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Message-ID: <20151019143359.GC18952@hard-bop>
Date: Mon, 19 Oct 2015 17:34:00 +0300
From: Teodora Baluta <teodora.baluta@...el.com>
To: Peter Meerwald <pmeerw@...erw.net>
Cc: jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
daniel.baluta@...el.com, dan.carpenter@...cle.com,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: accel: add support for Memsic MXC6255XC sensor
On Mon, Oct 19, 2015 at 01:08:50PM +0200, Peter Meerwald wrote:
> On Fri, 16 Oct 2015, Teodora Baluta wrote:
>
> > This patch adds a minimal implementation for the Memsic MXC6255XC
> > orientation sensing accelerometer. The supported operations are reading
> > raw acceleration values for X/Y axis that can be scaled using the
> > exposed scale.
>
> minor comments below
> link to datasheet?
The datasheet is not public. I've asked Memsic if they can make the
datasheet public or if we can distribute a private copy on request.
I'll address the comments in the v2 patch. Thanks for the review!
>
> > Signed-off-by: Teodora Baluta <teodora.baluta@...el.com>
> > ---
> > drivers/iio/accel/Kconfig | 11 +++
> > drivers/iio/accel/Makefile | 1 +
> > drivers/iio/accel/mxc6255.c | 210 ++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 222 insertions(+)
> > create mode 100644 drivers/iio/accel/mxc6255.c
> >
> > diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> > index 969428d..75ac087 100644
> > --- a/drivers/iio/accel/Kconfig
> > +++ b/drivers/iio/accel/Kconfig
> > @@ -158,6 +158,17 @@ config MXC4005
> > To compile this driver as a module, choose M. The module will be
> > called mxc4005.
> >
> > +config MXC6255
> > + tristate "Memsic MXC6255 Orientation Sensing Accelerometer Driver"
> > + depends on I2C
> > + select REGMAP_I2C
> > + help
> > + Say yes here to build support for the Memsic MXC6255 Orientation
> > + Sensing Accelerometer Driver.
> > +
> > + To compile this driver as a module, choose M here: the module will be
> > + called mxc6255.
> > +
> > config STK8312
> > tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
> > depends on I2C
> > diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> > index 7925f16..525ed52 100644
> > --- a/drivers/iio/accel/Makefile
> > +++ b/drivers/iio/accel/Makefile
> > @@ -17,6 +17,7 @@ obj-$(CONFIG_MMA9551) += mma9551.o
> > obj-$(CONFIG_MMA9553) += mma9553.o
> >
> > obj-$(CONFIG_MXC4005) += mxc4005.o
> > +obj-$(CONFIG_MXC6255) += mxc6255.o
> >
> > obj-$(CONFIG_STK8312) += stk8312.o
> > obj-$(CONFIG_STK8BA50) += stk8ba50.o
> > diff --git a/drivers/iio/accel/mxc6255.c b/drivers/iio/accel/mxc6255.c
> > new file mode 100644
> > index 0000000..ed0f1ab
> > --- /dev/null
> > +++ b/drivers/iio/accel/mxc6255.c
> > @@ -0,0 +1,210 @@
> > +/*
> > + * MXC6255 - MEMSIC orientation sensing accelerometer
> > + *
> > + * Copyright (c) 2015, Intel Corporation.
> > + *
> > + * This file is subject to the terms and conditions of version 2 of
> > + * the GNU General Public License. See the file COPYING in the main
> > + * directory of this archive for more details.
> > + *
> > + * IIO driver for MXC6255 (7-bit I2C slave address 0x15).
> > + *
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/delay.h>
> > +#include <linux/acpi.h>
> > +#include <linux/regmap.h>
> > +#include <linux/iio/sysfs.h>
> > +
> > +#define MXC6255_DRV_NAME "mxc6255"
> > +#define MXC6255_REGMAP_NAME "mxc6255_regmap"
> > +
> > +#define MXC6255_REG_XOUT 0x00
> > +#define MXC6255_REG_YOUT 0x01
> > +#define MXC6255_REG_CHIP_ID 0x08
> > +
> > +#define MXC6255_AXIS_TO_REG(axis) (MXC6255_REG_XOUT + axis)
> > +
> > +/*
> > + * MXC6255 has only one measurement range: +/- 2G.
> > + * The acceleration output is an 8-bit value.
>
> is a
I think it came from "an eight-bit value", so "is an" sounds right to
me.
>
> > + *
> > + * Scale is calculated as following:
>
> as follows
>
> > + * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
> > + *
> > + */
> > +#define MXC6255_SCALE_AVAIL "0.153829"
> > +
> > +enum mxc6255_axis {
> > + AXIS_X,
> > + AXIS_Y,
> > +};
> > +
> > +struct mxc6255_data {
> > + struct i2c_client *client;
> > + struct regmap *regmap;
> > +};
> > +
> > +/* scale value for +/- 2G measurement range */
> > +static const int mxc6255_scale = 153829;
>
> it is customary to use a #define
>
> > +
> > +static IIO_CONST_ATTR(in_accel_scale_available, MXC6255_SCALE_AVAIL);
> > +
> > +static struct attribute *mxc6255_attributes[] = {
> > + &iio_const_attr_in_accel_scale_available.dev_attr.attr,
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group mxc6255_attribute_group = {
> > + .attrs = mxc6255_attributes
> > +};
> > +
> > +static int mxc6255_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct mxc6255_data *data = iio_priv(indio_dev);
> > + unsigned int reg;
> > + int axis = chan->channel2 - 1;
> > + int ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + ret = regmap_read(data->regmap,
> > + MXC6255_AXIS_TO_REG(axis), ®);
>
> use chan->address, and drop the _AXIS_TO_REG macro and axis variable
>
> > + if (ret < 0) {
> > + dev_err(&data->client->dev,
> > + "Error reading axis %d\n", axis);
> > + return ret;
> > + }
> > +
> > + *val = sign_extend32(reg, 7);
> > + return IIO_VAL_INT;
> > + case IIO_CHAN_INFO_SCALE:
> > + *val = 0;
> > + *val2 = mxc6255_scale;
> > + return IIO_VAL_INT_PLUS_MICRO;
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static const struct iio_info mxc6255_info = {
> > + .driver_module = THIS_MODULE,
> > + .read_raw = mxc6255_read_raw,
> > + .attrs = &mxc6255_attribute_group,
> > +};
> > +
> > +#define MXC6255_CHANNEL(_axis) { \
> > + .type = IIO_ACCEL, \
> > + .modified = 1, \
> > + .channel2 = IIO_MOD_##_axis, \
> > + .address = AXIS_##_axis, \
>
> put MXC6255_REG_XOUT / MXC6255_REG_YOUT here, add parameter to _CHANNEL
> macro
>
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> > +}
> > +
> > +static const struct iio_chan_spec mxc6255_channels[] = {
> > + MXC6255_CHANNEL(X),
> > + MXC6255_CHANNEL(Y),
> > +};
> > +
> > +static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
> > +{
> > + switch (reg) {
> > + case MXC6255_REG_XOUT:
> > + case MXC6255_REG_YOUT:
> > + case MXC6255_REG_CHIP_ID:
> > + return true;
> > + default:
> > + return false;
> > + }
> > +}
> > +
> > +static const struct regmap_config mxc6255_regmap_config = {
> > + .name = MXC6255_REGMAP_NAME,
> > +
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > +
> > + .readable_reg = mxc6255_is_readable_reg,
> > +};
> > +
> > +static int mxc6255_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct mxc6255_data *data;
> > + struct iio_dev *indio_dev;
> > + struct regmap *regmap;
> > + unsigned int chip_id;
> > + int ret;
> > +
> > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
> > + if (IS_ERR(regmap)) {
> > + dev_err(&client->dev, "Error initializing regmap\n");
> > + return PTR_ERR(regmap);
> > + }
> > +
> > + data = iio_priv(indio_dev);
> > + i2c_set_clientdata(client, indio_dev);
> > + data->client = client;
> > + data->regmap = regmap;
> > +
> > + indio_dev->name = MXC6255_DRV_NAME;
> > + indio_dev->dev.parent = &client->dev;
> > + indio_dev->channels = mxc6255_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > + indio_dev->info = &mxc6255_info;
> > +
> > + ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "Error reading chip id %d\n", ret);
> > + return ret;
> > + }
> > +
> > + dev_dbg(&client->dev, "Chip id %x\n", chip_id);
>
> maybe check chip id?
Will do.
>
> > +
> > + ret = devm_iio_device_register(&client->dev, indio_dev);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "Could not register IIO device\n");
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static const struct acpi_device_id mxc6255_acpi_match[] = {
> > + {"MXC6255", 0},
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
> > +
> > +static const struct i2c_device_id mxc6255_id[] = {
> > + {"mxc6255", 0},
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, mxc6255_id);
> > +
> > +static struct i2c_driver mxc6255_driver = {
> > + .driver = {
> > + .name = MXC6255_DRV_NAME,
> > + .acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
> > + },
> > + .probe = mxc6255_probe,
> > + .id_table = mxc6255_id,
> > +};
> > +
> > +module_i2c_driver(mxc6255_driver);
> > +
> > +MODULE_AUTHOR("Teodora Baluta <teodora.baluta@...el.com>");
> > +MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
> > +MODULE_LICENSE("GPL v2");
> >
>
> --
>
> Peter Meerwald
> +43-664-2444418 (mobile)
--
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