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Commit 884ca456 authored by Tiberiu Breana's avatar Tiberiu Breana Committed by Jonathan Cameron
Browse files

iio: accel: Add support for Sensortek STK8BA50 

Minimal implementation of an IIO driver for the Sensortek
STK8BA50 3-axis accelerometer. Datasheet:
http://szgsensor.com/uploads/soft/141229/STK8BA50%D2%E5%BC%CE.pdf



Includes:
- ACPI support;
- read_raw for x,y,z axes;
- reading and setting the scale (range) parameter.
- power management

Signed-off-by: default avatarTiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 1250186a

drivers/iio/accel/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -147,4 +147,14 @@ config STK8312 
	  Choosing M will build the driver as a module. If so, the module

	  will be called stk8312.



config STK8BA50

	tristate "Sensortek STK8BA50 3-Axis Accelerometer Driver"

	depends on I2C

	help

	  Say yes here to get support for the Sensortek STK8BA50 3-axis

	  accelerometer.



	  Choosing M will build the driver as a module. If so, the module

	  will be called stk8ba50.



endmenu

drivers/iio/accel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ obj-$(CONFIG_MMA9551) += mma9551.o 
obj-$(CONFIG_MMA9553)		+= mma9553.o



obj-$(CONFIG_STK8312)		+= stk8312.o

obj-$(CONFIG_STK8BA50)		+= stk8ba50.o



obj-$(CONFIG_IIO_SSP_SENSORS_COMMONS) += ssp_accel_sensor.o

drivers/iio/accel/stk8ba50.c

0 → 100644
+302 −0
Original line number Diff line number Diff line 
/**

 * Sensortek STK8BA50 3-Axis 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.

 *

 * STK8BA50 7-bit I2C address: 0x18.

 */



#include <linux/acpi.h>

#include <linux/i2c.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>



#define STK8BA50_REG_XOUT			0x02

#define STK8BA50_REG_YOUT			0x04

#define STK8BA50_REG_ZOUT			0x06

#define STK8BA50_REG_RANGE			0x0F

#define STK8BA50_REG_POWMODE			0x11

#define STK8BA50_REG_SWRST			0x14



#define STK8BA50_MODE_NORMAL			0

#define STK8BA50_MODE_SUSPEND			1

#define STK8BA50_MODE_POWERBIT			BIT(7)

#define STK8BA50_DATA_SHIFT			6

#define STK8BA50_RESET_CMD			0xB6



#define STK8BA50_DRIVER_NAME			"stk8ba50"



#define STK8BA50_SCALE_AVAIL			"0.0384 0.0767 0.1534 0.3069"



/*

 * The accelerometer has four measurement ranges:

 * +/-2g; +/-4g; +/-8g; +/-16g

 *

 * Acceleration values are 10-bit, 2's complement.

 * Scales are calculated as following:

 *

 * scale1 = (2 + 2) * 9.81 / (2^10 - 1)   = 0.0384

 * scale2 = (4 + 4) * 9.81 / (2^10 - 1)   = 0.0767

 * etc.

 *

 * Scales are stored in this format:

 * { <register value>, <scale value> }

 *

 * Locally, the range is stored as a table index.

 */

static const int stk8ba50_scale_table[][2] = {

	{3, 38400}, {5, 76700}, {8, 153400}, {12, 306900}

};



struct stk8ba50_data {

	struct i2c_client *client;

	struct mutex lock;

	int range;

};



#define STK8BA50_ACCEL_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 stk8ba50_channels[] = {

	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_XOUT, X),

	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_YOUT, Y),

	STK8BA50_ACCEL_CHANNEL(STK8BA50_REG_ZOUT, Z),

};



static IIO_CONST_ATTR(in_accel_scale_available, STK8BA50_SCALE_AVAIL);



static struct attribute *stk8ba50_attributes[] = {

	&iio_const_attr_in_accel_scale_available.dev_attr.attr,

	NULL,

};



static const struct attribute_group stk8ba50_attribute_group = {

	.attrs = stk8ba50_attributes

};



static int stk8ba50_read_accel(struct stk8ba50_data *data, u8 reg)

{

	int ret;

	struct i2c_client *client = data->client;



	ret = i2c_smbus_read_word_data(client, reg);

	if (ret < 0) {

		dev_err(&client->dev, "register read failed\n");

		return ret;

	}



	return sign_extend32(ret >> STK8BA50_DATA_SHIFT, 9);

}



static int stk8ba50_read_raw(struct iio_dev *indio_dev,

			     struct iio_chan_spec const *chan,

			     int *val, int *val2, long mask)

{

	struct stk8ba50_data *data = iio_priv(indio_dev);



	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		mutex_lock(&data->lock);

		*val = stk8ba50_read_accel(data, chan->address);

		mutex_unlock(&data->lock);

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:

		*val = 0;

		*val2 = stk8ba50_scale_table[data->range][1];

		return IIO_VAL_INT_PLUS_MICRO;

	}



	return -EINVAL;

}



static int stk8ba50_write_raw(struct iio_dev *indio_dev,

			      struct iio_chan_spec const *chan,

			      int val, int val2, long mask)

{

	int ret;

	int i;

	int index = -1;

	struct stk8ba50_data *data = iio_priv(indio_dev);



	switch (mask) {

	case IIO_CHAN_INFO_SCALE:

		if (val != 0)

			return -EINVAL;



		for (i = 0; i < ARRAY_SIZE(stk8ba50_scale_table); i++)

			if (val2 == stk8ba50_scale_table[i][1]) {

				index = i;

				break;

			}

		if (index < 0)

			return -EINVAL;



		ret = i2c_smbus_write_byte_data(data->client,

				STK8BA50_REG_RANGE,

				stk8ba50_scale_table[index][0]);

		if (ret < 0)

			dev_err(&data->client->dev,

					"failed to set measurement range\n");

		else

			data->range = index;



		return ret;

	}



	return -EINVAL;

}



static const struct iio_info stk8ba50_info = {

	.driver_module		= THIS_MODULE,

	.read_raw		= stk8ba50_read_raw,

	.write_raw		= stk8ba50_write_raw,

	.attrs			= &stk8ba50_attribute_group,

};



static int stk8ba50_set_power(struct stk8ba50_data *data, bool mode)

{

	int ret;

	u8 masked_reg;

	struct i2c_client *client = data->client;



	ret = i2c_smbus_read_byte_data(client, STK8BA50_REG_POWMODE);

	if (ret < 0)

		goto exit_err;



	if (mode)

		masked_reg = ret | STK8BA50_MODE_POWERBIT;

	else

		masked_reg = ret & (~STK8BA50_MODE_POWERBIT);



	ret = i2c_smbus_write_byte_data(client, STK8BA50_REG_POWMODE,

					masked_reg);

	if (ret < 0)

		goto exit_err;



	return ret;



exit_err:

	dev_err(&client->dev, "failed to change sensor mode\n");

	return ret;

}



static int stk8ba50_probe(struct i2c_client *client,

			  const struct i2c_device_id *id)

{

	int ret;

	struct iio_dev *indio_dev;

	struct stk8ba50_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);



	indio_dev->dev.parent = &client->dev;

	indio_dev->info = &stk8ba50_info;

	indio_dev->name = STK8BA50_DRIVER_NAME;

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->channels = stk8ba50_channels;

	indio_dev->num_channels = ARRAY_SIZE(stk8ba50_channels);



	/* Reset all registers on startup */

	ret = i2c_smbus_write_byte_data(client,

			STK8BA50_REG_SWRST, STK8BA50_RESET_CMD);

	if (ret < 0) {

		dev_err(&client->dev, "failed to reset sensor\n");

		return ret;

	}



	/* The default range is +/-2g */

	data->range = 0;



	ret = iio_device_register(indio_dev);

	if (ret < 0) {

		dev_err(&client->dev, "device_register failed\n");

		stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);

	}



	return ret;

}



static int stk8ba50_remove(struct i2c_client *client)

{

	struct iio_dev *indio_dev = i2c_get_clientdata(client);



	iio_device_unregister(indio_dev);



	return stk8ba50_set_power(iio_priv(indio_dev), STK8BA50_MODE_SUSPEND);

}



#ifdef CONFIG_PM_SLEEP

static int stk8ba50_suspend(struct device *dev)

{

	struct stk8ba50_data *data;



	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));



	return stk8ba50_set_power(data, STK8BA50_MODE_SUSPEND);

}



static int stk8ba50_resume(struct device *dev)

{

	struct stk8ba50_data *data;



	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));



	return stk8ba50_set_power(data, STK8BA50_MODE_NORMAL);

}



static SIMPLE_DEV_PM_OPS(stk8ba50_pm_ops, stk8ba50_suspend, stk8ba50_resume);



#define STK8BA50_PM_OPS (&stk8ba50_pm_ops)

#else

#define STK8BA50_PM_OPS NULL

#endif



static const struct i2c_device_id stk8ba50_i2c_id[] = {

	{"stk8ba50", 0},

	{}

};



static const struct acpi_device_id stk8ba50_acpi_id[] = {

	{"STK8BA50", 0},

	{}

};



MODULE_DEVICE_TABLE(acpi, stk8ba50_acpi_id);



static struct i2c_driver stk8ba50_driver = {

	.driver = {

		.name = "stk8ba50",

		.pm = STK8BA50_PM_OPS,

		.acpi_match_table = ACPI_PTR(stk8ba50_acpi_id),

	},

	.probe =            stk8ba50_probe,

	.remove =           stk8ba50_remove,

	.id_table =         stk8ba50_i2c_id,

};



module_i2c_driver(stk8ba50_driver);



MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");

MODULE_DESCRIPTION("STK8BA50 3-Axis Accelerometer driver");

MODULE_LICENSE("GPL v2");