Re: [PATCH] iio: imu: Add support for Kionix KMX61 sensor

[Jonathan Cameron <jic23@kernel.org>]

On 06/11/14 12:29, Daniel Baluta wrote:
> Minimal implementation for KMX61 6-axis accelerometer/magnetometer. It exports
> raw accel/magn readings together with scale and sampling frequency.
> 
> Datasheet will be available at:
> http://www.kionix.com/6-axis-accelerometer-magnetometer/kmx61
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Very nice.  Only one comment inline.

There are some possible race conditions (I think) based on functions
doing read, modify, write.  Ideally they may want protecting with
a mutex.

Jonathan
> ---
> Accelerometer is somehow similar with KXCJK-1013 but the registers
> are different. Some code and ideas are borrowed from KXCJK-1013 driver.
> 
> Trying to implement KMX61 on top of kxcjk-1013.c would make code
> harder to read.
> 
>  drivers/iio/imu/Kconfig  |   9 +
>  drivers/iio/imu/Makefile |   2 +
>  drivers/iio/imu/kmx61.c  | 575 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 586 insertions(+)
>  create mode 100644 drivers/iio/imu/kmx61.c
> 
> diff --git a/drivers/iio/imu/Kconfig b/drivers/iio/imu/Kconfig
> index 2b0e451..d675f43 100644
> --- a/drivers/iio/imu/Kconfig
> +++ b/drivers/iio/imu/Kconfig
> @@ -25,6 +25,15 @@ config ADIS16480
>  	  Say yes here to build support for Analog Devices ADIS16375, ADIS16480,
>  	  ADIS16485, ADIS16488 inertial sensors.
>  
> +config KMX61
> +	tristate "Kionix KMX61 6-axis accelerometer and magnetometer"
> +	depends on I2C
> +	help
> +	  Say Y here if you want to build a driver for Kionix KMX61 6-axis accelerometer
> +	  and magnetometer.
> +	  To compile this driver as module, choose M here: the module will be called
> +	  kmx61.
> +
>  source "drivers/iio/imu/inv_mpu6050/Kconfig"
>  
>  endmenu
> diff --git a/drivers/iio/imu/Makefile b/drivers/iio/imu/Makefile
> index 114d2c1..e1e6e3d 100644
> --- a/drivers/iio/imu/Makefile
> +++ b/drivers/iio/imu/Makefile
> @@ -14,3 +14,5 @@ adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_buffer.o
>  obj-$(CONFIG_IIO_ADIS_LIB) += adis_lib.o
>  
>  obj-y += inv_mpu6050/
> +
> +obj-$(CONFIG_KMX61) += kmx61.o
> diff --git a/drivers/iio/imu/kmx61.c b/drivers/iio/imu/kmx61.c
> new file mode 100644
> index 0000000..124d75d
> --- /dev/null
> +++ b/drivers/iio/imu/kmx61.c
> @@ -0,0 +1,575 @@
> +/*
> + * KMX61 - Kionix 6-axis Accelerometer/Magnetometer
> + *
> + * Copyright (c) 2014, 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 KMX61 (7-bit I2C slave address 0x0E or 0x0F).
> + *
> + * TODO: buffer, interrupt, thresholds, acpi, temperature sensor
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define KMX61_DRV_NAME "kmx61"
> +
> +#define KMX61_REG_WHO_AM_I		0x00
> +
> +#define KMX61_ACC_XOUT_L		0x0A
> +
> +#define KMX61_ACC_XOUT_H		0x0B
> +#define KMX61_ACC_YOUT_L		0x0C
> +#define KMX61_ACC_YOUT_H		0x0D
> +#define KMX61_ACC_ZOUT_L		0x0E
> +#define KMX61_ACC_ZOUT_H		0x0F
> +
> +#define KMX61_MAG_XOUT_L		0x12
> +
> +#define KMX61_MAG_XOUT_H		0x13
> +#define KMX61_MAG_YOUT_L		0x14
> +#define KMX61_MAG_YOUT_H		0x15
> +#define KMX61_MAG_ZOUT_L		0x16
> +#define KMX61_MAG_ZOUT_H		0x17
> +
> +#define KMX61_REG_ODCNTL		0x2C
> +
> +#define KMX61_REG_STBY			0x29
> +#define KMX61_REG_CTRL1			0x2A
> +
> +#define KMX61_REG_COTR			0x3C
> +
> +#define KMX61_ACC_STBY_BIT	BIT(0)
> +#define KMX61_MAG_STBY_BIT	BIT(1)
> +#define KMX61_ACT_STBY_BIT	BIT(7)
> +
> +#define KMX61_ALL_STBY		(KMX61_ACC_STBY_BIT | KMX61_MAG_STBY_BIT)
> +
> +#define KMX61_REG_CTRL1_GSEL0_SHIFT	0
> +#define KMX61_REG_CTRL1_GSEL1_SHIFT	1
> +#define KMX61_REG_CTRL1_GSEL0_MASK	0x01
> +#define KMX61_REG_CTRL1_GSEL1_MASK	0x02
> +
> +#define KMX61_REG_CTRL1_BIT_RES		BIT(4)
> +
> +#define KMX61_ACC_ODR_SHIFT	0
> +#define KMX61_MAG_ODR_SHIFT	4
> +#define KMX61_ACC_ODR_MASK	0x0F
> +#define KMX61_MAG_ODR_MASK	0xF0
> +
> +#define KMX61_CHIP_ID		0x12
> +
> +struct kmx61_data {
> +	struct i2c_client *client;
> +	u8 range;
> +	u8 odr_bits;
> +};
> +
> +enum kmx61_range {
> +	KMX61_RANGE_2G,
> +	KMX61_RANGE_4G,
> +	KMX61_RANGE_8G,
> +};
> +
> +enum kmx61_scan {
> +	KMX61_SCAN_ACC_X,
> +	KMX61_SCAN_ACC_Y,
> +	KMX61_SCAN_ACC_Z,
> +	KMX61_SCAN_TEMP,
> +	KMX61_SCAN_MAG_X,
> +	KMX61_SCAN_MAG_Y,
> +	KMX61_SCAN_MAG_Z,
> +};
> +
> +static const struct {
> +	u16 scale;
> +	u8 gsel0;
> +	u8 gsel1;
> +} kmx61_scale_table[] = {
> +	{9582, 0, 0},
> +	{19163, 1, 0},
> +	{38326, 0, 1},
> +};
> +
> +/* KMX61 devices */
> +#define KMX61_ACC	0x01
> +#define KMX61_MAG	0x02
> +
> +static const struct {
> +	int val;
> +	int val2;
> +	int odr_bits;
> +} samp_freq_table[] = { {12, 500000, 0x00},
> +			{25, 0, 0x01},
> +			{50, 0, 0x02},
> +			{100, 0, 0x03},
> +			{200, 0, 0x04},
> +			{400, 0, 0x05},
> +			{800, 0, 0x06},
> +			{1600, 0, 0x07},
> +			{0, 781000, 0x08},
> +			{1, 563000, 0x09},
> +			{3, 125000, 0x0A},
> +			{6, 250000, 0x0B} };
> +
> +static IIO_CONST_ATTR(accel_scale_available, "0.009582 0.019163 0.038326");
> +static IIO_CONST_ATTR(magn_scale_available, "0.001465");
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
> +	"0.781000 1.563000 3.125000 6.250000 12.500000 25 50 100 200 400 800");
> +
> +static struct attribute *kmx61_attributes[] = {
> +	&iio_const_attr_accel_scale_available.dev_attr.attr,
> +	&iio_const_attr_magn_scale_available.dev_attr.attr,
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group kmx61_attribute_group = {
> +	.attrs = kmx61_attributes,
> +};
> +
> +#define KMX61_ACC_CHAN(_axis, _index) { \
> +	.type = IIO_ACCEL, \
> +	.modified = 1, \
> +	.channel2 = IIO_MOD_ ## _axis, \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> +				BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	.scan_index = _index, \
> +	.scan_type = { \
> +		.sign = 's', \
> +		.realbits = 12, \
> +		.storagebits = 16, \
> +		.shift = 4, \
> +		.endianness = IIO_BE, \
> +	}, \
> +}
> +
> +#define KMX61_MAG_CHAN(_axis, _index) { \
> +	.type = IIO_MAGN, \
> +	.modified = 1, \
> +	.channel2 = IIO_MOD_ ## _axis, \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> +				BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	.scan_index = _index, \
> +	.scan_type = { \
> +		.sign = 's', \
> +		.realbits = 14, \
> +		.storagebits = 16, \
> +		.shift = 2, \
> +		.endianness = IIO_BE, \
> +	}, \
> +}
> +
> +static const struct iio_chan_spec kmx61_channels[] = {
> +	KMX61_ACC_CHAN(X, KMX61_SCAN_ACC_X),
> +	KMX61_ACC_CHAN(Y, KMX61_SCAN_ACC_Y),
> +	KMX61_ACC_CHAN(Z, KMX61_SCAN_ACC_Z),
> +	KMX61_MAG_CHAN(X, KMX61_SCAN_MAG_X),
> +	KMX61_MAG_CHAN(Y, KMX61_SCAN_MAG_Y),
> +	KMX61_MAG_CHAN(Z, KMX61_SCAN_MAG_Z),
> +};
> +
> +static int kmx61_convert_freq_to_bit(int val, int val2)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(samp_freq_table); i++)
> +		if (val == samp_freq_table[i].val &&
> +		    val2 == samp_freq_table[i].val2)
> +			return samp_freq_table[i].odr_bits;
> +	return -EINVAL;
> +}
> +
> +static int kmx61_set_mode(struct kmx61_data *data, u8 mode, u8 device)
> +{
> +	int ret;
> +
Looks like a possible race in here given the read / write pair.
Perhaps a mutex to prevent it?

Obviously this applies in a few other places!
> +	ret = i2c_smbus_read_byte_data(data->client, KMX61_REG_STBY);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error reading reg_stby\n");
> +		return ret;
> +	}
> +	if (device & KMX61_ACC) {
> +		if (mode & KMX61_ACC_STBY_BIT)
> +			ret |= KMX61_ACC_STBY_BIT;
> +		else
> +			ret &= ~KMX61_ACC_STBY_BIT;
> +	}
> +
> +	if (device & KMX61_MAG) {
> +		if (mode & KMX61_MAG_STBY_BIT)
> +			ret |= KMX61_MAG_STBY_BIT;
> +		else
> +			ret &= ~KMX61_MAG_STBY_BIT;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(data->client, KMX61_REG_STBY, ret);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error writing reg_stby\n");
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int kmx61_get_mode(struct kmx61_data *data, u8 *mode, u8 device)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, KMX61_REG_STBY);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error reading reg_stby\n");
> +		return ret;
> +	}
> +	*mode = 0;
> +
> +	if (device & KMX61_ACC) {
> +		if (ret & KMX61_ACC_STBY_BIT)
> +			*mode |= KMX61_ACC_STBY_BIT;
> +		else
> +			*mode &= ~KMX61_ACC_STBY_BIT;
> +	}
> +
> +	if (device & KMX61_MAG) {
> +		if (ret & KMX61_MAG_STBY_BIT)
> +			*mode |= KMX61_MAG_STBY_BIT;
> +		else
> +			*mode &= ~KMX61_MAG_STBY_BIT;
> +	}
> +
> +	return 0;
> +}
> +
> +static int kmx61_set_odr(struct kmx61_data *data, int val, int val2, u8 device)
> +{
> +	int ret;
> +	u8 mode;
> +	int lodr_bits, odr_bits;
> +
> +	ret = kmx61_get_mode(data, &mode, KMX61_ACC | KMX61_MAG);
> +	if (ret < 0)
> +		return ret;
> +
> +	lodr_bits = kmx61_convert_freq_to_bit(val, val2);
> +	if (lodr_bits < 0)
> +		return lodr_bits;
> +
> +	/* To change ODR, accel and magn must be in STDBY */
> +	ret = kmx61_set_mode(data, KMX61_ALL_STBY, KMX61_ACC | KMX61_MAG);
> +	if (ret < 0)
> +		return ret;
> +
> +	odr_bits = 0;
> +	if (device & KMX61_ACC)
> +		odr_bits |= lodr_bits;
> +	if (device & KMX61_MAG)
> +		odr_bits |= (lodr_bits << KMX61_MAG_ODR_SHIFT);
> +
> +	ret = i2c_smbus_write_byte_data(data->client, KMX61_REG_ODCNTL,
> +					odr_bits);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = kmx61_set_mode(data, mode, KMX61_ACC | KMX61_MAG);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->odr_bits = lodr_bits;
> +
> +	return 0;
> +}
> +
> +static
> +int kmx61_get_odr(struct kmx61_data *data, int *val, int *val2, u8 device)
> +{	int i;
> +	u8 lodr_bits;
> +
> +	if (device & KMX61_ACC)
> +		lodr_bits = (data->odr_bits >> KMX61_ACC_ODR_SHIFT) &
> +			     KMX61_ACC_ODR_MASK;
> +	else if (device & KMX61_MAG)
> +		lodr_bits = (data->odr_bits >> KMX61_MAG_ODR_SHIFT) &
> +			     KMX61_MAG_ODR_MASK;
> +	else
> +		return -EINVAL;
> +
> +	for (i = 0; i < ARRAY_SIZE(samp_freq_table); i++)
> +		if (lodr_bits == samp_freq_table[i].odr_bits) {
> +			*val = samp_freq_table[i].val;
> +			*val2 = samp_freq_table[i].val2;
> +			return 0;
> +		}
> +	return -EINVAL;
> +}
> +
> +static int kmx61_set_range(struct kmx61_data *data, int range)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, KMX61_REG_CTRL1);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error reading reg_ctrl1\n");
> +		return ret;
> +	}
> +
> +	ret &= ~(KMX61_REG_CTRL1_GSEL0_MASK | KMX61_REG_CTRL1_GSEL1_MASK);
> +	ret |= kmx61_scale_table[range].gsel0 << KMX61_REG_CTRL1_GSEL0_SHIFT;
> +	ret |= kmx61_scale_table[range].gsel1 << KMX61_REG_CTRL1_GSEL1_SHIFT;
> +
> +	ret = i2c_smbus_write_byte_data(data->client, KMX61_REG_CTRL1, ret);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error writing reg_ctrl1\n");
> +		return ret;
> +	}
> +
> +	data->range = range;
> +
> +	return 0;
> +}
> +
> +static int kmx61_set_scale(struct kmx61_data *data, int val)
> +{
> +	int ret, i;
> +	u8  mode;
> +
> +	for (i = 0; i < ARRAY_SIZE(kmx61_scale_table); i++) {
> +		if (kmx61_scale_table[i].scale == val) {
> +			ret = kmx61_get_mode(data, &mode,
> +					     KMX61_ACC | KMX61_MAG);
> +			if (ret < 0)
> +				return ret;
> +
> +			ret = kmx61_set_mode(data, KMX61_ALL_STBY,
> +					     KMX61_ACC | KMX61_MAG);
> +			if (ret < 0)
> +				return ret;
> +
> +			ret = kmx61_set_range(data, i);
> +			if (ret < 0)
> +				return ret;
> +
> +			ret = kmx61_set_mode(data, mode,
> +					     KMX61_ACC | KMX61_MAG);
> +			if (ret < 0)
> +				return ret;
> +
> +			return 0;
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +static int kmx61_chip_init(struct kmx61_data *data)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, KMX61_REG_WHO_AM_I);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error reading who_am_i\n");
> +		return ret;
> +	}
> +
> +	if (ret != KMX61_CHIP_ID) {
> +		dev_err(&data->client->dev,
> +			"Wrong chip id, got %x expected %x\n",
> +			 ret, KMX61_CHIP_ID);
> +		return -EINVAL;
> +	}
> +
> +	/* set accel 12bit, 4g range */
> +	ret = kmx61_set_range(data, KMX61_RANGE_4G);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* put accel and magnetometer in operating mode */
> +	ret = kmx61_set_mode(data, 0, KMX61_ACC | KMX61_MAG);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int kmx61_read_measurement(struct kmx61_data *data, int base, int offset)
> +{
> +	int ret;
> +	u8 reg = base + offset * 2;
> +
> +	ret = i2c_smbus_read_word_data(data->client, reg);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "failed to read reg at %x\n", reg);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int kmx61_read_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan, int *val,
> +			      int *val2, long mask)
> +{
> +	struct kmx61_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 base_reg;
> +	u8 device;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_ACCEL: case IIO_MAGN:
> +			base_reg = KMX61_ACC_XOUT_L;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		ret = kmx61_read_measurement(data, base_reg, chan->scan_index);
> +		if (ret < 0)
> +			return ret;
> +		*val = sign_extend32(ret >> chan->scan_type.shift,
> +				     chan->scan_type.realbits - 1);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			*val = 0;
> +			*val2 = kmx61_scale_table[data->range].scale;
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		case IIO_MAGN:
> +			/* 14 bits res, 1465 microGauss per magn count */
> +			*val = 0;
> +			*val2 = 1465;
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			break;
> +		}
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			device = KMX61_ACC;
> +			break;
> +		case IIO_MAGN:
> +			device = KMX61_MAG;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		ret = kmx61_get_odr(data, val, val2, device);
> +		if (ret)
> +			return -EINVAL;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	}
> +	return -EINVAL;
> +}
> +
> +static int kmx61_write_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan, int val,
> +			       int val2, long mask)
> +{
> +	struct kmx61_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 device;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			device = KMX61_ACC;
> +			break;
> +		case IIO_MAGN:
> +			device = KMX61_MAG;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		ret = kmx61_set_odr(data, val, val2, device);
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ACCEL:
> +			ret = kmx61_set_scale(data, val2);
> +			break;
> +		default:
> +			ret  = -EINVAL;
> +		}
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct iio_info kmx61_info = {
> +	.driver_module		= THIS_MODULE,
> +	.read_raw		= kmx61_read_raw,
> +	.write_raw		= kmx61_write_raw,
> +	.attrs			= &kmx61_attribute_group,
> +};
> +
> +static int kmx61_probe(struct i2c_client *client,
> +		       const struct i2c_device_id *id)
> +{
> +	struct kmx61_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &kmx61_info;
> +	indio_dev->channels = kmx61_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(kmx61_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = kmx61_chip_init(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	return iio_device_register(indio_dev);
> +}
> +
> +static int kmx61_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct kmx61_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	return kmx61_set_mode(data, KMX61_ALL_STBY, KMX61_ACC | KMX61_MAG);
> +}
> +
> +static const struct i2c_device_id kmx61_id[] = {
> +	{"kmx61", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, kmx61_id);
> +
> +static struct i2c_driver kmx61_driver = {
> +	.driver = {
> +		.name = "kmx61",
> +	},
> +	.probe		= kmx61_probe,
> +	.remove		= kmx61_remove,
> +	.id_table	= kmx61_id,
> +};
> +
> +module_i2c_driver(kmx61_driver);
> +
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
> +MODULE_DESCRIPTION("KMX61 accelerometer/magnetometer driver");
> +MODULE_LICENSE("GPL v2");
>