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SubjectRe: [v3 1/2] iio: gyro: Add driver support for ADXRS290
On Fri, 24 Jul 2020 16:31:59 +0530
Nishant Malpani <nish.malpani25@gmail.com> wrote:

> ADXRS290 is a high performance MEMS pitch and roll (dual-axis in-plane)
> angular rate sensor (gyroscope) designed for use in stabilization
> applications. It also features an internal temperature sensor and
> programmable high-pass and low-pass filters.
>
> Add support for ADXRS290 in direct-access mode for now.
>
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXRS290.pdf
> Signed-off-by: Nishant Malpani <nish.malpani25@gmail.com>

Looks pretty good to me. A few minor comments seeing as you'll be doing
a v4 anyway to tidy up the bits Andy pointed out.

I've pointed out the locking is probably in excess of what is needed, but
I have no problem with you leaving it as it stands, in the interests of
having less fragile code as you extend the driver futher.

Thanks,

Jonathan

> ---
>
> Changes in v3:
> - drop "Link" tag & extra line in commit message
> - rename cut-off frequencies tables to
> 'adxrs290_{lpf, hpf}_3db_freq_hz_table' to be more descriptive
> - fix unsigned type errors
> - add comments on how to scale raw angular velocity and temperature
> values to appropriate units mentioned in the ABI
> - re-order declarations in reversed spruce tree order
> - remove 'indio_dev->dev.parent = &spi->dev' as the iio core handles it
> during iio_device_alloc()
> - use plain msleep() instead of the interruptible variant
> - remove extra terminal comma
>
> Changes in v2:
> - append copyright tag with author's info
> - remove asm/unaligned.h header
> - remove unnecessary comments about the registers' description
> - rephrase comment on the usage of mutex_lock
> - discard the usage of local tx, rx buffers; use DMA-safe buffers
> provided by the SPI core instead
> - utilize spi_w8r16 provided by the SPI core instead of writing a
> wrapper over spi_sync_transfer which semantically does the same
> - equip spi_write_then_read instead of plain spi_write since the
> latter requires a DMA-safe buffer
> - implement exact matching of filter 3db frequencies instead of
> finding the "closest" match; rounding complexity is left to the
> userspace
> - include 'info_mask_shared_by_type_available' when initialising
> iio_chan_spec instead of explicitly exposing attributes
> signifying available filter 3db frequencies; with this we can
> utilize read_avail core callback
> ---
> MAINTAINERS | 6 +
> drivers/iio/gyro/Kconfig | 10 +
> drivers/iio/gyro/Makefile | 1 +
> drivers/iio/gyro/adxrs290.c | 446 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 463 insertions(+)
> create mode 100644 drivers/iio/gyro/adxrs290.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9077411c9890..71ae9b184179 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1098,6 +1098,12 @@ L: linux-media@vger.kernel.org
> S: Maintained
> F: drivers/media/i2c/adv7842*
>
> +ANALOG DEVICES INC ADXRS290 DRIVER
> +M: Nishant Malpani <nish.malpani25@gmail.com>
> +L: linux-iio@vger.kernel.org
> +S: Supported
> +F: drivers/iio/gyro/adxrs290.c
> +
> ANALOG DEVICES INC ASOC CODEC DRIVERS
> M: Lars-Peter Clausen <lars@metafoo.de>
> M: Nuno Sá <nuno.sa@analog.com>
> diff --git a/drivers/iio/gyro/Kconfig b/drivers/iio/gyro/Kconfig
> index 6daeddf37f60..024a34139875 100644
> --- a/drivers/iio/gyro/Kconfig
> +++ b/drivers/iio/gyro/Kconfig
> @@ -41,6 +41,16 @@ config ADIS16260
> This driver can also be built as a module. If so, the module
> will be called adis16260.
>
> +config ADXRS290
> + tristate "Analog Devices ADXRS290 Dual-Axis MEMS Gyroscope SPI driver"
> + depends on SPI
> + help
> + Say yes here to build support for Analog Devices ADXRS290 programmable
> + digital output gyroscope.
> +
> + This driver can also be built as a module. If so, the module will be
> + called adxrs290.
> +
> config ADXRS450
> tristate "Analog Devices ADXRS450/3 Digital Output Gyroscope SPI driver"
> depends on SPI
> diff --git a/drivers/iio/gyro/Makefile b/drivers/iio/gyro/Makefile
> index 45cbd5dc644e..0319b397dc3f 100644
> --- a/drivers/iio/gyro/Makefile
> +++ b/drivers/iio/gyro/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_ADIS16080) += adis16080.o
> obj-$(CONFIG_ADIS16130) += adis16130.o
> obj-$(CONFIG_ADIS16136) += adis16136.o
> obj-$(CONFIG_ADIS16260) += adis16260.o
> +obj-$(CONFIG_ADXRS290) += adxrs290.o
> obj-$(CONFIG_ADXRS450) += adxrs450.o
> obj-$(CONFIG_BMG160) += bmg160_core.o
> obj-$(CONFIG_BMG160_I2C) += bmg160_i2c.o
> diff --git a/drivers/iio/gyro/adxrs290.c b/drivers/iio/gyro/adxrs290.c
> new file mode 100644
> index 000000000000..cff1af9211bc
> --- /dev/null
> +++ b/drivers/iio/gyro/adxrs290.c
> @@ -0,0 +1,446 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * ADXRS290 SPI Gyroscope Driver
> + *
> + * Copyright (C) 2020 Nishant Malpani <nish.malpani25@gmail.com>
> + * Copyright (C) 2020 Analog Devices, Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define ADXRS290_ADI_ID 0xAD
> +#define ADXRS290_MEMS_ID 0x1D
> +#define ADXRS290_DEV_ID 0x92
> +
> +#define ADXRS290_REG_ADI_ID 0x00
> +#define ADXRS290_REG_MEMS_ID 0x01
> +#define ADXRS290_REG_DEV_ID 0x02
> +#define ADXRS290_REG_REV_ID 0x03
> +#define ADXRS290_REG_SN0 0x04 /* Serial Number Registers, 4 bytes */
> +#define ADXRS290_REG_DATAX0 0x08 /* Roll Rate o/p Data Regs, 2 bytes */
> +#define ADXRS290_REG_DATAY0 0x0A /* Pitch Rate o/p Data Regs, 2 bytes */
> +#define ADXRS290_REG_TEMP0 0x0C
> +#define ADXRS290_REG_POWER_CTL 0x10
> +#define ADXRS290_REG_FILTER 0x11
> +#define ADXRS290_REG_DATA_RDY 0x12
> +
> +#define ADXRS290_READ BIT(7)
> +#define ADXRS290_TSM BIT(0)
> +#define ADXRS290_MEASUREMENT BIT(1)
> +#define ADXRS290_SYNC GENMASK(1, 0)
> +#define ADXRS290_LPF_MASK GENMASK(2, 0)
> +#define ADXRS290_LPF(x) FIELD_PREP(ADXRS290_LPF_MASK, x)
> +#define ADXRS290_HPF_MASK GENMASK(7, 4)
> +#define ADXRS290_HPF(x) FIELD_PREP(ADXRS290_HPF_MASK, x)
> +
> +#define ADXRS290_READ_REG(reg) (ADXRS290_READ | (reg))
> +
> +#define ADXRS290_MAX_TRANSITION_TIME_MS 100
> +
> +enum adxrs290_mode {
> + STANDBY,
> + MEASUREMENT,
> +};
> +
> +struct adxrs290_state {
> + struct spi_device *spi;
> + /* Serialize reads and their subsequent processing */
> + struct mutex lock;
> + enum adxrs290_mode mode;
> + unsigned int lpf_3db_freq_idx;
> + unsigned int hpf_3db_freq_idx;
> +};
> +
> +/*
> + * Available cut-off frequencies of the low pass filter in Hz.
> + * The integer part and fractional part are represented separately.
> + */
> +static const int adxrs290_lpf_3db_freq_hz_table[][2] = {
> + [0] = {480, 0},
> + [1] = {320, 0},
> + [2] = {160, 0},
> + [3] = {80, 0},
> + [4] = {56, 600000},
> + [5] = {40, 0},
> + [6] = {28, 300000},
> + [7] = {20, 0},
> +};
> +
> +/*
> + * Available cut-off frequencies of the high pass filter in Hz.
> + * The integer part and fractional part are represented separately.
> + */
> +static const int adxrs290_hpf_3db_freq_hz_table[][2] = {
> + [0] = {0, 0},
> + [1] = {0, 11000},
> + [2] = {0, 22000},
> + [3] = {0, 44000},
> + [4] = {0, 87000},
> + [5] = {0, 175000},
> + [6] = {0, 350000},
> + [7] = {0, 700000},
> + [8] = {1, 400000},
> + [9] = {2, 800000},
> + [10] = {11, 300000},
> +};
> +
> +static int adxrs290_get_rate_data(struct iio_dev *indio_dev, const u8 cmd,
> + unsigned int *val)

Why go through the effort of signed to unsigned to signed for val?

> +{
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + int ret = 0;
> + int temp;
> +
> + mutex_lock(&st->lock);
> + temp = spi_w8r16(st->spi, cmd);
> + if (temp < 0) {
> + ret = temp;
> + goto err_unlock;
> + }
> +
> + *val = temp;
> +
> +err_unlock:
> + mutex_unlock(&st->lock);
> + return ret;
> +}
> +
> +static int adxrs290_get_temp_data(struct iio_dev *indio_dev, unsigned int *val)
> +{
> + const u8 cmd = ADXRS290_READ_REG(ADXRS290_REG_TEMP0);
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + int ret = 0;
> + int temp;
> +
> + mutex_lock(&st->lock);

Just a quick note here. I don't think you actually need the lock
(yet) as you aren't doing any read modify write cycles and in this
particular case there is no local cached state to protect.
However, I don't mind if you want to leave them as it may make things
less fragile as you move forwards.

> + temp = spi_w8r16(st->spi, cmd);
> + if (temp < 0) {
> + ret = temp;
> + goto err_unlock;
> + }
> +
> + /* extract lower 12 bits temperature reading */
> + *val = temp & 0x0FFF;
> +
> +err_unlock:
> + mutex_unlock(&st->lock);
> + return ret;
> +}
> +
> +static int adxrs290_get_3db_freq(struct iio_dev *indio_dev, u8 *val, u8 *val2)
> +{
> + const u8 cmd = ADXRS290_READ_REG(ADXRS290_REG_FILTER);
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + int ret = 0;
> + short temp;
> +
> + mutex_lock(&st->lock);
> + temp = spi_w8r8(st->spi, cmd);
> + if (temp < 0) {
> + ret = temp;
> + goto err_unlock;
> + }
> +
> + *val = FIELD_GET(ADXRS290_LPF_MASK, temp);
> + *val2 = FIELD_GET(ADXRS290_HPF_MASK, temp);
> +
> +err_unlock:
> + mutex_unlock(&st->lock);
> + return ret;
> +}
> +
> +static int adxrs290_spi_write_reg(struct spi_device *spi, const u8 reg,
> + const u8 val)
> +{
> + u8 buf[2];
> +
> + buf[0] = reg;
> + buf[1] = val;
> +
> + return spi_write_then_read(spi, buf, ARRAY_SIZE(buf), NULL, 0);
> +}
> +
> +static int adxrs290_find_match(const int (*freq_tbl)[2], const int n,
> + const int val, const int val2)
> +{
> + int i;
> +
> + for (i = 0; i < n; i++) {
> + if (freq_tbl[i][0] == val && freq_tbl[i][1] == val2)
> + return i;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int adxrs290_set_filter_freq(struct iio_dev *indio_dev,
> + const unsigned int lpf_idx,
> + const unsigned int hpf_idx)
> +{
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + u8 val;
> +
> + val = ADXRS290_HPF(hpf_idx) | ADXRS290_LPF(lpf_idx);
> +
> + return adxrs290_spi_write_reg(st->spi, ADXRS290_REG_FILTER, val);
> +}
> +
> +static int adxrs290_initial_setup(struct iio_dev *indio_dev)
> +{
> + struct adxrs290_state *st = iio_priv(indio_dev);
> +
> + st->mode = MEASUREMENT;
> +
> + return adxrs290_spi_write_reg(st->spi,
> + ADXRS290_REG_POWER_CTL,
> + ADXRS290_MEASUREMENT | ADXRS290_TSM);
> +}
> +
> +static int adxrs290_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long mask)
> +{
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + unsigned int t;
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + switch (chan->type) {
> + case IIO_ANGL_VEL:
> + ret = adxrs290_get_rate_data(indio_dev,
> + ADXRS290_READ_REG(chan->address),
> + &t);
> + if (ret < 0)
> + return ret;
> + *val = t;

As mentioned above, you should be fine with using a signed value where you have &t.
As we don't use *val in the error case, it's fine to write directly into it and
avoid the need for the local variable t at all.

> + return IIO_VAL_INT;
> + case IIO_TEMP:
> + ret = adxrs290_get_temp_data(indio_dev, &t);
> + if (ret < 0)
> + return ret;
> + *val = t;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_SCALE:
> + switch (chan->type) {
> + case IIO_ANGL_VEL:
> + /* 1 LSB = 0.005 degrees/sec */
> + *val = 0;
> + *val2 = 87266;
> + return IIO_VAL_INT_PLUS_NANO;
> + case IIO_TEMP:
> + /* 1 LSB = 0.1 degrees Celsius */
> + *val = 100;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> + switch (chan->type) {
> + case IIO_ANGL_VEL:
> + t = st->lpf_3db_freq_idx;
> + *val = adxrs290_lpf_3db_freq_hz_table[t][0];
> + *val2 = adxrs290_lpf_3db_freq_hz_table[t][1];
> + return IIO_VAL_INT_PLUS_MICRO;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> + switch (chan->type) {
> + case IIO_ANGL_VEL:
> + t = st->hpf_3db_freq_idx;
> + *val = adxrs290_hpf_3db_freq_hz_table[t][0];
> + *val2 = adxrs290_hpf_3db_freq_hz_table[t][1];
> + return IIO_VAL_INT_PLUS_MICRO;
> + default:
> + return -EINVAL;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int adxrs290_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val,
> + int val2,
> + long mask)
> +{
> + struct adxrs290_state *st = iio_priv(indio_dev);
> + int lpf_idx, hpf_idx;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> + lpf_idx = adxrs290_find_match(adxrs290_lpf_3db_freq_hz_table,
> + ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table),
> + val, val2);
> + if (lpf_idx < 0)
> + return -EINVAL;
> + /* caching the updated state of the low-pass filter */
> + st->lpf_3db_freq_idx = lpf_idx;
> + /* retrieving the current state of the high-pass filter */
> + hpf_idx = st->hpf_3db_freq_idx;
> + return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> + case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> + hpf_idx = adxrs290_find_match(adxrs290_hpf_3db_freq_hz_table,
> + ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table),
> + val, val2);
> + if (hpf_idx < 0)
> + return -EINVAL;
> + /* caching the updated state of the high-pass filter */
> + st->hpf_3db_freq_idx = hpf_idx;
> + /* retrieving the current state of the low-pass filter */
> + lpf_idx = st->lpf_3db_freq_idx;
> + return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int adxrs290_read_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_LOW_PASS_FILTER_3DB_FREQUENCY:
> + *vals = (const int *)adxrs290_lpf_3db_freq_hz_table;
> + *type = IIO_VAL_INT_PLUS_MICRO;
> + /* Values are stored in a 2D matrix */
> + *length = ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table) * 2;
> +
> + return IIO_AVAIL_LIST;
> + case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> + *vals = (const int *)adxrs290_hpf_3db_freq_hz_table;
> + *type = IIO_VAL_INT_PLUS_MICRO;
> + /* Values are stored in a 2D matrix */
> + *length = ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table) * 2;
> +
> + return IIO_AVAIL_LIST;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +#define ADXRS290_ANGL_VEL_CHANNEL(reg, axis) { \
> + .type = IIO_ANGL_VEL, \
> + .address = reg, \
> + .modified = 1, \
> + .channel2 = IIO_MOD_##axis, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) | \
> + BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
> + .info_mask_shared_by_type_available = \
> + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) | \
> + BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
> +}
> +
> +static const struct iio_chan_spec adxrs290_channels[] = {
> + ADXRS290_ANGL_VEL_CHANNEL(ADXRS290_REG_DATAX0, X),
> + ADXRS290_ANGL_VEL_CHANNEL(ADXRS290_REG_DATAY0, Y),
> + {
> + .type = IIO_TEMP,
> + .address = ADXRS290_REG_TEMP0,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_SCALE),
> + },
> +};
> +
> +static const struct iio_info adxrs290_info = {
> + .read_raw = &adxrs290_read_raw,
> + .write_raw = &adxrs290_write_raw,
> + .read_avail = &adxrs290_read_avail,
> +};
> +
> +static int adxrs290_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct adxrs290_state *st;
> + u8 val, val2;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> + st->spi = spi;
> + spi_set_drvdata(spi, indio_dev);

As things currently stand I don't think you ever use this.
So drop it for now and reintroduce it when you need it (probably when
you add power management support).

> +
> + indio_dev->name = "adxrs290";
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = adxrs290_channels;
> + indio_dev->num_channels = ARRAY_SIZE(adxrs290_channels);
> + indio_dev->info = &adxrs290_info;
> +
> + val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_ADI_ID));
> + if (val != ADXRS290_ADI_ID) {
> + dev_err(&spi->dev, "Wrong ADI ID 0x%02x\n", val);
> + return -ENODEV;
> + }
> +
> + val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_MEMS_ID));
> + if (val != ADXRS290_MEMS_ID) {
> + dev_err(&spi->dev, "Wrong MEMS ID 0x%02x\n", val);
> + return -ENODEV;
> + }
> +
> + val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_DEV_ID));
> + if (val != ADXRS290_DEV_ID) {
> + dev_err(&spi->dev, "Wrong DEV ID 0x%02x\n", val);
> + return -ENODEV;
> + }
> +
> + /* default mode the gyroscope starts in */
> + st->mode = STANDBY;
> +
> + /* switch to measurement mode and switch on the temperature sensor */
> + ret = adxrs290_initial_setup(indio_dev);
> + if (ret < 0)
> + return ret;
> +
> + /* max transition time to measurement mode */
> + msleep(ADXRS290_MAX_TRANSITION_TIME_MS);
> +
> + ret = adxrs290_get_3db_freq(indio_dev, &val, &val2);
> + if (ret < 0)
> + return ret;
> +
> + st->lpf_3db_freq_idx = val;
> + st->hpf_3db_freq_idx = val2;
> +
> + return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct of_device_id adxrs290_of_match[] = {
> + { .compatible = "adi,adxrs290" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, adxrs290_of_match);
> +
> +static struct spi_driver adxrs290_driver = {
> + .driver = {
> + .name = "adxrs290",
> + .of_match_table = adxrs290_of_match,
> + },
> + .probe = adxrs290_probe,
> +};
> +module_spi_driver(adxrs290_driver);
> +
> +MODULE_AUTHOR("Nishant Malpani <nish.malpani25@gmail.com>");
> +MODULE_DESCRIPTION("Analog Devices ADXRS290 Gyroscope SPI driver");
> +MODULE_LICENSE("GPL");

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