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Subject[v3 1/2] iio: gyro: Add driver support for ADXRS290
Date
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>
---

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)
+{
+ 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);
+ 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;
+ 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);
+
+ 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");
--
2.20.1
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