Re: [PATCH v4 1/2] iio: adc: Add TI ADS8688

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On 13/10/15 10:46, Sean Nyekjær wrote:
> Hi
> 
> I'm having a problems with the ads8688_write_raw_get_fmt function.
> 
> Firstly the OFFSET and the SCALE its switched around. Ill fix that :-)
> Secondly the i'm not allowed to return IIO_VAL_INT, this results in the
> iio_write_channel_info() is returning -EINVAL. The iio_write_channel_info() only checks if the write_raw_get_fmt is existing...
> Do I need to convert the OFFSET to a IIO_VAL_INT_PLUS_NANO aswell or ?
Nope. The core needs extending to actually support IIO_VAL_INT.  Though cynically
setting it to IIO_VAL_INT_PLUS_MICRO and checking the val2 is 0 would work
as well if you want a quick solution.

Adding IIO_VAL_INT support should be fairly straightforward, though I'd
bypass the string to fixedpoint convertor in this case and do it with an
scanf.  


> 
> /Sean
> 
> On 2015-10-11 16:53, Jonathan Cameron wrote:
>> On 06/10/15 09:12, Sean Nyekjaer wrote:
>>> This patch adds support for the Texas Intruments ADS8688 ADC.
>>>
>>> Signed-off-by: Sean Nyekjaer <sean.nyekjaer-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>
>>> Reviewed-by: Martin Hundebøll <martin.hundeboll-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>
>> only one issue that I can see.  You do need locking to protect
>> your local buffers.  A local lock in the same structure would be
>> appropriate for this.
>>
>> Neither sysfs nor IIO provide any serialization guarantees
>> so multiple concurrent reads are more than possible and may
>> cause you data corruption as it stands.
>>
>> Other than that, it's looking very nice.
>>
>> Thanks,
>>
>> Jonathan
>>> ---
>>> Changes since v3:
>>> - fixed multiline comments
>>> - write_raw_get_fmt _SCALE is nano, _OFFSET is int
>>>
>>> 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 | 472 +++++++++++++++++++++++++++++++++++++++++++
>>>   3 files changed, 483 insertions(+)
>>>   create mode 100644 drivers/iio/adc/ti-ads8688.c
>>>
>>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>>> index 7868c74..4135d17 100644
>>> --- a/drivers/iio/adc/Kconfig
>>> +++ b/drivers/iio/adc/Kconfig
>>> @@ -333,6 +333,16 @@ 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 99b37a9..04ab2c8 100644
>>> --- a/drivers/iio/adc/Makefile
>>> +++ b/drivers/iio/adc/Makefile
>>> @@ -32,6 +32,7 @@ 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..537bb0a
>>> --- /dev/null
>>> +++ b/drivers/iio/adc/ti-ads8688.c
>>> @@ -0,0 +1,472 @@
>>> +/*
>>> + * 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];
>> Oops, missed this before.  You need to have locking around
>> your databuffer.  There is nothing in sysfs or the IIO
>> core to prevent multiple concurrent reads..
>>
>> I note you mention removing an unecessary lock. I think that
>> was a missunderstanding.  Locking is necessary, just not
>> using the IIO mutex that exists to protect against state
>> change issues (enabling buffers for example).
>>
>> So there should be a local lock to protect this next element.
>>
>>> +    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:
>>> +         * 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
>>> +         */
>>> +        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)
>>> +{
>>> +    switch (mask) {
>>> +    case IIO_CHAN_INFO_SCALE:
>>> +        return IIO_VAL_INT;
>>> +    case IIO_CHAN_INFO_OFFSET:
>>> +        return IIO_VAL_INT_PLUS_NANO;
>>> +    }
>>> +
>>> +    return -EINVAL;
>>> +}
>>> +
>>> +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-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>");
>>> +MODULE_DESCRIPTION("Texas Instruments ADS8688 driver");
>>> +MODULE_LICENSE("GPL v2");
>>>
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