Re: [PATCH v7 8/8] iio: adc: ad7606: add support for AD7606C-{16,18} parts

[Alexandru Ardelean]

On Thu, Sep 19, 2024 at 4:05 PM Alexandru Ardelean
<aardelean@xxxxxxxxxxxx> 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: https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606c-16.pdf
> Datasheet: 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     | 263 +++++++++++++++++++++++++++++++++--
>  drivers/iio/adc/ad7606.h     |  16 ++-
>  drivers/iio/adc/ad7606_spi.c |  55 ++++++++
>  3 files changed, 322 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
> index b909ee14fd81..f04e5660d2f8 100644
> --- a/drivers/iio/adc/ad7606.c
> +++ b/drivers/iio/adc/ad7606.c
> @@ -36,6 +36,33 @@ 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_16bit_single_ended_unipolar_scale_avail[3] = {
> +       76294, 152588, 190735,
> +};
> +
> +static const unsigned int ad7606c_16bit_single_ended_bipolar_scale_avail[5] = {
> +       76294, 152588, 190735, 305176, 381470
> +};
> +
> +static const unsigned int ad7606c_16bit_differential_bipolar_scale_avail[4] = {
> +       152588, 305176, 381470, 610352
> +};
> +
> +static const unsigned int ad7606c_18bit_single_ended_unipolar_scale_avail[3] = {
> +       19073, 38147, 47684
> +};
> +
> +static const unsigned int ad7606c_18bit_single_ended_bipolar_scale_avail[5] = {
> +       19073, 38147, 47684, 76294, 95367
> +};
> +
> +static const unsigned int ad7606c_18bit_differential_bipolar_scale_avail[4] = {
> +       38147, 76294, 95367, 152588
> +};
>
>  static const unsigned int ad7606_16bit_sw_scale_avail[3] = {
>         76293, 152588, 305176
> @@ -62,7 +89,8 @@ int ad7606_reset(struct ad7606_state *st)
>  }
>  EXPORT_SYMBOL_NS_GPL(ad7606_reset, IIO_AD7606);
>
> -static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st, int ch)
> +static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st,
> +                                        struct iio_chan_spec *chan, int ch)
>  {
>         struct ad7606_chan_scale *cs = &st->chan_scales[ch];
>
> @@ -83,6 +111,173 @@ static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st, int ch)
>         return 0;
>  }
>
> +static int ad7606_get_chan_config(struct ad7606_state *st, int ch,
> +                                 bool *bipolar, bool *differential)
> +{
> +       unsigned int num_channels = st->chip_info->num_channels - 1;
> +       struct device *dev = st->dev;
> +       int ret;
> +
> +       *bipolar = false;
> +       *differential = false;
> +
> +       device_for_each_child_node_scoped(dev, child) {
> +               u32 pins[2];
> +               int reg;
> +
> +               ret = fwnode_property_read_u32(child, "reg", &reg);
> +               if (ret)
> +                       continue;
> +
> +               /* channel number (here) is from 1 to num_channels */
> +               if (reg == 0 || reg > num_channels) {
> +                       dev_warn(dev,
> +                                "Invalid channel number (ignoring): %d\n", reg);
> +                       continue;
> +               }
> +
> +               if (reg != (ch + 1))
> +                       continue;
> +
> +               *bipolar = fwnode_property_read_bool(child, "bipolar");
> +
> +               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] != reg || pins[1] != reg)) {
> +                       dev_err(dev,
> +                               "Differential pins must be the same as 'reg'");
> +                       return -EINVAL;
> +               }
> +
> +               *differential = (ret == 0);
> +
> +               if (*differential && !*bipolar) {
> +                       dev_err(dev,
> +                               "'bipolar' must be added for diff channel %d\n",
> +                               reg);
> +                       return -EINVAL;
> +               }
> +
> +               return 0;
> +       }
> +
> +       return 0;
> +}
> +
> +static int ad7606c_18bit_chan_scale_setup(struct ad7606_state *st,
> +                                         struct iio_chan_spec *chan, int ch)
> +{
> +       struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> +       bool bipolar, differential;
> +       int ret;
> +
> +       if (!st->sw_mode_en) {
> +               cs->range = 0;
> +               cs->scale_avail = ad7606_18bit_hw_scale_avail;
> +               cs->num_scales = ARRAY_SIZE(ad7606_18bit_hw_scale_avail);
> +               return 0;
> +       }
> +
> +       ret = ad7606_get_chan_config(st, ch, &bipolar, &differential);
> +       if (ret)
> +               return ret;
> +
> +       if (differential) {
> +               cs->scale_avail = ad7606c_18bit_differential_bipolar_scale_avail;
> +               cs->num_scales =
> +                       ARRAY_SIZE(ad7606c_18bit_differential_bipolar_scale_avail);
> +               /* Bipolar differential ranges start at 8 (b1000) */
> +               cs->reg_offset = 8;
> +               cs->range = 1;
> +               chan->differential = 1;
> +               chan->channel2 = chan->channel;
> +
> +               return 0;
> +       }
> +
> +       chan->differential = 0;
> +
> +       if (bipolar) {
> +               cs->scale_avail = ad7606c_18bit_single_ended_bipolar_scale_avail;
> +               cs->num_scales =
> +                       ARRAY_SIZE(ad7606c_18bit_single_ended_bipolar_scale_avail);
> +               /* Bipolar single-ended ranges start at 0 (b0000) */
> +               cs->reg_offset = 0;
> +               cs->range = 3;
> +               chan->scan_type.sign = 's';
> +
> +               return 0;
> +       }
> +
> +       cs->scale_avail = ad7606c_18bit_single_ended_unipolar_scale_avail;
> +       cs->num_scales =
> +               ARRAY_SIZE(ad7606c_18bit_single_ended_unipolar_scale_avail);
> +       /* Unipolar single-ended ranges start at 5 (b0101) */
> +       cs->reg_offset = 5;
> +       cs->range = 1;
> +       chan->scan_type.sign = 'u';
> +
> +       return 0;
> +}
> +
> +static int ad7606c_16bit_chan_scale_setup(struct ad7606_state *st,
> +                                         struct iio_chan_spec *chan, int ch)
> +{
> +       struct ad7606_chan_scale *cs = &st->chan_scales[ch];
> +       bool bipolar, differential;
> +       int ret;
> +
> +       if (!st->sw_mode_en) {
> +               cs->range = 0;
> +               cs->scale_avail = ad7606_16bit_hw_scale_avail;
> +               cs->num_scales = ARRAY_SIZE(ad7606_16bit_hw_scale_avail);
> +               return 0;
> +       }
> +
> +       ret = ad7606_get_chan_config(st, ch, &bipolar, &differential);
> +       if (ret)
> +               return ret;
> +
> +       if (differential) {
> +               cs->scale_avail = ad7606c_16bit_differential_bipolar_scale_avail;
> +               cs->num_scales =
> +                       ARRAY_SIZE(ad7606c_16bit_differential_bipolar_scale_avail);
> +               /* Bipolar differential ranges start at 8 (b1000) */
> +               cs->reg_offset = 8;
> +               cs->range = 1;
> +               chan->differential = 1;
> +               chan->channel2 = chan->channel;
> +               chan->scan_type.sign = 's';
> +
> +               return 0;
> +       }
> +
> +       chan->differential = 0;
> +
> +       if (bipolar) {
> +               cs->scale_avail = ad7606c_16bit_single_ended_bipolar_scale_avail;
> +               cs->num_scales =
> +                       ARRAY_SIZE(ad7606c_16bit_single_ended_bipolar_scale_avail);
> +               /* Bipolar single-ended ranges start at 0 (b0000) */
> +               cs->reg_offset = 0;
> +               cs->range = 3;
> +               chan->scan_type.sign = 's';
> +
> +               return 0;
> +       }
> +
> +       cs->scale_avail = ad7606c_16bit_single_ended_unipolar_scale_avail;
> +       cs->num_scales =
> +               ARRAY_SIZE(ad7606c_16bit_single_ended_unipolar_scale_avail);
> +       /* Unipolar single-ended ranges start at 5 (b0101) */
> +       cs->reg_offset = 5;
> +       cs->range = 1;
> +       chan->scan_type.sign = 'u';
> +
> +       return 0;
> +}
> +
>  static int ad7606_reg_access(struct iio_dev *indio_dev,
>                              unsigned int reg,
>                              unsigned int writeval,
> @@ -107,9 +302,8 @@ static int ad7606_reg_access(struct iio_dev *indio_dev,
>  static int ad7606_read_samples(struct ad7606_state *st)
>  {
>         unsigned int num = st->chip_info->num_channels - 1;
> -       u16 *data = st->data;
>
> -       return st->bops->read_block(st->dev, num, data);
> +       return st->bops->read_block(st->dev, num, &st->data);
>  }
>
>  static irqreturn_t ad7606_trigger_handler(int irq, void *p)
> @@ -125,7 +319,7 @@ static irqreturn_t ad7606_trigger_handler(int irq, void *p)
>         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,
>                                            iio_get_time_ns(indio_dev));
>  error_ret:
>         iio_trigger_notify_done(indio_dev->trig);
> @@ -139,6 +333,8 @@ 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;
> +       const struct iio_chan_spec *chan;
>         int ret;
>
>         gpiod_set_value(st->gpio_convst, 1);
> @@ -153,7 +349,19 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
>         if (ret)
>                 goto error_ret;
>
> -       *val = sign_extend32(st->data[ch], 15);
> +       chan = &indio_dev->channels[ch + 1];
> +       if (chan->scan_type.sign == 'u') {
> +               if (storagebits > 16)
> +                       *val = st->data.buf32[ch];
> +               else
> +                       *val = st->data.buf16[ch];
> +               return 0;

Arrggh...
I messed up here.
Guillaume found a bug here, where this should be "goto error_ret" or
do an "if ()  {} else {}"
How should we do it here?

Do we send a fix-patch or send a new series?


> +       }
> +
> +       if (storagebits > 16)
> +               *val = sign_extend32(st->data.buf32[ch], 17);
> +       else
> +               *val = sign_extend32(st->data.buf16[ch], 15);
>
>  error_ret:
>         gpiod_set_value(st->gpio_convst, 0);
> @@ -266,7 +474,7 @@ 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;
> @@ -349,6 +557,18 @@ 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.
> @@ -414,6 +634,20 @@ 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,
> +               .scale_setup_cb = ad7606c_16bit_chan_scale_setup,
> +               .oversampling_avail = ad7606_oversampling_avail,
> +               .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
> +       },
> +       [ID_AD7606C_18] = {
> +               .channels = ad7606_channels_18bit,
> +               .num_channels = 9,
> +               .scale_setup_cb = ad7606c_18bit_chan_scale_setup,
> +               .oversampling_avail = ad7606_oversampling_avail,
> +               .oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
> +       },
>         [ID_AD7616] = {
>                 .channels = ad7616_channels,
>                 .num_channels = 17,
> @@ -586,7 +820,7 @@ 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 int ad7606_sw_mode_setup(struct iio_dev *indio_dev, unsigned int id)
>  {
>         struct ad7606_state *st = iio_priv(indio_dev);
>
> @@ -604,13 +838,24 @@ static int ad7606_chan_scales_setup(struct iio_dev *indio_dev)
>  {
>         unsigned int num_channels = indio_dev->num_channels - 1;
>         struct ad7606_state *st = iio_priv(indio_dev);
> +       struct iio_chan_spec *chans;
> +       size_t size;
>         int ch, ret;
>
> +       /* Clone IIO channels, since some may be differential */
> +       size = indio_dev->num_channels * sizeof(*indio_dev->channels);
> +       chans = devm_kzalloc(st->dev, size, GFP_KERNEL);
> +       if (!chans)
> +               return -ENOMEM;
> +
> +       memcpy(chans, indio_dev->channels, size);
> +       indio_dev->channels = chans;
> +
>         for (ch = 0; ch < num_channels; ch++) {
>                 struct ad7606_chan_scale *cs;
>                 int i;
>
> -               ret = st->chip_info->scale_setup_cb(st, ch);
> +               ret = st->chip_info->scale_setup_cb(st, &chans[ch + 1], ch);
>                 if (ret)
>                         return ret;
>
> @@ -698,7 +943,7 @@ 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 25e84efd15c3..14ee75aa225b 100644
> --- a/drivers/iio/adc/ad7606.h
> +++ b/drivers/iio/adc/ad7606.h
> @@ -63,7 +63,8 @@
>
>  struct ad7606_state;
>
> -typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st, int ch);
> +typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
> +                                      struct iio_chan_spec *chan, int ch);
>
>  /**
>   * struct ad7606_chip_info - chip specific information
> @@ -94,6 +95,8 @@ 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_SCALES              16
> @@ -102,6 +105,7 @@ struct ad7606_chan_scale {
>         int                             scale_avail_show[AD760X_MAX_SCALE_SHOW];
>         unsigned int                    num_scales;
>         unsigned int                    range;
> +       unsigned int                    reg_offset;
>  };
>
>  /**
> @@ -158,9 +162,13 @@ 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 {
> +               u16 buf16[20];
> +               u32 buf32[10];
> +       } data __aligned(IIO_DMA_MINALIGN);
>         __be16                          d16[2];
>  };
>
> @@ -201,6 +209,8 @@ 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..143440e73aab 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 * sizeof(u32),
> +               .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" },
>         { }
>  };
> --
> 2.46.0
>