RE: [PATCH v4 3/3] iio: imu: st_lsm6dsx: add i3c basic support for LSM6DSO and LSM6DSR

Vitor Soares
2019-07-12T18:43:13Z

From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Fri, Jul 12, 2019 at 17:43:23

> On Fri, 12 Jul 2019 16:28:02 +0000
> Vitor Soares <Vitor.Soares@synopsys.com> wrote:
>
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Date: Fri, Jul 12, 2019 at 17:14:29
> >
> > > On Fri, 12 Jul 2019 13:53:30 +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>
> > > > Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > > ---
> > > > Changes in v4:
> > > > Remove hw_id variable
> > > >
> > > > Changes in v3:
> > > > Remove unnecessary st_lsm6dsx_i3c_data table used to hold device name
> > > > Use st_lsm6dsx_probe new form
> > > >
> > > > 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 | 58 +++++++++++++++++++++++++++++
> > > > 3 files changed, 66 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 9e59297..6b5a73c 100644
> > > > --- a/drivers/iio/imu/st_lsm6dsx/Kconfig
> > > > +++ b/drivers/iio/imu/st_lsm6dsx/Kconfig
> > > > @@ -1,11 +1,12 @@
> > > >
> > > > 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,
> > > > @@ -23,3 +24,8 @@ 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 e5f733c..c676965 100644
> > > > --- a/drivers/iio/imu/st_lsm6dsx/Makefile
> > > > +++ b/drivers/iio/imu/st_lsm6dsx/Makefile
> > > > @@ -4,3 +4,4 @@ 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..2e89524
> > > > --- /dev/null
> > > > +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c
> > > > @@ -0,0 +1,58 @@
> > > > +// 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"
> > > > +
> > > > +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),
> > >
> > > I think you need an uintptr_t cast here:
> > >
> > > I3C_DEVICE(0x0104, 0x006C, (void *)(uintptr_t)ST_LSM6DSO_ID),
> > > I3C_DEVICE(0x0104, 0x006B, (void *)(uintptr_t)ST_LSM6DSR_ID),
> > >
> > > otherwise gcc might complain that the integer and pointer do not have
> > > the same size (on 64-bit architectures).
> >
> > I don't understand this part. Can you provide or point some background?
>
> If you don't do that you'll get the following warning:
>
> warning: cast to 'void *' from smaller integer type 'int' [-Wint-to-void-pointer-cast]

I don't get the warning during compilation. Is there any flag to enable
or so?

>
> >
> > >
> > > > + { /* sentinel */ },
> > > > +};
> > > > +MODULE_DEVICE_TABLE(i3c, st_lsm6dsx_i3c_ids);
> > > > +
> > > > +static const struct regmap_config st_lsm6dsx_i3c_regmap_config = {
> > > > + .reg_bits = 8,
> > > > + .val_bits = 8,
> > > > +};
> > >
> > > This can be moved ...
> > >
> > > > +
> > > > +static int st_lsm6dsx_i3c_probe(struct i3c_device *i3cdev)
> > > > +{
> > >
> > > ... here without the static and const qualifiers:
> >
> > I understand that can be move to here, but I don't understand the
> > advantages. Can you explain?
>
> It reduces the variable scope (this variable is only needed in the
> probe path) and avoids consuming space in the .bss section, though the
> second point is not so important.

Thanks,
Vitor Soares