Re: [PATCH v3 2/2] iio: accel: Add driver support for ADXL313

[Lucas Stankus <lucas.p.stankus@gmail.com>]

On Sun, Aug 15, 2021 at 12:23 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Wed, 11 Aug 2021 18:18:02 -0300
> Lucas Stankus <lucas.p.stankus@gmail.com> wrote:
>
> > ADXL313 is a small, thin, low power, 3-axis accelerometer with high
> > resolution measurement up to +/-4g. It includes an integrated 32-level
> > FIFO and has activity and inactivity sensing capabilities.
> >
> > Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> > Signed-off-by: Lucas Stankus <lucas.p.stankus@gmail.com>
> > Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
>
> Hi Lucas,
>
> I took another close look at this and I would like you to not use scan_index
> as you are here.  It has a meaning tightly coupled to 'scans' which only exist
> as a concept once you have buffered mode. The preferred way to get channel
> specific values is to use addr and add a level of indirection (so a lookup
> structure of some type).  A few more trivial things to add to what Andy raised
> inline below.
>
> Jonathan
>

Okay, sorry for the misuse from my side, I'll address it in the v4 as
well as the other minor comments.

>
> ...
>
> > +#endif /* _ADXL313_H_ */
> > diff --git a/drivers/iio/accel/adxl313_core.c b/drivers/iio/accel/adxl313_core.c
> > new file mode 100644
> > index 000000000000..8f3d4f5281c4
> > --- /dev/null
> > +++ b/drivers/iio/accel/adxl313_core.c
> > @@ -0,0 +1,331 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * ADXL313 3-Axis Digital Accelerometer
> > + *
> > + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@gmail.com>
> > + *
> > + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/module.h>
> > +#include <linux/regmap.h>
> > +
> > +#include "adxl313.h"
> > +
> > +const struct regmap_range adxl313_readable_reg_range[] = {
> > +     regmap_reg_range(ADXL313_REG_DEVID0, ADXL313_REG_XID),
> > +     regmap_reg_range(ADXL313_REG_SOFT_RESET, ADXL313_REG_SOFT_RESET),
> > +     regmap_reg_range(ADXL313_REG_OFS_AXIS(0), ADXL313_REG_OFS_AXIS(2)),
> > +     regmap_reg_range(ADXL313_REG_THRESH_ACT, ADXL313_REG_ACT_INACT_CTL),
> > +     regmap_reg_range(ADXL313_REG_BW_RATE, ADXL313_REG_FIFO_STATUS)
> > +};
> > +
> > +const struct regmap_access_table adxl313_readable_regs_table = {
> > +     .yes_ranges = adxl313_readable_reg_range,
> > +     .n_yes_ranges = ARRAY_SIZE(adxl313_readable_reg_range)
> > +};
> > +EXPORT_SYMBOL_GPL(adxl313_readable_regs_table);
> > +
> > +const struct regmap_range adxl313_writable_reg_range[] = {
> > +     regmap_reg_range(ADXL313_REG_SOFT_RESET, ADXL313_REG_SOFT_RESET),
> > +     regmap_reg_range(ADXL313_REG_OFS_AXIS(0), ADXL313_REG_OFS_AXIS(2)),
> > +     regmap_reg_range(ADXL313_REG_THRESH_ACT, ADXL313_REG_ACT_INACT_CTL),
> > +     regmap_reg_range(ADXL313_REG_BW_RATE, ADXL313_REG_INT_MAP),
> > +     regmap_reg_range(ADXL313_REG_DATA_FORMAT, ADXL313_REG_DATA_FORMAT),
> > +     regmap_reg_range(ADXL313_REG_FIFO_CTL, ADXL313_REG_FIFO_CTL)
> > +};
> > +
> > +const struct regmap_access_table adxl313_writable_regs_table = {
> > +     .yes_ranges = adxl313_writable_reg_range,
> > +     .n_yes_ranges = ARRAY_SIZE(adxl313_writable_reg_range)
> > +};
> > +EXPORT_SYMBOL_GPL(adxl313_writable_regs_table);
> > +
> > +struct adxl313_data {
> > +     struct regmap   *regmap;
> > +     struct mutex    lock; /* lock to protect transf_buf */
> > +     __le16          transf_buf ____cacheline_aligned;
> > +};
> > +
> > +static const int adxl313_odr_freqs[][2] = {
> > +     [0] = { 6, 250000 },
> > +     [1] = { 12, 500000 },
> > +     [2] = { 25, 0 },
> > +     [3] = { 50, 0 },
> > +     [4] = { 100, 0 },
> > +     [5] = { 200, 0 },
> > +     [6] = { 400, 0 },
> > +     [7] = { 800, 0 },
> > +     [8] = { 1600, 0 },
> > +     [9] = { 3200, 0 },
> > +};
> > +
> > +#define ADXL313_ACCEL_CHANNEL(index, addr, axis) {                   \
> > +     .type = IIO_ACCEL,                                              \
> > +     .address = addr,                                                \
> > +     .modified = 1,                                                  \
> > +     .channel2 = IIO_MOD_##axis,                                     \
> > +     .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |                  \
> > +                           BIT(IIO_CHAN_INFO_CALIBBIAS),             \
> > +     .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |          \
> > +                                 BIT(IIO_CHAN_INFO_SAMP_FREQ),       \
> > +     .info_mask_shared_by_type_available =                           \
> > +             BIT(IIO_CHAN_INFO_SAMP_FREQ),                           \
> > +     .scan_index = index,                                            \
>
> I'm not in general keen on seeing scan_index being set in a driver that isn't providing
> a buffer.  Whilst some of the scan_type can have valid meaning without buffering,
> scan_index should not.
>
> The use you are making of it here, should use addr.  So put a channel enum value
> into addr and use that to look up both the _raw address to read and anything else
> channel specific.  That will give more consistent code than you currently have
> with a mixture of addr and scan_index being used depending on the particular
> thing being read about the channel.
>
> > +     .scan_type = {                                                  \
> > +             .sign = 's',                                            \
> > +             .realbits = 13,                                         \
> > +             .storagebits = 16,                                      \
> > +             .endianness = IIO_LE,                                   \
>
> sign, storagebits and endianness are things that are only likely to matter once buffered
> supported is added (where they relect the datalayout).  For now please drop setting
> them at all.
>
> > +     },                                                              \
> > +}
> > +
> > +static const struct iio_chan_spec adxl313_channels[] = {
> > +     ADXL313_ACCEL_CHANNEL(0, ADXL313_REG_DATAX, X),
> > +     ADXL313_ACCEL_CHANNEL(1, ADXL313_REG_DATAY, Y),
> > +     ADXL313_ACCEL_CHANNEL(2, ADXL313_REG_DATAZ, Z),
> > +};
> > +
> > +static int adxl313_set_odr(struct adxl313_data *data,
> > +                        unsigned int freq1, unsigned int freq2)
> > +{
> > +     unsigned int i;
> > +
> > +     for (i = 0; i < ARRAY_SIZE(adxl313_odr_freqs); i++) {
> > +             if (adxl313_odr_freqs[i][0] == freq1 &&
> > +                 adxl313_odr_freqs[i][1] == freq2)
> > +                     break;
> > +     }
> > +
> > +     if (i == ARRAY_SIZE(adxl313_odr_freqs))
> > +             return -EINVAL;
> > +
> > +     return regmap_update_bits(data->regmap, ADXL313_REG_BW_RATE,
> > +                               ADXL313_RATE_MSK,
> > +                               FIELD_PREP(ADXL313_RATE_MSK,
> > +                                          ADXL313_RATE_BASE + i));
> > +}
> > +
> > +static int adxl313_read_axis(struct adxl313_data *data,
> > +                          struct iio_chan_spec const *chan)
> > +{
> > +     int ret;
> > +
> > +     mutex_lock(&data->lock);
> > +
> > +     ret = regmap_bulk_read(data->regmap,
> > +                            chan->address,
> > +                            &data->transf_buf, 2);
> sizeof(data->trasf_buf)
> > +     if (ret)
> > +             goto unlock_ret;
> > +
> > +     ret = le16_to_cpu(data->transf_buf);
> > +
> > +unlock_ret:
> > +     mutex_unlock(&data->lock);
> > +     return ret;
> > +}
> > +
> > +static int adxl313_read_freq_avail(struct iio_dev *indio_dev,
> > +                                struct iio_chan_spec const *chan,
> > +                                const int **vals, int *type, int *length,
> > +                                long mask)
> > +{
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_SAMP_FREQ:
> > +             *vals = (const int *)adxl313_odr_freqs;
> > +             *length = ARRAY_SIZE(adxl313_odr_freqs) * 2;
> > +             *type = IIO_VAL_INT_PLUS_MICRO;
> > +             return IIO_AVAIL_LIST;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int adxl313_read_raw(struct iio_dev *indio_dev,
> > +                         struct iio_chan_spec const *chan,
> > +                         int *val, int *val2, long mask)
> > +{
> > +     struct adxl313_data *data = iio_priv(indio_dev);
> > +     unsigned int regval;
> > +     int ret;
> > +
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_RAW:
> > +             ret = adxl313_read_axis(data, chan);
> > +             if (ret < 0)
> > +                     return ret;
> > +
> > +             *val = sign_extend32(ret, chan->scan_type.realbits - 1);
> > +             return IIO_VAL_INT;
> > +     case IIO_CHAN_INFO_SCALE:
> > +             /*
> > +              * Scale for any g range is given in datasheet as
> > +              * 1024 LSB/g = 0.0009765625 * 9.80665 = 0.009576806640625 m/s^2
> > +              */
> > +             *val = 0;
> > +             *val2 = 9576806;
> > +             return IIO_VAL_INT_PLUS_NANO;
> > +     case IIO_CHAN_INFO_CALIBBIAS:
> > +             ret = regmap_read(data->regmap,
> > +                               ADXL313_REG_OFS_AXIS(chan->scan_index),
> As mentioned above, don't use scan_index for this purpose.   There is no particular
> reason the scan_index for a given channel won't be changed in future as part of some layout
> optimization etc.  addr is for this purpose and often contains an enum value to that
> gives a driver specific index of channels, then used to do things like you are doing here.
>
> > +                               &regval);
> > +             if (ret)
> > +                     return ret;
> > +
> > +             /*
> > +              * 8-bit resolution at +/- 0.5g, that is 4x accel data scale
> > +              * factor at full resolution
> > +              */
> > +             *val = sign_extend32(regval, 7) * 4;
> > +             return IIO_VAL_INT;
> > +     case IIO_CHAN_INFO_SAMP_FREQ:
> > +             ret = regmap_read(data->regmap, ADXL313_REG_BW_RATE, &regval);
> > +             if (ret)
> > +                     return ret;
> > +
> > +             ret = FIELD_GET(ADXL313_RATE_MSK, regval) - ADXL313_RATE_BASE;
> > +             *val = adxl313_odr_freqs[ret][0];
> > +             *val2 = adxl313_odr_freqs[ret][1];
> > +             return IIO_VAL_INT_PLUS_MICRO;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int adxl313_write_raw(struct iio_dev *indio_dev,
> > +                          struct iio_chan_spec const *chan,
> > +                          int val, int val2, long mask)
> > +{
> > +     struct adxl313_data *data = iio_priv(indio_dev);
> > +
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_CALIBBIAS:
> > +             /*
> > +              * 8-bit resolution at +/- 0.5g, that is 4x accel data scale
> > +              * factor at full resolution
> > +              */
> > +             if (clamp_val(val, -128 * 4, 127 * 4) != val)
> > +                     return -EINVAL;
> > +
> > +             return regmap_write(data->regmap,
> > +                                 ADXL313_REG_OFS_AXIS(chan->scan_index),
> > +                                 val / 4);
> > +     case IIO_CHAN_INFO_SAMP_FREQ:
> > +             return adxl313_set_odr(data, val, val2);
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static const struct iio_info adxl313_info = {
> > +     .read_raw       = adxl313_read_raw,
> > +     .write_raw      = adxl313_write_raw,
> > +     .read_avail     = adxl313_read_freq_avail
> > +};
> > +
> > +static int adxl313_setup(struct device *dev, struct adxl313_data *data,
> > +                      int (*interface_specific_setup)(struct device *,
> > +                                                      struct regmap *))
> > +{
> > +     unsigned int regval;
> > +     int ret;
> > +
> > +     /* Ensures the device is in a consistent state after start up */
> > +     ret = regmap_write(data->regmap, ADXL313_REG_SOFT_RESET,
> > +                        ADXL313_SOFT_RESET);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (interface_specific_setup) {
> > +             ret = interface_specific_setup(dev, data->regmap);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     ret = regmap_read(data->regmap, ADXL313_REG_DEVID0, &regval);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (regval != ADXL313_DEVID0) {
> > +             dev_err(dev, "Invalid manufacturer ID: 0x%02x\n", regval);
> > +             return -ENODEV;
> > +     }
> > +
> > +     ret = regmap_read(data->regmap, ADXL313_REG_DEVID1, &regval);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (regval != ADXL313_DEVID1) {
> > +             dev_err(dev, "Invalid mems ID: 0x%02x\n", regval);
> > +             return -ENODEV;
> > +     }
> > +
> > +     ret = regmap_read(data->regmap, ADXL313_REG_PARTID, &regval);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (regval != ADXL313_PARTID) {
> > +             dev_err(dev, "Invalid device ID: 0x%02x\n", regval);
> > +             return -ENODEV;
> > +     }
> > +
> > +     /* Sets the range to +/- 4g */
> > +     ret = regmap_update_bits(data->regmap, ADXL313_REG_DATA_FORMAT,
> > +                              ADXL313_RANGE_MSK,
> > +                              FIELD_PREP(ADXL313_RANGE_MSK,
> > +                                         ADXL313_RANGE_4G));
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Enables full resolution */
> > +     ret = regmap_update_bits(data->regmap, ADXL313_REG_DATA_FORMAT,
> > +                              ADXL313_FULL_RES, ADXL313_FULL_RES);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Enables measurement mode */
> > +     return regmap_update_bits(data->regmap, ADXL313_REG_POWER_CTL,
> > +                               ADXL313_POWER_CTL_MSK,
> > +                               ADXL313_MEASUREMENT_MODE);
> > +}
> > +
> > +int adxl313_core_probe(struct device *dev,
> > +                    struct regmap *regmap,
> > +                    const char *name,
> > +                    int (*interface_specific_setup)(struct device *,
> > +                                                    struct regmap *))
> > +{
> > +     struct adxl313_data *data;
> > +     struct iio_dev *indio_dev;
> > +     int ret;
> > +
> > +     indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> > +     if (!indio_dev)
> > +             return -ENOMEM;
> > +
> > +     data = iio_priv(indio_dev);
> > +     data->regmap = regmap;
> > +     mutex_init(&data->lock);
> > +
> > +     indio_dev->name = name;
> > +     indio_dev->info = &adxl313_info;
> > +     indio_dev->modes = INDIO_DIRECT_MODE;
> > +     indio_dev->channels = adxl313_channels;
> > +     indio_dev->num_channels = ARRAY_SIZE(adxl313_channels);
> > +
> > +     ret = adxl313_setup(dev, data, interface_specific_setup);
> > +     if (ret) {
> > +             dev_err(dev, "ADXL313 setup failed\n");
> > +             return ret;
> > +     }
> > +
> > +     return devm_iio_device_register(dev, indio_dev);
> > +}
> > +EXPORT_SYMBOL_GPL(adxl313_core_probe);
> > +
> > +MODULE_AUTHOR("Lucas Stankus <lucas.p.stankus@gmail.com>");
> > +MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
> > +MODULE_LICENSE("GPL v2");
>
>
>
> > diff --git a/drivers/iio/accel/adxl313_spi.c b/drivers/iio/accel/adxl313_spi.c
> > new file mode 100644
> > index 000000000000..4d625b1753a5
> > --- /dev/null
> > +++ b/drivers/iio/accel/adxl313_spi.c
> > @@ -0,0 +1,91 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * ADXL313 3-Axis Digital Accelerometer
> > + *
> > + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@gmail.com>
> > + *
> > + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/regmap.h>
> > +#include <linux/spi/spi.h>
>
> Seeing as you are going to be doing a v4, please add explicit includes
>  for mod_devicetable.h which contains the of_device_id struct definition.
> Same for the i2c driver.
>
> > +
> > +#include "adxl313.h"
> > +
> ...