/**
 * 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");