ -706,7 +922,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
> >       st->write_scale = ad7606_write_scale_hw;
> >       st->write_os = ad7606_write_os_hw;
> >
> > -     ret = ad7606_sw_mode_setup(indio_dev);
> > +     ret = ad7606_sw_mode_setup(indio_dev, id);
> >       if (ret)
> >               return ret;
> >
> > diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
> > index 2113ad460c0f..6b0897aa2dc7 100644
> > --- a/drivers/iio/adc/ad7606.h
> > +++ b/drivers/iio/adc/ad7606.h
> > @@ -22,7 +22,7 @@
> >               .scan_type = {                                  \
> >                       .sign = 's',                            \
> >                       .realbits = (bits),                     \
> > -                     .storagebits = (bits),                  \
> > +                     .storagebits = (bits) > 16 ? 32 : 16,   \
> >                       .endianness = IIO_CPU,                  \
> >               },                                              \
> >  }
> > @@ -45,7 +45,7 @@
> >               .scan_type = {                                  \
> >                       .sign = 's',                            \
> >                       .realbits = (bits),                     \
> > -                     .storagebits = (bits),                  \
> > +                     .storagebits = (bits) > 16 ? 32 : 16,   \
> >                       .endianness = IIO_CPU,                  \
> >               },                                              \
> >  }
> > @@ -88,6 +88,8 @@ struct ad7606_chip_info {
> >   *                   such that it can be read via the 'read_avail' hook
> >   * @num_scales               number of elements stored in the scale_avail array
> >   * @range            voltage range selection, selects which scale to apply
> > + * @reg_offset               offset for the register value, to be applied when
> > + *                   writing the value of 'range' to the register value
> >   */
> >  struct ad7606_chan_scale {
> >  #define AD760X_MAX_SCALE_SHOW                (AD760X_MAX_CHANNELS * 2)
> > @@ -95,6 +97,7 @@ struct ad7606_chan_scale {
> >       int                             scale_avail_show[AD760X_MAX_SCALE_SHOW];
> >       unsigned int                    num_scales;
> >       unsigned int                    range;
> > +     unsigned int                    reg_offset;
> >  };
> >
> >  /**
> > @@ -151,9 +154,13 @@ struct ad7606_state {
> >       /*
> >        * DMA (thus cache coherency maintenance) may require the
> >        * transfer buffers to live in their own cache lines.
> > -      * 16 * 16-bit samples + 64-bit timestamp
> > +      * 16 * 16-bit samples + 64-bit timestamp - for AD7616
> > +      * 8 * 32-bit samples + 64-bit timestamp - for AD7616C-18 (and similar)
> >        */
> > -     unsigned short                  data[20] __aligned(IIO_DMA_MINALIGN);
> > +     union {
> > +             unsigned short d16[20];
> > +             unsigned int d32[10];
> > +     } data __aligned(IIO_DMA_MINALIGN);
> >       __be16                          d16[2];
> >  };
> >
> > @@ -192,6 +199,8 @@ enum ad7606_supported_device_ids {
> >       ID_AD7606_6,
> >       ID_AD7606_4,
> >       ID_AD7606B,
> > +     ID_AD7606C_16,
> > +     ID_AD7606C_18,
> >       ID_AD7616,
> >  };
> >
> > diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
> > index e00f58a6a0e9..b8d630ad156d 100644
> > --- a/drivers/iio/adc/ad7606_spi.c
> > +++ b/drivers/iio/adc/ad7606_spi.c
> > @@ -77,6 +77,18 @@ static const struct iio_chan_spec ad7606b_sw_channels[] = {
> >       AD7606_SW_CHANNEL(7, 16),
> >  };
> >
> > +static const struct iio_chan_spec ad7606c_18_sw_channels[] = {
> > +     IIO_CHAN_SOFT_TIMESTAMP(8),
> > +     AD7606_SW_CHANNEL(0, 18),
> > +     AD7606_SW_CHANNEL(1, 18),
> > +     AD7606_SW_CHANNEL(2, 18),
> > +     AD7606_SW_CHANNEL(3, 18),
> > +     AD7606_SW_CHANNEL(4, 18),
> > +     AD7606_SW_CHANNEL(5, 18),
> > +     AD7606_SW_CHANNEL(6, 18),
> > +     AD7606_SW_CHANNEL(7, 18),
> > +};
> > +
> >  static const unsigned int ad7606B_oversampling_avail[9] = {
> >       1, 2, 4, 8, 16, 32, 64, 128, 256
> >  };
> > @@ -120,6 +132,19 @@ static int ad7606_spi_read_block(struct device *dev,
> >       return 0;
> >  }
> >
> > +static int ad7606_spi_read_block18to32(struct device *dev,
> > +                                    int count, void *buf)
> > +{
> > +     struct spi_device *spi = to_spi_device(dev);
> > +     struct spi_transfer xfer = {
> > +             .bits_per_word = 18,
> > +             .len = count,
>
> Isn't count the number of words? .len needs to be the number
> of bytes, so 4 * count.

Oh.
Hmm, I need to check.
I assumed .len is the count of elements, not of bytes.

>
> > +             .rx_buf = buf,
> > +     };
> > +
> > +     return spi_sync_transfer(spi, &xfer, 1);
> > +}
> > +
> >  static int ad7606_spi_reg_read(struct ad7606_state *st, unsigned int addr)
> >  {
> >       struct spi_device *spi = to_spi_device(st->dev);
> > @@ -283,6 +308,19 @@ static int ad7606B_sw_mode_config(struct iio_dev *indio_dev)
> >       return 0;
> >  }
> >
> > +static int ad7606c_18_sw_mode_config(struct iio_dev *indio_dev)
> > +{
> > +     int ret;
> > +
> > +     ret = ad7606B_sw_mode_config(indio_dev);
> > +     if (ret)
> > +             return ret;
> > +
> > +     indio_dev->channels = ad7606c_18_sw_channels;
> > +
> > +     return 0;
> > +}
> > +
> >  static const struct ad7606_bus_ops ad7606_spi_bops = {
> >       .read_block = ad7606_spi_read_block,
> >  };
> > @@ -305,6 +343,15 @@ static const struct ad7606_bus_ops ad7606B_spi_bops = {
> >       .sw_mode_config = ad7606B_sw_mode_config,
> >  };
> >
> > +static const struct ad7606_bus_ops ad7606c_18_spi_bops = {
> > +     .read_block = ad7606_spi_read_block18to32,
> > +     .reg_read = ad7606_spi_reg_read,
> > +     .reg_write = ad7606_spi_reg_write,
> > +     .write_mask = ad7606_spi_write_mask,
> > +     .rd_wr_cmd = ad7606B_spi_rd_wr_cmd,
> > +     .sw_mode_config = ad7606c_18_sw_mode_config,
> > +};
> > +
> >  static int ad7606_spi_probe(struct spi_device *spi)
> >  {
> >       const struct spi_device_id *id = spi_get_device_id(spi);
> > @@ -315,8 +362,12 @@ static int ad7606_spi_probe(struct spi_device *spi)
> >               bops = &ad7616_spi_bops;
> >               break;
> >       case ID_AD7606B:
> > +     case ID_AD7606C_16:
> >               bops = &ad7606B_spi_bops;
> >               break;
> > +     case ID_AD7606C_18:
> > +             bops = &ad7606c_18_spi_bops;
> > +             break;
> >       default:
> >               bops = &ad7606_spi_bops;
> >               break;
> > @@ -333,6 +384,8 @@ static const struct spi_device_id ad7606_id_table[] = {
> >       { "ad7606-6", ID_AD7606_6 },
> >       { "ad7606-8", ID_AD7606_8 },
> >       { "ad7606b",  ID_AD7606B },
> > +     { "ad7606c-16",  ID_AD7606C_16 },
> > +     { "ad7606c-18",  ID_AD7606C_18 },
> >       { "ad7616",   ID_AD7616 },
> >       { }
> >  };
> > @@ -344,6 +397,8 @@ static const struct of_device_id ad7606_of_match[] = {
> >       { .compatible = "adi,ad7606-6" },
> >       { .compatible = "adi,ad7606-8" },
> >       { .compatible = "adi,ad7606b" },
> > +     { .compatible = "adi,ad7606c-16" },
> > +     { .compatible = "adi,ad7606c-18" },
> >       { .compatible = "adi,ad7616" },
> >       { }
> >  };
>





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