Re: [PATCH] iio: add ad5761 DAC driver

Peter Meerwald-Stadler
2015-12-19T17:06:36Z

> ad5761 is a 1-channel DAC with configurable output range.
> The driver uses the regulator interface for its voltage ref.

some nitpicking below

> It shares its register layout with ad5761r, ad5721 and ad5721r.
>
> Differences:
> ad5761* are 16 bit, ad5721* are 12 bits.
> ad57*1r have an internal reference.
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> ---
> CREDITS | 1 +
> drivers/iio/dac/Kconfig | 10 ++
> drivers/iio/dac/Makefile | 1 +
> drivers/iio/dac/ad5761.c | 425 +++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 437 insertions(+)
> create mode 100644 drivers/iio/dac/ad5761.c
>
> diff --git a/CREDITS b/CREDITS
> index 8207cc62ee9d..44ea433d70a1 100644
> --- a/CREDITS
> +++ b/CREDITS
> @@ -3035,6 +3035,7 @@ D: PLX USB338x driver
> D: PCA9634 driver
> D: Option GTM671WFS
> D: Fintek F81216A
> +D: AD5761 iio driver
> D: Various kernel hacks
> S: Qtechnology A/S
> S: Valby Langgade 142
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index e701e28fb1cd..4caedd671360 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -111,6 +111,16 @@ config AD5755
> To compile this driver as a module, choose M here: the
> module will be called ad5755.
>
> +config AD5761
> + tristate "Analog Devices AD5761/61R/21/21R DAC driver"
> + depends on SPI_MASTER
> + help
> + Say yes here to build support for Analog Devices AD5761, AD5761R, AD5721,
> + AD5721R Digital to Analog Converter.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called ad5761.
> +
> config AD5764
> tristate "Analog Devices AD5764/64R/44/44R DAC driver"
> depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 63ae05633e0c..cb525b53fc7b 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_AD5504) += ad5504.o
> obj-$(CONFIG_AD5446) += ad5446.o
> obj-$(CONFIG_AD5449) += ad5449.o
> obj-$(CONFIG_AD5755) += ad5755.o
> +obj-$(CONFIG_AD5761) += ad5761.o
> obj-$(CONFIG_AD5764) += ad5764.o
> obj-$(CONFIG_AD5791) += ad5791.o
> obj-$(CONFIG_AD5686) += ad5686.o
> diff --git a/drivers/iio/dac/ad5761.c b/drivers/iio/dac/ad5761.c
> new file mode 100644
> index 000000000000..b4eac59ef81f
> --- /dev/null
> +++ b/drivers/iio/dac/ad5761.c
> @@ -0,0 +1,425 @@
> +/*
> + * AD5721, AD5721R, AD5761, AD5761R, Voltage Output Digital to Analog Converter
> + *
> + * Copyright 2015 Qtechnology A/S
> + *
> + * Licensed under the GPL-2.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define AD5761_ADDR(addr) ((addr&0xf) << 16)

maybe add whitespace around &

> +#define AD5761_ADDR_NOOP 0x0
> +#define AD5761_ADDR_DAC_WRITE 0x3
> +#define AD5761_ADDR_CTRL_WRITE_REG 0x4
> +#define AD5761_ADDR_SW_DATA_RESET 0x7
> +#define AD5761_ADDR_DAC_READ 0xb
> +#define AD5761_ADDR_CTRL_READ_REG 0xc
> +#define AD5761_ADDR_SW_FULL_RESET 0xf
> +
> +#define AD5761_CTRL_USE_INTVREF BIT(5)
> +#define AD5761_CTRL_ETS BIT(6)
> +
> +/**
> + * struct ad5761_chip_info - chip specific information
> + * @int_vref: Value of the internal reference voltage in mV - 0 if external
> + * reference voltage is used
> + * @channel channel specification

@channel:

> +*/
> +
> +struct ad5761_chip_info {
> + unsigned long int_vref;
> + const struct iio_chan_spec channel;
> +};
> +
> +struct ad5761_range_params {
> + int m;
> + int c;
> +};
> +
> +/**
> + * ad5761_supported_device_ids:
> + */
> +
> +enum ad5761_supported_device_ids {
> + ID_AD5721,
> + ID_AD5721R,
> + ID_AD5761,
> + ID_AD5761R,
> +};
> +
> +/**
> + * struct ad5761_state - driver instance specific data
> + * @spi: spi_device
> + * @chip_info: chip model specific constants
> + * @vref_mv: actual reference voltage used

there is no chip_info and no vref_mv in ad5761_state

vref_reg, use_intref, vref, range, data exist but have no explanation

> + */
> +struct ad5761_state {
> + struct spi_device *spi;
> + struct regulator *vref_reg;
> +
> + bool use_intref;
> + int vref;
> + int range;
> +
> + /*
> + * DMA (thus cache coherency maintenance) requires the
> + * transfer buffers to live in their own cache lines.
> + */
> + union {
> + __be32 d32;
> + u8 d8[4];
> + } data[3] ____cacheline_aligned;
> +};
> +
> +enum ad5761_range_ids {
> + MODE_M10V_10V,
> + MODE_0V_10V,
> + MODE_M5V_5V,
> + MODE_0V_5V,
> + MODE_M2V5_7V5,
> + MODE_M3V_3V,
> + MODE_0V_16V,
> + MODE_0V_20V,
> +};
> +
> +static const struct ad5761_range_params ad5761_range_params[] = {
> + [MODE_M10V_10V] = {
> + .m = 80,
> + .c = 40,
> + },
> + [MODE_0V_10V] = {
> + .m = 40,
> + .c = 0,
> + },
> + [MODE_M5V_5V] = {
> + .m = 40,
> + .c = 20,
> + },
> + [MODE_0V_5V] = {
> + .m = 20,
> + .c = 0,
> + },
> + [MODE_M2V5_7V5] = {
> + .m = 40,
> + .c = 10,
> + },
> + [MODE_M3V_3V] = {
> + .m = 24,
> + .c = 12,
> + },
> + [MODE_0V_16V] = {
> + .m = 64,
> + .c = 0,
> + },
> + [MODE_0V_20V] = {
> + .m = 80,
> + .c = 0,
> + },
> +};
> +
> +static const char * const ad5761_ranges[] = {
> + [MODE_M10V_10V] = "-10V_10V",
> + [MODE_0V_10V] = "0V_10V",
> + [MODE_M5V_5V] = "-5V_5V",
> + [MODE_0V_5V] = "0V_5V",
> + [MODE_M2V5_7V5] = "-2V5_7V5",
> + [MODE_M3V_3V] = "-3V_3V",
> + [MODE_0V_16V] = "0V_16V",
> + [MODE_0V_20V] = "0V_20V",
> +};
> +
> +static int ad5761_spi_write(struct ad5761_state *st, u8 addr, u16 val)
> +{
> + st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr) | val);
> +
> + return spi_write(st->spi, &st->data[0].d8[1], 3);
> +}
> +
> +static int ad5761_spi_read(struct ad5761_state *st, u8 addr, u16 *val)
> +{
> + int ret;
> + struct spi_transfer xfers[] = {
> + {
> + .tx_buf = &st->data[0].d8[1],
> + .bits_per_word = 8,
> + .len = 3,
> + .cs_change = true,
> + }, {
> + .tx_buf = &st->data[1].d8[1],
> + .rx_buf = &st->data[2].d8[1],
> + .bits_per_word = 8,
> + .len = 3,
> + },
> + };
> +
> + st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr));
> + st->data[1].d32 = cpu_to_be32(AD5761_ADDR(AD5761_ADDR_NOOP));
> +
> + ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
> +
> + *val = be32_to_cpu(st->data[2].d32);
> +
> + return ret;
> +}
> +
> +static int ad5761_spi_set_range(struct ad5761_state *st, int range)
> +{
> + u16 aux;
> + int ret;
> +
> + aux = range;
> + aux |= AD5761_CTRL_ETS;
> + if (st->use_intref)
> + aux |= AD5761_CTRL_USE_INTVREF;
> + ret = ad5761_spi_write(st, AD5761_ADDR_CTRL_WRITE_REG, aux);
> + if (ret)
> + return ret;
> + ret = ad5761_spi_write(st, AD5761_ADDR_SW_DATA_RESET, 0);
> + if (ret)
> + return ret;
> +
> + st->range = range;
> + return 0;
> +}
> +
> +static int ad5761_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long m)

often 'mask' is used instead of m

> +{
> + struct ad5761_state *st = iio_priv(indio_dev);
> + int ret;
> + u16 aux;
> +
> + switch (m) {
> + case IIO_CHAN_INFO_RAW:
> + ret = ad5761_spi_read(st, AD5761_ADDR_DAC_READ, &aux);
> + if (ret)
> + return ret;
> + *val = aux >> chan->scan_type.shift;
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + *val = st->vref * ad5761_range_params[st->range].m;
> + *val /= 10;
> + *val2 = chan->scan_type.realbits;
> + return IIO_VAL_FRACTIONAL_LOG2;
> + case IIO_CHAN_INFO_OFFSET:
> + *val = -(1<<chan->scan_type.realbits);

whitespace around <<

> + *val *= ad5761_range_params[st->range].c;
> + *val /= ad5761_range_params[st->range].m;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +

delete newline

> +}
> +
> +static int ad5761_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val,
> + int val2,
> + long mask)
> +{
> + struct ad5761_state *st = iio_priv(indio_dev);
> + u16 aux;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + aux = val << chan->scan_type.shift;

delete extra space before val

> + return ad5761_spi_write(st, AD5761_ADDR_DAC_WRITE, aux);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int ad5761_set_range(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan, unsigned int range)
> +{
> + struct ad5761_state *st = iio_priv(indio_dev);
> +
> + return ad5761_spi_set_range(st, range);
> +}
> +
> +static int ad5761_get_range(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan)
> +{
> + struct ad5761_state *st = iio_priv(indio_dev);
> + u16 aux;
> + int ret;
> +
> + ret = ad5761_spi_read(st, AD5761_ADDR_CTRL_READ_REG, &aux);
> + if (ret)
> + return ret;
> +
> + return aux & 0x7;
> +}
> +
> +static const struct iio_info ad5761_info = {
> + .read_raw = &ad5761_read_raw,
> + .write_raw = &ad5761_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static const struct iio_enum ad5761_range_enum = {
> + .items = ad5761_ranges,
> + .num_items = ARRAY_SIZE(ad5761_ranges),
> + .get = ad5761_get_range,
> + .set = ad5761_set_range,
> +};
> +
> +static struct iio_chan_spec_ext_info ad5761_ext_info[] = {
> + IIO_ENUM("range", IIO_SHARED_BY_TYPE,
> + &ad5761_range_enum),
> + IIO_ENUM_AVAILABLE("range", &ad5761_range_enum),
> + { },
> +};
> +
> +#define AD5761_CHAN(_bits) { \
> + .type = IIO_VOLTAGE, \
> + .output = 1, \
> + .indexed = 1, \

since there is only one channel, .indexed could be 0 (or not set)

> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_OFFSET), \
> + .scan_type = { \

the driver does not support buffered mode, not sure if scan_type should be
used to store the number of bits; I think it would be cleaner to put this
in chip_info

> + .sign = 'u', \
> + .realbits = (_bits), \
> + .storagebits = 16, \
> + .shift = 16 - (_bits), \
> + }, \
> + .ext_info = ad5761_ext_info, \
> +}
> +
> +static const struct ad5761_chip_info ad5761_chip_infos[] = {
> + [ID_AD5721] = {
> + .int_vref = 0,
> + .channel = AD5761_CHAN(12),
> + },
> + [ID_AD5721R] = {
> + .int_vref = 2500,
> + .channel = AD5761_CHAN(12),
> + },
> + [ID_AD5761] = {
> + .int_vref = 0,
> + .channel = AD5761_CHAN(16),
> + },
> + [ID_AD5761R] = {
> + .int_vref = 2500,
> + .channel = AD5761_CHAN(16),
> + },
> +};
> +
> +static void ad5761_get_vref(struct ad5761_state *st)
> +{
> + int ret;
> +

delete extra newline

> +
> + st->vref_reg = devm_regulator_get(&st->spi->dev, "vref");
> + if (IS_ERR(st->vref_reg))
> + return;
> +
> + ret = regulator_enable(st->vref_reg);
> + if (ret) {
> + dev_warn(&st->spi->dev, "Failed to enable vref. Using internal");

put \n at the end of the message (here and elsewhere)

> + return;
> + }
> +
> + ret = regulator_get_voltage(st->vref_reg);
> + if (ret < 0) {
> + regulator_disable(st->vref_reg);
> + dev_warn(&st->spi->dev,
> + "Failed to get vref value. Using internal");
> + return;
> + }
> +
> + if (ret < 2000000 || ret > 3000000) {
> + regulator_disable(st->vref_reg);
> + dev_warn(&st->spi->dev,
> + "Invalid external vref value. Using internal");
> + return;
> + }
> +
> + st->vref = ret / 1000;
> + st->use_intref = false;
> +}
> +
> +static int ad5761_probe(struct spi_device *spi)
> +{
> + struct iio_dev *iio_dev;
> + struct ad5761_state *st;
> + int ret;
> + const struct ad5761_chip_info *chip_info =
> + &ad5761_chip_infos[spi_get_device_id(spi)->driver_data];
> +
> + iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> + if (!iio_dev)
> + return -ENOMEM;
> + st = iio_priv(iio_dev);
> +
> + st->spi = spi;
> + spi_set_drvdata(spi, iio_dev);
> +
> + st->use_intref = true;
> + st->vref = chip_info->int_vref;
> + ad5761_get_vref(st);

this is ugly, I'd prefer to return something from _get_vref() instead of
first setting a could of variable and then checking a couple of variables

> + if (st->use_intref && !chip_info->int_vref) {
> + dev_err(&spi->dev, "Missing vref, cannot continue");
> + return -EIO;
> + }
> +
> + ad5761_spi_set_range(st, MODE_0V_5V);

this can fail, retval not checked

> +
> + iio_dev->dev.parent = &spi->dev;
> + iio_dev->info = &ad5761_info;
> + iio_dev->modes = INDIO_DIRECT_MODE;
> + iio_dev->channels = &chip_info->channel;
> + iio_dev->num_channels = 1;
> + iio_dev->name = spi_get_device_id(st->spi)->name;
> + ret = iio_device_register(iio_dev);
> + if (ret && !IS_ERR(st->vref_reg))
> + regulator_disable(st->vref_reg);

maybe vref_reg is disabled twice, here and in get_vref()

> +
> + return ret;
> +}
> +
> +static int ad5761_remove(struct spi_device *spi)
> +{
> + struct iio_dev *iio_dev = spi_get_drvdata(spi);
> + struct ad5761_state *st = iio_priv(iio_dev);
> +
> + if (!IS_ERR(st->vref_reg))
> + regulator_disable(st->vref_reg);
> + iio_device_unregister(iio_dev);
> + return 0;
> +}
> +
> +static const struct spi_device_id ad5761_id[] = {
> + {"ad5721", ID_AD5721},
> + {"ad5721r", ID_AD5721R},
> + {"ad5761", ID_AD5761},
> + {"ad5761r", ID_AD5761R},
> + {}
> +};
> +MODULE_DEVICE_TABLE(spi, ad5761_id);
> +
> +static struct spi_driver ad5761_driver = {
> + .driver = {
> + .name = "ad5761",
> + .owner = THIS_MODULE,
> + },
> + .probe = ad5761_probe,
> + .remove = ad5761_remove,
> + .id_table = ad5761_id,
> +};
> +module_spi_driver(ad5761_driver);
> +
> +MODULE_AUTHOR("Ricardo Ribalda <ricardo.ribalda@gmail.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5721, AD5721R, AD5761, AD5761R driver");
> +MODULE_LICENSE("GPL v2");
>

--

Peter Meerwald-Stadler
+43-664-2444418 (mobile)