[deliverable/linux.git] / drivers / staging / iio / magnetometer / ak8975.c

/*
 * A sensor driver for the magnetometer AK8975.
 *
 * Magnetic compass sensor driver for monitoring magnetic flux information.
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA	02110-1301, USA.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>

#include <linux/gpio.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/*
 * Register definitions, as well as various shifts and masks to get at the
 * individual fields of the registers.
 */
#define AK8975_REG_WIA			0x00
#define AK8975_DEVICE_ID		0x48

#define AK8975_REG_INFO			0x01

#define AK8975_REG_ST1			0x02
#define AK8975_REG_ST1_DRDY_SHIFT	0
#define AK8975_REG_ST1_DRDY_MASK	(1 << AK8975_REG_ST1_DRDY_SHIFT)

#define AK8975_REG_HXL			0x03
#define AK8975_REG_HXH			0x04
#define AK8975_REG_HYL			0x05
#define AK8975_REG_HYH			0x06
#define AK8975_REG_HZL			0x07
#define AK8975_REG_HZH			0x08
#define AK8975_REG_ST2			0x09
#define AK8975_REG_ST2_DERR_SHIFT	2
#define AK8975_REG_ST2_DERR_MASK	(1 << AK8975_REG_ST2_DERR_SHIFT)

#define AK8975_REG_ST2_HOFL_SHIFT	3
#define AK8975_REG_ST2_HOFL_MASK	(1 << AK8975_REG_ST2_HOFL_SHIFT)

#define AK8975_REG_CNTL			0x0A
#define AK8975_REG_CNTL_MODE_SHIFT	0
#define AK8975_REG_CNTL_MODE_MASK	(0xF << AK8975_REG_CNTL_MODE_SHIFT)
#define AK8975_REG_CNTL_MODE_POWER_DOWN	0
#define AK8975_REG_CNTL_MODE_ONCE	1
#define AK8975_REG_CNTL_MODE_SELF_TEST	8
#define AK8975_REG_CNTL_MODE_FUSE_ROM	0xF

#define AK8975_REG_RSVC			0x0B
#define AK8975_REG_ASTC			0x0C
#define AK8975_REG_TS1			0x0D
#define AK8975_REG_TS2			0x0E
#define AK8975_REG_I2CDIS		0x0F
#define AK8975_REG_ASAX			0x10
#define AK8975_REG_ASAY			0x11
#define AK8975_REG_ASAZ			0x12

#define AK8975_MAX_REGS			AK8975_REG_ASAZ

/*
 * Miscellaneous values.
 */
#define AK8975_MAX_CONVERSION_TIMEOUT	500
#define AK8975_CONVERSION_DONE_POLL_TIME 10

/*
 * Per-instance context data for the device.
 */
struct ak8975_data {
	struct i2c_client	*client;
	struct attribute_group	attrs;
	struct mutex		lock;
	u8			asa[3];
	long			raw_to_gauss[3];
	u8			reg_cache[AK8975_MAX_REGS];
	int			eoc_gpio;
	int			eoc_irq;
};

static const int ak8975_index_to_reg[] = {
	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
};

/*
 * Helper function to write to the I2C device's registers.
 */
static int ak8975_write_data(struct i2c_client *client,
			     u8 reg, u8 val, u8 mask, u8 shift)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);
	u8 regval;
	int ret;

	regval = (data->reg_cache[reg] & ~mask) | (val << shift);
	ret = i2c_smbus_write_byte_data(client, reg, regval);
	if (ret < 0) {
		dev_err(&client->dev, "Write to device fails status %x\n", ret);
		return ret;
	}
	data->reg_cache[reg] = regval;

	return 0;
}

/*
 * Helper function to read a contiguous set of the I2C device's registers.
 */
static int ak8975_read_data(struct i2c_client *client,
			    u8 reg, u8 length, u8 *buffer)
{
	int ret;
	struct i2c_msg msg[2] = {
		{
			.addr = client->addr,
			.flags = I2C_M_NOSTART,
			.len = 1,
			.buf = &reg,
		}, {
			.addr = client->addr,
			.flags = I2C_M_RD,
			.len = length,
			.buf = buffer,
		}
	};

	ret = i2c_transfer(client->adapter, msg, 2);
	if (ret < 0) {
		dev_err(&client->dev, "Read from device fails\n");
		return ret;
	}

	return 0;
}

/*
 * Perform some start-of-day setup, including reading the asa calibration
 * values and caching them.
 */
static int ak8975_setup(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);
	u8 device_id;
	int ret;

	/* Confirm that the device we're talking to is really an AK8975. */
	ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id);
	if (ret < 0) {
		dev_err(&client->dev, "Error reading WIA\n");
		return ret;
	}
	if (device_id != AK8975_DEVICE_ID) {
		dev_err(&client->dev, "Device ak8975 not found\n");
		return -ENODEV;
	}

	/* Write the fused rom access mode. */
	ret = ak8975_write_data(client,
				AK8975_REG_CNTL,
				AK8975_REG_CNTL_MODE_FUSE_ROM,
				AK8975_REG_CNTL_MODE_MASK,
				AK8975_REG_CNTL_MODE_SHIFT);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting fuse access mode\n");
		return ret;
	}

	/* Get asa data and store in the device data. */
	ret = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa);
	if (ret < 0) {
		dev_err(&client->dev, "Not able to read asa data\n");
		return ret;
	}

	/* After reading fuse ROM data set power-down mode */
	ret = ak8975_write_data(client,
				AK8975_REG_CNTL,
				AK8975_REG_CNTL_MODE_POWER_DOWN,
				AK8975_REG_CNTL_MODE_MASK,
				AK8975_REG_CNTL_MODE_SHIFT);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting power-down mode\n");
		return ret;
	}

/*
 * Precalculate scale factor (in Gauss units) for each axis and
 * store in the device data.
 *
 * This scale factor is axis-dependent, and is derived from 3 calibration
 * factors ASA(x), ASA(y), and ASA(z).
 *
 * These ASA values are read from the sensor device at start of day, and
 * cached in the device context struct.
 *
 * Adjusting the flux value with the sensitivity adjustment value should be
 * done via the following formula:
 *
 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
 *
 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
 * is the resultant adjusted value.
 *
 * We reduce the formula to:
 *
 * Hadj = H * (ASA + 128) / 256
 *
 * H is in the range of -4096 to 4095.  The magnetometer has a range of
 * +-1229uT.  To go from the raw value to uT is:
 *
 * HuT = H * 1229/4096, or roughly, 3/10.
 *
 * Since 1uT = 100 gauss, our final scale factor becomes:
 *
 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
 * Hadj = H * ((ASA + 128) * 30 / 256
 *
 * Since ASA doesn't change, we cache the resultant scale factor into the
 * device context in ak8975_setup().
 */
	data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
	data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
	data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;

	return 0;
}

static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	u8 read_status;
	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	int ret;

	/* Wait for the conversion to complete. */
	while (timeout_ms) {
		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
		if (gpio_get_value(data->eoc_gpio))
			break;
		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	}
	if (!timeout_ms) {
		dev_err(&client->dev, "Conversion timeout happened\n");
		return -EINVAL;
	}

	ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
	if (ret < 0) {
		dev_err(&client->dev, "Error in reading ST1\n");
		return ret;
	}
	return read_status;
}

static int wait_conversion_complete_polled(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	u8 read_status;
	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	int ret;

	/* Wait for the conversion to complete. */
	while (timeout_ms) {
		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
		ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST1\n");
			return ret;
		}
		if (read_status)
			break;
		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	}
	if (!timeout_ms) {
		dev_err(&client->dev, "Conversion timeout happened\n");
		return -EINVAL;
	}
	return read_status;
}

/*
 * Emits the raw flux value for the x, y, or z axis.
 */
static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
	struct ak8975_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;
	u16 meas_reg;
	s16 raw;
	u8 read_status;
	int ret;

	mutex_lock(&data->lock);

	/* Set up the device for taking a sample. */
	ret = ak8975_write_data(client,
				AK8975_REG_CNTL,
				AK8975_REG_CNTL_MODE_ONCE,
				AK8975_REG_CNTL_MODE_MASK,
				AK8975_REG_CNTL_MODE_SHIFT);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting operating mode\n");
		goto exit;
	}

	/* Wait for the conversion to complete. */
	if (gpio_is_valid(data->eoc_gpio))
		ret = wait_conversion_complete_gpio(data);
	else
		ret = wait_conversion_complete_polled(data);
	if (ret < 0)
		goto exit;

	read_status = ret;

	if (read_status & AK8975_REG_ST1_DRDY_MASK) {
		ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST2\n");
			goto exit;
		}
		if (read_status & (AK8975_REG_ST2_DERR_MASK |
				   AK8975_REG_ST2_HOFL_MASK)) {
			dev_err(&client->dev, "ST2 status error 0x%x\n",
				read_status);
			ret = -EINVAL;
			goto exit;
		}
	}

	/* Read the flux value from the appropriate register
	   (the register is specified in the iio device attributes). */
	ret = ak8975_read_data(client, ak8975_index_to_reg[index],
			       2, (u8 *)&meas_reg);
	if (ret < 0) {
		dev_err(&client->dev, "Read axis data fails\n");
		goto exit;
	}

	mutex_unlock(&data->lock);

	/* Endian conversion of the measured values. */
	raw = (s16) (le16_to_cpu(meas_reg));

	/* Clamp to valid range. */
	raw = clamp_t(s16, raw, -4096, 4095);
	*val = raw;
	return IIO_VAL_INT;

exit:
	mutex_unlock(&data->lock);
	return ret;
}

static int ak8975_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val, int *val2,
			   long mask)
{
	struct ak8975_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return ak8975_read_axis(indio_dev, chan->address, val);
	case IIO_CHAN_INFO_SCALE:
		*val = data->raw_to_gauss[chan->address];
		return IIO_VAL_INT;
	}
	return -EINVAL;
}

#define AK8975_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 ak8975_channels[] = {
	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
};

static const struct iio_info ak8975_info = {
	.read_raw = &ak8975_read_raw,
	.driver_module = THIS_MODULE,
};

static int ak8975_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct ak8975_data *data;
	struct iio_dev *indio_dev;
	int eoc_gpio;
	int err;

	/* Grab and set up the supplied GPIO. */
	if (client->dev.platform_data == NULL)
		eoc_gpio = -1;
	else
		eoc_gpio = *(int *)(client->dev.platform_data);

	/* We may not have a GPIO based IRQ to scan, that is fine, we will
	   poll if so */
	if (gpio_is_valid(eoc_gpio)) {
		err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
		if (err < 0) {
			dev_err(&client->dev,
				"failed to request GPIO %d, error %d\n",
							eoc_gpio, err);
			goto exit;
		}
	}

	/* Register with IIO */
	indio_dev = iio_device_alloc(sizeof(*data));
	if (indio_dev == NULL) {
		err = -ENOMEM;
		goto exit_gpio;
	}
	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	/* Perform some basic start-of-day setup of the device. */
	err = ak8975_setup(client);
	if (err < 0) {
		dev_err(&client->dev, "AK8975 initialization fails\n");
		goto exit_free_iio;
	}

	data->client = client;
	mutex_init(&data->lock);
	data->eoc_irq = client->irq;
	data->eoc_gpio = eoc_gpio;
	indio_dev->dev.parent = &client->dev;
	indio_dev->channels = ak8975_channels;
	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
	indio_dev->info = &ak8975_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	err = iio_device_register(indio_dev);
	if (err < 0)
		goto exit_free_iio;

	return 0;

exit_free_iio:
	iio_device_free(indio_dev);
exit_gpio:
	if (gpio_is_valid(eoc_gpio))
		gpio_free(eoc_gpio);
exit:
	return err;
}

static int ak8975_remove(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	if (gpio_is_valid(data->eoc_gpio))
		gpio_free(data->eoc_gpio);

	iio_device_free(indio_dev);

	return 0;
}

static const struct i2c_device_id ak8975_id[] = {
	{"ak8975", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, ak8975_id);

static const struct of_device_id ak8975_of_match[] = {
	{ .compatible = "asahi-kasei,ak8975", },
	{ .compatible = "ak8975", },
	{ }
};
MODULE_DEVICE_TABLE(of, ak8975_of_match);

static struct i2c_driver ak8975_driver = {
	.driver = {
		.name	= "ak8975",
		.of_match_table = ak8975_of_match,
	},
	.probe		= ak8975_probe,
	.remove		= ak8975_remove,
	.id_table	= ak8975_id,
};
module_i2c_driver(ak8975_driver);

MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_DESCRIPTION("AK8975 magnetometer driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
3285aae1 AC	1	/*
	2	* A sensor driver for the magnetometer AK8975.
	3	*
	4	* Magnetic compass sensor driver for monitoring magnetic flux information.
	5	*
	6	* Copyright (c) 2010, NVIDIA Corporation.
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful, but WITHOUT
	14	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	15	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	16	* more details.
	17	*
	18	* You should have received a copy of the GNU General Public License along
	19	* with this program; if not, write to the Free Software Foundation, Inc.,
	20	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	21	*/
	22
	23	#include <linux/module.h>
	24	#include <linux/kernel.h>
	25	#include <linux/slab.h>
	26	#include <linux/i2c.h>
	27	#include <linux/err.h>
	28	#include <linux/mutex.h>
	29	#include <linux/delay.h>
	30
	31	#include <linux/gpio.h>
	32
06458e27 JC	33	#include <linux/iio/iio.h>
06458e27 JC	34	#include <linux/iio/sysfs.h>
3285aae1 AC	35	/*
	36	* Register definitions, as well as various shifts and masks to get at the
	37	* individual fields of the registers.
	38	*/
	39	#define AK8975_REG_WIA 0x00
	40	#define AK8975_DEVICE_ID 0x48
	41
	42	#define AK8975_REG_INFO 0x01
	43
	44	#define AK8975_REG_ST1 0x02
	45	#define AK8975_REG_ST1_DRDY_SHIFT 0
	46	#define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT)
	47
	48	#define AK8975_REG_HXL 0x03
	49	#define AK8975_REG_HXH 0x04
	50	#define AK8975_REG_HYL 0x05
	51	#define AK8975_REG_HYH 0x06
	52	#define AK8975_REG_HZL 0x07
	53	#define AK8975_REG_HZH 0x08
	54	#define AK8975_REG_ST2 0x09
	55	#define AK8975_REG_ST2_DERR_SHIFT 2
	56	#define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT)
	57
	58	#define AK8975_REG_ST2_HOFL_SHIFT 3
	59	#define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
	60
	61	#define AK8975_REG_CNTL 0x0A
	62	#define AK8975_REG_CNTL_MODE_SHIFT 0
	63	#define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT)
	64	#define AK8975_REG_CNTL_MODE_POWER_DOWN 0
	65	#define AK8975_REG_CNTL_MODE_ONCE 1
	66	#define AK8975_REG_CNTL_MODE_SELF_TEST 8
	67	#define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF
	68
	69	#define AK8975_REG_RSVC 0x0B
	70	#define AK8975_REG_ASTC 0x0C
	71	#define AK8975_REG_TS1 0x0D
	72	#define AK8975_REG_TS2 0x0E
	73	#define AK8975_REG_I2CDIS 0x0F
	74	#define AK8975_REG_ASAX 0x10
	75	#define AK8975_REG_ASAY 0x11
	76	#define AK8975_REG_ASAZ 0x12
	77
	78	#define AK8975_MAX_REGS AK8975_REG_ASAZ
	79
	80	/*
	81	* Miscellaneous values.
	82	*/
	83	#define AK8975_MAX_CONVERSION_TIMEOUT 500
	84	#define AK8975_CONVERSION_DONE_POLL_TIME 10
	85
	86	/*
	87	* Per-instance context data for the device.
	88	*/
	89	struct ak8975_data {
	90	struct i2c_client *client;
3285aae1 AC	91	struct attribute_group attrs;
	92	struct mutex lock;
	93	u8 asa[3];
	94	long raw_to_gauss[3];
3285aae1 AC	95	u8 reg_cache[AK8975_MAX_REGS];
	96	int eoc_gpio;
	97	int eoc_irq;
	98	};
	99
694e1b5f JC	100	static const int ak8975_index_to_reg[] = {
	101	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
	102	};
	103
3285aae1 AC	104	/*
	105	* Helper function to write to the I2C device's registers.
	106	*/
	107	static int ak8975_write_data(struct i2c_client *client,
	108	u8 reg, u8 val, u8 mask, u8 shift)
	109	{
40f32d93 PC	110	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	111	struct ak8975_data *data = iio_priv(indio_dev);
694e1b5f JC	112	u8 regval;
694e1b5f JC	113	int ret;
3285aae1	114
694e1b5f JC	115	regval = (data->reg_cache[reg] & ~mask) \| (val << shift);
694e1b5f JC	116	ret = i2c_smbus_write_byte_data(client, reg, regval);
3285aae1 AC	117	if (ret < 0) {
	118	dev_err(&client->dev, "Write to device fails status %x\n", ret);
	119	return ret;
	120	}
	121	data->reg_cache[reg] = regval;
	122
	123	return 0;
	124	}
	125
	126	/*
	127	* Helper function to read a contiguous set of the I2C device's registers.
	128	*/
	129	static int ak8975_read_data(struct i2c_client *client,
	130	u8 reg, u8 length, u8 *buffer)
	131	{
3285aae1	132	int ret;
694e1b5f JC	133	struct i2c_msg msg[2] = {
	134	{
	135	.addr = client->addr,
	136	.flags = I2C_M_NOSTART,
	137	.len = 1,
	138	.buf = &reg,
	139	}, {
	140	.addr = client->addr,
	141	.flags = I2C_M_RD,
	142	.len = length,
	143	.buf = buffer,
	144	}
	145	};
3285aae1 AC	146
	147	ret = i2c_transfer(client->adapter, msg, 2);
	148	if (ret < 0) {
	149	dev_err(&client->dev, "Read from device fails\n");
	150	return ret;
	151	}
	152
	153	return 0;
	154	}
	155
	156	/*
	157	* Perform some start-of-day setup, including reading the asa calibration
	158	* values and caching them.
	159	*/
	160	static int ak8975_setup(struct i2c_client *client)
	161	{
40f32d93 PC	162	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	163	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1 AC	164	u8 device_id;
	165	int ret;
	166
	167	/* Confirm that the device we're talking to is really an AK8975. */
	168	ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id);
	169	if (ret < 0) {
	170	dev_err(&client->dev, "Error reading WIA\n");
	171	return ret;
	172	}
	173	if (device_id != AK8975_DEVICE_ID) {
	174	dev_err(&client->dev, "Device ak8975 not found\n");
	175	return -ENODEV;
	176	}
	177
	178	/* Write the fused rom access mode. */
	179	ret = ak8975_write_data(client,
	180	AK8975_REG_CNTL,
	181	AK8975_REG_CNTL_MODE_FUSE_ROM,
	182	AK8975_REG_CNTL_MODE_MASK,
	183	AK8975_REG_CNTL_MODE_SHIFT);
	184	if (ret < 0) {
	185	dev_err(&client->dev, "Error in setting fuse access mode\n");
	186	return ret;
	187	}
	188
	189	/* Get asa data and store in the device data. */
	190	ret = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa);
	191	if (ret < 0) {
	192	dev_err(&client->dev, "Not able to read asa data\n");
	193	return ret;
	194	}
	195
040f3e58 LA	196	/* After reading fuse ROM data set power-down mode */
	197	ret = ak8975_write_data(client,
	198	AK8975_REG_CNTL,
	199	AK8975_REG_CNTL_MODE_POWER_DOWN,
	200	AK8975_REG_CNTL_MODE_MASK,
	201	AK8975_REG_CNTL_MODE_SHIFT);
	202	if (ret < 0) {
	203	dev_err(&client->dev, "Error in setting power-down mode\n");
	204	return ret;
	205	}
	206
694e1b5f JC	207	/*
	208	* Precalculate scale factor (in Gauss units) for each axis and
	209	* store in the device data.
	210	*
	211	* This scale factor is axis-dependent, and is derived from 3 calibration
	212	* factors ASA(x), ASA(y), and ASA(z).
	213	*
	214	* These ASA values are read from the sensor device at start of day, and
	215	* cached in the device context struct.
	216	*
	217	* Adjusting the flux value with the sensitivity adjustment value should be
	218	* done via the following formula:
	219	*
	220	* Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
	221	*
	222	* where H is the raw value, ASA is the sensitivity adjustment, and Hadj
	223	* is the resultant adjusted value.
	224	*
	225	* We reduce the formula to:
	226	*
	227	* Hadj = H * (ASA + 128) / 256
	228	*
	229	* H is in the range of -4096 to 4095. The magnetometer has a range of
	230	* +-1229uT. To go from the raw value to uT is:
	231	*
	232	* HuT = H * 1229/4096, or roughly, 3/10.
	233	*
	234	* Since 1uT = 100 gauss, our final scale factor becomes:
	235	*
	236	* Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
	237	* Hadj = H * ((ASA + 128) * 30 / 256
	238	*
	239	* Since ASA doesn't change, we cache the resultant scale factor into the
	240	* device context in ak8975_setup().
	241	*/
3285aae1 AC	242	data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
	243	data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
	244	data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
	245
	246	return 0;
	247	}
	248
01fbb478 AC	249	static int wait_conversion_complete_gpio(struct ak8975_data *data)
	250	{
	251	struct i2c_client *client = data->client;
	252	u8 read_status;
	253	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	254	int ret;
	255
	256	/* Wait for the conversion to complete. */
	257	while (timeout_ms) {
	258	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
	259	if (gpio_get_value(data->eoc_gpio))
	260	break;
	261	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	262	}
	263	if (!timeout_ms) {
	264	dev_err(&client->dev, "Conversion timeout happened\n");
	265	return -EINVAL;
	266	}
	267
	268	ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
	269	if (ret < 0) {
	270	dev_err(&client->dev, "Error in reading ST1\n");
	271	return ret;
	272	}
	273	return read_status;
	274	}
	275
	276	static int wait_conversion_complete_polled(struct ak8975_data *data)
	277	{
	278	struct i2c_client *client = data->client;
	279	u8 read_status;
	280	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	281	int ret;
	282
	283	/* Wait for the conversion to complete. */
	284	while (timeout_ms) {
	285	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
	286	ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
	287	if (ret < 0) {
	288	dev_err(&client->dev, "Error in reading ST1\n");
	289	return ret;
	290	}
	291	if (read_status)
	292	break;
	293	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	294	}
	295	if (!timeout_ms) {
	296	dev_err(&client->dev, "Conversion timeout happened\n");
	297	return -EINVAL;
	298	}
	299	return read_status;
	300	}
	301
3285aae1 AC	302	/*
	303	* Emits the raw flux value for the x, y, or z axis.
	304	*/
694e1b5f	305	static int ak8975_read_axis(struct iio_dev indio_dev, int index, int val)
3285aae1	306	{
338473c8	307	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1	308	struct i2c_client *client = data->client;
3285aae1 AC	309	u16 meas_reg;
	310	s16 raw;
	311	u8 read_status;
	312	int ret;
	313
	314	mutex_lock(&data->lock);
	315
3285aae1 AC	316	/* Set up the device for taking a sample. */
	317	ret = ak8975_write_data(client,
	318	AK8975_REG_CNTL,
	319	AK8975_REG_CNTL_MODE_ONCE,
	320	AK8975_REG_CNTL_MODE_MASK,
	321	AK8975_REG_CNTL_MODE_SHIFT);
	322	if (ret < 0) {
	323	dev_err(&client->dev, "Error in setting operating mode\n");
	324	goto exit;
	325	}
	326
	327	/* Wait for the conversion to complete. */
7c6c9368	328	if (gpio_is_valid(data->eoc_gpio))
01fbb478 AC	329	ret = wait_conversion_complete_gpio(data);
	330	else
	331	ret = wait_conversion_complete_polled(data);
	332	if (ret < 0)
3285aae1	333	goto exit;
3285aae1	334
01fbb478	335	read_status = ret;
3285aae1 AC	336
	337	if (read_status & AK8975_REG_ST1_DRDY_MASK) {
	338	ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
	339	if (ret < 0) {
	340	dev_err(&client->dev, "Error in reading ST2\n");
	341	goto exit;
	342	}
	343	if (read_status & (AK8975_REG_ST2_DERR_MASK \|
	344	AK8975_REG_ST2_HOFL_MASK)) {
	345	dev_err(&client->dev, "ST2 status error 0x%x\n",
	346	read_status);
	347	ret = -EINVAL;
	348	goto exit;
	349	}
	350	}
	351
	352	/* Read the flux value from the appropriate register
	353	(the register is specified in the iio device attributes). */
694e1b5f JC	354	ret = ak8975_read_data(client, ak8975_index_to_reg[index],
694e1b5f JC	355	2, (u8 *)&meas_reg);
3285aae1 AC	356	if (ret < 0) {
	357	dev_err(&client->dev, "Read axis data fails\n");
	358	goto exit;
	359	}
	360
	361	mutex_unlock(&data->lock);
	362
	363	/* Endian conversion of the measured values. */
	364	raw = (s16) (le16_to_cpu(meas_reg));
	365
	366	/* Clamp to valid range. */
	367	raw = clamp_t(s16, raw, -4096, 4095);
694e1b5f JC	368	*val = raw;
694e1b5f JC	369	return IIO_VAL_INT;
3285aae1 AC	370
	371	exit:
	372	mutex_unlock(&data->lock);
	373	return ret;
	374	}
	375
694e1b5f JC	376	static int ak8975_read_raw(struct iio_dev *indio_dev,
	377	struct iio_chan_spec const *chan,
	378	int val, int val2,
	379	long mask)
	380	{
	381	struct ak8975_data *data = iio_priv(indio_dev);
	382
	383	switch (mask) {
4d9948b3	384	case IIO_CHAN_INFO_RAW:
694e1b5f	385	return ak8975_read_axis(indio_dev, chan->address, val);
c8a9f805	386	case IIO_CHAN_INFO_SCALE:
694e1b5f JC	387	*val = data->raw_to_gauss[chan->address];
	388	return IIO_VAL_INT;
	389	}
	390	return -EINVAL;
	391	}
	392
	393	#define AK8975_CHANNEL(axis, index) \
	394	{ \
	395	.type = IIO_MAGN, \
	396	.modified = 1, \
	397	.channel2 = IIO_MOD_##axis, \
3a0b4422 JC	398	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \| \
3a0b4422 JC	399	BIT(IIO_CHAN_INFO_SCALE), \
694e1b5f JC	400	.address = index, \
	401	}
	402
	403	static const struct iio_chan_spec ak8975_channels[] = {
	404	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
	405	};
	406
6fe8135f	407	static const struct iio_info ak8975_info = {
694e1b5f	408	.read_raw = &ak8975_read_raw,
6fe8135f JC	409	.driver_module = THIS_MODULE,
	410	};
	411
4ae1c61f	412	static int ak8975_probe(struct i2c_client *client,
3285aae1 AC	413	const struct i2c_device_id *id)
	414	{
	415	struct ak8975_data *data;
338473c8 JC	416	struct iio_dev *indio_dev;
338473c8 JC	417	int eoc_gpio;
3285aae1 AC	418	int err;
3285aae1 AC	419
3285aae1	420	/* Grab and set up the supplied GPIO. */
f6d838d7 JC	421	if (client->dev.platform_data == NULL)
	422	eoc_gpio = -1;
	423	else
	424	eoc_gpio = (int )(client->dev.platform_data);
3285aae1	425
01fbb478 AC	426	/* We may not have a GPIO based IRQ to scan, that is fine, we will
01fbb478 AC	427	poll if so */
7c6c9368	428	if (gpio_is_valid(eoc_gpio)) {
82f2acdc	429	err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
01fbb478 AC	430	if (err < 0) {
	431	dev_err(&client->dev,
	432	"failed to request GPIO %d, error %d\n",
338473c8 JC	433	eoc_gpio, err);
338473c8 JC	434	goto exit;
01fbb478	435	}
7c6c9368	436	}
3285aae1	437
338473c8	438	/* Register with IIO */
7cbb7537	439	indio_dev = iio_device_alloc(sizeof(*data));
338473c8 JC	440	if (indio_dev == NULL) {
	441	err = -ENOMEM;
	442	goto exit_gpio;
	443	}
	444	data = iio_priv(indio_dev);
40f32d93	445	i2c_set_clientdata(client, indio_dev);
3285aae1 AC	446	/* Perform some basic start-of-day setup of the device. */
	447	err = ak8975_setup(client);
	448	if (err < 0) {
	449	dev_err(&client->dev, "AK8975 initialization fails\n");
ad31d250	450	goto exit_free_iio;
3285aae1 AC	451	}
3285aae1 AC	452
338473c8 JC	453	data->client = client;
	454	mutex_init(&data->lock);
	455	data->eoc_irq = client->irq;
	456	data->eoc_gpio = eoc_gpio;
	457	indio_dev->dev.parent = &client->dev;
694e1b5f JC	458	indio_dev->channels = ak8975_channels;
694e1b5f JC	459	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
338473c8 JC	460	indio_dev->info = &ak8975_info;
338473c8 JC	461	indio_dev->modes = INDIO_DIRECT_MODE;
3285aae1	462
338473c8	463	err = iio_device_register(indio_dev);
3285aae1 AC	464	if (err < 0)
	465	goto exit_free_iio;
	466
	467	return 0;
	468
	469	exit_free_iio:
7cbb7537	470	iio_device_free(indio_dev);
3285aae1	471	exit_gpio:
7c6c9368	472	if (gpio_is_valid(eoc_gpio))
338473c8	473	gpio_free(eoc_gpio);
3285aae1 AC	474	exit:
	475	return err;
	476	}
	477
447d4f29	478	static int ak8975_remove(struct i2c_client *client)
3285aae1	479	{
338473c8 JC	480	struct iio_dev *indio_dev = i2c_get_clientdata(client);
338473c8 JC	481	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1	482
338473c8	483	iio_device_unregister(indio_dev);
3285aae1	484
d2fffd6c JC	485	if (gpio_is_valid(data->eoc_gpio))
	486	gpio_free(data->eoc_gpio);
	487
7cbb7537	488	iio_device_free(indio_dev);
3285aae1 AC	489
	490	return 0;
	491	}
	492
	493	static const struct i2c_device_id ak8975_id[] = {
	494	{"ak8975", 0},
	495	{}
	496	};
	497
	498	MODULE_DEVICE_TABLE(i2c, ak8975_id);
	499
54461c30 OJ	500	static const struct of_device_id ak8975_of_match[] = {
	501	{ .compatible = "asahi-kasei,ak8975", },
	502	{ .compatible = "ak8975", },
	503	{ }
	504	};
	505	MODULE_DEVICE_TABLE(of, ak8975_of_match);
	506
3285aae1 AC	507	static struct i2c_driver ak8975_driver = {
	508	.driver = {
	509	.name = "ak8975",
54461c30	510	.of_match_table = ak8975_of_match,
3285aae1 AC	511	},
3285aae1 AC	512	.probe = ak8975_probe,
e543acf0	513	.remove = ak8975_remove,
3285aae1 AC	514	.id_table = ak8975_id,
3285aae1 AC	515	};
6e5af184	516	module_i2c_driver(ak8975_driver);
3285aae1 AC	517
	518	MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
	519	MODULE_DESCRIPTION("AK8975 magnetometer driver");
	520	MODULE_LICENSE("GPL");