Re: [PATCH v8 7/8] iio: dac: ad3552r: add high-speed platform driver

["Nuno Sá" <noname.nuno@gmail.com>]

On Fri, 2024-10-25 at 11:49 +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>
> ---

LGTM, just one question inline. If not an issue:

Reviewed-by: Nuno Sa <nuno.sa@analog.com>

>  drivers/iio/dac/Kconfig      |  14 ++
>  drivers/iio/dac/Makefile     |   1 +
>  drivers/iio/dac/ad3552r-hs.c | 530 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/iio/dac/ad3552r-hs.h |  19 ++
>  drivers/iio/dac/ad3552r.h    |   4 +
>  5 files changed, 568 insertions(+)
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 26f9de55b79f..f76eaba140d8 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..97dfc598aec6
> --- /dev/null
> +++ b/drivers/iio/dac/ad3552r-hs.c
> @@ -0,0 +1,530 @@
> +// 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:
> +		/*
> +		 * Using 4 lanes (QSPI), then using 2 as DDR mode is
> +		 * considered always on (considering buffering mode always).
> +		 */
> +		*val = DIV_ROUND_CLOSEST(st->data->bus_sample_data_clock_hz *
> +					 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;

Is there any potential issue by doing a raw access when streaming?

- Nuno Sá