Re: [v2 10/10] iio: imu: add BNO055 I2C driver

From: Andrea Merello <andrea.merello@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	linux-iio <linux-iio@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	devicetree <devicetree@vger.kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Rob Herring <robh+dt@kernel.org>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Matt Ranostay <matt.ranostay@konsulko.com>,
	Alexandru Ardelean <ardeleanalex@gmail.com>,
	Jacopo Mondi <jacopo@jmondi.org>,
	Andrea Merello <andrea.merello@iit.it>
Subject: Re: [v2 10/10] iio: imu: add BNO055 I2C driver
Date: Thu, 11 Nov 2021 11:12:58 +0100	[thread overview]
Message-ID: <CAN8YU5PjJ9e8_RuLpY0JgLek-+HwxOLJ61MAGBqqzbqd6KWuYA@mail.gmail.com> (raw)
In-Reply-To: <20211028121001.73d8abbe@jic23-huawei>

Just an inline comment; OK for the rest.

Il giorno gio 28 ott 2021 alle ore 13:05 Jonathan Cameron
<jic23@kernel.org> ha scritto:
>
> On Thu, 28 Oct 2021 12:18:40 +0200
> Andrea Merello <andrea.merello@gmail.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@iit.it>
> Hi Andrea,
>
> A few minor things inline.
>
> Jonathan
>
> > ---
> >  drivers/iio/imu/bno055/Kconfig      |  6 ++++
> >  drivers/iio/imu/bno055/Makefile     |  1 +
> >  drivers/iio/imu/bno055/bno055_i2c.c | 54 +++++++++++++++++++++++++++++
> >  3 files changed, 61 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 941e43f0368d..87200787d548 100644
> > --- a/drivers/iio/imu/bno055/Kconfig
> > +++ b/drivers/iio/imu/bno055/Kconfig
> > @@ -7,3 +7,9 @@ config BOSH_BNO055_SERIAL
> >       tristate "Bosh BNO055 attached via serial bus"
> >       depends on SERIAL_DEV_BUS
> >       select BOSH_BNO055_IIO
> > +
> > +config BOSH_BNO055_I2C
> > +     tristate "Bosh BNO055 attached via I2C bus"
> > +     depends on I2C
> > +     select REGMAP_I2C
> > +     select BOSH_BNO055_IIO
> > diff --git a/drivers/iio/imu/bno055/Makefile b/drivers/iio/imu/bno055/Makefile
> > index 7285ade2f4b9..eaf24018cb28 100644
> > --- a/drivers/iio/imu/bno055/Makefile
> > +++ b/drivers/iio/imu/bno055/Makefile
> > @@ -2,3 +2,4 @@
> >
> >  obj-$(CONFIG_BOSH_BNO055_IIO) += bno055.o
> >  obj-$(CONFIG_BOSH_BNO055_SERIAL) += bno055_sl.o
> > +obj-$(CONFIG_BOSH_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..eea0daa6a61d
> > --- /dev/null
> > +++ b/drivers/iio/imu/bno055/bno055_i2c.c
> > @@ -0,0 +1,54 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * I2C interface for Bosh BNO055 IMU.
> > + * This file implements I2C communication up to the register read/write
> > + * level.
>
> Not really. It just uses regmap, so I'd drop this comment.
>
> > + *
> > + * Copyright (C) 2021 Istituto Italiano di Tecnologia
> > + * Electronic Design Laboratory
> > + * Written by Andrea Merello <andrea.merello@iit.it>
> > + */
> > +
> > +#include <linux/i2c.h>
>
> Why?  I'm not seeing an i2c specific calls in here.

Because of the definition of struct i2c_client, that is being accessed
in lines like this
dev_err(&client->dev, "Unable to init register map");

> > +#include <linux/regmap.h>
> > +#include <linux/module.h>
>
> mod_devicetable.h for struct i2c_device_id
>
> > +
> > +#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);
> > +
> > +     return 0;
>
> ?
>
> > +}
> > +
> > +static const struct i2c_device_id bno055_i2c_id[] = {
> > +     {"bno055", 0},
> > +     { },
>
> It's at terminator, so don't put a comma as we'll never add entries after this.
>
> > +};
> > +MODULE_DEVICE_TABLE(i2c, bno055_i2c_id);
> > +
> > +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");
>