[deliverable/linux.git] / drivers / 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/interrupt.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/gpio.h>
#include <linux/of_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
#define AK8975_DATA_READY_TIMEOUT	((100*HZ)/1000)
#define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256)
#define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256)

/* Compatible Asahi Kasei Compass parts */
enum asahi_compass_chipset {
	AK8975,
	AK8963,
};

/*
 * 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;
	wait_queue_head_t	data_ready_queue;
	unsigned long		flags;
	enum asahi_compass_chipset chipset;
};

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;
}

/*
 * Handle data ready irq
 */
static irqreturn_t ak8975_irq_handler(int irq, void *data)
{
	struct ak8975_data *ak8975 = data;

	set_bit(0, &ak8975->flags);
	wake_up(&ak8975->data_ready_queue);

	return IRQ_HANDLED;
}

/*
 * Install data ready interrupt handler
 */
static int ak8975_setup_irq(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	int rc;
	int irq;

	if (client->irq)
		irq = client->irq;
	else
		irq = gpio_to_irq(data->eoc_gpio);

	rc = request_irq(irq, ak8975_irq_handler,
			 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
			 dev_name(&client->dev), data);
	if (rc < 0) {
		dev_err(&client->dev,
			"irq %d request failed, (gpio %d): %d\n",
			irq, data->eoc_gpio, rc);
		return rc;
	}

	init_waitqueue_head(&data->data_ready_queue);
	clear_bit(0, &data->flags);
	data->eoc_irq = irq;

	return rc;
}


/*
 * 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 = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
	if (ret < 0) {
		dev_err(&client->dev, "Error reading WIA\n");
		return ret;
	}
	device_id = 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 = i2c_smbus_read_i2c_block_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 (data->eoc_gpio > 0 || client->irq) {
		ret = ak8975_setup_irq(data);
		if (ret < 0) {
			dev_err(&client->dev,
				"Error setting data ready interrupt\n");
			return ret;
		}
	}

	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 = 0.01 gauss, our final scale factor becomes:
 *
 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
 * Hadj = H * ((ASA + 128) * 0.003) / 256
 *
 * Since ASA doesn't change, we cache the resultant scale factor into the
 * device context in ak8975_setup().
 */
	if (data->chipset == AK8963) {
		/*
		 * H range is +-8190 and magnetometer range is +-4912.
		 * So HuT using the above explanation for 8975,
		 * 4912/8190 = ~ 6/10.
		 * So the Hadj should use 6/10 instead of 3/10.
		 */
		data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]);
		data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]);
		data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]);
	} else {
		data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]);
		data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]);
		data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]);
	}

	return 0;
}

static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	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 = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
	if (ret < 0)
		dev_err(&client->dev, "Error in reading ST1\n");

	return ret;
}

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 = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST1\n");
			return ret;
		}
		read_status = 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;
}

/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
static int wait_conversion_complete_interrupt(struct ak8975_data *data)
{
	int ret;

	ret = wait_event_timeout(data->data_ready_queue,
				 test_bit(0, &data->flags),
				 AK8975_DATA_READY_TIMEOUT);
	clear_bit(0, &data->flags);

	return ret > 0 ? 0 : -ETIME;
}

/*
 * 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;
	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 (data->eoc_irq)
		ret = wait_conversion_complete_interrupt(data);
	else 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;

	/* This will be executed only for non-interrupt based waiting case */
	if (ret & AK8975_REG_ST1_DRDY_MASK) {
		ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST2\n");
			goto exit;
		}
		if (ret & (AK8975_REG_ST2_DERR_MASK |
			   AK8975_REG_ST2_HOFL_MASK)) {
			dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
			ret = -EINVAL;
			goto exit;
		}
	}

	/* Read the flux value from the appropriate register
	   (the register is specified in the iio device attributes). */
	ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
	if (ret < 0) {
		dev_err(&client->dev, "Read axis data fails\n");
		goto exit;
	}
	meas_reg = ret;

	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 = 0;
		*val2 = data->raw_to_gauss[chan->address];
		return IIO_VAL_INT_PLUS_MICRO;
	}
	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)
		eoc_gpio = *(int *)(client->dev.platform_data);
	else if (client->dev.of_node)
		eoc_gpio = of_get_gpio(client->dev.of_node, 0);
	else
		eoc_gpio = -1;

	if (eoc_gpio == -EPROBE_DEFER)
		return -EPROBE_DEFER;

	/* 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);

	data->client = client;
	data->eoc_gpio = eoc_gpio;
	data->eoc_irq = 0;

	data->chipset = (enum asahi_compass_chipset)(id->driver_data);
	dev_dbg(&client->dev, "Asahi compass chip %s\n", id->name);

	/* 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_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->name = id->name;
	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);
	if (data->eoc_irq)
		free_irq(data->eoc_irq, data);
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 (data->eoc_irq)
		free_irq(data->eoc_irq, data);

	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", AK8975},
	{"ak8963", AK8963},
	{}
};

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>
94a6d5cf	27	#include <linux/interrupt.h>
3285aae1 AC	28	#include <linux/err.h>
	29	#include <linux/mutex.h>
	30	#include <linux/delay.h>
94a6d5cf	31	#include <linux/bitops.h>
3285aae1	32	#include <linux/gpio.h>
f4b7f751	33	#include <linux/of_gpio.h>
3285aae1	34
06458e27 JC	35	#include <linux/iio/iio.h>
06458e27 JC	36	#include <linux/iio/sysfs.h>
3285aae1 AC	37	/*
	38	* Register definitions, as well as various shifts and masks to get at the
	39	* individual fields of the registers.
	40	*/
	41	#define AK8975_REG_WIA 0x00
	42	#define AK8975_DEVICE_ID 0x48
	43
	44	#define AK8975_REG_INFO 0x01
	45
	46	#define AK8975_REG_ST1 0x02
	47	#define AK8975_REG_ST1_DRDY_SHIFT 0
	48	#define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT)
	49
	50	#define AK8975_REG_HXL 0x03
	51	#define AK8975_REG_HXH 0x04
	52	#define AK8975_REG_HYL 0x05
	53	#define AK8975_REG_HYH 0x06
	54	#define AK8975_REG_HZL 0x07
	55	#define AK8975_REG_HZH 0x08
	56	#define AK8975_REG_ST2 0x09
	57	#define AK8975_REG_ST2_DERR_SHIFT 2
	58	#define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT)
	59
	60	#define AK8975_REG_ST2_HOFL_SHIFT 3
	61	#define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
	62
	63	#define AK8975_REG_CNTL 0x0A
	64	#define AK8975_REG_CNTL_MODE_SHIFT 0
	65	#define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT)
	66	#define AK8975_REG_CNTL_MODE_POWER_DOWN 0
	67	#define AK8975_REG_CNTL_MODE_ONCE 1
	68	#define AK8975_REG_CNTL_MODE_SELF_TEST 8
	69	#define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF
	70
	71	#define AK8975_REG_RSVC 0x0B
	72	#define AK8975_REG_ASTC 0x0C
	73	#define AK8975_REG_TS1 0x0D
	74	#define AK8975_REG_TS2 0x0E
	75	#define AK8975_REG_I2CDIS 0x0F
	76	#define AK8975_REG_ASAX 0x10
	77	#define AK8975_REG_ASAY 0x11
	78	#define AK8975_REG_ASAZ 0x12
	79
	80	#define AK8975_MAX_REGS AK8975_REG_ASAZ
	81
	82	/*
	83	* Miscellaneous values.
	84	*/
	85	#define AK8975_MAX_CONVERSION_TIMEOUT 500
	86	#define AK8975_CONVERSION_DONE_POLL_TIME 10
94a6d5cf	87	#define AK8975_DATA_READY_TIMEOUT ((100*HZ)/1000)
6027c077 SP	88	#define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256)
	89	#define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256)
	90
	91	/* Compatible Asahi Kasei Compass parts */
	92	enum asahi_compass_chipset {
	93	AK8975,
	94	AK8963,
	95	};
3285aae1 AC	96
	97	/*
	98	* Per-instance context data for the device.
	99	*/
	100	struct ak8975_data {
	101	struct i2c_client *client;
3285aae1 AC	102	struct attribute_group attrs;
	103	struct mutex lock;
	104	u8 asa[3];
	105	long raw_to_gauss[3];
3285aae1 AC	106	u8 reg_cache[AK8975_MAX_REGS];
3285aae1 AC	107	int eoc_gpio;
94a6d5cf JA	108	int eoc_irq;
	109	wait_queue_head_t data_ready_queue;
	110	unsigned long flags;
6027c077	111	enum asahi_compass_chipset chipset;
3285aae1 AC	112	};
3285aae1 AC	113
694e1b5f JC	114	static const int ak8975_index_to_reg[] = {
	115	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
	116	};
	117
3285aae1 AC	118	/*
	119	* Helper function to write to the I2C device's registers.
	120	*/
	121	static int ak8975_write_data(struct i2c_client *client,
	122	u8 reg, u8 val, u8 mask, u8 shift)
	123	{
40f32d93 PC	124	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	125	struct ak8975_data *data = iio_priv(indio_dev);
694e1b5f JC	126	u8 regval;
694e1b5f JC	127	int ret;
3285aae1	128
694e1b5f JC	129	regval = (data->reg_cache[reg] & ~mask) \| (val << shift);
694e1b5f JC	130	ret = i2c_smbus_write_byte_data(client, reg, regval);
3285aae1 AC	131	if (ret < 0) {
	132	dev_err(&client->dev, "Write to device fails status %x\n", ret);
	133	return ret;
	134	}
	135	data->reg_cache[reg] = regval;
	136
	137	return 0;
	138	}
	139
94a6d5cf JA	140	/*
	141	* Handle data ready irq
	142	*/
	143	static irqreturn_t ak8975_irq_handler(int irq, void *data)
	144	{
	145	struct ak8975_data *ak8975 = data;
	146
	147	set_bit(0, &ak8975->flags);
	148	wake_up(&ak8975->data_ready_queue);
	149
	150	return IRQ_HANDLED;
	151	}
	152
	153	/*
	154	* Install data ready interrupt handler
	155	*/
	156	static int ak8975_setup_irq(struct ak8975_data *data)
	157	{
	158	struct i2c_client *client = data->client;
	159	int rc;
	160	int irq;
	161
	162	if (client->irq)
	163	irq = client->irq;
	164	else
	165	irq = gpio_to_irq(data->eoc_gpio);
	166
	167	rc = request_irq(irq, ak8975_irq_handler,
	168	IRQF_TRIGGER_RISING \| IRQF_ONESHOT,
	169	dev_name(&client->dev), data);
	170	if (rc < 0) {
	171	dev_err(&client->dev,
	172	"irq %d request failed, (gpio %d): %d\n",
	173	irq, data->eoc_gpio, rc);
	174	return rc;
	175	}
	176
	177	init_waitqueue_head(&data->data_ready_queue);
	178	clear_bit(0, &data->flags);
	179	data->eoc_irq = irq;
	180
	181	return rc;
	182	}
	183
	184
3285aae1 AC	185	/*
	186	* Perform some start-of-day setup, including reading the asa calibration
	187	* values and caching them.
	188	*/
	189	static int ak8975_setup(struct i2c_client *client)
	190	{
40f32d93 PC	191	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	192	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1 AC	193	u8 device_id;
	194	int ret;
	195
	196	/* Confirm that the device we're talking to is really an AK8975. */
c411f600	197	ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
3285aae1 AC	198	if (ret < 0) {
	199	dev_err(&client->dev, "Error reading WIA\n");
	200	return ret;
	201	}
c411f600	202	device_id = ret;
3285aae1 AC	203	if (device_id != AK8975_DEVICE_ID) {
	204	dev_err(&client->dev, "Device ak8975 not found\n");
	205	return -ENODEV;
	206	}
	207
	208	/* Write the fused rom access mode. */
	209	ret = ak8975_write_data(client,
	210	AK8975_REG_CNTL,
	211	AK8975_REG_CNTL_MODE_FUSE_ROM,
	212	AK8975_REG_CNTL_MODE_MASK,
	213	AK8975_REG_CNTL_MODE_SHIFT);
	214	if (ret < 0) {
	215	dev_err(&client->dev, "Error in setting fuse access mode\n");
	216	return ret;
	217	}
	218
	219	/* Get asa data and store in the device data. */
c411f600 JC	220	ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX,
c411f600 JC	221	3, data->asa);
3285aae1 AC	222	if (ret < 0) {
	223	dev_err(&client->dev, "Not able to read asa data\n");
	224	return ret;
	225	}
	226
040f3e58 LA	227	/* After reading fuse ROM data set power-down mode */
	228	ret = ak8975_write_data(client,
	229	AK8975_REG_CNTL,
	230	AK8975_REG_CNTL_MODE_POWER_DOWN,
	231	AK8975_REG_CNTL_MODE_MASK,
	232	AK8975_REG_CNTL_MODE_SHIFT);
94a6d5cf JA	233
	234	if (data->eoc_gpio > 0 \|\| client->irq) {
	235	ret = ak8975_setup_irq(data);
	236	if (ret < 0) {
	237	dev_err(&client->dev,
	238	"Error setting data ready interrupt\n");
	239	return ret;
	240	}
	241	}
	242
040f3e58 LA	243	if (ret < 0) {
	244	dev_err(&client->dev, "Error in setting power-down mode\n");
	245	return ret;
	246	}
	247
694e1b5f JC	248	/*
	249	* Precalculate scale factor (in Gauss units) for each axis and
	250	* store in the device data.
	251	*
	252	* This scale factor is axis-dependent, and is derived from 3 calibration
	253	* factors ASA(x), ASA(y), and ASA(z).
	254	*
	255	* These ASA values are read from the sensor device at start of day, and
	256	* cached in the device context struct.
	257	*
	258	* Adjusting the flux value with the sensitivity adjustment value should be
	259	* done via the following formula:
	260	*
	261	* Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
	262	*
	263	* where H is the raw value, ASA is the sensitivity adjustment, and Hadj
	264	* is the resultant adjusted value.
	265	*
	266	* We reduce the formula to:
	267	*
	268	* Hadj = H * (ASA + 128) / 256
	269	*
	270	* H is in the range of -4096 to 4095. The magnetometer has a range of
	271	* +-1229uT. To go from the raw value to uT is:
	272	*
	273	* HuT = H * 1229/4096, or roughly, 3/10.
	274	*
eb03610a	275	* Since 1uT = 0.01 gauss, our final scale factor becomes:
694e1b5f	276	*
bef44abc BS	277	* Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
bef44abc BS	278	* Hadj = H * ((ASA + 128) * 0.003) / 256
694e1b5f JC	279	*
	280	* Since ASA doesn't change, we cache the resultant scale factor into the
	281	* device context in ak8975_setup().
	282	*/
6027c077 SP	283	if (data->chipset == AK8963) {
	284	/*
	285	* H range is +-8190 and magnetometer range is +-4912.
	286	* So HuT using the above explanation for 8975,
	287	* 4912/8190 = ~ 6/10.
	288	* So the Hadj should use 6/10 instead of 3/10.
	289	*/
	290	data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]);
	291	data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]);
	292	data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]);
	293	} else {
	294	data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]);
	295	data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]);
	296	data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]);
	297	}
3285aae1 AC	298
	299	return 0;
	300	}
	301
01fbb478 AC	302	static int wait_conversion_complete_gpio(struct ak8975_data *data)
	303	{
	304	struct i2c_client *client = data->client;
01fbb478 AC	305	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	306	int ret;
	307
	308	/* Wait for the conversion to complete. */
	309	while (timeout_ms) {
	310	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
	311	if (gpio_get_value(data->eoc_gpio))
	312	break;
	313	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	314	}
	315	if (!timeout_ms) {
	316	dev_err(&client->dev, "Conversion timeout happened\n");
	317	return -EINVAL;
	318	}
	319
c411f600 JC	320	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
c411f600 JC	321	if (ret < 0)
01fbb478	322	dev_err(&client->dev, "Error in reading ST1\n");
c411f600 JC	323
c411f600 JC	324	return ret;
01fbb478 AC	325	}
	326
	327	static int wait_conversion_complete_polled(struct ak8975_data *data)
	328	{
	329	struct i2c_client *client = data->client;
	330	u8 read_status;
	331	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	332	int ret;
	333
	334	/* Wait for the conversion to complete. */
	335	while (timeout_ms) {
	336	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
c411f600	337	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
01fbb478 AC	338	if (ret < 0) {
	339	dev_err(&client->dev, "Error in reading ST1\n");
	340	return ret;
	341	}
c411f600	342	read_status = ret;
01fbb478 AC	343	if (read_status)
	344	break;
	345	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	346	}
	347	if (!timeout_ms) {
	348	dev_err(&client->dev, "Conversion timeout happened\n");
	349	return -EINVAL;
	350	}
94a6d5cf	351
01fbb478 AC	352	return read_status;
	353	}
	354
94a6d5cf JA	355	/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
	356	static int wait_conversion_complete_interrupt(struct ak8975_data *data)
	357	{
	358	int ret;
	359
	360	ret = wait_event_timeout(data->data_ready_queue,
	361	test_bit(0, &data->flags),
	362	AK8975_DATA_READY_TIMEOUT);
	363	clear_bit(0, &data->flags);
	364
	365	return ret > 0 ? 0 : -ETIME;
	366	}
	367
3285aae1 AC	368	/*
	369	* Emits the raw flux value for the x, y, or z axis.
	370	*/
694e1b5f	371	static int ak8975_read_axis(struct iio_dev indio_dev, int index, int val)
3285aae1	372	{
338473c8	373	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1	374	struct i2c_client *client = data->client;
3285aae1 AC	375	u16 meas_reg;
3285aae1 AC	376	s16 raw;
3285aae1 AC	377	int ret;
	378
	379	mutex_lock(&data->lock);
	380
3285aae1 AC	381	/* Set up the device for taking a sample. */
	382	ret = ak8975_write_data(client,
	383	AK8975_REG_CNTL,
	384	AK8975_REG_CNTL_MODE_ONCE,
	385	AK8975_REG_CNTL_MODE_MASK,
	386	AK8975_REG_CNTL_MODE_SHIFT);
	387	if (ret < 0) {
	388	dev_err(&client->dev, "Error in setting operating mode\n");
	389	goto exit;
	390	}
	391
	392	/* Wait for the conversion to complete. */
94a6d5cf JA	393	if (data->eoc_irq)
	394	ret = wait_conversion_complete_interrupt(data);
	395	else if (gpio_is_valid(data->eoc_gpio))
01fbb478 AC	396	ret = wait_conversion_complete_gpio(data);
	397	else
	398	ret = wait_conversion_complete_polled(data);
	399	if (ret < 0)
3285aae1	400	goto exit;
3285aae1	401
94a6d5cf	402	/* This will be executed only for non-interrupt based waiting case */
c411f600 JC	403	if (ret & AK8975_REG_ST1_DRDY_MASK) {
c411f600 JC	404	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
3285aae1 AC	405	if (ret < 0) {
	406	dev_err(&client->dev, "Error in reading ST2\n");
	407	goto exit;
	408	}
c411f600 JC	409	if (ret & (AK8975_REG_ST2_DERR_MASK \|
	410	AK8975_REG_ST2_HOFL_MASK)) {
	411	dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
3285aae1 AC	412	ret = -EINVAL;
	413	goto exit;
	414	}
	415	}
	416
	417	/* Read the flux value from the appropriate register
	418	(the register is specified in the iio device attributes). */
c411f600	419	ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
3285aae1 AC	420	if (ret < 0) {
	421	dev_err(&client->dev, "Read axis data fails\n");
	422	goto exit;
	423	}
c411f600	424	meas_reg = ret;
3285aae1 AC	425
	426	mutex_unlock(&data->lock);
	427
	428	/* Endian conversion of the measured values. */
	429	raw = (s16) (le16_to_cpu(meas_reg));
	430
	431	/* Clamp to valid range. */
	432	raw = clamp_t(s16, raw, -4096, 4095);
694e1b5f JC	433	*val = raw;
694e1b5f JC	434	return IIO_VAL_INT;
3285aae1 AC	435
	436	exit:
	437	mutex_unlock(&data->lock);
	438	return ret;
	439	}
	440
694e1b5f JC	441	static int ak8975_read_raw(struct iio_dev *indio_dev,
	442	struct iio_chan_spec const *chan,
	443	int val, int val2,
	444	long mask)
	445	{
	446	struct ak8975_data *data = iio_priv(indio_dev);
	447
	448	switch (mask) {
4d9948b3	449	case IIO_CHAN_INFO_RAW:
694e1b5f	450	return ak8975_read_axis(indio_dev, chan->address, val);
c8a9f805	451	case IIO_CHAN_INFO_SCALE:
bef44abc BS	452	*val = 0;
	453	*val2 = data->raw_to_gauss[chan->address];
	454	return IIO_VAL_INT_PLUS_MICRO;
694e1b5f JC	455	}
	456	return -EINVAL;
	457	}
	458
	459	#define AK8975_CHANNEL(axis, index) \
	460	{ \
	461	.type = IIO_MAGN, \
	462	.modified = 1, \
	463	.channel2 = IIO_MOD_##axis, \
3a0b4422 JC	464	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \| \
3a0b4422 JC	465	BIT(IIO_CHAN_INFO_SCALE), \
694e1b5f JC	466	.address = index, \
	467	}
	468
	469	static const struct iio_chan_spec ak8975_channels[] = {
	470	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
	471	};
	472
6fe8135f	473	static const struct iio_info ak8975_info = {
694e1b5f	474	.read_raw = &ak8975_read_raw,
6fe8135f JC	475	.driver_module = THIS_MODULE,
	476	};
	477
4ae1c61f	478	static int ak8975_probe(struct i2c_client *client,
3285aae1 AC	479	const struct i2c_device_id *id)
	480	{
	481	struct ak8975_data *data;
338473c8 JC	482	struct iio_dev *indio_dev;
338473c8 JC	483	int eoc_gpio;
3285aae1 AC	484	int err;
3285aae1 AC	485
3285aae1	486	/* Grab and set up the supplied GPIO. */
f4b7f751	487	if (client->dev.platform_data)
f6d838d7	488	eoc_gpio = (int )(client->dev.platform_data);
f4b7f751 JA	489	else if (client->dev.of_node)
	490	eoc_gpio = of_get_gpio(client->dev.of_node, 0);
	491	else
	492	eoc_gpio = -1;
	493
	494	if (eoc_gpio == -EPROBE_DEFER)
	495	return -EPROBE_DEFER;
3285aae1	496
01fbb478 AC	497	/* We may not have a GPIO based IRQ to scan, that is fine, we will
01fbb478 AC	498	poll if so */
7c6c9368	499	if (gpio_is_valid(eoc_gpio)) {
82f2acdc	500	err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
01fbb478 AC	501	if (err < 0) {
	502	dev_err(&client->dev,
	503	"failed to request GPIO %d, error %d\n",
338473c8 JC	504	eoc_gpio, err);
338473c8 JC	505	goto exit;
01fbb478	506	}
7c6c9368	507	}
3285aae1	508
338473c8	509	/* Register with IIO */
7cbb7537	510	indio_dev = iio_device_alloc(sizeof(*data));
338473c8 JC	511	if (indio_dev == NULL) {
	512	err = -ENOMEM;
	513	goto exit_gpio;
	514	}
	515	data = iio_priv(indio_dev);
40f32d93	516	i2c_set_clientdata(client, indio_dev);
94a6d5cf JA	517
	518	data->client = client;
	519	data->eoc_gpio = eoc_gpio;
	520	data->eoc_irq = 0;
	521
6027c077 SP	522	data->chipset = (enum asahi_compass_chipset)(id->driver_data);
	523	dev_dbg(&client->dev, "Asahi compass chip %s\n", id->name);
	524
3285aae1 AC	525	/* Perform some basic start-of-day setup of the device. */
	526	err = ak8975_setup(client);
	527	if (err < 0) {
	528	dev_err(&client->dev, "AK8975 initialization fails\n");
ad31d250	529	goto exit_free_iio;
3285aae1 AC	530	}
3285aae1 AC	531
338473c8 JC	532	data->client = client;
338473c8 JC	533	mutex_init(&data->lock);
338473c8 JC	534	data->eoc_gpio = eoc_gpio;
338473c8 JC	535	indio_dev->dev.parent = &client->dev;
694e1b5f JC	536	indio_dev->channels = ak8975_channels;
694e1b5f JC	537	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
338473c8	538	indio_dev->info = &ak8975_info;
54ab3e24	539	indio_dev->name = id->name;
338473c8	540	indio_dev->modes = INDIO_DIRECT_MODE;
3285aae1	541
338473c8	542	err = iio_device_register(indio_dev);
3285aae1 AC	543	if (err < 0)
	544	goto exit_free_iio;
	545
	546	return 0;
	547
	548	exit_free_iio:
7cbb7537	549	iio_device_free(indio_dev);
94a6d5cf JA	550	if (data->eoc_irq)
94a6d5cf JA	551	free_irq(data->eoc_irq, data);
3285aae1	552	exit_gpio:
7c6c9368	553	if (gpio_is_valid(eoc_gpio))
338473c8	554	gpio_free(eoc_gpio);
3285aae1 AC	555	exit:
	556	return err;
	557	}
	558
447d4f29	559	static int ak8975_remove(struct i2c_client *client)
3285aae1	560	{
338473c8 JC	561	struct iio_dev *indio_dev = i2c_get_clientdata(client);
338473c8 JC	562	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1	563
338473c8	564	iio_device_unregister(indio_dev);
3285aae1	565
94a6d5cf JA	566	if (data->eoc_irq)
	567	free_irq(data->eoc_irq, data);
	568
d2fffd6c JC	569	if (gpio_is_valid(data->eoc_gpio))
	570	gpio_free(data->eoc_gpio);
	571
7cbb7537	572	iio_device_free(indio_dev);
3285aae1 AC	573
	574	return 0;
	575	}
	576
	577	static const struct i2c_device_id ak8975_id[] = {
6027c077 SP	578	{"ak8975", AK8975},
6027c077 SP	579	{"ak8963", AK8963},
3285aae1 AC	580	{}
	581	};
	582
	583	MODULE_DEVICE_TABLE(i2c, ak8975_id);
	584
54461c30 OJ	585	static const struct of_device_id ak8975_of_match[] = {
	586	{ .compatible = "asahi-kasei,ak8975", },
	587	{ .compatible = "ak8975", },
	588	{ }
	589	};
	590	MODULE_DEVICE_TABLE(of, ak8975_of_match);
	591
3285aae1 AC	592	static struct i2c_driver ak8975_driver = {
	593	.driver = {
	594	.name = "ak8975",
54461c30	595	.of_match_table = ak8975_of_match,
3285aae1 AC	596	},
3285aae1 AC	597	.probe = ak8975_probe,
e543acf0	598	.remove = ak8975_remove,
3285aae1 AC	599	.id_table = ak8975_id,
3285aae1 AC	600	};
6e5af184	601	module_i2c_driver(ak8975_driver);
3285aae1 AC	602
	603	MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
	604	MODULE_DESCRIPTION("AK8975 magnetometer driver");
	605	MODULE_LICENSE("GPL");