Re: [PATCH v4 8/8] iio: adc: ad7606: add support for AD7606C-{16,18} parts
From: David Lechner
Date: Thu Sep 05 2024 - 19:31:55 EST
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.
> 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
> + 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?
> 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?
> + 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.
> + .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?
> + 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.
> + 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.
> +
> + 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.
> +
> + 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.
> + .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" },
> { }
> };