Re: [PATCH v6 2/2] iio: adc: max14001: New driver

Jonathan Cameron
2023-06-17T18:31:00Z

On Wed, 14 Jun 2023 12:11:55 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Wed, Jun 14, 2023 at 3:49 AM Kim Seer Paller
> <kimseer.paller@analog.com> wrote:
> >
> > The MAX14001 is configurable, isolated 10-bit ADCs for multi-range
> > binary inputs.
>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> One question below.
>
> > Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
> > ---
> > V5 -> V6: Replaced fixed length assignment with dynamic size
> > assignment in xfers struct initialization. Removed .channel
> > assignment in max14001_channels definition.
> > V4 -> V5: No changes.
> > V3 -> V4: Removed regmap setup, structures, and include.
> >
> > MAINTAINERS | 1 +
> > drivers/iio/adc/Kconfig | 10 ++
> > drivers/iio/adc/Makefile | 1 +
> > drivers/iio/adc/max14001.c | 327 +++++++++++++++++++++++++++++++++++++
> > 4 files changed, 339 insertions(+)
> > create mode 100644 drivers/iio/adc/max14001.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index dcea2c31f920..b527cf471d7a 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -12676,6 +12676,7 @@ L: linux-iio@vger.kernel.org
> > S: Supported
> > W: https://ez.analog.com/linux-software-drivers
> > F: Documentation/devicetree/bindings/iio/adc/adi,max14001.yaml
> > +F: drivers/iio/adc/max14001.c
> >
> > MAXBOTIX ULTRASONIC RANGER IIO DRIVER
> > M: Andreas Klinger <ak@it-klinger.de>
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index eb2b09ef5d5b..e599d166e98d 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -706,6 +706,16 @@ config MAX11410
> > To compile this driver as a module, choose M here: the module will be
> > called max11410.
> >
> > +config MAX14001
> > + tristate "Analog Devices MAX14001 ADC driver"
> > + depends on SPI
> > + help
> > + Say yes here to build support for Analog Devices MAX14001 Configurable,
> > + Isolated 10-bit ADCs for Multi-Range Binary Inputs.
> > +
> > + To compile this driver as a module, choose M here: the module will be
> > + called max14001.
> > +
> > config MAX1241
> > tristate "Maxim max1241 ADC driver"
> > depends on SPI_MASTER
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index e07e4a3e6237..9f8964258f03 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -65,6 +65,7 @@ obj-$(CONFIG_MAX11100) += max11100.o
> > obj-$(CONFIG_MAX1118) += max1118.o
> > obj-$(CONFIG_MAX11205) += max11205.o
> > obj-$(CONFIG_MAX11410) += max11410.o
> > +obj-$(CONFIG_MAX14001) += max14001.o
> > obj-$(CONFIG_MAX1241) += max1241.o
> > obj-$(CONFIG_MAX1363) += max1363.o
> > obj-$(CONFIG_MAX9611) += max9611.o
> > diff --git a/drivers/iio/adc/max14001.c b/drivers/iio/adc/max14001.c
> > new file mode 100644
> > index 000000000000..b4d10539398b
> > --- /dev/null
> > +++ b/drivers/iio/adc/max14001.c
> > @@ -0,0 +1,327 @@
> > +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
> > +/*
> > + * Analog Devices MAX14001 ADC driver
> > + *
> > + * Copyright 2023 Analog Devices Inc.
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bitrev.h>
> > +#include <linux/device.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/property.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +
> > +#include <asm/unaligned.h>
> > +
> > +/* MAX14001 Registers Address */
> > +#define MAX14001_ADC 0x00
> > +#define MAX14001_FADC 0x01
> > +#define MAX14001_FLAGS 0x02
> > +#define MAX14001_FLTEN 0x03
> > +#define MAX14001_THL 0x04
> > +#define MAX14001_THU 0x05
> > +#define MAX14001_INRR 0x06
> > +#define MAX14001_INRT 0x07
> > +#define MAX14001_INRP 0x08
> > +#define MAX14001_CFG 0x09
> > +#define MAX14001_ENBL 0x0A
> > +#define MAX14001_ACT 0x0B
> > +#define MAX14001_WEN 0x0C
> > +
> > +#define MAX14001_VERIFICATION_REG(x) ((x) + 0x10)
> > +
> > +#define MAX14001_CFG_EXRF BIT(5)
> > +
> > +#define MAX14001_ADDR_MASK GENMASK(15, 11)
> > +#define MAX14001_DATA_MASK GENMASK(9, 0)
> > +#define MAX14001_FILTER_MASK GENMASK(3, 2)
> > +
> > +#define MAX14001_SET_WRITE_BIT BIT(10)
> > +#define MAX14001_WRITE_WEN 0x294
> > +
> > +struct max14001_state {
> > + struct spi_device *spi;
> > + /*
> > + * lock protect against multiple concurrent accesses, RMW sequence, and
> > + * SPI transfer
> > + */
> > + struct mutex lock;
> > + int vref_mv;
> > + /*
> > + * DMA (thus cache coherency maintenance) requires the
> > + * transfer buffers to live in their own cache lines.
> > + */
> > + __be16 spi_tx_buffer __aligned(IIO_DMA_MINALIGN);
> > + __be16 spi_rx_buffer;
> > +};
> > +
> > +static int max14001_read(void *context, unsigned int reg_addr, unsigned int *data)
> > +{
> > + struct max14001_state *st = context;
> > + int ret;
> > +
> > + struct spi_transfer xfers[] = {
> > + {
> > + .tx_buf = &st->spi_tx_buffer,
> > + .len = sizeof(st->spi_tx_buffer),
> > + .cs_change = 1,
> > + }, {
> > + .rx_buf = &st->spi_rx_buffer,
> > + .len = sizeof(st->spi_rx_buffer),
> > + },
> > + };
> > +
> > + st->spi_tx_buffer = bitrev16(cpu_to_be16(FIELD_PREP(MAX14001_ADDR_MASK,
> > + reg_addr)));
> > +
> > + ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
> > + if (ret)
> > + return ret;
> > +
> > + *data = bitrev16(be16_to_cpu(st->spi_rx_buffer)) & MAX14001_DATA_MASK;
> > +
> > + return 0;
> > +}
> > +
> > +static int max14001_write(void *context, unsigned int reg_addr, unsigned int data)
> > +{
> > + struct max14001_state *st = context;
> > +
> > + st->spi_tx_buffer = bitrev16(cpu_to_be16(
> > + FIELD_PREP(MAX14001_ADDR_MASK, reg_addr) |
> > + FIELD_PREP(MAX14001_SET_WRITE_BIT, 1) |
> > + FIELD_PREP(MAX14001_DATA_MASK, data)));
> > +
> > + return spi_write(st->spi, &st->spi_tx_buffer, sizeof(st->spi_tx_buffer));
> > +}
> > +
> > +static int max14001_write_verification_reg(struct max14001_state *st,
> > + unsigned int reg_addr)
> > +{
> > + unsigned int reg_data;
> > + int ret;
> > +
> > + ret = max14001_read(st, reg_addr, &reg_data);
> > + if (ret)
> > + return ret;
> > +
> > + return max14001_write(st, MAX14001_VERIFICATION_REG(reg_addr), reg_data);
> > +}
> > +
> > +static int max14001_reg_update(struct max14001_state *st,
> > + unsigned int reg_addr,
> > + unsigned int mask,
> > + unsigned int val)
> > +{
> > + int ret;
> > + unsigned int reg_data;
> > +
> > + /* Enable SPI Registers Write */
> > + ret = max14001_write(st, MAX14001_WEN, MAX14001_WRITE_WEN);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_read(st, reg_addr, &reg_data);
> > + if (ret)
> > + return ret;
> > +
> > + reg_data = FIELD_PREP(mask, val);
> > +
> > + ret = max14001_write(st, reg_addr, reg_data);
> > + if (ret)
> > + return ret;
> > +
> > + /* Write Verification Register */
> > + ret = max14001_write_verification_reg(st, reg_addr);
> > + if (ret)
> > + return ret;
> > +
> > + /* Disable SPI Registers Write */
> > + return max14001_write(st, MAX14001_WEN, 0);
> > +}
> > +
> > +static int max14001_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct max14001_state *st = iio_priv(indio_dev);
> > + unsigned int data;
> > + int ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + mutex_lock(&st->lock);
> > + ret = max14001_read(st, MAX14001_ADC, &data);
> > + mutex_unlock(&st->lock);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = data;
> > +
> > + return IIO_VAL_INT;
> > +
> > + case IIO_CHAN_INFO_SCALE:
> > + *val = st->vref_mv;
> > + *val2 = 10;
> > +
> > + return IIO_VAL_FRACTIONAL_LOG2;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static const struct iio_info max14001_info = {
> > + .read_raw = max14001_read_raw,
> > +};
> > +
> > +static const struct iio_chan_spec max14001_channels[] = {
> > + {
> > + .type = IIO_VOLTAGE,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > + BIT(IIO_CHAN_INFO_SCALE),
> > + }
> > +};
> > +
> > +static void max14001_regulator_disable(void *data)
> > +{
> > + struct regulator *reg = data;
> > +
> > + regulator_disable(reg);
> > +}
> > +
> > +static int max14001_init(struct max14001_state *st)
> > +{
> > + int ret;
> > +
> > + /* Enable SPI Registers Write */
> > + ret = max14001_write(st, MAX14001_WEN, MAX14001_WRITE_WEN);
> > + if (ret)
> > + return ret;
> > +
> > + /*
> > + * Reads all registers and writes the values back to their appropriate
> > + * verification registers to clear the Memory Validation fault.
> > + */
> > + ret = max14001_write_verification_reg(st, MAX14001_FLTEN);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_THL);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_THU);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_INRR);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_INRT);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_INRP);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_CFG);
> > + if (ret)
> > + return ret;
> > +
> > + ret = max14001_write_verification_reg(st, MAX14001_ENBL);
> > + if (ret)
> > + return ret;
> > +
> > + /* Disable SPI Registers Write */
> > + return max14001_write(st, MAX14001_WEN, 0);
> > +}
> > +
> > +static int max14001_probe(struct spi_device *spi)
> > +{
> > + struct iio_dev *indio_dev;
> > + struct max14001_state *st;
> > + struct regulator *vref;
> > + struct device *dev = &spi->dev;
> > + int ret;
> > +
> > + indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + st = iio_priv(indio_dev);
> > + st->spi = spi;
> > +
> > + indio_dev->name = "max14001";
> > + indio_dev->info = &max14001_info;
> > + indio_dev->channels = max14001_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(max14001_channels);
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > + ret = max14001_init(st);
> > + if (ret)
> > + return ret;
> > +
> > + vref = devm_regulator_get_optional(dev, "vref");
> > + if (IS_ERR(vref)) {
> > + if (PTR_ERR(vref) != -ENODEV)
> > + return dev_err_probe(dev, PTR_ERR(vref),
> > + "Failed to get vref regulator");
> > +
> > + /* internal reference */
> > + st->vref_mv = 1250;
> > + } else {
> > + ret = regulator_enable(vref);
> > + if (ret)
> > + return dev_err_probe(dev, ret,
> > + "Failed to enable vref regulators\n");
> > +
> > + ret = devm_add_action_or_reset(dev, max14001_regulator_disable,
> > + vref);
> > + if (ret)
> > + return ret;
>
> > + /* select external voltage reference source for the ADC */
> > + ret = max14001_reg_update(st, MAX14001_CFG,
> > + MAX14001_CFG_EXRF, 1);
> > +

ret not checked.

> > + ret = regulator_get_voltage(vref);
> > + if (ret < 0)
> > + return dev_err_probe(dev, ret,
> > + "Failed to get vref\n");
>
> Is it important to choose the external reference source _before_
> getting the voltage of the regulator? If not, I would swap these
> calls, otherwise the comment is needed to explain why the sequence is
> important in the way it's written.
>
> > + st->vref_mv = ret / 1000;
> > + }
> > +
> > + mutex_init(&st->lock);
> > +
> > + return devm_iio_device_register(dev, indio_dev);
> > +}
> > +
> > +static const struct of_device_id max14001_of_match[] = {
> > + { .compatible = "adi,max14001" },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(of, max14001_of_match);
> > +
> > +static struct spi_driver max14001_driver = {
> > + .driver = {
> > + .name = "max14001",
> > + .of_match_table = max14001_of_match,
> > + },
> > + .probe = max14001_probe,
> > +};
> > +module_spi_driver(max14001_driver);
> > +
> > +MODULE_AUTHOR("Kim Seer Paller");
> > +MODULE_DESCRIPTION("MAX14001 ADC driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.34.1
> >
>
>