Re: [PATCH v3] iio: accel: Add support for Freescale MMA7660FC

[Jonathan Cameron]

On 29/04/16 13:19, Constantin Musca wrote:
> Minimal implementation of an IIO driver for the Freescale
> MMA7660FC 3-axis accelerometer. Datasheet:
> http://www.freescale.com.cn/files/sensors/doc/data_sheet/MMA7660FC.pdf
> 
> Includes:
> - ACPI support;
> - read_raw for x,y,z axes;
> - reading and setting the scale (range) parameter.
> - power management
> 
> Signed-off-by: Constantin Musca <constantin.musca@xxxxxxxxx>
Couple of trivial bits inline as well as that request to update the link above
if possible...

Why the retries? (I'm on a train without internet access for quite a few
hours yet hence I can't dig into the datasheet!)

Anyhow, even if it's obvious from the datasheet, that sort of 'magic' needs
an explanation comment...

Jonathan
> ---
>  drivers/iio/accel/Kconfig   |  10 ++
>  drivers/iio/accel/Makefile  |   2 +
>  drivers/iio/accel/mma7660.c | 269 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 281 insertions(+)
>  create mode 100644 drivers/iio/accel/mma7660.c
> 
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index e4a758c..1df6361 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -136,6 +136,16 @@ config MMA7455_SPI
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called mma7455_spi.
>  
> +config MMA7660
> +	tristate "Freescale MMA7660FC 3-Axis Accelerometer Driver"
> +	depends on I2C
> +	help
> +	  Say yes here to get support for the Freescale MMA7660FC 3-Axis
> +	  accelerometer.
> +
> +	  Choosing M will build the driver as a module. If so, the module
> +	  will be called mma7660.
> +
>  config MMA8452
>  	tristate "Freescale MMA8452Q and similar Accelerometers Driver"
>  	depends on I2C
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 71b6794..ba1165f 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -15,6 +15,8 @@ obj-$(CONFIG_MMA7455)		+= mma7455_core.o
>  obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o
>  obj-$(CONFIG_MMA7455_SPI)	+= mma7455_spi.o
>  
> +obj-$(CONFIG_MMA7660)	+= mma7660.o
> +
>  obj-$(CONFIG_MMA8452)	+= mma8452.o
>  
>  obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o
> diff --git a/drivers/iio/accel/mma7660.c b/drivers/iio/accel/mma7660.c
> new file mode 100644
> index 0000000..94b2999
> --- /dev/null
> +++ b/drivers/iio/accel/mma7660.c
> @@ -0,0 +1,269 @@
> +/**
> + * Freescale MMA7660FC 3-Axis Accelerometer
> + *
> + * Copyright (c) 2016, 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 Freescale MMA7660FC; 7-bit I2C address: 0x4c.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define MMA7660_DRIVER_NAME	"mma7660"
> +
> +#define MMA7660_REG_XOUT	0x00
> +#define MMA7660_REG_YOUT	0x01
> +#define MMA7660_REG_ZOUT	0x02
> +#define MMA7660_REG_OUT_BIT_ALERT	BIT(6)
> +
> +#define MMA7660_REG_MODE	0x07
> +#define MMA7660_REG_MODE_BIT_MODE	BIT(0)
> +#define MMA7660_REG_MODE_BIT_TON	BIT(2)
> +
> +#define MMA7660_I2C_READ_RETRIES	5
> +
> +/*
> + * The accelerometer has one measurement range:
> + *
> + * -1.5g - +1.5g (6-bit, signed)
> + *
> + * scale = (1.5 + 1.5) * 9.81 / (2^6 - 1)	= 0.467142857
> + */
> +
> +#define MMA7660_SCALE_AVAIL	"0.467142857"
> +
> +const int mma7660_nscale = 467142857;
> +
> +#define MMA7660_CHANNEL(reg, axis) {	\
> +	.type = IIO_ACCEL,	\
> +	.address = reg,	\
> +	.modified = 1,	\
> +	.channel2 = IIO_MOD_##axis,	\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +}
> +
> +static const struct iio_chan_spec mma7660_channels[] = {
> +	MMA7660_CHANNEL(MMA7660_REG_XOUT, X),
> +	MMA7660_CHANNEL(MMA7660_REG_YOUT, Y),
> +	MMA7660_CHANNEL(MMA7660_REG_ZOUT, Z),
> +};
> +
> +enum mma7660_mode {
> +	MMA7660_MODE_STANDBY,
> +	MMA7660_MODE_ACTIVE
> +};
> +
> +struct mma7660_data {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	enum mma7660_mode mode;
> +};
> +
> +static IIO_CONST_ATTR(in_accel_scale_available, MMA7660_SCALE_AVAIL);
> +
> +static struct attribute *mma7660_attributes[] = {
> +	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group mma7660_attribute_group = {
> +	.attrs = mma7660_attributes
> +};
> +
> +static int mma7660_set_mode(struct mma7660_data *data,
> +				enum mma7660_mode mode)
> +{
> +	int ret;
> +	struct i2c_client *client = data->client;
> +
> +	if (mode == data->mode)
> +		return 0;
> +
> +	ret = i2c_smbus_read_byte_data(client, MMA7660_REG_MODE);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to read sensor mode\n");
> +		return ret;
> +	}
> +
> +	if (mode == MMA7660_MODE_ACTIVE) {
> +		ret &= ~MMA7660_REG_MODE_BIT_TON;
> +		ret |= MMA7660_REG_MODE_BIT_MODE;
> +	} else {
> +		ret &= ~MMA7660_REG_MODE_BIT_TON;
> +		ret &= ~MMA7660_REG_MODE_BIT_MODE;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(client, MMA7660_REG_MODE, ret);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to change sensor mode\n");
> +		return ret;
> +	}
> +
> +	data->mode = mode;
blank line here (slightly prefered)...
> +	return ret;
> +}
> +
> +static int mma7660_read_accel(struct mma7660_data *data, u8 address)
> +{
> +	int ret, retries = MMA7660_I2C_READ_RETRIES;
> +	struct i2c_client *client = data->client;
> +
This needs a comment to explain why a number of tries might be needed. 
> +	do {
> +		ret = i2c_smbus_read_byte_data(client, address);
> +		if (ret < 0) {
> +			dev_err(&client->dev, "register read failed\n");
> +			return ret;
> +		}
> +	} while (retries-- > 0 && ret & MMA7660_REG_OUT_BIT_ALERT);
> +
> +	if (ret & MMA7660_REG_OUT_BIT_ALERT) {
> +		dev_err(&client->dev, "all register read retries failed\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	return ret;
> +}
> +
> +static int mma7660_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val, int *val2, long mask)
> +{
> +	struct mma7660_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&data->lock);
> +		ret = mma7660_read_accel(data, chan->address);
> +		mutex_unlock(&data->lock);
> +		if (ret < 0)
> +			return ret;
> +		*val = sign_extend32(ret, 5);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 0;
> +		*val2 = mma7660_nscale;
> +		return IIO_VAL_INT_PLUS_NANO;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info mma7660_info = {
> +	.driver_module	= THIS_MODULE,
> +	.read_raw		= mma7660_read_raw,
> +	.attrs			= &mma7660_attribute_group,
> +};
> +
> +static int mma7660_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	int ret;
> +	struct iio_dev *indio_dev;
> +	struct mma7660_data *data;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev) {
> +		dev_err(&client->dev, "iio allocation failed!\n");
> +		return -ENOMEM;
> +	}
> +
> +	data = iio_priv(indio_dev);
> +	data->client = client;
> +	i2c_set_clientdata(client, indio_dev);
> +	mutex_init(&data->lock);
> +	data->mode = MMA7660_MODE_STANDBY;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &mma7660_info;
> +	indio_dev->name = MMA7660_DRIVER_NAME;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = mma7660_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(mma7660_channels);
> +
> +	ret = mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "device_register failed\n");
> +		mma7660_set_mode(data, MMA7660_MODE_STANDBY);
> +	}
> +
> +	return ret;
> +}
> +
> +static int mma7660_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	return mma7660_set_mode(iio_priv(indio_dev), MMA7660_MODE_STANDBY);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int mma7660_suspend(struct device *dev)
> +{
> +	struct mma7660_data *data;
> +
> +	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> +	return mma7660_set_mode(data, MMA7660_MODE_STANDBY);
> +}
> +
> +static int mma7660_resume(struct device *dev)
> +{
> +	struct mma7660_data *data;
> +
> +	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> +	return mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(mma7660_pm_ops, mma7660_suspend, mma7660_resume);
> +
> +#define MMA7660_PM_OPS (&mma7660_pm_ops)
> +#else
> +#define MMA7660_PM_OPS NULL
> +#endif
> +
> +static const struct i2c_device_id mma7660_i2c_id[] = {
> +	{"mma7660", 0},
> +	{}
> +};
> +
> +static const struct acpi_device_id mma7660_acpi_id[] = {
> +	{"MMA7660", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, mma7660_acpi_id);
> +
> +static struct i2c_driver mma7660_driver = {
> +	.driver = {
> +		.name = "mma7660",
> +		.pm = MMA7660_PM_OPS,
> +		.acpi_match_table = ACPI_PTR(mma7660_acpi_id),
> +	},
> +	.probe		= mma7660_probe,
> +	.remove		= mma7660_remove,
> +	.id_table	= mma7660_i2c_id,
> +};
> +
> +module_i2c_driver(mma7660_driver);
> +
> +MODULE_AUTHOR("Constantin Musca <constantin.musca@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Freescale MMA7660FC 3-Axis Accelerometer driver");
> +MODULE_LICENSE("GPL v2");
>