Re: [PATCH v7 7/8] iio: dac: ad3552r: add high-speed platform driver

Nuno Sá
2024-10-22T12:23:56Z

On Mon, 2024-10-21 at 14:40 +0200, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@baylibre.com>
>
> Add High Speed ad3552r platform driver.
>
> The ad3552r DAC is controlled by a custom (fpga-based) DAC IP
> through the current AXI backend, or similar alternative IIO backend.
>
> Compared to the existing driver (ad3552r.c), that is a simple SPI
> driver, this driver is coupled with a DAC IIO backend that finally
> controls the ad3552r by a fpga-based "QSPI+DDR" interface, to reach
> maximum transfer rate of 33MUPS using dma stream capabilities.
>
> All commands involving QSPI bus read/write are delegated to the backend
> through the provided APIs for bus read/write.
>
> Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
> ---
>  drivers/iio/dac/Kconfig      |  14 ++
>  drivers/iio/dac/Makefile     |   1 +
>  drivers/iio/dac/ad3552r-hs.c | 547
> +++++++++++++++++++++++++++++++++++++++++++
>  drivers/iio/dac/ad3552r-hs.h |  18 ++
>  drivers/iio/dac/ad3552r.h    |   4 +
>  5 files changed, 584 insertions(+)
>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index fa091995d002..fc11698e88f2 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -6,6 +6,20 @@
>
>  menu "Digital to analog converters"
>
> +config AD3552R_HS
> + tristate "Analog Devices AD3552R DAC High Speed driver"
> + select ADI_AXI_DAC
> + help
> +   Say yes here to build support for Analog Devices AD3552R
> +   Digital to Analog Converter High Speed driver.
> +
> +          The driver requires the assistance of an IP core to operate,
> +          since data is streamed into target device via DMA, sent over a
> +   QSPI + DDR (Double Data Rate) bus.
> +
> +   To compile this driver as a module, choose M here: the
> +   module will be called ad3552r-hs.
> +
>  config AD3552R
>   tristate "Analog Devices AD3552R DAC driver"
>   depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index c92de0366238..d92e08ca93ca 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -4,6 +4,7 @@
>  #
>
>  # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_AD3552R_HS) += ad3552r-hs.o ad3552r-common.o
>  obj-$(CONFIG_AD3552R) += ad3552r.o ad3552r-common.o
>  obj-$(CONFIG_AD5360) += ad5360.o
>  obj-$(CONFIG_AD5380) += ad5380.o
> diff --git a/drivers/iio/dac/ad3552r-hs.c b/drivers/iio/dac/ad3552r-hs.c
> new file mode 100644
> index 000000000000..27bdc35fdc29
> --- /dev/null
> +++ b/drivers/iio/dac/ad3552r-hs.c
> @@ -0,0 +1,547 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Analog Devices AD3552R
> + * Digital to Analog converter driver, High Speed version
> + *
> + * Copyright 2024 Analog Devices Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/backend.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/units.h>
> +
> +#include "ad3552r.h"
> +#include "ad3552r-hs.h"
> +
> +struct ad3552r_hs_state {
> + const struct ad3552r_model_data *model_data;
> + struct gpio_desc *reset_gpio;
> + struct device *dev;
> + struct iio_backend *back;
> + bool single_channel;
> + struct ad3552r_ch_data ch_data[AD3552R_MAX_CH];
> + struct ad3552r_hs_platform_data *data;
> +};
> +
> +static int ad3552r_qspi_update_reg_bits(struct ad3552r_hs_state *st,
> + u32 reg, u32 mask, u32 val,
> + size_t xfer_size)
> +{
> + u32 rval;
> + int ret;
> +
> + ret = st->data->bus_reg_read(st->back, reg, &rval, xfer_size);
> + if (ret)
> + return ret;
> +
> + rval = (rval & ~mask) | val;
> +
> + return st->data->bus_reg_write(st->back, reg, rval, xfer_size);
> +}
> +
> +static int ad3552r_hs_read_raw(struct iio_dev *indio_dev,
> +        struct iio_chan_spec const *chan,
> +        int *val, int *val2, long mask)
> +{
> + struct ad3552r_hs_state *st = iio_priv(indio_dev);
> + int ret;
> + int ch = chan->channel;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ: {
> + int sclk;
> +
> + ret = iio_backend_read_raw(st->back, chan, &sclk, 0,
> +    IIO_CHAN_INFO_FREQUENCY);
> + if (ret != IIO_VAL_INT)
> + return -EINVAL;
> +

I just saw you had some questions on v6 that everyone failed to see. See my
reply to David here:

https://lore.kernel.org/linux-iio/61cf3072af74a8b2951c948ddc2383ba1e55954d.camel@gmail.com/

It should be easy and it's something that makes sense (at least to me :))

> + /*
> + * Using 4 lanes (QSPI), then using 2 as DDR mode is
> + * considered always on (considering buffering mode always).
> + */
> + *val = DIV_ROUND_CLOSEST(sclk * 4 * 2,
> + chan->scan_type.realbits);
> +
> + return IIO_VAL_INT;
> + }
> + case IIO_CHAN_INFO_RAW:
> + ret = st->data->bus_reg_read(st->back,
> + AD3552R_REG_ADDR_CH_DAC_16B(chan->channel),
> + val, 2);
> + if (ret)
> + return ret;
> +
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + *val = st->ch_data[ch].scale_int;
> + *val2 = st->ch_data[ch].scale_dec;
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_OFFSET:
> + *val = st->ch_data[ch].offset_int;
> + *val2 = st->ch_data[ch].offset_dec;
> + return IIO_VAL_INT_PLUS_MICRO;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int ad3552r_hs_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct ad3552r_hs_state *st = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
> + return st->data->bus_reg_write(st->back,
> +     AD3552R_REG_ADDR_CH_DAC_16B(chan-
> >channel),
> +     val, 2);
> + }

Maybe we'll get the new stuff in time for this :)

...

> +
> +static int ad3552r_hs_reset(struct ad3552r_hs_state *st)
> +{
> + int ret;
> +
> + /*
> + * Using inverted "active-high" logic here, since ad3552r classic-spi
> + * fdt node (and driver) is using the same logic.
> + */
> +

I don't understand this. This is a new device with a different compatible. Why
keeping the wrong logic? AFAICT, there's nothing in the bindings about the pin
polarity.

> + st->reset_gpio = devm_gpiod_get_optional(st->dev,
> + "reset", GPIOD_OUT_LOW);
> + if (IS_ERR(st->reset_gpio))
> + return PTR_ERR(st->reset_gpio);
> +
> + if (st->reset_gpio) {
> + fsleep(10);
> + gpiod_set_value_cansleep(st->reset_gpio, 1);
> + } else {
> + ret = ad3552r_qspi_update_reg_bits(st,
> + AD3552R_REG_ADDR_INTERFACE_CONFIG_A,
> + AD3552R_MASK_SOFTWARE_RESET,
> + AD3552R_MASK_SOFTWARE_RESET, 1);
> + if (ret)
> + return ret;
> + }
> + msleep(100);
> +
> + return 0;
> +}
> +
> +static int ad3552r_hs_scratch_pad_test(struct ad3552r_hs_state *st)
> +{
> + int ret, val;
> +
> + ret = st->data->bus_reg_write(st->back, AD3552R_REG_ADDR_SCRATCH_PAD,
> +       AD3552R_SCRATCH_PAD_TEST_VAL1, 1);
> + if (ret)
> + return ret;
> +
> + ret = st->data->bus_reg_read(st->back, AD3552R_REG_ADDR_SCRATCH_PAD,
> +      &val, 1);
> + if (ret)
> + return ret;
> +
> + if (val != AD3552R_SCRATCH_PAD_TEST_VAL1)
> + return dev_err_probe(st->dev, -EIO,
> + "SCRATCH_PAD_TEST mismatch. Expected 0x%x, Read
> 0x%x\n",
> + AD3552R_SCRATCH_PAD_TEST_VAL1, val);
> +
> + ret = st->data->bus_reg_write(st->back, AD3552R_REG_ADDR_SCRATCH_PAD,
> +       AD3552R_SCRATCH_PAD_TEST_VAL2, 1);
> + if (ret)
> + return ret;
> +
> + ret = st->data->bus_reg_read(st->back, AD3552R_REG_ADDR_SCRATCH_PAD,
> +      &val, 1);
> + if (ret)
> + return ret;
> +
> + if (val != AD3552R_SCRATCH_PAD_TEST_VAL2)
> + return dev_err_probe(st->dev, -EIO,
> + "SCRATCH_PAD_TEST mismatch. Expected 0x%x, Read
> 0x%x\n",
> + AD3552R_SCRATCH_PAD_TEST_VAL2, val);
> +
> + return 0;
> +}
> +
> +static int ad3552r_hs_setup_custom_gain(struct ad3552r_hs_state *st,
> + int ch, u16 gain, u16 offset)
> +{
> + int ret;
> +
> + ret = st->data->bus_reg_write(st->back,
> AD3552R_REG_ADDR_CH_OFFSET(ch),
> +       offset, 1);
> + if (ret)
> + return dev_err_probe(st->dev, ret, "Error writing
> register\n");
> +
> + ret = st->data->bus_reg_write(st->back, AD3552R_REG_ADDR_CH_GAIN(ch),
> +       gain, 1);
> + if (ret)
> + return dev_err_probe(st->dev, ret, "Error writing
> register\n");
> +
> + return 0;

nit: Not a big fan of these logs on read/write registers functions... Also seems
that you're not being consistent (either you have them or not). FWIW, I would
simplify and drop them. That would allow to do

return st->data->bus_reg_write(st->back, AD3552R_REG_ADDR_CH_GAIN(ch), gain, 1);

> +}
> +
> +static int ad3552r_hs_setup(struct ad3552r_hs_state *st)
> +{
> + s16 goffs;
> + u16 id;
> + u16 gain = 0, offset = 0;
> + u32 ch, val, range;
> + int ret;
> +
> + ret = ad3552r_hs_reset(st);
> + if (ret)
> + return ret;
> +
> + ret = iio_backend_ddr_disable(st->back);
> + if (ret)
> + return ret;
> +
> + ret = ad3552r_hs_scratch_pad_test(st);
> + if (ret)
> + return ret;
> +
> + ret = st->data->bus_reg_read(st->back, AD3552R_REG_ADDR_PRODUCT_ID_L,
> +      &val, 1);
> + if (ret)
> + return ret;
> +
> + id = val;
> +
> + ret = st->data->bus_reg_read(st->back, AD3552R_REG_ADDR_PRODUCT_ID_H,
> +      &val, 1);
> + if (ret)
> + return ret;
> +
> + id |= val << 8;
> + if (id != st->model_data->chip_id)
> + dev_info(st->dev, "Chip ID error. Expected 0x%x, Read
> 0x%x\n",
> + AD3552R_ID, id);
> +
> + ret = st->data->bus_reg_write(st->back,
> +       AD3552R_REG_ADDR_SH_REFERENCE_CONFIG,
> +       0, 1);
> + if (ret)
> + return ret;
> +
> + ret = st->data->bus_reg_write(st->back,
> + AD3552R_REG_ADDR_TRANSFER_REGISTER,
> + FIELD_PREP(AD3552R_MASK_MULTI_IO_MODE,
> +    AD3552R_QUAD_SPI) |
> + AD3552R_MASK_STREAM_LENGTH_KEEP_VALUE, 1);
> + if (ret)
> + return ret;
> +
> + ret = iio_backend_data_source_set(st->back, 0, IIO_BACKEND_EXTERNAL);
> + if (ret)
> + return ret;
> +
> + ret = iio_backend_data_source_set(st->back, 1, IIO_BACKEND_EXTERNAL);
> + if (ret)
> + return ret;
> +
> + ret = ad3552r_get_ref_voltage(st->dev, &val);
> + if (ret < 0)
> + return ret;
> +
> + val = ret;
> +
> + ret = ad3552r_qspi_update_reg_bits(st,
> + AD3552R_REG_ADDR_SH_REFERENCE_CONFIG,
> + AD3552R_MASK_REFERENCE_VOLTAGE_SEL,
> + val, 1);
> + if (ret)
> + return ret;
> +
> + ret = ad3552r_get_drive_strength(st->dev, &val);
> + if (!ret) {
> + ret = ad3552r_qspi_update_reg_bits(st,
> + AD3552R_REG_ADDR_INTERFACE_CONFIG_D,
> + AD3552R_MASK_SDO_DRIVE_STRENGTH,
> + val, 1);
> + if (ret)
> + return ret;
> + }
> +
> + device_for_each_child_node_scoped(st->dev, child) {
> + ret = fwnode_property_read_u32(child, "reg", &ch);
> + if (ret)
> + return dev_err_probe(st->dev, ret,
> +      "reg property missing\n");
> +
> + ret = ad3552r_get_output_range(st->dev, st->model_data,
> child,
> +        &range);
> + if (!ret) {
> + st->ch_data[ch].range = range;
> +
> + ret = ad3552r_hs_set_output_range(st, ch, range);
> + if (ret)
> + return ret;
> +
> + } else if (ret == -ENOENT) {
> + ret = ad3552r_get_custom_gain(st->dev, child,
> + &st->ch_data[ch].p,
> + &st->ch_data[ch].n,
> + &st->ch_data[ch].rfb,
> + &st-
> >ch_data[ch].gain_offset);
> + if (ret)
> + return ret;
> +
> + gain = ad3552r_calc_custom_gain(st->ch_data[ch].p,
> + st->ch_data[ch].n,
> + st->ch_data[ch].gain_offset);
> + offset = abs(goffs);
> +
> + st->ch_data[ch].range_override = 1;
> +
> + ret = ad3552r_hs_setup_custom_gain(st, ch, gain,
> +    offset);
> + if (ret)
> + return ret;
> + } else {
> + return ret;
> + }

Just personal preference... I think this would be neater:
if (ret && ret != ENOENT)
return ret;
if (ret == -ENOENT) {
...
} else {
...
}

Advantage is that it also handles errors first (which is the typical pattern)

> +
> + ad3552r_calc_gain_and_offset(&st->ch_data[ch], st-
> >model_data);
> + }
> +
> + return 0;
> +}
> +
> +static const struct iio_buffer_setup_ops ad3552r_hs_buffer_setup_ops = {
> + .postenable = ad3552r_hs_buffer_postenable,
> + .predisable = ad3552r_hs_buffer_predisable,
> +};
> +
> +#define AD3552R_CHANNEL(ch) { \
> + .type = IIO_VOLTAGE, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> +       BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> +       BIT(IIO_CHAN_INFO_SCALE) | \
> +       BIT(IIO_CHAN_INFO_OFFSET), \
> + .output = 1, \
> + .indexed = 1, \
> + .channel = (ch), \
> + .scan_index = (ch), \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 16, \
> + .storagebits = 16, \
> + .endianness = IIO_BE, \
> + } \
> +}
> +
> +static const struct iio_chan_spec ad3552r_hs_channels[] = {
> + AD3552R_CHANNEL(0),
> + AD3552R_CHANNEL(1),
> +};
> +
> +static const struct iio_info ad3552r_hs_info = {
> + .read_raw = &ad3552r_hs_read_raw,
> + .write_raw = &ad3552r_hs_write_raw,
> +};
> +
> +static int ad3552r_hs_probe(struct platform_device *pdev)
> +{
> + struct ad3552r_hs_state *st;
> + struct iio_dev *indio_dev;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> + st->dev = &pdev->dev;
> +
> + st->data = pdev->dev.platform_data;

dev_get_platdata()

- Nuno Sá