linux-kernel - Re: [v3 12/13] iio: imu: add BNO055 I2C driver

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Message-ID: <20220219170313.78e64ddd@jic23-huawei>
Date:   Sat, 19 Feb 2022 17:03:13 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Andrea Merello <andrea.merello@...il.com>
Cc:     mchehab+huawei@...nel.org, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        lars@...afoo.de, robh+dt@...nel.org, andy.shevchenko@...il.com,
        matt.ranostay@...sulko.com, ardeleanalex@...il.com,
        jacopo@...ndi.org, Andrea Merello <andrea.merello@....it>
Subject: Re: [v3 12/13] iio: imu: add BNO055 I2C driver

On Thu, 17 Feb 2022 17:27:09 +0100
Andrea Merello <andrea.merello@...il.com> wrote:

> This path adds an I2C driver for communicating to a BNO055 IMU via I2C
> bus and it enables the BNO055 core driver to work in this scenario.
> 
> Signed-off-by: Andrea Merello <andrea.merello@....it>

Minor comment inline to add an of_device_id table.
Isn't i2c so much nicer than serial? :) 

Thanks,

Jonathan


> ---
>  drivers/iio/imu/bno055/Kconfig      | 11 +++++++
>  drivers/iio/imu/bno055/Makefile     |  1 +
>  drivers/iio/imu/bno055/bno055_i2c.c | 50 +++++++++++++++++++++++++++++
>  3 files changed, 62 insertions(+)
>  create mode 100644 drivers/iio/imu/bno055/bno055_i2c.c
> 
> diff --git a/drivers/iio/imu/bno055/Kconfig b/drivers/iio/imu/bno055/Kconfig
> index 8a83639ad2a9..3693a408e270 100644
> --- a/drivers/iio/imu/bno055/Kconfig
> +++ b/drivers/iio/imu/bno055/Kconfig
> @@ -12,3 +12,14 @@ config BOSCH_BNO055_SERIAL
>  
>  	  This driver can also be built as a module. If so, the module will be
>  	  called bno055_sl.
> +
> +config BOSCH_BNO055_I2C
> +	tristate "Bosch BNO055 attached via I2C bus"
> +	depends on I2C
> +	select REGMAP_I2C
> +	select BOSCH_BNO055_IIO
> +	help
> +	  Enable this to support Bosch BNO055 IMUs attached via I2C bus.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called bno055_i2c.
> diff --git a/drivers/iio/imu/bno055/Makefile b/drivers/iio/imu/bno055/Makefile
> index 416f0ff96de5..2fe2b0857903 100644
> --- a/drivers/iio/imu/bno055/Makefile
> +++ b/drivers/iio/imu/bno055/Makefile
> @@ -2,3 +2,4 @@
>  
>  obj-$(CONFIG_BOSCH_BNO055_IIO) += bno055.o
>  obj-$(CONFIG_BOSCH_BNO055_SERIAL) += bno055_sl.o
> +obj-$(CONFIG_BOSCH_BNO055_I2C) += bno055_i2c.o
> diff --git a/drivers/iio/imu/bno055/bno055_i2c.c b/drivers/iio/imu/bno055/bno055_i2c.c
> new file mode 100644
> index 000000000000..9900e2a4d905
> --- /dev/null
> +++ b/drivers/iio/imu/bno055/bno055_i2c.c
> @@ -0,0 +1,50 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Support for I2C-interfaced Bosch BNO055 IMU.
> + *
> + * Copyright (C) 2021 Istituto Italiano di Tecnologia
> + * Electronic Design Laboratory
> + * Written by Andrea Merello <andrea.merello@....it>
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +#include <linux/module.h>
> +
> +#include "bno055.h"
> +
> +#define BNO055_I2C_XFER_BURST_BREAK_THRESHOLD 3 /* FIXME */
> +
> +static int bno055_i2c_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct regmap *regmap =
> +		devm_regmap_init_i2c(client, &bno055_regmap_config);
> +
> +	if (IS_ERR(regmap)) {
> +		dev_err(&client->dev, "Unable to init register map");
> +		return PTR_ERR(regmap);
> +	}
> +
> +	return bno055_probe(&client->dev, regmap,
> +			    BNO055_I2C_XFER_BURST_BREAK_THRESHOLD, true);
> +}
> +
> +static const struct i2c_device_id bno055_i2c_id[] = {
> +	{"bno055", 0},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, bno055_i2c_id);

No of_device_id table?  Whilst the fallback path that
usese the i2c_device_id will mostly work, it leaves us in theory
more susceptible to naming clashes and is generally not as nice.
Hence definitely prefer it if we have an of_device_id table as well
as the i2c_device_id one.

> +
> +static struct i2c_driver bno055_driver = {
> +	.driver = {
> +		.name = "bno055-i2c",
> +	},
> +	.probe = bno055_i2c_probe,
> +	.id_table = bno055_i2c_id
> +};
> +module_i2c_driver(bno055_driver);
> +
> +MODULE_AUTHOR("Andrea Merello");
> +MODULE_DESCRIPTION("Bosch BNO055 I2C interface");
> +MODULE_LICENSE("GPL v2");