/*
 * AK09911 3-axis compass driver
 * Copyright (c) 2014, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/acpi.h>
#include <linux/iio/iio.h>

#define AK09911_REG_WIA1		0x00
#define AK09911_REG_WIA2		0x01
#define AK09911_WIA1_VALUE		0x48
#define AK09911_WIA2_VALUE		0x05

#define AK09911_REG_ST1			0x10
#define AK09911_REG_HXL			0x11
#define AK09911_REG_HXH			0x12
#define AK09911_REG_HYL			0x13
#define AK09911_REG_HYH			0x14
#define AK09911_REG_HZL			0x15
#define AK09911_REG_HZH			0x16

#define AK09911_REG_ASAX		0x60
#define AK09911_REG_ASAY		0x61
#define AK09911_REG_ASAZ		0x62

#define AK09911_REG_CNTL1		0x30
#define AK09911_REG_CNTL2		0x31
#define AK09911_REG_CNTL3		0x32

#define AK09911_MODE_SNG_MEASURE	0x01
#define AK09911_MODE_SELF_TEST		0x10
#define AK09911_MODE_FUSE_ACCESS	0x1F
#define AK09911_MODE_POWERDOWN		0x00
#define AK09911_RESET_DATA		0x01

#define AK09911_REG_CNTL1		0x30
#define AK09911_REG_CNTL2		0x31
#define AK09911_REG_CNTL3		0x32

#define AK09911_RAW_TO_GAUSS(asa)	((((asa) + 128) * 6000) / 256)

#define AK09911_MAX_CONVERSION_TIMEOUT_MS	500
#define AK09911_CONVERSION_DONE_POLL_TIME_MS	10

struct ak09911_data {
	struct i2c_client	*client;
	struct mutex		lock;
	u8			asa[3];
	long			raw_to_gauss[3];
};

static const int ak09911_index_to_reg[] = {
	AK09911_REG_HXL, AK09911_REG_HYL, AK09911_REG_HZL,
};

static int ak09911_set_mode(struct i2c_client *client, u8 mode)
{
	int ret;

	switch (mode) {
	case AK09911_MODE_SNG_MEASURE:
	case AK09911_MODE_SELF_TEST:
	case AK09911_MODE_FUSE_ACCESS:
	case AK09911_MODE_POWERDOWN:
		ret = i2c_smbus_write_byte_data(client,
						AK09911_REG_CNTL2, mode);
		if (ret < 0) {
			dev_err(&client->dev, "set_mode error\n");
			return ret;
		}
		/* After mode change wait atleast 100us */
		usleep_range(100, 500);
		break;
	default:
		dev_err(&client->dev,
			"%s: Unknown mode(%d).", __func__, mode);
		return -EINVAL;
	}

	return ret;
}

/* Get Sensitivity Adjustment value */
static int ak09911_get_asa(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak09911_data *data = iio_priv(indio_dev);
	int ret;

	ret = ak09911_set_mode(client, AK09911_MODE_FUSE_ACCESS);
	if (ret < 0)
		return ret;

	/* Get asa data and store in the device data. */
	ret = i2c_smbus_read_i2c_block_data(client, AK09911_REG_ASAX,
					    3, data->asa);
	if (ret < 0) {
		dev_err(&client->dev, "Not able to read asa data\n");
		return ret;
	}

	ret = ak09911_set_mode(client,  AK09911_MODE_POWERDOWN);
	if (ret < 0)
		return ret;

	data->raw_to_gauss[0] = AK09911_RAW_TO_GAUSS(data->asa[0]);
	data->raw_to_gauss[1] = AK09911_RAW_TO_GAUSS(data->asa[1]);
	data->raw_to_gauss[2] = AK09911_RAW_TO_GAUSS(data->asa[2]);

	return 0;
}

static int ak09911_verify_chip_id(struct i2c_client *client)
{
	u8 wia_val[2];
	int ret;

	ret = i2c_smbus_read_i2c_block_data(client, AK09911_REG_WIA1,
					    2, wia_val);
	if (ret < 0) {
		dev_err(&client->dev, "Error reading WIA\n");
		return ret;
	}

	dev_dbg(&client->dev, "WIA %02x %02x\n", wia_val[0], wia_val[1]);

	if (wia_val[0] != AK09911_WIA1_VALUE ||
		wia_val[1] != AK09911_WIA2_VALUE) {
		dev_err(&client->dev, "Device ak09911 not found\n");
		return -ENODEV;
	}

	return 0;
}

static int wait_conversion_complete_polled(struct ak09911_data *data)
{
	struct i2c_client *client = data->client;
	u8 read_status;
	u32 timeout_ms = AK09911_MAX_CONVERSION_TIMEOUT_MS;
	int ret;

	/* Wait for the conversion to complete. */
	while (timeout_ms) {
		msleep_interruptible(AK09911_CONVERSION_DONE_POLL_TIME_MS);
		ret = i2c_smbus_read_byte_data(client, AK09911_REG_ST1);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST1\n");
			return ret;
		}
		read_status = ret & 0x01;
		if (read_status)
			break;
		timeout_ms -= AK09911_CONVERSION_DONE_POLL_TIME_MS;
	}
	if (!timeout_ms) {
		dev_err(&client->dev, "Conversion timeout happened\n");
		return -EIO;
	}

	return read_status;
}

static int ak09911_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
	struct ak09911_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;
	int ret;

	mutex_lock(&data->lock);

	ret = ak09911_set_mode(client, AK09911_MODE_SNG_MEASURE);
	if (ret < 0)
		goto fn_exit;

	ret = wait_conversion_complete_polled(data);
	if (ret < 0)
		goto fn_exit;

	/* Read data */
	ret = i2c_smbus_read_word_data(client, ak09911_index_to_reg[index]);
	if (ret < 0) {
		dev_err(&client->dev, "Read axis data fails\n");
		goto fn_exit;
	}

	mutex_unlock(&data->lock);

	/* Clamp to valid range. */
	*val = sign_extend32(clamp_t(s16, ret, -8192, 8191), 13);

	return IIO_VAL_INT;

fn_exit:
	mutex_unlock(&data->lock);

	return ret;
}

static int ak09911_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2,
			    long mask)
{
	struct ak09911_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return ak09911_read_axis(indio_dev, chan->address, val);
	case IIO_CHAN_INFO_SCALE:
		*val = 0;
		*val2 = data->raw_to_gauss[chan->address];
		return IIO_VAL_INT_PLUS_MICRO;
	}

	return -EINVAL;
}

#define AK09911_CHANNEL(axis, index)					\
	{								\
		.type = IIO_MAGN,					\
		.modified = 1,						\
		.channel2 = IIO_MOD_##axis,				\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
			     BIT(IIO_CHAN_INFO_SCALE),			\
		.address = index,					\
	}

static const struct iio_chan_spec ak09911_channels[] = {
	AK09911_CHANNEL(X, 0), AK09911_CHANNEL(Y, 1), AK09911_CHANNEL(Z, 2),
};

static const struct iio_info ak09911_info = {
	.read_raw = &ak09911_read_raw,
	.driver_module = THIS_MODULE,
};

static const struct acpi_device_id ak_acpi_match[] = {
	{"AK009911", 0},
	{ },
};
MODULE_DEVICE_TABLE(acpi, ak_acpi_match);

static int ak09911_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct iio_dev *indio_dev;
	struct ak09911_data *data;
	const char *name;
	int ret;

	ret = ak09911_verify_chip_id(client);
	if (ret) {
		dev_err(&client->dev, "AK00911 not detected\n");
		return -ENODEV;
	}

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (indio_dev == NULL)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);

	data->client = client;
	mutex_init(&data->lock);

	ret = ak09911_get_asa(client);
	if (ret)
		return ret;

	if (id)
		name = id->name;
	else if (ACPI_HANDLE(&client->dev))
		name = dev_name(&client->dev);
	else
		return -ENODEV;

	dev_dbg(&client->dev, "Asahi compass chip %s\n", name);

	indio_dev->dev.parent = &client->dev;
	indio_dev->channels = ak09911_channels;
	indio_dev->num_channels = ARRAY_SIZE(ak09911_channels);
	indio_dev->info = &ak09911_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->name = name;

	return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id ak09911_id[] = {
	{"ak09911", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, ak09911_id);

static struct i2c_driver ak09911_driver = {
	.driver = {
		.name	= "ak09911",
		.acpi_match_table = ACPI_PTR(ak_acpi_match),
	},
	.probe		= ak09911_probe,
	.id_table	= ak09911_id,
};
module_i2c_driver(ak09911_driver);

MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("AK09911 Compass driver");