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Message-ID: <9f00e86e8a7d8f821cdb79d5b083235daec481a9.camel@gmail.com>
Date: Tue, 22 Oct 2024 14:28:12 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>, Nuno Sá
	 <nuno.sa@...log.com>, Lars-Peter Clausen <lars@...afoo.de>, Michael
 Hennerich	 <Michael.Hennerich@...log.com>, Jonathan Cameron
 <jic23@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley	 <conor+dt@...nel.org>, Olivier Moysan
 <olivier.moysan@...s.st.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, dlechner@...libre.com, Mark Brown
	 <broonie@...nel.org>
Subject: Re: [PATCH v7 7/8] iio: dac: ad3552r: add high-speed platform driver

On Mon, 2024-10-21 at 14:40 +0200, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@...libre.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@...libre.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



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