Re: [PATCH v2] iio: accel: add support for Memsic MXC6255XC sensor

[Jonathan Cameron <jic23@kernel.org>]

On 25/10/15 11:49, Jonathan Cameron wrote:
> On 22/10/15 13:44, 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.
>>
>> Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
> Other than a tiny nitpick below (which I'll fix up when applying)
> looks good to me.  Small and perfectly formed!
oops - forgot to say

Applied to the togreg branch of iio.git. Initially pushed out as testing
for the autobuilders to play with it.

Jonathan
> 
> Jonathan
>> ---
>> Changes since v1:
>>
>> - remove scale_available attribute
>> - use chan->address instead
>> - drop _AXIS_TO_REG macro
>> - put register address in .address field of MXC6255_CHANNEL macro
>> - check chip id
>> - use "as follows" instead of "as following"
>>
>>  drivers/iio/accel/Kconfig   |  11 +++
>>  drivers/iio/accel/Makefile  |   1 +
>>  drivers/iio/accel/mxc6255.c | 199 ++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 211 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..b853ff0
>> --- /dev/null
>> +++ b/drivers/iio/accel/mxc6255.c
>> @@ -0,0 +1,199 @@
>> +/*
>> + * 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).
> No need for the blank line below.
>> + *
>> + */
>> +
>> +#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_CHIP_ID			0x05
>> +
>> +/*
>> + * MXC6255 has only one measurement range: +/- 2G.
>> + * The acceleration output is an 8-bit value.
>> + *
>> + * Scale is calculated as follows:
>> + * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
>> + *
>> + * Scale value for +/- 2G measurement range
>> + */
>> +#define MXC6255_SCALE			153829
>> +
>> +enum mxc6255_axis {
>> +	AXIS_X,
>> +	AXIS_Y,
>> +};
>> +
>> +struct mxc6255_data {
>> +	struct i2c_client *client;
>> +	struct regmap *regmap;
>> +};
>> +
>> +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 ret;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		ret = regmap_read(data->regmap, chan->address, &reg);
>> +		if (ret < 0) {
>> +			dev_err(&data->client->dev,
>> +				"Error reading reg %lu\n", chan->address);
>> +			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,
>> +};
>> +
>> +#define MXC6255_CHANNEL(_axis, reg) {				\
>> +	.type = IIO_ACCEL,					\
>> +	.modified = 1,						\
>> +	.channel2 = IIO_MOD_##_axis,				\
>> +	.address = reg,						\
>> +	.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_REG_XOUT),
>> +	MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
>> +};
>> +
>> +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;
>> +	}
>> +
>> +	if (chip_id != MXC6255_CHIP_ID) {
>> +		dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
>> +		return -ENODEV;
>> +	}
>> +
>> +	dev_dbg(&client->dev, "Chip id %x\n", chip_id);
>> +
>> +	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@intel.com>");
>> +MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
>> +MODULE_LICENSE("GPL v2");
>>
> 
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