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References: <20180904200434.10442-1-afonsobordado@az8.co>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Tue, 4 Sep 2018 22:18:51 +0300
Message-ID: <CAHp75Ve6BoP9H4rK7ZZMn=DAZ43zfqPRRCrD+hZz8hrvFpo1zQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/4] iio: gyro: add support for fxas21002c
To:     afonsobordado@az8.co
Cc:     Jonathan Cameron <jic23@kernel.org>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald <pmeerw@pmeerw.net>,
        linux-iio <linux-iio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Tue, Sep 4, 2018 at 10:08 PM Afonso Bordado <afonsobordado@az8.co> wrote:
>
> FXAS21002C is a 3 axis gyroscope with integrated temperature sensor
>
> Signed-off-by: Afonso Bordado <afonsobordado@az8.co>
> ---
>  Changes in v3
>    - Use unsigned int on regmap functions
>    - Remove the export of the regmap config
>    - Fix undefined behaviour on dev_err call
>    - Minor cleanups
>
>  Changes in v2
>    - Use ANSI C Comments
>    - Minor cleanups
>    - More dscriptive devicetree bindings
>
>  drivers/iio/gyro/Kconfig      |  11 +
>  drivers/iio/gyro/Makefile     |   1 +
>  drivers/iio/gyro/fxas21002c.c | 372 ++++++++++++++++++++++++++++++++++
>  3 files changed, 384 insertions(+)
>  create mode 100644 drivers/iio/gyro/fxas21002c.c
>
> diff --git a/drivers/iio/gyro/Kconfig b/drivers/iio/gyro/Kconfig
> index 3126cf05e6b9..d71e33ea9fa4 100644
> --- a/drivers/iio/gyro/Kconfig
> +++ b/drivers/iio/gyro/Kconfig
> @@ -73,6 +73,17 @@ config BMG160_SPI
>         tristate
>         select REGMAP_SPI
>
> +config FXAS21002C
> +       tristate "Freescale FXAS21002C Gyroscope"
> +       depends on I2C
> +       select REGMAP_I2C
> +       help
> +         Say yes here to build support for the Freescale FXAS21002C Gyroscope
> +         driver connected via I2C.
> +
> +         This driver can also be built as a module. If so, the module
> +         will be called fxas21002c.
> +
>  config HID_SENSOR_GYRO_3D
>         depends on HID_SENSOR_HUB
>         select IIO_BUFFER
> diff --git a/drivers/iio/gyro/Makefile b/drivers/iio/gyro/Makefile
> index 295ec780c4eb..ec3e2aeae92a 100644
> --- a/drivers/iio/gyro/Makefile
> +++ b/drivers/iio/gyro/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_ADXRS450) += adxrs450.o
>  obj-$(CONFIG_BMG160) += bmg160_core.o
>  obj-$(CONFIG_BMG160_I2C) += bmg160_i2c.o
>  obj-$(CONFIG_BMG160_SPI) += bmg160_spi.o
> +obj-$(CONFIG_FXAS21002C) += fxas21002c.o
>
>  obj-$(CONFIG_HID_SENSOR_GYRO_3D) += hid-sensor-gyro-3d.o
>
> diff --git a/drivers/iio/gyro/fxas21002c.c b/drivers/iio/gyro/fxas21002c.c
> new file mode 100644
> index 000000000000..1668e6f3fe11
> --- /dev/null
> +++ b/drivers/iio/gyro/fxas21002c.c
> @@ -0,0 +1,372 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * FXAS21002C - Digital Angular Rate Gyroscope driver
> + *
> + * Copyright (c) 2018, Afonso Bordado <afonsobordado@az8.co>
> + *
> + * IIO driver for FXAS21002C (7-bit I2C slave address 0x20 or 0x21).
> + * Datasheet: https://www.nxp.com/docs/en/data-sheet/FXAS21002.pdf
> + * TODO:
> + *        ODR / Scale Support
> + *        Devicetree
> + *        Power management
> + *        GPIO Reset
> + *        Power supplies
> + *        Mount Matrix
> + *        LowPass/HighPass Filters
> + *        Buffers
> + *        Interrupts
> + *        Alarms
> + *        SPI Support
> + */

With this rather long TODO list it sounds like a staging candidate,
though if it allows us to use it in the shape provided by the change,
code looks good
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> +
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define FXAS21002C_DRV_NAME "fxas21002c"
> +
> +#define FXAS21002C_MAX_TRANSITION_TIME_MS 61
> +
> +#define FXAS21002C_CHIP_ID             0xD7
> +
> +#define FXAS21002C_REG_STATUS          0x00
> +#define FXAS21002C_REG_OUT_X_MSB       0x01
> +#define FXAS21002C_REG_OUT_X_LSB       0x02
> +#define FXAS21002C_REG_OUT_Y_MSB       0x03
> +#define FXAS21002C_REG_OUT_Y_LSB       0x04
> +#define FXAS21002C_REG_OUT_Z_MSB       0x05
> +#define FXAS21002C_REG_OUT_Z_LSB       0x06
> +#define FXAS21002C_REG_DR_STATUS       0x07
> +#define FXAS21002C_REG_F_STATUS        0x08
> +#define FXAS21002C_REG_F_SETUP         0x09
> +#define FXAS21002C_REG_F_EVENT         0x0A
> +#define FXAS21002C_REG_INT_SRC_FLAG    0x0B
> +#define FXAS21002C_REG_WHO_AM_I        0x0C
> +#define FXAS21002C_REG_CTRL_REG0       0x0D
> +#define FXAS21002C_REG_RT_CFG          0x0E
> +#define FXAS21002C_REG_RT_SRC          0x0F
> +#define FXAS21002C_REG_RT_THS          0x10
> +#define FXAS21002C_REG_RT_COUNT        0x11
> +#define FXAS21002C_REG_TEMP            0x12
> +
> +#define FXAS21002C_REG_CTRL_REG1       0x13
> +#define FXAS21002C_RST_BIT             BIT(6)
> +#define FXAS21002C_ACTIVE_BIT          BIT(1)
> +#define FXAS21002C_READY_BIT           BIT(0)
> +
> +#define FXAS21002C_REG_CTRL_REG2       0x14
> +#define FXAS21002C_REG_CTRL_REG3       0x15
> +
> +#define FXAS21002C_DEFAULT_ODR_HZ      800
> +
> +/* 0.0625 deg/s */
> +#define FXAS21002C_DEFAULT_SENSITIVITY IIO_DEGREE_TO_RAD(62500)
> +
> +#define FXAS21002C_TEMP_SCALE          1000
> +
> +enum {
> +       ID_FXAS21002C,
> +};
> +
> +enum fxas21002c_operating_mode {
> +       FXAS21002C_OM_BOOT,
> +       FXAS21002C_OM_STANDBY,
> +       FXAS21002C_OM_READY,
> +       FXAS21002C_OM_ACTIVE,
> +};
> +
> +struct fxas21002c_data {
> +       struct i2c_client *client;
> +       struct regmap *regmap;
> +};
> +
> +static const struct regmap_range fxas21002c_writable_ranges[] = {
> +       regmap_reg_range(FXAS21002C_REG_F_SETUP, FXAS21002C_REG_F_SETUP),
> +       regmap_reg_range(FXAS21002C_REG_CTRL_REG0, FXAS21002C_REG_RT_CFG),
> +       regmap_reg_range(FXAS21002C_REG_RT_THS, FXAS21002C_REG_RT_COUNT),
> +       regmap_reg_range(FXAS21002C_REG_CTRL_REG1, FXAS21002C_REG_CTRL_REG3),
> +};
> +
> +static const struct regmap_access_table fxas21002c_writable_table = {
> +       .yes_ranges = fxas21002c_writable_ranges,
> +       .n_yes_ranges = ARRAY_SIZE(fxas21002c_writable_ranges),
> +};
> +
> +static const struct regmap_range fxas21002c_volatile_ranges[] = {
> +       regmap_reg_range(FXAS21002C_REG_STATUS, FXAS21002C_REG_F_STATUS),
> +       regmap_reg_range(FXAS21002C_REG_F_EVENT, FXAS21002C_REG_INT_SRC_FLAG),
> +       regmap_reg_range(FXAS21002C_REG_RT_COUNT, FXAS21002C_REG_CTRL_REG1),
> +};
> +
> +static const struct regmap_access_table fxas21002c_volatile_table = {
> +       .yes_ranges = fxas21002c_volatile_ranges,
> +       .n_yes_ranges = ARRAY_SIZE(fxas21002c_volatile_ranges),
> +};
> +
> +const struct regmap_config fxas21002c_regmap_config = {
> +       .reg_bits = 8,
> +       .val_bits = 8,
> +
> +       .max_register = FXAS21002C_REG_CTRL_REG3,
> +       /* We don't specify a .rd_table because everything is readable */
> +       .wr_table = &fxas21002c_writable_table,
> +       .volatile_table = &fxas21002c_volatile_table,
> +};
> +
> +#define FXAS21002C_GYRO_CHAN(_axis) {                                  \
> +       .type = IIO_ANGL_VEL,                                           \
> +       .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_SAMP_FREQ),       \
> +       .address = FXAS21002C_REG_OUT_ ## _axis ## _MSB,                \
> +}
> +
> +static const struct iio_chan_spec fxas21002c_channels[] = {
> +       {
> +               .type = IIO_TEMP,
> +               .address = FXAS21002C_REG_TEMP,
> +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +                                     BIT(IIO_CHAN_INFO_SCALE),
> +       },
> +       FXAS21002C_GYRO_CHAN(X),
> +       FXAS21002C_GYRO_CHAN(Y),
> +       FXAS21002C_GYRO_CHAN(Z),
> +       IIO_CHAN_SOFT_TIMESTAMP(3),
> +};
> +
> +static int fxas21002c_set_operating_mode(struct fxas21002c_data *data,
> +                                        enum fxas21002c_operating_mode om)
> +{
> +       int ret;
> +       int mask;
> +
> +       switch (om) {
> +       case FXAS21002C_OM_STANDBY:
> +               mask = 0;
> +               break;
> +       case FXAS21002C_OM_READY:
> +               mask = FXAS21002C_READY_BIT;
> +               break;
> +       case FXAS21002C_OM_ACTIVE:
> +               mask = FXAS21002C_ACTIVE_BIT;
> +               break;
> +
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       ret = regmap_write(data->regmap, FXAS21002C_REG_CTRL_REG1, mask);
> +       if (ret) {
> +               dev_err(&data->client->dev,
> +                       "could not switch operating mode\n");
> +               return ret;
> +       }
> +
> +       msleep(FXAS21002C_MAX_TRANSITION_TIME_MS);
> +
> +       return 0;
> +}
> +
> +static void fxas21002c_standby(void *_data)
> +{
> +       struct fxas21002c_data *data = _data;
> +
> +       fxas21002c_set_operating_mode(data, FXAS21002C_OM_STANDBY);
> +}
> +
> +static int fxas21002c_reset(struct fxas21002c_data *data)
> +{
> +       int ret;
> +
> +       /*
> +        * On issuing a Software Reset command over an I2C interface,
> +        * the device immediately resets and does not send any
> +        * acknowledgment (ACK) of the written byte to the Master.
> +        *
> +        * This is documented in table 46 on the datasheet. Due to this
> +        * the write will fail with EREMOTEIO.
> +        */
> +       ret = regmap_write(data->regmap,
> +                          FXAS21002C_REG_CTRL_REG1, FXAS21002C_RST_BIT);
> +
> +       if (ret != -EREMOTEIO) {
> +               dev_err(&data->client->dev, "could not reset device\n");
> +               return ret;
> +       }
> +
> +       regcache_mark_dirty(data->regmap);
> +
> +       /* Wait for device to boot up */
> +       msleep(FXAS21002C_MAX_TRANSITION_TIME_MS);
> +
> +       return 0;
> +}
> +
> +static int fxas21002c_verify_chip(struct fxas21002c_data *data)
> +{
> +       int ret;
> +       unsigned int chip_id;
> +
> +       ret = regmap_read(data->regmap, FXAS21002C_REG_WHO_AM_I, &chip_id);
> +       if (ret) {
> +               dev_err(&data->client->dev, "could not read device id\n");
> +               return ret;
> +       }
> +
> +       if (chip_id != FXAS21002C_CHIP_ID) {
> +               dev_err(&data->client->dev,
> +                       "unsupported chip id %02x\n", chip_id);
> +               return -ENODEV;
> +       }
> +
> +       return 0;
> +}
> +
> +static int fxas21002c_read_oneshot(struct fxas21002c_data *data,
> +                                  struct iio_chan_spec const *chan, int *val)
> +{
> +       int ret;
> +       __be16 bulk_raw;
> +       unsigned int uval;
> +
> +       switch (chan->type) {
> +       case IIO_ANGL_VEL:
> +               ret = regmap_bulk_read(data->regmap, chan->address,
> +                                      &bulk_raw, sizeof(bulk_raw));
> +               if (ret)
> +                       return ret;
> +
> +               *val = sign_extend32(be16_to_cpu(bulk_raw), 15);
> +               return IIO_VAL_INT;
> +       case IIO_TEMP:
> +               ret = regmap_read(data->regmap, chan->address, &uval);
> +               if (ret)
> +                       return ret;
> +
> +               *val = sign_extend32(uval, 7);
> +               return IIO_VAL_INT;
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +static int fxas21002c_read_raw(struct iio_dev *indio_dev,
> +                              struct iio_chan_spec const *chan, int *val,
> +                              int *val2, long mask)
> +{
> +       struct fxas21002c_data *data = iio_priv(indio_dev);
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_RAW:
> +               return fxas21002c_read_oneshot(data, chan, val);
> +       case IIO_CHAN_INFO_SCALE:
> +               switch (chan->type) {
> +               case IIO_ANGL_VEL:
> +                       *val = 0;
> +                       *val2 = FXAS21002C_DEFAULT_SENSITIVITY;
> +
> +                       return IIO_VAL_INT_PLUS_MICRO;
> +               case IIO_TEMP:
> +                       *val = FXAS21002C_TEMP_SCALE;
> +
> +                       return IIO_VAL_INT;
> +               default:
> +                       return -EINVAL;
> +               }
> +       case IIO_CHAN_INFO_SAMP_FREQ:
> +               if (chan->type != IIO_ANGL_VEL)
> +                       return -EINVAL;
> +
> +               *val = FXAS21002C_DEFAULT_ODR_HZ;
> +
> +               return IIO_VAL_INT;
> +       }
> +
> +       return -EINVAL;
> +}
> +
> +static const struct iio_info fxas21002c_info = {
> +       .read_raw               = fxas21002c_read_raw,
> +};
> +
> +static int fxas21002c_probe(struct i2c_client *client,
> +                           const struct i2c_device_id *id)
> +{
> +       int ret;
> +       struct iio_dev *indio_dev;
> +       struct fxas21002c_data *data;
> +
> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +       if (!indio_dev)
> +               return -ENOMEM;
> +
> +       i2c_set_clientdata(client, indio_dev);
> +       data = iio_priv(indio_dev);
> +       data->client = client;
> +
> +       data->regmap = devm_regmap_init_i2c(client, &fxas21002c_regmap_config);
> +       if (IS_ERR(data->regmap)) {
> +               ret = PTR_ERR(data->regmap);
> +               dev_err(&client->dev,
> +                       "Failed to allocate regmap, err: %d\n", ret);
> +               return ret;
> +       }
> +
> +       indio_dev->dev.parent = &client->dev;
> +       indio_dev->channels = fxas21002c_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(fxas21002c_channels);
> +       indio_dev->name = id->name;
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +       indio_dev->info = &fxas21002c_info;
> +
> +       ret = fxas21002c_verify_chip(data);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = fxas21002c_reset(data);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = fxas21002c_set_operating_mode(data, FXAS21002C_OM_ACTIVE);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = devm_add_action(&client->dev, fxas21002c_standby, data);
> +       if (ret < 0) {
> +               fxas21002c_standby(data);
> +               dev_err(&client->dev, "failed to add standby action\n");
> +               return ret;
> +       }
> +
> +       ret = iio_device_register(indio_dev);
> +       if (ret < 0)
> +               dev_err(&client->dev, "failed to register iio device\n");
> +
> +       return ret;
> +}
> +
> +static const struct i2c_device_id fxas21002c_id[] = {
> +       {"fxas21002c", ID_FXAS21002C},
> +       {}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, fxas21002c_id);
> +
> +static struct i2c_driver fxas21002c_driver = {
> +       .driver = {
> +               .name = FXAS21002C_DRV_NAME,
> +       },
> +       .probe          = fxas21002c_probe,
> +       .id_table       = fxas21002c_id,
> +};
> +
> +module_i2c_driver(fxas21002c_driver);
> +
> +MODULE_AUTHOR("Afonso Bordado <afonsobordado@az8.co>");
> +MODULE_DESCRIPTION("FXAS21002C Digital Angular Rate Gyroscope driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.18.0
>
>


-- 
With Best Regards,
Andy Shevchenko