[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/acpi.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 = devm_request_irq(&client->dev, 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;
	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;
	}

	mutex_unlock(&data->lock);

	/* Clamp to valid range. */
	*val = clamp_t(s16, ret, -4096, 4095);
	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 const struct acpi_device_id ak_acpi_match[] = {
	{"AK8975", AK8975},
	{"AK8963", AK8963},
	{"INVN6500", AK8963},
	{ },
};
MODULE_DEVICE_TABLE(acpi, ak_acpi_match);

static const char *ak8975_match_acpi_device(struct device *dev,
					    enum asahi_compass_chipset *chipset)
{
	const struct acpi_device_id *id;

	id = acpi_match_device(dev->driver->acpi_match_table, dev);
	if (!id)
		return NULL;
	*chipset = (int)id->driver_data;

	return dev_name(dev);
}

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;
	const char *name = NULL;

	/* 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 = devm_gpio_request_one(&client->dev, eoc_gpio,
							GPIOF_IN, "ak_8975");
		if (err < 0) {
			dev_err(&client->dev,
				"failed to request GPIO %d, error %d\n",
							eoc_gpio, err);
			return err;
		}
	}

	/* Register with IIO */
	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;
	data->eoc_gpio = eoc_gpio;
	data->eoc_irq = 0;

	/* id will be NULL when enumerated via ACPI */
	if (id) {
		data->chipset =
			(enum asahi_compass_chipset)(id->driver_data);
		name = id->name;
	} else if (ACPI_HANDLE(&client->dev))
		name = ak8975_match_acpi_device(&client->dev, &data->chipset);
	else
		return -ENOSYS;

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

	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->modes = INDIO_DIRECT_MODE;
	indio_dev->name = name;
	err = devm_iio_device_register(&client->dev, indio_dev);
	if (err < 0)
		return err;

	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,
		.acpi_match_table = ACPI_PTR(ak_acpi_match),
	},
	.probe		= ak8975_probe,
	.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>
d913971e	34	#include <linux/acpi.h>
3285aae1	35
06458e27 JC	36	#include <linux/iio/iio.h>
06458e27 JC	37	#include <linux/iio/sysfs.h>
3285aae1 AC	38	/*
	39	* Register definitions, as well as various shifts and masks to get at the
	40	* individual fields of the registers.
	41	*/
	42	#define AK8975_REG_WIA 0x00
	43	#define AK8975_DEVICE_ID 0x48
	44
	45	#define AK8975_REG_INFO 0x01
	46
	47	#define AK8975_REG_ST1 0x02
	48	#define AK8975_REG_ST1_DRDY_SHIFT 0
	49	#define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT)
	50
	51	#define AK8975_REG_HXL 0x03
	52	#define AK8975_REG_HXH 0x04
	53	#define AK8975_REG_HYL 0x05
	54	#define AK8975_REG_HYH 0x06
	55	#define AK8975_REG_HZL 0x07
	56	#define AK8975_REG_HZH 0x08
	57	#define AK8975_REG_ST2 0x09
	58	#define AK8975_REG_ST2_DERR_SHIFT 2
	59	#define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT)
	60
	61	#define AK8975_REG_ST2_HOFL_SHIFT 3
	62	#define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
	63
	64	#define AK8975_REG_CNTL 0x0A
	65	#define AK8975_REG_CNTL_MODE_SHIFT 0
	66	#define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT)
	67	#define AK8975_REG_CNTL_MODE_POWER_DOWN 0
	68	#define AK8975_REG_CNTL_MODE_ONCE 1
	69	#define AK8975_REG_CNTL_MODE_SELF_TEST 8
	70	#define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF
	71
	72	#define AK8975_REG_RSVC 0x0B
	73	#define AK8975_REG_ASTC 0x0C
	74	#define AK8975_REG_TS1 0x0D
	75	#define AK8975_REG_TS2 0x0E
	76	#define AK8975_REG_I2CDIS 0x0F
	77	#define AK8975_REG_ASAX 0x10
	78	#define AK8975_REG_ASAY 0x11
	79	#define AK8975_REG_ASAZ 0x12
	80
	81	#define AK8975_MAX_REGS AK8975_REG_ASAZ
	82
	83	/*
	84	* Miscellaneous values.
	85	*/
	86	#define AK8975_MAX_CONVERSION_TIMEOUT 500
	87	#define AK8975_CONVERSION_DONE_POLL_TIME 10
94a6d5cf	88	#define AK8975_DATA_READY_TIMEOUT ((100*HZ)/1000)
6027c077 SP	89	#define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256)
	90	#define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256)
	91
	92	/* Compatible Asahi Kasei Compass parts */
	93	enum asahi_compass_chipset {
	94	AK8975,
	95	AK8963,
	96	};
3285aae1 AC	97
	98	/*
	99	* Per-instance context data for the device.
	100	*/
	101	struct ak8975_data {
	102	struct i2c_client *client;
3285aae1 AC	103	struct attribute_group attrs;
	104	struct mutex lock;
	105	u8 asa[3];
	106	long raw_to_gauss[3];
3285aae1 AC	107	u8 reg_cache[AK8975_MAX_REGS];
3285aae1 AC	108	int eoc_gpio;
94a6d5cf JA	109	int eoc_irq;
	110	wait_queue_head_t data_ready_queue;
	111	unsigned long flags;
6027c077	112	enum asahi_compass_chipset chipset;
3285aae1 AC	113	};
3285aae1 AC	114
694e1b5f JC	115	static const int ak8975_index_to_reg[] = {
	116	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
	117	};
	118
3285aae1 AC	119	/*
	120	* Helper function to write to the I2C device's registers.
	121	*/
	122	static int ak8975_write_data(struct i2c_client *client,
	123	u8 reg, u8 val, u8 mask, u8 shift)
	124	{
40f32d93 PC	125	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	126	struct ak8975_data *data = iio_priv(indio_dev);
694e1b5f JC	127	u8 regval;
694e1b5f JC	128	int ret;
3285aae1	129
694e1b5f JC	130	regval = (data->reg_cache[reg] & ~mask) \| (val << shift);
694e1b5f JC	131	ret = i2c_smbus_write_byte_data(client, reg, regval);
3285aae1 AC	132	if (ret < 0) {
	133	dev_err(&client->dev, "Write to device fails status %x\n", ret);
	134	return ret;
	135	}
	136	data->reg_cache[reg] = regval;
	137
	138	return 0;
	139	}
	140
94a6d5cf JA	141	/*
	142	* Handle data ready irq
	143	*/
	144	static irqreturn_t ak8975_irq_handler(int irq, void *data)
	145	{
	146	struct ak8975_data *ak8975 = data;
	147
	148	set_bit(0, &ak8975->flags);
	149	wake_up(&ak8975->data_ready_queue);
	150
	151	return IRQ_HANDLED;
	152	}
	153
	154	/*
	155	* Install data ready interrupt handler
	156	*/
	157	static int ak8975_setup_irq(struct ak8975_data *data)
	158	{
	159	struct i2c_client *client = data->client;
	160	int rc;
	161	int irq;
	162
	163	if (client->irq)
	164	irq = client->irq;
	165	else
	166	irq = gpio_to_irq(data->eoc_gpio);
	167
a845a3aa	168	rc = devm_request_irq(&client->dev, irq, ak8975_irq_handler,
94a6d5cf JA	169	IRQF_TRIGGER_RISING \| IRQF_ONESHOT,
	170	dev_name(&client->dev), data);
	171	if (rc < 0) {
	172	dev_err(&client->dev,
	173	"irq %d request failed, (gpio %d): %d\n",
	174	irq, data->eoc_gpio, rc);
	175	return rc;
	176	}
	177
	178	init_waitqueue_head(&data->data_ready_queue);
	179	clear_bit(0, &data->flags);
	180	data->eoc_irq = irq;
	181
	182	return rc;
	183	}
	184
	185
3285aae1 AC	186	/*
	187	* Perform some start-of-day setup, including reading the asa calibration
	188	* values and caching them.
	189	*/
	190	static int ak8975_setup(struct i2c_client *client)
	191	{
40f32d93 PC	192	struct iio_dev *indio_dev = i2c_get_clientdata(client);
40f32d93 PC	193	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1 AC	194	u8 device_id;
	195	int ret;
	196
	197	/* Confirm that the device we're talking to is really an AK8975. */
c411f600	198	ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
3285aae1 AC	199	if (ret < 0) {
	200	dev_err(&client->dev, "Error reading WIA\n");
	201	return ret;
	202	}
c411f600	203	device_id = ret;
3285aae1 AC	204	if (device_id != AK8975_DEVICE_ID) {
	205	dev_err(&client->dev, "Device ak8975 not found\n");
	206	return -ENODEV;
	207	}
	208
	209	/* Write the fused rom access mode. */
	210	ret = ak8975_write_data(client,
	211	AK8975_REG_CNTL,
	212	AK8975_REG_CNTL_MODE_FUSE_ROM,
	213	AK8975_REG_CNTL_MODE_MASK,
	214	AK8975_REG_CNTL_MODE_SHIFT);
	215	if (ret < 0) {
	216	dev_err(&client->dev, "Error in setting fuse access mode\n");
	217	return ret;
	218	}
	219
	220	/* Get asa data and store in the device data. */
c411f600 JC	221	ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX,
c411f600 JC	222	3, data->asa);
3285aae1 AC	223	if (ret < 0) {
	224	dev_err(&client->dev, "Not able to read asa data\n");
	225	return ret;
	226	}
	227
040f3e58 LA	228	/* After reading fuse ROM data set power-down mode */
	229	ret = ak8975_write_data(client,
	230	AK8975_REG_CNTL,
	231	AK8975_REG_CNTL_MODE_POWER_DOWN,
	232	AK8975_REG_CNTL_MODE_MASK,
	233	AK8975_REG_CNTL_MODE_SHIFT);
94a6d5cf JA	234
	235	if (data->eoc_gpio > 0 \|\| client->irq) {
	236	ret = ak8975_setup_irq(data);
	237	if (ret < 0) {
	238	dev_err(&client->dev,
	239	"Error setting data ready interrupt\n");
	240	return ret;
	241	}
	242	}
	243
040f3e58 LA	244	if (ret < 0) {
	245	dev_err(&client->dev, "Error in setting power-down mode\n");
	246	return ret;
	247	}
	248
694e1b5f JC	249	/*
	250	* Precalculate scale factor (in Gauss units) for each axis and
	251	* store in the device data.
	252	*
	253	* This scale factor is axis-dependent, and is derived from 3 calibration
	254	* factors ASA(x), ASA(y), and ASA(z).
	255	*
	256	* These ASA values are read from the sensor device at start of day, and
	257	* cached in the device context struct.
	258	*
	259	* Adjusting the flux value with the sensitivity adjustment value should be
	260	* done via the following formula:
	261	*
	262	* Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
	263	*
	264	* where H is the raw value, ASA is the sensitivity adjustment, and Hadj
	265	* is the resultant adjusted value.
	266	*
	267	* We reduce the formula to:
	268	*
	269	* Hadj = H * (ASA + 128) / 256
	270	*
	271	* H is in the range of -4096 to 4095. The magnetometer has a range of
	272	* +-1229uT. To go from the raw value to uT is:
	273	*
	274	* HuT = H * 1229/4096, or roughly, 3/10.
	275	*
eb03610a	276	* Since 1uT = 0.01 gauss, our final scale factor becomes:
694e1b5f	277	*
bef44abc BS	278	* Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
bef44abc BS	279	* Hadj = H * ((ASA + 128) * 0.003) / 256
694e1b5f JC	280	*
	281	* Since ASA doesn't change, we cache the resultant scale factor into the
	282	* device context in ak8975_setup().
	283	*/
6027c077 SP	284	if (data->chipset == AK8963) {
	285	/*
	286	* H range is +-8190 and magnetometer range is +-4912.
	287	* So HuT using the above explanation for 8975,
	288	* 4912/8190 = ~ 6/10.
	289	* So the Hadj should use 6/10 instead of 3/10.
	290	*/
	291	data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]);
	292	data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]);
	293	data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]);
	294	} else {
	295	data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]);
	296	data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]);
	297	data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]);
	298	}
3285aae1 AC	299
	300	return 0;
	301	}
	302
01fbb478 AC	303	static int wait_conversion_complete_gpio(struct ak8975_data *data)
	304	{
	305	struct i2c_client *client = data->client;
01fbb478 AC	306	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	307	int ret;
	308
	309	/* Wait for the conversion to complete. */
	310	while (timeout_ms) {
	311	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
	312	if (gpio_get_value(data->eoc_gpio))
	313	break;
	314	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	315	}
	316	if (!timeout_ms) {
	317	dev_err(&client->dev, "Conversion timeout happened\n");
	318	return -EINVAL;
	319	}
	320
c411f600 JC	321	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
c411f600 JC	322	if (ret < 0)
01fbb478	323	dev_err(&client->dev, "Error in reading ST1\n");
c411f600 JC	324
c411f600 JC	325	return ret;
01fbb478 AC	326	}
	327
	328	static int wait_conversion_complete_polled(struct ak8975_data *data)
	329	{
	330	struct i2c_client *client = data->client;
	331	u8 read_status;
	332	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	333	int ret;
	334
	335	/* Wait for the conversion to complete. */
	336	while (timeout_ms) {
	337	msleep(AK8975_CONVERSION_DONE_POLL_TIME);
c411f600	338	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
01fbb478 AC	339	if (ret < 0) {
	340	dev_err(&client->dev, "Error in reading ST1\n");
	341	return ret;
	342	}
c411f600	343	read_status = ret;
01fbb478 AC	344	if (read_status)
	345	break;
	346	timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	347	}
	348	if (!timeout_ms) {
	349	dev_err(&client->dev, "Conversion timeout happened\n");
	350	return -EINVAL;
	351	}
94a6d5cf	352
01fbb478 AC	353	return read_status;
	354	}
	355
94a6d5cf JA	356	/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
	357	static int wait_conversion_complete_interrupt(struct ak8975_data *data)
	358	{
	359	int ret;
	360
	361	ret = wait_event_timeout(data->data_ready_queue,
	362	test_bit(0, &data->flags),
	363	AK8975_DATA_READY_TIMEOUT);
	364	clear_bit(0, &data->flags);
	365
	366	return ret > 0 ? 0 : -ETIME;
	367	}
	368
3285aae1 AC	369	/*
	370	* Emits the raw flux value for the x, y, or z axis.
	371	*/
694e1b5f	372	static int ak8975_read_axis(struct iio_dev indio_dev, int index, int val)
3285aae1	373	{
338473c8	374	struct ak8975_data *data = iio_priv(indio_dev);
3285aae1	375	struct i2c_client *client = data->client;
3285aae1 AC	376	int ret;
	377
	378	mutex_lock(&data->lock);
	379
3285aae1 AC	380	/* Set up the device for taking a sample. */
	381	ret = ak8975_write_data(client,
	382	AK8975_REG_CNTL,
	383	AK8975_REG_CNTL_MODE_ONCE,
	384	AK8975_REG_CNTL_MODE_MASK,
	385	AK8975_REG_CNTL_MODE_SHIFT);
	386	if (ret < 0) {
	387	dev_err(&client->dev, "Error in setting operating mode\n");
	388	goto exit;
	389	}
	390
	391	/* Wait for the conversion to complete. */
94a6d5cf JA	392	if (data->eoc_irq)
	393	ret = wait_conversion_complete_interrupt(data);
	394	else if (gpio_is_valid(data->eoc_gpio))
01fbb478 AC	395	ret = wait_conversion_complete_gpio(data);
	396	else
	397	ret = wait_conversion_complete_polled(data);
	398	if (ret < 0)
3285aae1	399	goto exit;
3285aae1	400
94a6d5cf	401	/* This will be executed only for non-interrupt based waiting case */
c411f600 JC	402	if (ret & AK8975_REG_ST1_DRDY_MASK) {
c411f600 JC	403	ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
3285aae1 AC	404	if (ret < 0) {
	405	dev_err(&client->dev, "Error in reading ST2\n");
	406	goto exit;
	407	}
c411f600 JC	408	if (ret & (AK8975_REG_ST2_DERR_MASK \|
	409	AK8975_REG_ST2_HOFL_MASK)) {
	410	dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
3285aae1 AC	411	ret = -EINVAL;
	412	goto exit;
	413	}
	414	}
	415
	416	/* Read the flux value from the appropriate register
	417	(the register is specified in the iio device attributes). */
c411f600	418	ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
3285aae1 AC	419	if (ret < 0) {
	420	dev_err(&client->dev, "Read axis data fails\n");
	421	goto exit;
	422	}
	423
	424	mutex_unlock(&data->lock);
	425
3285aae1	426	/* Clamp to valid range. */
8ba42fb7	427	*val = clamp_t(s16, ret, -4096, 4095);
694e1b5f	428	return IIO_VAL_INT;
3285aae1 AC	429
	430	exit:
	431	mutex_unlock(&data->lock);
	432	return ret;
	433	}
	434
694e1b5f JC	435	static int ak8975_read_raw(struct iio_dev *indio_dev,
	436	struct iio_chan_spec const *chan,
	437	int val, int val2,
	438	long mask)
	439	{
	440	struct ak8975_data *data = iio_priv(indio_dev);
	441
	442	switch (mask) {
4d9948b3	443	case IIO_CHAN_INFO_RAW:
694e1b5f	444	return ak8975_read_axis(indio_dev, chan->address, val);
c8a9f805	445	case IIO_CHAN_INFO_SCALE:
bef44abc BS	446	*val = 0;
	447	*val2 = data->raw_to_gauss[chan->address];
	448	return IIO_VAL_INT_PLUS_MICRO;
694e1b5f JC	449	}
	450	return -EINVAL;
	451	}
	452
	453	#define AK8975_CHANNEL(axis, index) \
	454	{ \
	455	.type = IIO_MAGN, \
	456	.modified = 1, \
	457	.channel2 = IIO_MOD_##axis, \
3a0b4422 JC	458	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \| \
3a0b4422 JC	459	BIT(IIO_CHAN_INFO_SCALE), \
694e1b5f JC	460	.address = index, \
	461	}
	462
	463	static const struct iio_chan_spec ak8975_channels[] = {
	464	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
	465	};
	466
6fe8135f	467	static const struct iio_info ak8975_info = {
694e1b5f	468	.read_raw = &ak8975_read_raw,
6fe8135f JC	469	.driver_module = THIS_MODULE,
	470	};
	471
d913971e SP	472	static const struct acpi_device_id ak_acpi_match[] = {
	473	{"AK8975", AK8975},
	474	{"AK8963", AK8963},
	475	{"INVN6500", AK8963},
	476	{ },
	477	};
	478	MODULE_DEVICE_TABLE(acpi, ak_acpi_match);
	479
48edc374 IT	480	static const char ak8975_match_acpi_device(struct device dev,
48edc374 IT	481	enum asahi_compass_chipset *chipset)
d913971e SP	482	{
	483	const struct acpi_device_id *id;
	484
	485	id = acpi_match_device(dev->driver->acpi_match_table, dev);
	486	if (!id)
	487	return NULL;
	488	*chipset = (int)id->driver_data;
	489
48edc374	490	return dev_name(dev);
d913971e SP	491	}
d913971e SP	492
4ae1c61f	493	static int ak8975_probe(struct i2c_client *client,
3285aae1 AC	494	const struct i2c_device_id *id)
	495	{
	496	struct ak8975_data *data;
338473c8 JC	497	struct iio_dev *indio_dev;
338473c8 JC	498	int eoc_gpio;
3285aae1	499	int err;
48edc374	500	const char *name = NULL;
3285aae1	501
3285aae1	502	/* Grab and set up the supplied GPIO. */
f4b7f751	503	if (client->dev.platform_data)
f6d838d7	504	eoc_gpio = (int )(client->dev.platform_data);
f4b7f751 JA	505	else if (client->dev.of_node)
	506	eoc_gpio = of_get_gpio(client->dev.of_node, 0);
	507	else
	508	eoc_gpio = -1;
	509
	510	if (eoc_gpio == -EPROBE_DEFER)
	511	return -EPROBE_DEFER;
3285aae1	512
01fbb478 AC	513	/* We may not have a GPIO based IRQ to scan, that is fine, we will
01fbb478 AC	514	poll if so */
7c6c9368	515	if (gpio_is_valid(eoc_gpio)) {
a845a3aa BS	516	err = devm_gpio_request_one(&client->dev, eoc_gpio,
a845a3aa BS	517	GPIOF_IN, "ak_8975");
01fbb478 AC	518	if (err < 0) {
	519	dev_err(&client->dev,
	520	"failed to request GPIO %d, error %d\n",
338473c8	521	eoc_gpio, err);
a845a3aa	522	return err;
01fbb478	523	}
7c6c9368	524	}
3285aae1	525
338473c8	526	/* Register with IIO */
a845a3aa BS	527	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	528	if (indio_dev == NULL)
	529	return -ENOMEM;
	530
338473c8	531	data = iio_priv(indio_dev);
40f32d93	532	i2c_set_clientdata(client, indio_dev);
94a6d5cf JA	533
	534	data->client = client;
	535	data->eoc_gpio = eoc_gpio;
	536	data->eoc_irq = 0;
	537
d913971e SP	538	/* id will be NULL when enumerated via ACPI */
	539	if (id) {
	540	data->chipset =
	541	(enum asahi_compass_chipset)(id->driver_data);
48edc374	542	name = id->name;
d913971e SP	543	} else if (ACPI_HANDLE(&client->dev))
d913971e SP	544	name = ak8975_match_acpi_device(&client->dev, &data->chipset);
a845a3aa BS	545	else
	546	return -ENOSYS;
	547
d913971e	548	dev_dbg(&client->dev, "Asahi compass chip %s\n", name);
6027c077	549
3285aae1 AC	550	/* Perform some basic start-of-day setup of the device. */
	551	err = ak8975_setup(client);
	552	if (err < 0) {
	553	dev_err(&client->dev, "AK8975 initialization fails\n");
a845a3aa	554	return err;
3285aae1 AC	555	}
3285aae1 AC	556
338473c8 JC	557	data->client = client;
338473c8 JC	558	mutex_init(&data->lock);
338473c8 JC	559	data->eoc_gpio = eoc_gpio;
338473c8 JC	560	indio_dev->dev.parent = &client->dev;
694e1b5f JC	561	indio_dev->channels = ak8975_channels;
694e1b5f JC	562	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
338473c8 JC	563	indio_dev->info = &ak8975_info;
338473c8 JC	564	indio_dev->modes = INDIO_DIRECT_MODE;
d913971e	565	indio_dev->name = name;
a845a3aa	566	err = devm_iio_device_register(&client->dev, indio_dev);
3285aae1	567	if (err < 0)
a845a3aa	568	return err;
3285aae1 AC	569
	570	return 0;
	571	}
	572
	573	static const struct i2c_device_id ak8975_id[] = {
6027c077 SP	574	{"ak8975", AK8975},
6027c077 SP	575	{"ak8963", AK8963},
3285aae1 AC	576	{}
	577	};
	578
	579	MODULE_DEVICE_TABLE(i2c, ak8975_id);
	580
54461c30 OJ	581	static const struct of_device_id ak8975_of_match[] = {
	582	{ .compatible = "asahi-kasei,ak8975", },
	583	{ .compatible = "ak8975", },
	584	{ }
	585	};
	586	MODULE_DEVICE_TABLE(of, ak8975_of_match);
	587
3285aae1 AC	588	static struct i2c_driver ak8975_driver = {
	589	.driver = {
	590	.name = "ak8975",
54461c30	591	.of_match_table = ak8975_of_match,
d913971e	592	.acpi_match_table = ACPI_PTR(ak_acpi_match),
3285aae1 AC	593	},
3285aae1 AC	594	.probe = ak8975_probe,
3285aae1 AC	595	.id_table = ak8975_id,
3285aae1 AC	596	};
6e5af184	597	module_i2c_driver(ak8975_driver);
3285aae1 AC	598
	599	MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
	600	MODULE_DESCRIPTION("AK8975 magnetometer driver");
	601	MODULE_LICENSE("GPL");