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Date: Sun, 14 Nov 2021 13:07:45 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Mihail Chindris <mihail.chindris@...log.com>
Cc: <linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>,
<lars@...afoo.de>, <Michael.Hennerich@...log.com>,
<nuno.sa@...log.com>, <dragos.bogdan@...log.com>,
<alexandru.ardelean@...log.com>
Subject: Re: [PATCH v5 2/2] drivers:iio:dac: Add AD3552R driver support
On Mon, 8 Nov 2021 08:24:47 +0000
Mihail Chindris <mihail.chindris@...log.com> wrote:
> The AD3552R-16 is a low drift ultrafast, 16-bit accuracy,
> current output digital-to-analog converter (DAC) designed
> to generate multiple output voltage span ranges.
> The AD3552R-16 operates with a fixed 2.5V reference.
>
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad3552r.pdf
>
> Signed-off-by: Mihail Chindris <mihail.chindris@...log.com>
Hi Mihail,
Main thing here is to give time for Rob and others to take a look at the dt-binding
but in meantime I thought I'd give the driver one last look and spotted a few minor things.
Jonathan
> ---
> drivers/iio/dac/Kconfig | 10 +
> drivers/iio/dac/Makefile | 1 +
> drivers/iio/dac/ad3552r.c | 1199 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 1210 insertions(+)
> create mode 100644 drivers/iio/dac/ad3552r.c
>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 75e1f2b48638..ced6428f2c92 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -6,6 +6,16 @@
>
> menu "Digital to analog converters"
>
> +config AD3552R
> + tristate "Analog Devices AD3552R DAC driver"
> + depends on SPI_MASTER
> + help
> + Say yes here to build support for Analog Devices AD3552R
> + Digital to Analog Converter.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called ad3552r.
> +
> config AD5064
> tristate "Analog Devices AD5064 and similar multi-channel DAC driver"
> depends on (SPI_MASTER && I2C!=m) || I2C
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 33e16f14902a..dffe36efd8ff 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-$(CONFIG_AD3552R) += ad3552r.o
> obj-$(CONFIG_AD5360) += ad5360.o
> obj-$(CONFIG_AD5380) += ad5380.o
> obj-$(CONFIG_AD5421) += ad5421.o
> diff --git a/drivers/iio/dac/ad3552r.c b/drivers/iio/dac/ad3552r.c
> new file mode 100644
> index 000000000000..4a98fa734e8a
> --- /dev/null
> +++ b/drivers/iio/dac/ad3552r.c
> @@ -0,0 +1,1199 @@
...
> +
> +/* Useful defines */
> +#define AD3552R_NUM_CH 2
> +#define AD3552R_MASK_CH(ch) BIT(ch)
> +#define AD3552R_MASK_ALL_CH GENMASK(1, 0)
> +#define AD3552R_MAX_REG_SIZE 3
> +#define AD3552R_READ_BIT (1 << 7)
BIT(7)?
> +#define AD3552R_ADDR_MASK GENMASK(6, 0)
> +#define AD3552R_CRC_ENABLE_VALUE (BIT(6) | BIT(1))
> +#define AD3552R_CRC_DISABLE_VALUE GENMASK(1, 0)
> +#define AD3552R_CRC_POLY 0x07
> +#define AD3552R_CRC_SEED 0xA5
> +#define AD3552R_MASK_DAC_12B 0xFFF0
> +#define AD3552R_DEFAULT_CONFIG_B_VALUE 0x8
> +#define AD3552R_SCRATCH_PAD_TEST_VAL1 0x34
> +#define AD3552R_SCRATCH_PAD_TEST_VAL2 0xB2
> +#define AD3552R_GAIN_SCALE 1000
> +#define AD3552R_LDAC_PULSE_US 100
> +
> +
> +struct ad3552r_desc {
> + /*
> + * Used to look the spi bus for atomic operations where needed and
> + * also protect access to buf_data below
> + */
> + struct mutex lock;
> + struct gpio_desc *gpio_reset;
> + struct gpio_desc *gpio_ldac;
> + struct spi_device *spi;
> + struct ad3552r_ch_data ch_data[AD3552R_NUM_CH];
> + struct iio_chan_spec channels[AD3552R_NUM_CH + 1];
> + unsigned long enabled_ch;
> + unsigned int num_ch;
> + enum ad3542r_id chip_id;
> + /*
> + * The maximum spi transfer size consist 1 bytes (reg address)
> + * + 2 registers of 3 bytes + 1 reg of 1 byte (SW LDAC)
> + */
> + u8 buf_data[8] ____cacheline_aligned;
As mentioned below - given how this is used as a bounce buffer, you could just use
spi_write_then_read() in all paths and avoid the complexity.
> +};
> +
...
> +/* 0 -> reg addr, 1->ch0 mask, 2->ch1 mask */
> +static const u16 addr_mask_map_ch[][3] = {
> + [AD3552R_CH_DAC_POWERDOWN] = {
> + AD3552R_REG_ADDR_POWERDOWN_CONFIG,
> + AD3552R_MASK_CH_DAC_POWERDOWN(0),
> + AD3552R_MASK_CH_DAC_POWERDOWN(1)
> + },
> + [AD3552R_CH_AMPLIFIER_POWERDOWN] = {
> + AD3552R_REG_ADDR_POWERDOWN_CONFIG,
> + AD3552R_MASK_CH_AMPLIFIER_POWERDOWN(0),
> + AD3552R_MASK_CH_AMPLIFIER_POWERDOWN(1)
> + },
> + [AD3552R_CH_OUTPUT_RANGE_SEL] = {
> + AD3552R_REG_ADDR_CH0_CH1_OUTPUT_RANGE,
> + AD3552R_MASK_CH_OUTPUT_RANGE_SEL(0),
> + AD3552R_MASK_CH_OUTPUT_RANGE_SEL(1)
> + },
> + /*
> + * This attributes are update by the chip on 16B and 24B no matter to
> + * what register the write is done
> + */
> + [AD3552R_CH_TRIGGER_SOFTWARE_LDAC] = {
Is this used?
> + AD3552R_REG_ADDR_SW_LDAC_16B,
> + AD3552R_MASK_CH(0),
> + AD3552R_MASK_CH(1)
> + },
> + [AD3552R_CH_HW_LDAC_MASK] = {
> + AD3552R_REG_ADDR_HW_LDAC_16B,
> + AD3552R_MASK_CH(0),
> + AD3552R_MASK_CH(1)
> + },
> + [AD3552R_CH_SELECT] = {
> + AD3552R_REG_ADDR_CH_SELECT_16B,
> + AD3552R_MASK_CH(0),
> + AD3552R_MASK_CH(1)
> + }
> +};
> +
> +
> +/* SPI transfer to device */
> +static int ad3552r_transfer(struct ad3552r_desc *dac, u8 addr, u32 len,
> + u8 *data, bool is_read)
> +{
> + u8 instr;
> +
> + instr = addr & AD3552R_ADDR_MASK;
> + instr |= is_read ? AD3552R_READ_BIT : 0;
> + if (is_read)
> + return spi_write_then_read(dac->spi, &instr, 1, data, len);
> +
> + dac->buf_data[0] = instr;
> + memcpy(dac->buf_data + 1, data, len);
> + return spi_write(dac->spi, dac->buf_data, len + 1);
If you are going to have to do a small memory copy anyway, you could just
use spi_write_then_read() with a 0 size read. It ends up very similar
to what you are doing here.
> +}
> +
> +
> +/*
> + * Device type specific information.
> + */
Not sure this is a particularly useful comment - I'd drop it.
> +static const struct iio_info ad3552r_iio_info = {
> + .read_raw = ad3552r_read_raw,
> + .write_raw = ad3552r_write_raw
> +};
> +
...
> +static int ad3552r_configure_custom_gain(struct ad3552r_desc *dac,
> + struct fwnode_handle *child,
> + u32 ch)
> +{
> + struct device *dev = &dac->spi->dev;
> + struct fwnode_handle *gain_child;
> + u32 val;
> + int err;
> + u8 addr;
> + u16 mask = 0, reg = 0, offset;
> +
> + gain_child = fwnode_get_named_child_node(child,
> + "custom-output-range-config");
> + if (IS_ERR(gain_child)) {
> + dev_err(dev,
> + "mandatory custom-output-range-config property missing\n");
> + return PTR_ERR(gain_child);
> + }
> +
> + dac->ch_data[ch].range_override = 1;
> + reg |= ad3552r_field_prep(1, AD3552R_MASK_CH_RANGE_OVERRIDE);
> + mask |= AD3552R_MASK_CH_RANGE_OVERRIDE;
> +
> + err = fwnode_property_read_u32(gain_child, "adi,gain-scaling-p", &val);
> + if (err) {
> + dev_err(dev, "mandatory adi,gain-scaling-p property missing\n");
> + goto put_child;
> + }
> + reg |= ad3552r_field_prep(val, AD3552R_MASK_CH_GAIN_SCALING_P);
> + mask |= AD3552R_MASK_CH_GAIN_SCALING_P;
> + dac->ch_data[ch].p = val;
> +
> + err = fwnode_property_read_u32(gain_child, "adi,gain-scaling-n", &val);
> + if (err) {
> + dev_err(dev, "mandatory adi,gain-scaling-n property missing\n");
> + goto put_child;
> + }
> + reg |= ad3552r_field_prep(val, AD3552R_MASK_CH_GAIN_SCALING_N);
> + mask |= AD3552R_MASK_CH_GAIN_SCALING_N;
> + dac->ch_data[ch].n = val;
> +
> + err = fwnode_property_read_u32(gain_child, "adi,rfb-ohms", &val);
> + if (err) {
> + dev_err(dev, "mandatory adi,rfb-ohms property missing\n");
> + goto put_child;
> + }
> + dac->ch_data[ch].rfb = val;
> +
> + err = fwnode_property_read_u32(gain_child, "adi,gain-offset", &val);
> + if (err) {
> + dev_err(dev, "mandatory adi,gain-offset property missing\n");
> + goto put_child;
> + }
> + dac->ch_data[ch].gain_offset = val;
> +
> + offset = abs((s32)val);
> + reg |= ad3552r_field_prep((offset >> 8), AD3552R_MASK_CH_OFFSET_BIT_8);
> + mask |= AD3552R_MASK_CH_OFFSET_BIT_8;
> +
> + reg |= ad3552r_field_prep((s32)val < 0, AD3552R_MASK_CH_OFFSET_POLARITY);
> + mask |= AD3552R_MASK_CH_OFFSET_POLARITY;
mask never used? I'm guessing left over from before you introduced your
field_prep function.
> + addr = AD3552R_REG_ADDR_CH_GAIN(ch);
> + err = ad3552r_write_reg(dac, addr,
> + offset & AD3552R_MASK_CH_OFFSET_BITS_0_7);
> + if (err) {
> + dev_err(dev, "Error writing register\n");
> + goto put_child;
> + }
> +
> + err = ad3552r_write_reg(dac, addr, reg);
> + if (err) {
> + dev_err(dev, "Error writing register\n");
> + goto put_child;
> + }
> +
> +put_child:
> + fwnode_handle_put(gain_child);
> +
> + return err;
> +}
> +
> +static int ad3552r_configure_device(struct ad3552r_desc *dac)
> +{
> + struct device *dev = &dac->spi->dev;
> + struct fwnode_handle *child;
> + struct regulator *vref;
> + int err, cnt = 0, voltage, delta = 100000;
> + u32 vals[2], val, ch;
> +
> + dac->gpio_ldac = devm_gpiod_get_optional(dev, "ldac", GPIOD_OUT_HIGH);
> + if (IS_ERR(dac->gpio_ldac))
> + return dev_err_probe(dev, PTR_ERR(dac->gpio_ldac),
> + "Error getting gpio ldac");
> +
> + vref = devm_regulator_get_optional(dev, "vref");
> + if (IS_ERR(vref)) {
> + if (PTR_ERR(vref) != -ENODEV)
> + return dev_err_probe(dev, PTR_ERR(vref),
> + "Error getting vref");
> + vref = NULL;
> + }
Perhaps use an else branch for this so that we don't need to bother with
setting vref = NULL
if (IS_ERR(vref)) {
if (PTR_ERR(vref) != -ENODEV)
return dev_err_probe(dev, PTR_ERR(vref),
"Error getting vref");
if (device_property_read_bool(dev, "adi,vref-out-en"))
val = AD3552R_INTERNAL_VREF_PIN_2P5V;
else
val = AD3552R_INTERNAL_VREF_PIN_FLOATING;
} else {
// Need to turn it on somewhere, so regulator_enable() + devm handler to turn it off again.
voltage = regulator_get_voltage(vref);
if (voltage > 2500000 + delta || voltage < 2500000 - delta) {
dev_warn(dev, "vref-supply must be 2.5V");
return -EINVAL;
}
val = AD3552R_EXTERNAL_VREF_PIN_INPUT;
}
> + if (vref) {
> + voltage = regulator_get_voltage(vref);
> + if (voltage > 2500000 + delta || voltage < 2500000 - delta) {
> + dev_warn(dev, "vref-supply must be 2.5V");
> + return -EINVAL;
> + }
> + val = AD3552R_EXTERNAL_VREF_PIN_INPUT;
> + } else {
> + if (device_property_read_bool(dev, "adi,vref-out-en"))
> + val = AD3552R_INTERNAL_VREF_PIN_2P5V;
> + else
> + val = AD3552R_INTERNAL_VREF_PIN_FLOATING;
> + }
> + err = ad3552r_update_reg_field(dac,
> + addr_mask_map[AD3552R_VREF_SELECT][0],
> + addr_mask_map[AD3552R_VREF_SELECT][1],
> + val);
> + if (err)
> + return err;
> +
> + err = device_property_read_u32(dev, "adi,sdo-drive-strength", &val);
> + if (!err) {
> + if (val > 3) {
> + dev_err(dev, "adi,sdo-drive-strength must be less than 4\n");
> + return -EINVAL;
> + }
> +
> + err = ad3552r_update_reg_field(dac,
> + addr_mask_map[AD3552R_SDO_DRIVE_STRENGTH][0],
> + addr_mask_map[AD3552R_SDO_DRIVE_STRENGTH][1],
> + val);
> + if (err)
> + return err;
> + }
> +
> + dac->num_ch = device_get_child_node_count(dev);
> + if (!dac->num_ch) {
> + dev_err(dev, "No channels defined\n");
> + return -ENODEV;
> + }
> +
> + device_for_each_child_node(dev, child) {
> + err = fwnode_property_read_u32(child, "reg", &ch);
> + if (err) {
> + dev_err(dev, "mandatory reg property missing\n");
> + goto put_child;
> + }
> + if (ch >= AD3552R_NUM_CH) {
> + dev_err(dev, "reg must be less than %d\n",
> + AD3552R_NUM_CH);
> + err = -EINVAL;
> + goto put_child;
> + }
> +
> + if (fwnode_property_present(child, "adi,output-range-microvolt")) {
> + err = fwnode_property_read_u32_array(child,
> + "adi,output-range-microvolt",
> + vals,
> + 2);
> + if (err) {
> + dev_err(dev,
> + "mandatory adi,output-range-microvolt property missing\n");
> + goto put_child;
> + }
> +
> + err = ad3552r_find_range(dac->chip_id, vals);
> + if (err < 0) {
> + dev_err(dev,
> + "Invalid adi,output-range-microvolt value\n");
> + goto put_child;
> + }
> + val = err;
> + err = ad3552r_set_ch_value(dac,
> + AD3552R_CH_OUTPUT_RANGE_SEL,
> + ch, val);
> + if (err)
> + goto put_child;
> +
> + dac->ch_data[ch].range = val;
> + } else {
> + err = ad3552r_configure_custom_gain(dac, child, ch);
> + if (err)
> + goto put_child;
> + }
> +
> + ad3552r_calc_gain_and_offset(dac, ch);
> + dac->enabled_ch |= BIT(ch);
> +
> + err = ad3552r_set_ch_value(dac, AD3552R_CH_SELECT, ch, 1);
> + if (err < 0)
> + goto put_child;
> +
> + dac->channels[cnt] = AD3552R_CH_DAC(ch);
> + ++cnt;
> +
> + }
> +
> + /* Disable unused channels */
> + for_each_clear_bit(ch, &dac->enabled_ch, AD3552R_NUM_CH) {
> + err = ad3552r_set_ch_value(dac, AD3552R_CH_AMPLIFIER_POWERDOWN,
> + ch, 0);
> + if (err)
> + return err;
> + }
> +
> + dac->num_ch = cnt;
> +
> + return 0;
> +put_child:
> + fwnode_handle_put(child);
> +
> + return err;
> +}
...
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