> This patch adds support for the Texas Intruments ADS8688 ADC.
nitpicking below
> Signed-off-by: Sean Nyekjaer <sean.nyekjaer@xxxxxxxxx>
> Reviewed-by: Martin Hundebøll <martin.hundeboll@xxxxxxxxx>
> ---
> Changes since v2:
> - Removed unused variables
> - Removed unnecessary mutex lock
> - Range array is a enum
> - Made the read and write functions less complex and easier to read
> - Added inline comments
> - Added callback to write_raw_get_fmt
>
> Changes since v1:
> - Now possible to read and write the actual offset and scale values
> - Removed unused includes
> - Removed unused buffer references
>
> drivers/iio/adc/Kconfig | 10 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/ti-ads8688.c | 463 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 474 insertions(+)
> create mode 100644 drivers/iio/adc/ti-ads8688.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index deea62c..9605aa0 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -322,6 +322,16 @@ config TI_ADC128S052
> This driver can also be built as a module. If so, the module will be
> called ti-adc128s052.
>
> +config TI_ADS8688
> + tristate "Texas Instruments ADS8688"
> + depends on SPI && OF
> + help
> + If you say yes here you get support for Texas Instruments ADS8684 and
> + and ADS8688 ADC chips
> +
> + This driver can also be built as a module. If so, the module will be
> + called ti-ads8688.
> +
> config TI_AM335X_ADC
> tristate "TI's AM335X ADC driver"
> depends on MFD_TI_AM335X_TSCADC
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index fa5723a..08a4dda 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
> obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> +obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
> obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
> obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
> obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
> diff --git a/drivers/iio/adc/ti-ads8688.c b/drivers/iio/adc/ti-ads8688.c
> new file mode 100644
> index 0000000..fc422c3
> --- /dev/null
> +++ b/drivers/iio/adc/ti-ads8688.c
> @@ -0,0 +1,463 @@
> +/*
> + * Copyright (C) 2015 Prevas A/S
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/spi/spi.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define ADS8688_CMD_REG(x) (x << 8)
> +#define ADS8688_CMD_REG_NOOP 0x00
> +#define ADS8688_CMD_REG_RST 0x85
> +#define ADS8688_CMD_REG_MAN_CH(chan) (0xC0 | (4 * chan))
> +#define ADS8688_CMD_DONT_CARE_BITS 16
> +
> +#define ADS8688_PROG_REG(x) (x << 9)
> +#define ADS8688_PROG_REG_RANGE_CH(chan) (0x05 + chan)
> +#define ADS8688_PROG_WR_BIT BIT(8)
> +#define ADS8688_PROG_DONT_CARE_BITS 8
> +
> +#define ADS8688_REG_PLUSMINUS25VREF 0
> +#define ADS8688_REG_PLUSMINUS125VREF 1
> +#define ADS8688_REG_PLUSMINUS0625VREF 2
> +#define ADS8688_REG_PLUS25VREF 5
> +#define ADS8688_REG_PLUS125VREF 6
> +
> +#define ADS8688_VREF_MV 4096
> +#define ADS8688_REALBITS 16
> +
> +/*
> + * enum ads8688_range - ADS8688 reference voltage range
> + * @ADS8688_PLUSMINUS25VREF: Device is configured for input range ±2.5 * VREF
> + * @ADS8688_PLUSMINUS125VREF: Device is configured for input range ±1.25 * VREF
> + * @ADS8688_PLUSMINUS0625VREF: Device is configured for input range ±0.625 * VREF
> + * @ADS8688_PLUS25VREF: Device is configured for input range 0 - 2.5 * VREF
> + * @ADS8688_PLUS125VREF: Device is configured for input range 0 - 1.25 * VREF
> + */
> +enum ads8688_range {
> + ADS8688_PLUSMINUS25VREF,
> + ADS8688_PLUSMINUS125VREF,
> + ADS8688_PLUSMINUS0625VREF,
> + ADS8688_PLUS25VREF,
> + ADS8688_PLUS125VREF,
> +};
> +
> +struct ads8688_chip_info {
> + const struct iio_chan_spec *channels;
> + unsigned int num_channels;
> +};
> +
> +struct ads8688_state {
> + const struct ads8688_chip_info *chip_info;
> + struct spi_device *spi;
> + struct regulator *reg;
> + unsigned int vref_mv;
> + enum ads8688_range range[8];
> + union {
> + __be32 d32;
> + u8 d8[4];
> + } data[2] ____cacheline_aligned;
> +};
> +
> +enum ads8688_id {
> + ID_ADS8684,
> + ID_ADS8688,
> +};
> +
> +struct ads8688_ranges {
> + enum ads8688_range range;
> + unsigned int scale;
> + int offset;
> + u8 reg;
> +};
> +
> +static const struct ads8688_ranges ads8688_range_def[5] = {
> + {
> + .range = ADS8688_PLUSMINUS25VREF,
> + .scale = 76295,
> + .offset = -(1 << (ADS8688_REALBITS - 1)),
> + .reg = ADS8688_REG_PLUSMINUS25VREF,
> + }, {
> + .range = ADS8688_PLUSMINUS125VREF,
> + .scale = 38148,
> + .offset = -(1 << (ADS8688_REALBITS - 1)),
> + .reg = ADS8688_REG_PLUSMINUS125VREF,
> + }, {
> + .range = ADS8688_PLUSMINUS0625VREF,
> + .scale = 19074,
> + .offset = -(1 << (ADS8688_REALBITS - 1)),
> + .reg = ADS8688_REG_PLUSMINUS0625VREF,
> + }, {
> + .range = ADS8688_PLUS25VREF,
> + .scale = 38148,
> + .offset = 0,
> + .reg = ADS8688_REG_PLUS25VREF,
> + }, {
> + .range = ADS8688_PLUS125VREF,
> + .scale = 19074,
> + .offset = 0,
> + .reg = ADS8688_REG_PLUS125VREF,
> + }
> +};
> +
> +static ssize_t ads8688_show_scales(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct ads8688_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> + return sprintf(buf, "0.%09u 0.%09u 0.%09u\n",
> + ads8688_range_def[0].scale * st->vref_mv,
> + ads8688_range_def[1].scale * st->vref_mv,
> + ads8688_range_def[2].scale * st->vref_mv);
> +}
> +
> +static ssize_t ads8688_show_offsets(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d %d\n", ads8688_range_def[0].offset,
> + ads8688_range_def[3].offset);
> +}
> +
> +static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
> + ads8688_show_scales, NULL, 0);
> +static IIO_DEVICE_ATTR(in_voltage_offset_available, S_IRUGO,
> + ads8688_show_offsets, NULL, 0);
> +
> +static struct attribute *ads8688_attributes[] = {
> + &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
> + &iio_dev_attr_in_voltage_offset_available.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group ads8688_attribute_group = {
> + .attrs = ads8688_attributes,
> +};
> +
> +#define ADS8688_CHAN(index) \
> +{ \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = index, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
> + | BIT(IIO_CHAN_INFO_SCALE) \
> + | BIT(IIO_CHAN_INFO_OFFSET), \
> +}
> +
> +static const struct iio_chan_spec ads8684_channels[] = {
> + ADS8688_CHAN(0),
> + ADS8688_CHAN(1),
> + ADS8688_CHAN(2),
> + ADS8688_CHAN(3),
> +};
> +
> +static const struct iio_chan_spec ads8688_channels[] = {
> + ADS8688_CHAN(0),
> + ADS8688_CHAN(1),
> + ADS8688_CHAN(2),
> + ADS8688_CHAN(3),
> + ADS8688_CHAN(4),
> + ADS8688_CHAN(5),
> + ADS8688_CHAN(6),
> + ADS8688_CHAN(7),
> +};
> +
> +static int ads8688_prog_write(struct iio_dev *indio_dev, unsigned int addr,
> + unsigned int val)
> +{
> + struct ads8688_state *st = iio_priv(indio_dev);
> + u32 tmp;
> +
> + tmp = ADS8688_PROG_REG(addr) | ADS8688_PROG_WR_BIT | val;
> + tmp <<= ADS8688_PROG_DONT_CARE_BITS;
> + st->data[0].d32 = cpu_to_be32(tmp);
> +
> + return spi_write(st->spi, &st->data[0].d8[1], 3);
> +}
> +
> +static int ads8688_reset(struct iio_dev *indio_dev)
> +{
> + struct ads8688_state *st = iio_priv(indio_dev);
> + u32 tmp;
> +
> + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_RST);
> + tmp <<= ADS8688_CMD_DONT_CARE_BITS;
> + st->data[0].d32 = cpu_to_be32(tmp);
> +
> + return spi_write(st->spi, &st->data[0].d8[0], 4);
> +}
> +
> +static int ads8688_read(struct iio_dev *indio_dev, unsigned int chan)
> +{
> + struct ads8688_state *st = iio_priv(indio_dev);
> + int ret;
> + u32 tmp;
> + struct spi_transfer t[] = {
> + {
> + .tx_buf = &st->data[0].d8[0],
> + .len = 4,
> + .cs_change = 1,
> + }, {
> + .tx_buf = &st->data[1].d8[0],
> + .rx_buf = &st->data[1].d8[0],
> + .len = 4,
> + },
> + };
> +
> + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_MAN_CH(chan));
> + tmp <<= ADS8688_CMD_DONT_CARE_BITS;
> + st->data[0].d32 = cpu_to_be32(tmp);
> +
> + tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_NOOP);
> + tmp <<= ADS8688_CMD_DONT_CARE_BITS;
> + st->data[1].d32 = cpu_to_be32(tmp);
> +
> + ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
> + if (ret < 0)
> + return ret;
> +
> + return be32_to_cpu(st->data[1].d32) & 0xffff;
> +}
> +
> +static int ads8688_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long m)
> +{
> + int ret, offset;
> + unsigned long scale_mv;
> +
> + struct ads8688_state *st = iio_priv(indio_dev);
> +
> + switch (m) {
> + case IIO_CHAN_INFO_RAW:
> + ret = ads8688_read(indio_dev, chan->channel);
> + if (ret < 0)
> + return ret;
> + *val = ret;
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + scale_mv = st->vref_mv;
> + scale_mv *= ads8688_range_def[st->range[chan->channel]].scale;
> + *val = 0;
> + *val2 = scale_mv;
> + return IIO_VAL_INT_PLUS_NANO;
> + case IIO_CHAN_INFO_OFFSET:
> + offset = ads8688_range_def[st->range[chan->channel]].offset;
> + *val = offset;
> + return IIO_VAL_INT;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int ads8688_write_reg_range(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + enum ads8688_range range)
> +{
> + unsigned int tmp;
> + int ret;
> +
> + tmp = ADS8688_PROG_REG_RANGE_CH(chan->channel);
> + ret = ads8688_prog_write(indio_dev, tmp, range);
> +
> + return ret;
> +}
> +
> +static int ads8688_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct ads8688_state *st = iio_priv(indio_dev);
> + unsigned int scale = 0;
> + int ret = -EINVAL, i, offset = 0;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> + /* If the offset is 0 the ±2.5 * VREF mode is not available */
> + offset = ads8688_range_def[st->range[chan->channel]].offset;
> + if (offset == 0 && val2 == ads8688_range_def[0].scale * st->vref_mv)
> + return -EINVAL;
> +
> + /* Lookup new mode */
> + for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
> + if (val2 == ads8688_range_def[i].scale * st->vref_mv &&
> + offset == ads8688_range_def[i].offset) {
> + ret = ads8688_write_reg_range(indio_dev, chan,
> + ads8688_range_def[i].reg);
> + break;
> + }
> + break;
> + case IIO_CHAN_INFO_OFFSET:
> + /* There are only two available offsets:
not a proper multi-line comment, here and below
> + * 0 and -(1 << (ADS8688_REALBITS - 1))
> + */
> + if (!(ads8688_range_def[0].offset == val ||
> + ads8688_range_def[3].offset == val))
> + return -EINVAL;
> +
> + /* If the device are in ±2.5 * VREF mode, it's not allowed to
> + * switch to a mode where the offset is 0
> + */
check that val2 is 0
> + if (0 == val &&
> + st->range[chan->channel] == ADS8688_PLUSMINUS25VREF)
> + return -EINVAL;
> +
> + scale = ads8688_range_def[st->range[chan->channel]].scale;
> +
> + /* Lookup new mode */
> + for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
> + if (val == ads8688_range_def[i].offset &&
> + scale == ads8688_range_def[i].scale) {
> + ret = ads8688_write_reg_range(indio_dev, chan,
> + ads8688_range_def[i].reg);
> + break;
> + }
> + break;
> + }
> +
> + if (!ret)
> + st->range[chan->channel] = ads8688_range_def[i].range;
> +
> + return ret;
> +}
> +
> +static int ads8688_write_raw_get_fmt(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + long mask)
> +{
only _SCALE is nano, _OFFSET is int
> + return IIO_VAL_INT_PLUS_NANO;
> +}
> +
> +static const struct iio_info ads8688_info = {
> + .read_raw = &ads8688_read_raw,
> + .write_raw = &ads8688_write_raw,
> + .write_raw_get_fmt = &ads8688_write_raw_get_fmt,
> + .attrs = &ads8688_attribute_group,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static const struct ads8688_chip_info ads8688_chip_info_tbl[] = {
> + [ID_ADS8684] = {
> + .channels = ads8684_channels,
> + .num_channels = ARRAY_SIZE(ads8684_channels),
> + },
> + [ID_ADS8688] = {
> + .channels = ads8688_channels,
> + .num_channels = ARRAY_SIZE(ads8688_channels),
> + },
> +};
> +
> +static int ads8688_probe(struct spi_device *spi)
> +{
> + struct ads8688_state *st;
> + struct iio_dev *indio_dev;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> + if (indio_dev == NULL)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> +
> + if (spi->dev.of_node && of_property_read_bool(spi->dev.of_node,
> + "vref-supply")) {
> + st->reg = devm_regulator_get(&spi->dev, "vref");
> + if (!IS_ERR(st->reg)) {
> + ret = regulator_enable(st->reg);
> + if (ret)
> + return ret;
> +
> + ret = regulator_get_voltage(st->reg);
> + if (ret < 0)
> + goto error_out;
> +
> + st->vref_mv = ret / 1000;
> + }
> + } else {
> + /* Use internal reference */
> + st->vref_mv = ADS8688_VREF_MV;
> + }
> +
> + st->chip_info = &ads8688_chip_info_tbl[spi_get_device_id(spi)->driver_data];
> +
> + spi->mode = SPI_MODE_1;
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + st->spi = spi;
> +
> + indio_dev->name = spi_get_device_id(spi)->name;
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = st->chip_info->channels;
> + indio_dev->num_channels = st->chip_info->num_channels;
> + indio_dev->info = &ads8688_info;
> +
> + ads8688_reset(indio_dev);
> +
> + ret = iio_device_register(indio_dev);
> + if (ret)
> + goto error_out;
> +
> + return 0;
> +
> +error_out:
> + if (!IS_ERR_OR_NULL(st->reg))
> + regulator_disable(st->reg);
> +
> + return ret;
> +}
> +
> +static int ads8688_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct ads8688_state *st = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> +
> + if (!IS_ERR_OR_NULL(st->reg))
> + regulator_disable(st->reg);
> +
> + return 0;
> +}
> +
> +static const struct spi_device_id ads8688_id[] = {
> + {"ads8684", ID_ADS8684},
> + {"ads8688", ID_ADS8688},
> + {}
> +};
> +MODULE_DEVICE_TABLE(spi, ads8688_id);
> +
> +static const struct of_device_id ads8688_of_match[] = {
> + { .compatible = "ti,ads8684" },
> + { .compatible = "ti,ads8688" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, ads8688_of_match);
> +
> +static struct spi_driver ads8688_driver = {
> + .driver = {
> + .name = "ads8688",
> + .owner = THIS_MODULE,
> + },
> + .probe = ads8688_probe,
> + .remove = ads8688_remove,
> + .id_table = ads8688_id,
> +};
> +module_spi_driver(ads8688_driver);
> +
> +MODULE_AUTHOR("Sean Nyekjaer <sean.nyekjaer@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Texas Instruments ADS8688 driver");
> +MODULE_LICENSE("GPL v2");
>
--
Peter Meerwald
+43-664-2444418 (mobile)
