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SubjectRe: [PATCH v2 3/3] iio: imu: st_lsm6dsx: add i3c basic support for LSM6DSO and LSM6DSR
On Thu,  6 Jun 2019 17:12:04 +0200
Vitor Soares <Vitor.Soares@synopsys.com> wrote:

> For today the st_lsm6dsx driver support LSM6DSO and LSM6DSR sensor only in
> spi and i2c mode.
>
> The LSM6DSO and LSM6DSR are also i3c capable so lets give i3c support to
> them.
>
> Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
> ---
> Changes in v2:
> Add support for LSM6DSR
> Set pm_ops to st_lsm6dsx_pm_ops
>
> drivers/iio/imu/st_lsm6dsx/Kconfig | 8 ++-
> drivers/iio/imu/st_lsm6dsx/Makefile | 1 +
> drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c | 76 +++++++++++++++++++++++++++++
> 3 files changed, 84 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c
>
> diff --git a/drivers/iio/imu/st_lsm6dsx/Kconfig b/drivers/iio/imu/st_lsm6dsx/Kconfig
> index 002a423..8115936 100644
> --- a/drivers/iio/imu/st_lsm6dsx/Kconfig
> +++ b/drivers/iio/imu/st_lsm6dsx/Kconfig
> @@ -2,11 +2,12 @@
>
> config IIO_ST_LSM6DSX
> tristate "ST_LSM6DSx driver for STM 6-axis IMU MEMS sensors"
> - depends on (I2C || SPI)
> + depends on (I2C || SPI || I3C)
> select IIO_BUFFER
> select IIO_KFIFO_BUF
> select IIO_ST_LSM6DSX_I2C if (I2C)
> select IIO_ST_LSM6DSX_SPI if (SPI_MASTER)
> + select IIO_ST_LSM6DSX_I3C if (I3C)
> help
> Say yes here to build support for STMicroelectronics LSM6DSx imu
> sensor. Supported devices: lsm6ds3, lsm6ds3h, lsm6dsl, lsm6dsm,
> @@ -24,3 +25,8 @@ config IIO_ST_LSM6DSX_SPI
> tristate
> depends on IIO_ST_LSM6DSX
> select REGMAP_SPI
> +
> +config IIO_ST_LSM6DSX_I3C
> + tristate
> + depends on IIO_ST_LSM6DSX
> + select REGMAP_I3C
> diff --git a/drivers/iio/imu/st_lsm6dsx/Makefile b/drivers/iio/imu/st_lsm6dsx/Makefile
> index 28cc673..57cbcd6 100644
> --- a/drivers/iio/imu/st_lsm6dsx/Makefile
> +++ b/drivers/iio/imu/st_lsm6dsx/Makefile
> @@ -5,3 +5,4 @@ st_lsm6dsx-y := st_lsm6dsx_core.o st_lsm6dsx_buffer.o \
> obj-$(CONFIG_IIO_ST_LSM6DSX) += st_lsm6dsx.o
> obj-$(CONFIG_IIO_ST_LSM6DSX_I2C) += st_lsm6dsx_i2c.o
> obj-$(CONFIG_IIO_ST_LSM6DSX_SPI) += st_lsm6dsx_spi.o
> +obj-$(CONFIG_IIO_ST_LSM6DSX_I3C) += st_lsm6dsx_i3c.o
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c
> new file mode 100644
> index 0000000..70b70d1
> --- /dev/null
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c
> @@ -0,0 +1,76 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018 Synopsys, Inc. and/or its affiliates.
> + *
> + * Author: Vitor Soares <vitor.soares@synopsys.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/i3c/device.h>
> +#include <linux/i3c/master.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +
> +#include "st_lsm6dsx.h"
> +
> +#define NAME_SIZE 32
> +
> +struct st_lsm6dsx_i3c_data {
> + const char name[NAME_SIZE];

I think I mentioned already that you can simply have

const char *name;

> + enum st_lsm6dsx_hw_id id;
> +};
> +
> +enum st_lsm6dsx_i3c_data_id {
> + ST_LSM6DSO_I3C_DATA_ID,
> + ST_LSM6DSR_I3C_DATA_ID,
> +};
> +
> +static const struct st_lsm6dsx_i3c_data hw_data[] = {
> + { ST_LSM6DSO_DEV_NAME, ST_LSM6DSO_ID },
> + { ST_LSM6DSR_DEV_NAME, ST_LSM6DSR_ID },
> +};
> +
> +static const struct regmap_config st_lsm6dsx_i3c_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> +};
> +
> +static int st_lsm6dsx_i3c_probe(struct i3c_device *i3cdev)
> +{
> + const struct i3c_device_id *id = i3c_get_device_id(i3cdev);
> + const struct st_lsm6dsx_i3c_data *hw_data = id->data;
> + struct regmap *regmap;
> +
> + regmap = devm_regmap_init_i3c(i3cdev, &st_lsm6dsx_i3c_regmap_config);
> + if (IS_ERR(regmap)) {
> + dev_err(&i3cdev->dev, "Failed to register i3c regmap %d\n",
> + (int)PTR_ERR(regmap));
> + return PTR_ERR(regmap);
> + }
> +
> + return st_lsm6dsx_probe(&i3cdev->dev, 0, hw_data->id,
> + hw_data->name, regmap);
> +}
> +
> +static const struct i3c_device_id st_lsm6dsx_i3c_ids[] = {
> + I3C_DEVICE(0x0104, 0x006C, &hw_data[ST_LSM6DSO_I3C_DATA_ID]),
> + I3C_DEVICE(0x0104, 0x006B, &hw_data[ST_LSM6DSR_I3C_DATA_ID]),

Still find that form counter-intuitive since you'd have to first go
look at what's the value of ST_LSM6DSO_I3C_DATA_ID, then go check the
entry in hw_data to find what's in there. Too many ways to get things
wrong IMHO.

The following form would make it much more obvious/easy to follow:

static const st_lsm6dsx_i3c_data st_lsm6dso_i3c_data = {
ST_LSM6DSO_DEV_NAME, ST_LSM6DSO_ID,
};

static const st_lsm6dsx_i3c_data st_lsm6dsr_i3c_data = {
ST_LSM6DSR_DEV_NAME, ST_LSM6DSR_ID,
};

static const struct i3c_device_id st_lsm6dsx_i3c_ids[] = {
I3C_DEVICE(0x0104, 0x006C, &st_lsm6dso_i3c_data),
I3C_DEVICE(0x0104, 0x006B, &st_lsm6dsr_i3c_data),
};

Note that I don't see why we need to pass both the name and the ID to
st_lsm6dsx_probe(). I'd expect the name to be easily deducible from the
ID (using a name table whose index would match the ST_XXX_ID).

If you do this change you would actually get rid of the
st_lsm6dsx_i3c_data struct and instead have:

static const struct i3c_device_id st_lsm6dsx_i3c_ids[] = {
I3C_DEVICE(0x0104, 0x006C, (void *)ST_LSM6DSO_ID),
I3C_DEVICE(0x0104, 0x006B, (void *)ST_LSM6DSR_ID),
};

> + { /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(i3c, st_lsm6dsx_i3c_ids);
> +
> +static struct i3c_driver st_lsm6dsx_driver = {
> + .driver = {
> + .name = "st_lsm6dsx_i3c",
> + .pm = &st_lsm6dsx_pm_ops,
> + },
> + .probe = st_lsm6dsx_i3c_probe,
> + .id_table = st_lsm6dsx_i3c_ids,
> +};
> +module_i3c_driver(st_lsm6dsx_driver);
> +
> +MODULE_AUTHOR("Vitor Soares <vitor.soares@synopsys.com>");
> +MODULE_DESCRIPTION("STMicroelectronics st_lsm6dsx i3c driver");
> +MODULE_LICENSE("GPL v2");

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