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Commit 90bad33a authored by Tiberiu Breana's avatar Tiberiu Breana Committed by Jonathan Cameron
Browse files

iio: accel: Add support for Sensortek STK8312 

Minimal implementation of an IIO driver for the Sensortek
STK8312 3-axis accelerometer. Datasheet:
http://www.syi-group.com/uploadpic/data/201361817562681623.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 c16bff48

drivers/iio/accel/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -136,4 +136,15 @@ config MMA9553 


	  To compile this driver as a module, choose M here: the module

	  will be called mma9553.



config STK8312

	tristate "Sensortek STK8312 3-Axis Accelerometer Driver"

	depends on I2C

	help

	  Say yes here to get support for the Sensortek STK8312 3-axis

	  accelerometer.



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

	  will be called stk8312.



endmenu

drivers/iio/accel/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ obj-$(CONFIG_MMA9551_CORE) += mma9551_core.o 
obj-$(CONFIG_MMA9551)		+= mma9551.o

obj-$(CONFIG_MMA9553)		+= mma9553.o



obj-$(CONFIG_STK8312)		+= stk8312.o



obj-$(CONFIG_IIO_SSP_SENSORS_COMMONS) += ssp_accel_sensor.o



obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o

drivers/iio/accel/stk8312.c

0 → 100644
+390 −0
Original line number Diff line number Diff line 
/**

 * Sensortek STK8312 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.

 *

 * IIO driver for STK8312; 7-bit I2C address: 0x3D.

 */



#include <linux/acpi.h>

#include <linux/i2c.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/delay.h>

#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>



#define STK8312_REG_XOUT		0x00

#define STK8312_REG_YOUT		0x01

#define STK8312_REG_ZOUT		0x02

#define STK8312_REG_MODE		0x07

#define STK8312_REG_STH			0x13

#define STK8312_REG_RESET		0x20

#define STK8312_REG_AFECTRL		0x24

#define STK8312_REG_OTPADDR		0x3D

#define STK8312_REG_OTPDATA		0x3E

#define STK8312_REG_OTPCTRL		0x3F



#define STK8312_MODE_ACTIVE		1

#define STK8312_MODE_STANDBY		0

#define STK8312_MODE_MASK		0x01

#define STK8312_RNG_MASK		0xC0

#define STK8312_RNG_SHIFT		6

#define STK8312_READ_RETRIES		16



#define STK8312_DRIVER_NAME		"stk8312"



/*

 * The accelerometer has two measurement ranges:

 *

 * -6g - +6g (8-bit, signed)

 * -16g - +16g (8-bit, signed)

 *

 * scale1 = (6 + 6) * 9.81 / (2^8 - 1)     = 0.4616

 * scale2 = (16 + 16) * 9.81 / (2^8 - 1)   = 1.2311

 */

#define STK8312_SCALE_AVAIL		"0.4616 1.2311"



static const int stk8312_scale_table[][2] = {

	{0, 461600}, {1, 231100}

};



#define STK8312_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 stk8312_channels[] = {

	STK8312_ACCEL_CHANNEL(STK8312_REG_XOUT, X),

	STK8312_ACCEL_CHANNEL(STK8312_REG_YOUT, Y),

	STK8312_ACCEL_CHANNEL(STK8312_REG_ZOUT, Z),

};



struct stk8312_data {

	struct i2c_client *client;

	struct mutex lock;

	int range;

	u8 mode;

};



static IIO_CONST_ATTR(in_accel_scale_available, STK8312_SCALE_AVAIL);



static struct attribute *stk8312_attributes[] = {

	&iio_const_attr_in_accel_scale_available.dev_attr.attr,

	NULL,

};



static const struct attribute_group stk8312_attribute_group = {

	.attrs = stk8312_attributes

};



static int stk8312_otp_init(struct stk8312_data *data)

{

	int ret;

	int count = 10;

	struct i2c_client *client = data->client;



	ret = i2c_smbus_write_byte_data(client, STK8312_REG_OTPADDR, 0x70);

	if (ret < 0)

		goto exit_err;

	ret = i2c_smbus_write_byte_data(client, STK8312_REG_OTPCTRL, 0x02);

	if (ret < 0)

		goto exit_err;



	do {

		usleep_range(1000, 5000);

		ret = i2c_smbus_read_byte_data(client, STK8312_REG_OTPCTRL);

		if (ret < 0)

			goto exit_err;

		count--;

	} while (!(ret & 0x80) && count > 0);



	if (count == 0)

		goto exit_err;



	ret = i2c_smbus_read_byte_data(client, STK8312_REG_OTPDATA);

	if (ret < 0)

		goto exit_err;



	ret = i2c_smbus_write_byte_data(data->client,

			STK8312_REG_AFECTRL, ret);

	if (ret < 0)

		goto exit_err;

	msleep(150);



	return ret;



exit_err:

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

	return ret;

}



static int stk8312_set_mode(struct stk8312_data *data, u8 mode)

{

	int ret;

	u8 masked_reg;

	struct i2c_client *client = data->client;



	if (mode > 1)

		return -EINVAL;

	else if (mode == data->mode)

		return 0;



	ret = i2c_smbus_read_byte_data(client, STK8312_REG_MODE);

	if (ret < 0) {

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

		return ret;

	}

	masked_reg = ret & (~STK8312_MODE_MASK);

	masked_reg |= mode;



	ret = i2c_smbus_write_byte_data(client,

			STK8312_REG_MODE, masked_reg);

	if (ret < 0) {

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

		return ret;

	}



	data->mode = mode;

	if (mode == STK8312_MODE_ACTIVE) {

		/* Need to run OTP sequence before entering active mode */

		usleep_range(1000, 5000);

		ret = stk8312_otp_init(data);

	}



	return ret;

}



static int stk8312_set_range(struct stk8312_data *data, u8 range)

{

	int ret;

	u8 masked_reg;

	u8 mode;

	struct i2c_client *client = data->client;



	if (range != 1 && range != 2)

		return -EINVAL;

	else if (range == data->range)

		return 0;



	mode = data->mode;

	/* We need to go in standby mode to modify registers */

	ret = stk8312_set_mode(data, STK8312_MODE_STANDBY);

	if (ret < 0)

		return ret;



	ret = i2c_smbus_read_byte_data(client, STK8312_REG_STH);

	if (ret < 0) {

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

		return ret;

	}



	masked_reg = ret & (~STK8312_RNG_MASK);

	masked_reg |= range << STK8312_RNG_SHIFT;



	ret = i2c_smbus_write_byte_data(client, STK8312_REG_STH, masked_reg);

	if (ret < 0)

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

	else

		data->range = range;



	return stk8312_set_mode(data, mode);

}



static int stk8312_read_accel(struct stk8312_data *data, u8 address)

{

	int ret;

	struct i2c_client *client = data->client;



	if (address > 2)

		return -EINVAL;



	ret = i2c_smbus_read_byte_data(client, address);

	if (ret < 0) {

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

		return ret;

	}



	return sign_extend32(ret, 7);

}



static int stk8312_read_raw(struct iio_dev *indio_dev,

			    struct iio_chan_spec const *chan,

			    int *val, int *val2, long mask)

{

	struct stk8312_data *data = iio_priv(indio_dev);



	if (chan->type != IIO_ACCEL)

		return -EINVAL;



	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		mutex_lock(&data->lock);

		*val = stk8312_read_accel(data, chan->address);

		mutex_unlock(&data->lock);

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:

		*val = stk8312_scale_table[data->range - 1][0];

		*val2 = stk8312_scale_table[data->range - 1][1];

		return IIO_VAL_INT_PLUS_MICRO;

	}



	return -EINVAL;

}



static int stk8312_write_raw(struct iio_dev *indio_dev,

			     struct iio_chan_spec const *chan,

			     int val, int val2, long mask)

{

	int i;

	int index = -1;

	int ret;

	struct stk8312_data *data = iio_priv(indio_dev);



	switch (mask) {

	case IIO_CHAN_INFO_SCALE:

		for (i = 0; i < ARRAY_SIZE(stk8312_scale_table); i++)

			if (val == stk8312_scale_table[i][0] &&

			    val2 == stk8312_scale_table[i][1]) {

				index = i + 1;

				break;

			}

		if (index < 0)

			return -EINVAL;



		mutex_lock(&data->lock);

		ret = stk8312_set_range(data, index);

		mutex_unlock(&data->lock);



		return ret;

	}



	return -EINVAL;

}



static const struct iio_info stk8312_info = {

	.driver_module		= THIS_MODULE,

	.read_raw		= stk8312_read_raw,

	.write_raw		= stk8312_write_raw,

	.attrs			= &stk8312_attribute_group,

};



static int stk8312_probe(struct i2c_client *client,

			 const struct i2c_device_id *id)

{

	int ret;

	struct iio_dev *indio_dev;

	struct stk8312_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 = &stk8312_info;

	indio_dev->name = STK8312_DRIVER_NAME;

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->channels = stk8312_channels;

	indio_dev->num_channels = ARRAY_SIZE(stk8312_channels);



	/* A software reset is recommended at power-on */

	ret = i2c_smbus_write_byte_data(data->client, STK8312_REG_RESET, 0x00);

	if (ret < 0) {

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

		return ret;

	}

	ret = stk8312_set_range(data, 1);

	if (ret < 0)

		return ret;



	ret = stk8312_set_mode(data, STK8312_MODE_ACTIVE);

	if (ret < 0)

		return ret;



	ret = iio_device_register(indio_dev);

	if (ret < 0) {

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

		stk8312_set_mode(data, STK8312_MODE_STANDBY);

	}



	return ret;

}



static int stk8312_remove(struct i2c_client *client)

{

	struct iio_dev *indio_dev = i2c_get_clientdata(client);



	iio_device_unregister(indio_dev);



	return stk8312_set_mode(iio_priv(indio_dev), STK8312_MODE_STANDBY);

}



#ifdef CONFIG_PM_SLEEP

static int stk8312_suspend(struct device *dev)

{

	struct stk8312_data *data;



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



	return stk8312_set_mode(data, STK8312_MODE_STANDBY);

}



static int stk8312_resume(struct device *dev)

{

	struct stk8312_data *data;



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



	return stk8312_set_mode(data, STK8312_MODE_ACTIVE);

}



static SIMPLE_DEV_PM_OPS(stk8312_pm_ops, stk8312_suspend, stk8312_resume);



#define STK8312_PM_OPS (&stk8312_pm_ops)

#else

#define STK8312_PM_OPS NULL

#endif



static const struct i2c_device_id stk8312_i2c_id[] = {

	{"STK8312", 0},

	{}

};



static const struct acpi_device_id stk8312_acpi_id[] = {

	{"STK8312", 0},

	{}

};



MODULE_DEVICE_TABLE(acpi, stk8312_acpi_id);



static struct i2c_driver stk8312_driver = {

	.driver = {

		.name = "stk8312",

		.pm = STK8312_PM_OPS,

		.acpi_match_table = ACPI_PTR(stk8312_acpi_id),

	},

	.probe =            stk8312_probe,

	.remove =           stk8312_remove,

	.id_table =         stk8312_i2c_id,

};



module_i2c_driver(stk8312_driver);



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

MODULE_DESCRIPTION("STK8312 3-Axis Accelerometer driver");

MODULE_LICENSE("GPL v2");