Re: [v3 1/2] iio: gyro: Add driver support for ADXRS290

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On 26/07/20 1:33 pm, Andy Shevchenko wrote:
On Fri, Jul 24, 2020 at 2:02 PM Nishant Malpani
<nish.malpani25@xxxxxxxxx> 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.

Thanks for an update!
My nits below, after addressing them

Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

Thanks!

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXRS290.pdf
Signed-off-by: Nishant Malpani <nish.malpani25@xxxxxxxxx>
---

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@xxxxxxxxxxxxxxx
  S:     Maintained
  F:     drivers/media/i2c/adv7842*

+ANALOG DEVICES INC ADXRS290 DRIVER
+M:     Nishant Malpani <nish.malpani25@xxxxxxxxx>
+L:     linux-iio@xxxxxxxxxxxxxxx
+S:     Supported
+F:     drivers/iio/gyro/adxrs290.c
+
  ANALOG DEVICES INC ASOC CODEC DRIVERS
  M:     Lars-Peter Clausen <lars@xxxxxxxxxx>
  M:     Nuno Sá <nuno.sa@xxxxxxxxxx>
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@xxxxxxxxx>
+ * Copyright (C) 2020 Analog Devices, Inc.
+ */
+
+#include <linux/bitfield.h>

+#include <linux/device.h>
+#include <linux/delay.h>

Keep it ordered?

Ah, missed it somehow. Will reorder in v4.

+#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,
+};

Perhaps a prefix
ADXRS290_STANDBY,
etc.

Makes sense. I'll prefix with 'ADXRS290_MODE_' (in v4) as 'ADXRS290_MEASUREMENT' is already a macro defintion.

+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)

Please, revisit all ' < 0' checks and drop ones that are not necessary
(above seems fine, but here and below are subject to revisit).

Revisited all '< 0' checks and I consider them all necessary as they (mostly) reflect failed spi transactions.

With regards,
Nishant Malpani

+                               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@xxxxxxxxx>");
+MODULE_DESCRIPTION("Analog Devices ADXRS290 Gyroscope SPI driver");
+MODULE_LICENSE("GPL");
--
2.20.1






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