Re: [PATCH 1/2] iio: adc: Add driver support for AD7292
From: Marcelo Schmitt
Date: Tue Oct 15 2019 - 12:45:19 EST
Hi Jonathan,
Thanks for the review. I'll send a v2 soon.
On 10/14, Jonathan Cameron wrote:
> On Sun, 13 Oct 2019 11:13:22 -0300
> Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx> wrote:
>
> > The AD7292 is a 10-bit monitor and control system with ADC, DACs,
> > temperature sensor, and GPIOs.
> >
> > Configure AD7292 devices in direct access mode, enabling single-ended
> > ADC readings.
> >
> > Datasheet:
> > Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ad7292.pdf
> >
> > Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx>
> Hi Marcelo
>
> A few minor bits inline. Mostly just the DT binding question.
>
> Thanks,
>
> Jonathan
>
> > ---
> > MAINTAINERS | 7 +
> > drivers/iio/adc/Kconfig | 10 ++
> > drivers/iio/adc/Makefile | 1 +
> > drivers/iio/adc/ad7292.c | 350 +++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 368 insertions(+)
> > create mode 100644 drivers/iio/adc/ad7292.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 32bf5f8116d0..e78317a5f4f1 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -813,6 +813,13 @@ S: Supported
> > F: drivers/iio/adc/ad7124.c
> > F: Documentation/devicetree/bindings/iio/adc/adi,ad7124.txt
> >
> > +ANALOG DEVICES INC AD7292 DRIVER
> > +M: Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx>
> > +L: linux-iio@xxxxxxxxxxxxxxx
> > +W: http://ez.analog.com/community/linux-device-drivers
> > +S: Supported
> > +F: drivers/iio/adc/ad7292.c
> > +
> > ANALOG DEVICES INC AD7606 DRIVER
> > M: Stefan Popa <stefan.popa@xxxxxxxxxx>
> > L: linux-iio@xxxxxxxxxxxxxxx
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 632b331429c6..02587c990cb5 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -59,6 +59,16 @@ config AD7291
> > To compile this driver as a module, choose M here: the
> > module will be called ad7291.
> >
> > +config AD7292
> > + tristate "Analog Devices AD7292 ADC driver"
> > + depends on SPI
> > + help
> > + Say yes here to build support for Analog Devices AD7292
> > + 8 Channel ADC with temperature sensor.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called ad7292.
> > +
> > config AD7298
> > tristate "Analog Devices AD7298 ADC driver"
> > depends on SPI
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index 4779ab3ff8fb..1818f2f66566 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -11,6 +11,7 @@ obj-$(CONFIG_AD7124) += ad7124.o
> > obj-$(CONFIG_AD7173) += ad7173.o
> > obj-$(CONFIG_AD7266) += ad7266.o
> > obj-$(CONFIG_AD7291) += ad7291.o
> > +obj-$(CONFIG_AD7292) += ad7292.o
> > obj-$(CONFIG_AD7298) += ad7298.o
> > obj-$(CONFIG_AD738X) += ad738x.o
> > obj-$(CONFIG_AD7768) += ad7768-1.o
> > diff --git a/drivers/iio/adc/ad7292.c b/drivers/iio/adc/ad7292.c
> > new file mode 100644
> > index 000000000000..076bd49a2571
> > --- /dev/null
> > +++ b/drivers/iio/adc/ad7292.c
> > @@ -0,0 +1,350 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Analog Devices AD7292 SPI ADC driver
> > + *
> > + * Copyright 2019 Analog Devices Inc.
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/spi/spi.h>
> > +
> > +#include <linux/iio/iio.h>
> > +
> > +#define ADI_VENDOR_ID 0x0018
> > +
> > +/* AD7292 registers definition */
> > +#define AD7292_REG_VENDOR_ID 0x00
> > +#define AD7292_REG_CONF_BANK 0x05
> > +#define AD7292_REG_CONV_COMM 0x0E
> > +#define AD7292_REG_ADC_CH(x) (0x10 + (x))
> > +
> > +/* AD7292 configuration bank subregisters definition */
> > +#define AD7292_BANK_REG_VIN_RNG0 0x10
> > +#define AD7292_BANK_REG_VIN_RNG1 0x11
> > +#define AD7292_BANK_REG_SAMP_MODE 0x12
> > +
> > +#define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F))
> > +
> > +/* AD7292_REG_ADC_CONVERSION */
> > +#define AD7292_ADC_DATA_MASK GENMASK(15, 6)
> > +#define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x)
> > +
> > +/* AD7292_CHANNEL_SAMPLING_MODE */
> > +#define AD7292_CH_SAMP_MODE(reg, ch) ((reg >> 8) & BIT(ch))
> > +
> > +/* AD7292_CHANNEL_VIN_RANGE */
> > +#define AD7292_CH_VIN_RANGE(reg, ch) (reg & BIT(ch))
> > +
> > +#define AD7291_VOLTAGE_CHAN(_chan) \
> > +{ \
> > + .type = IIO_VOLTAGE, \
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > + BIT(IIO_CHAN_INFO_SCALE), \
> > + .indexed = 1, \
> > + .channel = _chan, \
> > +}
> > +
> > +static const struct iio_chan_spec ad7292_channels[] = {
> > + AD7291_VOLTAGE_CHAN(0),
> > + AD7291_VOLTAGE_CHAN(1),
> > + AD7291_VOLTAGE_CHAN(2),
> > + AD7291_VOLTAGE_CHAN(3),
> > + AD7291_VOLTAGE_CHAN(4),
> > + AD7291_VOLTAGE_CHAN(5),
> > + AD7291_VOLTAGE_CHAN(6),
> > + AD7291_VOLTAGE_CHAN(7)
> > +};
> > +
> > +static const struct iio_chan_spec ad7292_channels_diff[] = {
> > + {
> > + .type = IIO_VOLTAGE,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> > + .indexed = 1,
> > + .differential = 1,
> > + .channel = 0,
> > + .channel2 = 1,
> > + },
> > + AD7291_VOLTAGE_CHAN(2),
> > + AD7291_VOLTAGE_CHAN(3),
> > + AD7291_VOLTAGE_CHAN(4),
> > + AD7291_VOLTAGE_CHAN(5),
> > + AD7291_VOLTAGE_CHAN(6),
> > + AD7291_VOLTAGE_CHAN(7)
> > +};
> > +
> > +struct ad7292_state {
> > + struct spi_device *spi;
> > + struct regulator *reg;
> > + unsigned short vref_mv;
> > + union {
> > + __be16 d16;
> > + u8 d8[2];
> > + } data ____cacheline_aligned;
>
> Given it is a whole cacheline long anyway, I'd be tempted to just have
> these as separate fields.
>
> > +};
> > +
> > +static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
> > +{
> > + int ret;
> > +
> > + st->data.d8[0] = AD7292_RD_FLAG_MSK(addr);
> > +
> > + ret = spi_write_then_read(st->spi, st->data.d8, 1, &st->data.d16, 2);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return be16_to_cpu(st->data.d16);
> > +}
> > +
> > +static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
> > + unsigned int sub_addr, unsigned int len)
> > +{
> > + unsigned int shift = 16 - (8 * len);
> > + int ret;
> > +
> > + st->data.d8[0] = AD7292_RD_FLAG_MSK(addr);
> > + st->data.d8[1] = sub_addr;
> > +
> > + ret = spi_write_then_read(st->spi, st->data.d8, 2, &st->data.d16, len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return (be16_to_cpu(st->data.d16) >> shift);
> > +}
> > +
> > +static int ad7292_single_conversion(struct ad7292_state *st,
> > + unsigned int chan_addr)
> > +{
> > + int ret;
> > +
> > + struct spi_transfer t[] = {
> > + {
> > + .tx_buf = &st->data,
> > + .len = 4,
> > + .delay_usecs = 6,
> > + }, {
> > + .rx_buf = &st->data.d16,
> > + .len = 2,
> > + },
> > + };
> > +
> > + st->data.d8[0] = chan_addr;
> > + st->data.d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
> > +
> > + ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
> > +
> > + if (ret < 0)
> > + return ret;
> > +
> > + return be16_to_cpu(st->data.d16);
> > +}
> > +
> > +static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
> > +{
> > + int samp_mode, range0, range1;
> > + int factor = 1;
> > +
> > + /*
> > + * Every AD7292 ADC channel may have its input range adjusted according
> > + * to the settings at the ADC sampling mode and VIN range subregisters.
> > + * For a given channel, the minimum input range is equal to Vref, and it
> > + * may be increased by a multiplier factor of 2 or 4 according to the
> > + * following rule:
> > + * If channel is being sampled wiht respect to AGND:
> > + * factor = 4 if VIN range0 and VIN range1 equal 0
> > + * factor = 2 if only one of VIN ranges equal 1
> > + * factor = 1 if both VIN range0 and VIN range1 equal 1
> > + * If channel is being sampled with respect to AVDD:
> > + * factor = 4 if VIN range0 and VIN range1 equal 0
> > + * Behavior is undefined if any of VIN range doesn't equal 0
> > + */
> > +
> > + samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
> > + AD7292_BANK_REG_SAMP_MODE, 2);
> > +
> > + if (samp_mode < 0)
> > + return samp_mode;
> > +
> > + range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
> > + AD7292_BANK_REG_VIN_RNG0, 2);
> > +
> > + if (range0 < 0)
> > + return range0;
> > +
> > + range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
> > + AD7292_BANK_REG_VIN_RNG1, 2);
> > +
> > + if (range1 < 0)
> > + return range1;
> > +
> > + if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
> > + /* Sampling with respect to AGND */
> > + if (!AD7292_CH_VIN_RANGE(range0, channel))
> > + factor *= 2;
> > +
> > + if (!AD7292_CH_VIN_RANGE(range1, channel))
> > + factor *= 2;
> > +
> > + } else {
> > + /* Sampling with respect to AVDD */
> > + if (AD7292_CH_VIN_RANGE(range0, channel) ||
> > + AD7292_CH_VIN_RANGE(range1, channel))
> > + return -EPERM;
> > +
> > + factor = 4;
> > + }
> > +
> > + return factor;
> > +}
> > +
> > +static int ad7292_read_raw(struct iio_dev *indio_dev,
> > + const struct iio_chan_spec *chan,
> > + int *val, int *val2, long info)
> > +{
> > + struct ad7292_state *st = iio_priv(indio_dev);
> > + unsigned int ch_addr;
> > + int ret;
> > +
> > + switch (info) {
> > + case IIO_CHAN_INFO_RAW:
> > + ch_addr = AD7292_REG_ADC_CH(chan->channel);
> > + ret = ad7292_single_conversion(st, ch_addr);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = AD7292_ADC_DATA(ret);
> > +
> > + return IIO_VAL_INT;
> > + case IIO_CHAN_INFO_SCALE:
> > + /*
> > + * To convert a raw value to standard units, the IIO defines
> > + * this formula: Scaled value = (raw + offset) * scale.
> > + * For the scale to be a correct multiplier for (raw + offset),
> > + * it must be calculated as the input range divided by the
> > + * number of possible distinct input values. Given the ADC data
> > + * is 10 bit long, it may assume only 2^10 distinct values.
> > + * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
> > + * return type indicates to the IIO API to divide *val by 2 to
> > + * the power of *val2 when returning from read_raw.
> > + */
> > +
> > + *val = regulator_get_voltage(st->reg);
> > + if (*val < 0)
> > + *val = st->vref_mv;
> > + else
> > + *val /= 1000;
> > +
> > + ret = ad7292_vin_range_multiplier(st, chan->channel);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val *= ret;
> > + *val2 = 10;
> > + return IIO_VAL_FRACTIONAL_LOG2;
> > + default:
> > + break;
> > + }
> > + return -EINVAL;
> > +}
> > +
> > +static const struct iio_info ad7292_info = {
> > + .read_raw = ad7292_read_raw,
> > +};
> > +
> > +static void ad7292_regulator_disable(void *data)
> > +{
> > + struct ad7292_state *st = data;
> > +
> > + regulator_disable(st->reg);
> > +}
> > +
> > +static int ad7292_probe(struct spi_device *spi)
> > +{
> > + struct ad7292_state *st;
> > + struct iio_dev *indio_dev;
> > + int ret;
> > +
> > + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + st = iio_priv(indio_dev);
> > + st->spi = spi;
> > +
> > + ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
> > + if (ret != ADI_VENDOR_ID) {
> > + dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
> > + return -EINVAL;
> > + }
> > +
> > + spi_set_drvdata(spi, indio_dev);
> > +
> > + st->reg = devm_regulator_get_optional(&spi->dev, "vref");
> > + if (!IS_ERR(st->reg)) {
> > + ret = regulator_enable(st->reg);
> > + if (ret) {
> > + dev_err(&spi->dev,
> > + "Failed to enable external vref supply\n");
> > + return ret;
> > + }
> > +
> > + ret = devm_add_action_or_reset(&spi->dev,
> > + ad7292_regulator_disable, st);
> > + if (ret) {
> > + regulator_disable(st->reg);
> > + return ret;
> > + }
> > +
> > + ret = regulator_get_voltage(st->reg);
> > + if (ret < 0)
> > + return ret;
>
> We get the voltage here, but then I think we throw it away by rereading it
> each time above. No need to get it in both places.
>
> > +
> > + st->vref_mv = ret / 1000;
> > + } else {
>
> Perhaps add a comment here to say this is the internal reference.
>
> > + st->vref_mv = 1250;
> > + }
> > +
> > + indio_dev->dev.parent = &spi->dev;
> > + indio_dev->name = spi_get_device_id(spi)->name;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > + indio_dev->info = &ad7292_info;
> > +
> > + ret = of_property_read_bool(spi->dev.of_node, "diff-channels");
>
> I mention in review of the dt patch that this should use the generic
> binding support for specifying differential channels.
>
> > + if (ret) {
> > + indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
> > + indio_dev->channels = ad7292_channels_diff;
> > + } else {
> > + indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
> > + indio_dev->channels = ad7292_channels;
> > + }
> > +
> > + return devm_iio_device_register(&spi->dev, indio_dev);
> > +}
> > +
> > +static const struct spi_device_id ad7292_id_table[] = {
> > + { "ad7292", 0 },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(spi, ad7292_id_table);
> > +
> > +static const struct of_device_id ad7292_of_match[] = {
> > + { .compatible = "adi,ad7292" },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, ad7292_of_match);
> > +
> > +static struct spi_driver ad7292_driver = {
> > + .driver = {
> > + .name = "ad7292",
> > + .of_match_table = ad7292_of_match,
> > + },
> > + .probe = ad7292_probe,
> > + .id_table = ad7292_id_table,
> > +};
> > +module_spi_driver(ad7292_driver);
> > +
> > +MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx>");
> > +MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
> > +MODULE_LICENSE("GPL v2");
>
>