Message-Id: <1282910083-8629-2-git-send-email-samu.p.onkalo@nokia.com>
Date:	Fri, 27 Aug 2010 14:54:41 +0300
From:	Samu Onkalo <samu.p.onkalo@...ia.com>
To:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: [PATCH 1/3] drivers: misc: ak8974 / ami305 magnetometer driver

Patch provides support for ak8974 / ami305 3-axis magnetometer chip.
Results are provided via misc character device.
Driver supports multiple instaces of the chip.
Driver has PM and regulator framework support.

Signed-off-by: Samu Onkalo <samu.p.onkalo@...ia.com>
---
 drivers/misc/ak8974.c      |  703 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/ak8974.h |   50 ++++
 2 files changed, 753 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/ak8974.c
 create mode 100644 include/linux/i2c/ak8974.h

diff --git a/drivers/misc/ak8974.c b/drivers/misc/ak8974.c
new file mode 100644
index 0000000..e480314
--- /dev/null
+++ b/drivers/misc/ak8974.c
@@ -0,0 +1,703 @@
+/*
+ * Driver for ak8974 (Asahi Kasei EMD Corporation)
+ * and ami305 (Aichi Steel) magnetometer chip.
+ *
+ * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+ *
+ * Contact: Samu Onkalo <samu.p.onkalo@...ia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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 St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#include <asm/atomic.h>
+#include <linux/delay.h>
+#include <linux/i2c/ak8974.h>
+#include <linux/regulator/consumer.h>
+#include <linux/poll.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/slab.h>
+
+/*
+ * 16-bit registers are little-endian. LSB is at the address defined below
+ * and MSB is at the next higher address.
+ */
+
+/* for AK8974 and AMI305 registers */
+#define AK8974_SELFTEST		0x0C
+#define AK8974_INFO		0x0D
+#define AK8974_WHOAMI		0x0F
+#define AK8974_DATA_X		0x10
+#define AK8974_DATA_Y		0x12
+#define AK8974_DATA_Z		0x14
+#define AK8974_INT_SRC		0x16
+#define AK8974_STATUS		0x18
+#define AK8974_INT_CLEAR	0x1A
+#define AK8974_CTRL1		0x1B
+#define AK8974_CTRL2		0x1C
+#define AK8974_CTRL3		0x1D
+#define AK8974_INT_CTRL		0x1E
+#define AK8974_OFFSET_X		0x20
+#define AK8974_OFFSET_Y		0x22
+#define AK8974_OFFSET_Z		0x24
+#define AK8974_INT_THRES	0x26  /* absolute any axis value threshold */
+#define AK8974_PRESET		0x30
+#define AK8974_TEMP		0x31
+
+#define AK8974_SELFTEST_IDLE	0x55
+#define AK8974_SELFTEST_OK	0xAA
+
+#define AK8974_WHOAMI_VALUE_AMI305 0x47
+#define AK8974_WHOAMI_VALUE_AK8974 0x48
+#define AK8974_INT_X_HIGH	0x80  /* Axis over +threshold  */
+#define AK8974_INT_Y_HIGH	0x40
+#define AK8974_INT_Z_HIGH	0x20
+#define AK8974_INT_X_LOW	0x10  /* Axis below -threshold	*/
+#define AK8974_INT_Y_LOW	0x08
+#define AK8974_INT_Z_LOW	0x04
+#define AK8974_INT_RANGE	0x02  /* Range overflow (any axis)   */
+
+#define AK8974_STATUS_DRDY	0x40  /* Data ready	    */
+#define AK8974_STATUS_OVERRUN	0x20  /* Data overrun	    */
+#define AK8974_STATUS_INT	0x10  /* Interrupt occurred */
+
+#define AK8974_CTRL1_POWER	0x80  /* 0 = standby; 1 = active */
+#define AK8974_CTRL1_RATE	0x10  /* 0 = 10 Hz;   1 = 20 Hz	 */
+#define AK8974_CTRL1_FORCE_EN	0x02  /* 0 = normal;  1 = force	 */
+#define AK8974_CTRL1_MODE2	0x01  /* 0 */
+
+#define AK8974_CTRL2_INT_EN	0x10  /* 1 = enable interrupts	      */
+#define AK8974_CTRL2_DRDY_EN	0x08  /* 1 = enable data ready signal */
+#define AK8974_CTRL2_DRDY_POL	0x04  /* 1 = data ready active high   */
+#define AK8974_CTRL2_RESDEF	(AK8974_CTRL2_DRDY_POL)
+
+#define AK8974_CTRL3_RESET	0x80  /* Software reset		  */
+#define AK8974_CTRL3_FORCE	0x40  /* Start forced measurement */
+#define AK8974_CTRL3_SELFTEST	0x10  /* Set selftest register	  */
+#define AK8974_CTRL3_RESDEF	0x00
+
+#define AK8974_INT_CTRL_XEN	0x80  /* Enable interrupt for this axis */
+#define AK8974_INT_CTRL_YEN	0x40
+#define AK8974_INT_CTRL_ZEN	0x20
+#define AK8974_INT_CTRL_XYZEN	0xE0
+#define AK8974_INT_CTRL_POL	0x08  /* 0 = active low; 1 = active high     */
+#define AK8974_INT_CTRL_PULSE	0x02  /* 0 = latched;	 1 = pulse (50 usec) */
+#define AK8974_INT_CTRL_RESDEF	(AK8974_INT_CTRL_XYZEN | AK8974_INT_CTRL_POL)
+
+#define AK8974_INT_SCR_MROI	0x02
+
+#define AK8974_MAX_RANGE	2048
+
+#define AK8974_POWERON_DELAY	50
+#define AK8974_ACTIVATE_DELAY	1
+#define AK8974_SELFTEST_DELAY	1
+
+#define AK8974_MEASTIME		3
+
+#define AK8974_PWR_ON		1
+#define AK8974_PWR_OFF		0
+
+struct ak8974_chip {
+	struct miscdevice	miscdev;
+	struct mutex		lock;	/* Serialize access to chip */
+	struct mutex		users_lock;
+	struct i2c_client	*client;
+	struct regulator_bulk_data regs[2];
+	struct work_struct	work;
+	wait_queue_head_t	misc_wait;
+	loff_t			offset;
+
+	int			max_range;
+	int			users;
+
+	const char		*id;
+	u8			info[2];
+
+	s16			x, y, z; /* Latest measurements */
+	s8			axis_x;
+	s8			axis_y;
+	s8			axis_z;
+	bool			valid;
+
+	char			name[20];
+};
+
+static const char reg_avdd[] = "AVdd";
+static const char reg_dvdd[] = "DVdd";
+static atomic_t device_number = ATOMIC_INIT(0);
+
+static inline int ak8974_write(struct ak8974_chip *chip, u8 reg, u8 data)
+{
+	return i2c_smbus_write_byte_data(chip->client, reg, data);
+}
+
+static inline int ak8974_read(struct ak8974_chip *chip, u8 reg)
+{
+	return i2c_smbus_read_byte_data(chip->client, reg);
+}
+
+static inline int ak8974_read_block(struct ak8974_chip *chip, u8 reg,
+				u8 *data, u8 length)
+{
+	return i2c_smbus_read_i2c_block_data(chip->client, reg, length, data);
+}
+
+static int ak8974_enable(struct ak8974_chip *chip, bool mode)
+{
+	int r, v;
+
+	v = mode ? AK8974_CTRL1_POWER : 0;
+	v |= AK8974_CTRL1_FORCE_EN;
+	r = ak8974_write(chip, AK8974_CTRL1, v);
+	if (r < 0)
+		return r;
+
+	if (mode)
+		msleep(AK8974_ACTIVATE_DELAY);
+
+	return 0;
+}
+
+static int ak8974_reset(struct ak8974_chip *chip)
+{
+	int r;
+
+	/* Power on to get register access. Sets CTRL1 reg to reset state */
+	r = ak8974_enable(chip, AK8974_PWR_ON);
+	r |= ak8974_write(chip, AK8974_CTRL2, AK8974_CTRL2_RESDEF);
+	r |= ak8974_write(chip, AK8974_CTRL3, AK8974_CTRL3_RESDEF);
+	r |= ak8974_write(chip, AK8974_INT_CTRL, AK8974_INT_CTRL_RESDEF);
+
+	/* After reset, power off is default state */
+	r |= ak8974_enable(chip, AK8974_PWR_OFF);
+
+	return r;
+}
+
+static int ak8974_configure(struct ak8974_chip *chip)
+{
+	int err;
+
+	err = ak8974_write(chip, AK8974_CTRL2, AK8974_CTRL2_DRDY_EN |
+			AK8974_CTRL2_INT_EN);
+	err |= ak8974_write(chip, AK8974_CTRL3, 0);
+	err |= ak8974_write(chip, AK8974_INT_CTRL, AK8974_INT_CTRL_POL);
+	err |= ak8974_write(chip, AK8974_PRESET, 0);
+
+	return err;
+}
+
+static int ak8974_poll_drdy(struct ak8974_chip *chip)
+{
+	int timeout = 2;
+	int ret;
+
+	do {
+		msleep(AK8974_MEASTIME);
+		ret = ak8974_read(chip, AK8974_STATUS);
+		if (ret < 0)
+			return ret;
+		if (ret & AK8974_STATUS_DRDY)
+			return 0;
+	} while (--timeout);
+	return ret;
+}
+
+static int ak8974_trigmeas(struct ak8974_chip *chip)
+{
+	int ctrl3;
+
+	/* Clear previous measurement overflow status */
+	ak8974_read(chip, AK8974_INT_CLEAR);
+
+	ctrl3 = ak8974_read(chip, AK8974_CTRL3);
+	if (ctrl3 < 0)
+		return ctrl3;
+
+	return ak8974_write(chip, AK8974_CTRL3, ctrl3 | AK8974_CTRL3_FORCE);
+}
+
+static int ak8974_getresult(struct ak8974_chip *chip, s16 *result)
+{
+	int ret;
+	int i;
+
+	ret = ak8974_poll_drdy(chip);
+	/* Measurement overflow ? */
+	ret |= ak8974_read(chip, AK8974_INT_SRC);
+	if (ret < 0)
+		return ret;
+	if (ret & AK8974_INT_SCR_MROI)
+		ret = -ERANGE;
+	else
+		ret = 0;
+
+	ak8974_read_block(chip, AK8974_DATA_X, (u8 *)result, 6);
+	for (i = 0; i < 3; i++)
+		result[i] = le16_to_cpu(result[i]);
+
+	return ret;
+}
+
+static int ak8974_selftest(struct ak8974_chip *chip)
+{
+	int r;
+	int ret = -EIO;
+
+	r = ak8974_read(chip, AK8974_SELFTEST);
+	if (r != AK8974_SELFTEST_IDLE)
+		goto out;
+
+	r = ak8974_read(chip, AK8974_CTRL3);
+	if (r < 0)
+		goto out;
+
+	r = ak8974_write(chip, AK8974_CTRL3, r | AK8974_CTRL3_SELFTEST);
+	if (r < 0)
+		goto out;
+
+	msleep(AK8974_SELFTEST_DELAY);
+
+	r = ak8974_read(chip, AK8974_SELFTEST);
+	if (r != AK8974_SELFTEST_OK)
+		goto out;
+
+	r = ak8974_read(chip, AK8974_SELFTEST);
+	if (r == AK8974_SELFTEST_IDLE)
+		ret = 0;
+
+out:
+	return ret;
+}
+
+static int ak8974_regulators_on(struct ak8974_chip *chip)
+{
+	int ret;
+	ret = regulator_bulk_enable(ARRAY_SIZE(chip->regs), chip->regs);
+	if (ret == 0)
+		msleep(AK8974_POWERON_DELAY);
+
+	return ret;
+}
+
+static inline void ak8974_regulators_off(struct ak8974_chip *chip)
+{
+	regulator_bulk_disable(ARRAY_SIZE(chip->regs), chip->regs);
+}
+
+static int ak8974_add_users(struct ak8974_chip *chip)
+{
+	int r = 0;
+	mutex_lock(&chip->users_lock);
+
+	if (chip->users == 0) {
+		r = ak8974_regulators_on(chip);
+		if (r < 0)
+			goto release_lock;
+		r = ak8974_enable(chip, AK8974_PWR_ON);
+		if (r < 0)
+			goto fail2;
+		r = ak8974_configure(chip);
+		if (r < 0)
+			goto fail3;
+	}
+	chip->users++;
+	goto release_lock;
+fail3:
+	ak8974_enable(chip, AK8974_PWR_OFF);
+fail2:
+	ak8974_regulators_off(chip);
+release_lock:
+	mutex_unlock(&chip->users_lock);
+	return r;
+}
+
+static void ak8974_remove_users(struct ak8974_chip *chip)
+{
+	mutex_lock(&chip->users_lock);
+
+	if (chip->users != 0)
+		chip->users--;
+
+	if (chip->users == 0) {
+		ak8974_enable(chip, AK8974_PWR_OFF);
+		ak8974_regulators_off(chip);
+	}
+	mutex_unlock(&chip->users_lock);
+}
+
+static int ak8974_get_axis(s8 axis, s16 hw_values[3])
+{
+	if (axis > 0)
+		return hw_values[axis - 1];
+	else
+		return -hw_values[-axis - 1];
+}
+
+static int ak8974_read_values(struct ak8974_chip *chip)
+{
+	s16 hw_values[3];
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ak8974_trigmeas(chip);
+	ret = ak8974_getresult(chip, hw_values);
+	chip->x = ak8974_get_axis(chip->axis_x, hw_values);
+	chip->y = ak8974_get_axis(chip->axis_y, hw_values);
+	chip->z = ak8974_get_axis(chip->axis_z, hw_values);
+	chip->valid = (ret == 0) ? 1 : 0;
+	chip->offset += sizeof(struct ak8974_data);
+	mutex_unlock(&chip->lock);
+	wake_up_interruptible(&chip->misc_wait);
+	return 0;
+}
+
+static void ak8974_work(struct work_struct *work)
+{
+	struct ak8974_chip *chip = container_of(work,
+						struct ak8974_chip,
+						work);
+	ak8974_read_values(chip);
+}
+
+static int ak8974_misc_open(struct inode *inode, struct file *file)
+{
+	struct ak8974_chip *chip = container_of(file->private_data,
+						struct ak8974_chip,
+						miscdev);
+	file->f_pos = chip->offset;
+	return ak8974_add_users(chip);
+}
+
+static int ak8974_misc_close(struct inode *inode, struct file *file)
+{
+	struct ak8974_chip *chip = container_of(file->private_data,
+						struct ak8974_chip,
+						miscdev);
+	ak8974_remove_users(chip);
+	return 0;
+}
+
+static ssize_t ak8974_misc_read(struct file *file, char __user *buf,
+			size_t count, loff_t *offset)
+{
+	struct ak8974_chip *chip = container_of(file->private_data,
+						struct ak8974_chip,
+						miscdev);
+	struct ak8974_data data;
+
+	if (count < sizeof(data))
+		return -EINVAL;
+
+	if (*offset >= chip->offset) {
+		schedule_work(&chip->work);
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		if (wait_event_interruptible(chip->misc_wait,
+						(*offset < chip->offset)))
+			return -ERESTARTSYS;
+	}
+
+	mutex_lock(&chip->lock);
+	data.x = chip->x;
+	data.y = chip->y;
+	data.z = chip->z;
+	data.valid = chip->valid;
+	*offset = chip->offset;
+	mutex_unlock(&chip->lock);
+
+	return copy_to_user(buf, &data, sizeof(data)) ? -EFAULT : sizeof(data);
+}
+
+static ssize_t ak8974_show_selftest(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct ak8974_chip *chip = dev_get_drvdata(dev);
+	int ret;
+
+	ak8974_add_users(chip);
+	mutex_lock(&chip->lock);
+	ret = ak8974_selftest(chip);
+	mutex_unlock(&chip->lock);
+	ak8974_remove_users(chip);
+
+	return sprintf(buf, "%s\n", ret ? "FAIL" : "OK");
+}
+
+static DEVICE_ATTR(selftest, S_IRUGO, ak8974_show_selftest, NULL);
+
+static ssize_t ak8974_show_chip_id(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct ak8974_chip *chip = dev_get_drvdata(dev);
+	return sprintf(buf, "%s rev %d\n", chip->id,
+		chip->info[0] | (u16)chip->info[1] << 8);
+}
+
+static DEVICE_ATTR(chip_id, S_IRUGO, ak8974_show_chip_id, NULL);
+
+static ssize_t ak8974_show_range(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct ak8974_chip *chip = dev_get_drvdata(dev);
+	return sprintf(buf, "%d\n", chip->max_range);
+}
+
+static DEVICE_ATTR(range, S_IRUGO, ak8974_show_range, NULL);
+
+static struct attribute *sysfs_attrs[] = {
+	&dev_attr_selftest.attr,
+	&dev_attr_range.attr,
+	&dev_attr_chip_id.attr,
+	NULL
+};
+
+static struct attribute_group ak8974_attribute_group = {
+	.attrs = sysfs_attrs
+};
+
+static const struct file_operations ak8974_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.read		= ak8974_misc_read,
+	.open		= ak8974_misc_open,
+	.release	= ak8974_misc_close,
+};
+
+static int ak8974_detect(struct ak8974_chip *chip, const char *name)
+{
+	int whoiam;
+	whoiam = ak8974_read(chip, AK8974_WHOAMI);
+
+	switch (whoiam) {
+	case AK8974_WHOAMI_VALUE_AMI305:
+		chip->id = chip->client->driver->id_table[0].name;
+		break;
+	case AK8974_WHOAMI_VALUE_AK8974:
+		chip->id = chip->client->driver->id_table[1].name;
+		break;
+	default:
+		dev_dbg(&chip->client->dev, "unsupported device\n");
+		return -ENODEV;
+	}
+
+	ak8974_read_block(chip, AK8974_INFO, chip->info, 2);
+
+	chip->max_range = AK8974_MAX_RANGE;
+
+	return 0;
+}
+
+static int __devinit ak8974_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	struct ak8974_chip *chip;
+	struct ak8974_platform_data *pdata;
+	int err;
+	int x, y, z;
+
+	chip = kzalloc(sizeof *chip, GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, chip);
+	chip->client  = client;
+
+	pdata = client->dev.platform_data;
+
+	x = AK8974_DEV_X;
+	y = AK8974_DEV_Y;
+	z = AK8974_DEV_Z;
+
+	if (pdata) {
+		/* Remap axes */
+		x = pdata->axis_x ? pdata->axis_x : x;
+		y = pdata->axis_y ? pdata->axis_y : y;
+		z = pdata->axis_z ? pdata->axis_z : z;
+	}
+
+	if ((abs(x) > 3) || (abs(y) > 3) || (abs(z) > 3)) {
+		dev_err(&client->dev, "Incorrect platform data\n");
+		err = -EINVAL;
+		goto fail1;
+	}
+
+	chip->axis_x = x;
+	chip->axis_y = y;
+	chip->axis_z = z;
+
+	mutex_init(&chip->lock);
+	mutex_init(&chip->users_lock);
+	init_waitqueue_head(&chip->misc_wait);
+	INIT_WORK(&chip->work, ak8974_work);
+
+	chip->regs[0].supply = reg_avdd;
+	chip->regs[1].supply = reg_dvdd;
+
+	err = regulator_bulk_get(&client->dev,
+				 ARRAY_SIZE(chip->regs), chip->regs);
+	if (err < 0) {
+		dev_err(&client->dev, "Cannot get regulators\n");
+		goto fail1;
+	}
+
+	err = ak8974_regulators_on(chip);
+	if (err < 0) {
+		dev_err(&client->dev, "Cannot enable regulators\n");
+		goto fail2;
+	}
+
+	err = ak8974_detect(chip, id->name);
+	if (err < 0) {
+		dev_err(&client->dev, "Neither AK8974 nor ami305 found\n");
+		goto fail3;
+	}
+
+	snprintf(chip->name, sizeof(chip->name), "ak8974%d",
+		atomic_add_return(1, &device_number) - 1);
+
+	err = ak8974_reset(chip);
+	if (err) {
+		dev_err(&client->dev, "Chip reset failed");
+		goto fail3;
+	}
+
+	ak8974_regulators_off(chip);
+
+	chip->miscdev.minor  = MISC_DYNAMIC_MINOR;
+	chip->miscdev.name   = chip->name;
+	chip->miscdev.fops   = &ak8974_fops;
+	chip->miscdev.parent = &chip->client->dev;
+	err = misc_register(&chip->miscdev);
+	if (err < 0) {
+		dev_err(&chip->client->dev, "Device registration failed\n");
+		goto fail3;
+	}
+
+	err = sysfs_create_group(&chip->client->dev.kobj,
+				&ak8974_attribute_group);
+	if (err) {
+		dev_err(&client->dev, "Sysfs registration failed\n");
+		goto fail4;
+	}
+
+
+	return 0;
+fail4:
+	misc_deregister(&chip->miscdev);
+fail3:
+	ak8974_regulators_off(chip);
+fail2:
+	regulator_bulk_free(ARRAY_SIZE(chip->regs), chip->regs);
+fail1:
+	kfree(chip);
+	return err;
+}
+
+static int __devexit ak8974_remove(struct i2c_client *client)
+{
+	struct ak8974_chip *chip = i2c_get_clientdata(client);
+	misc_deregister(&chip->miscdev);
+	cancel_work_sync(&chip->work);
+	sysfs_remove_group(&chip->client->dev.kobj,
+			&ak8974_attribute_group);
+	/* No users after sysfs removal and unregisterin of input device */
+	regulator_bulk_free(ARRAY_SIZE(chip->regs), chip->regs);
+	kfree(chip);
+	return 0;
+}
+
+
+#ifdef CONFIG_PM
+static int ak8974_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+	struct ak8974_chip *chip = i2c_get_clientdata(client);
+	mutex_lock(&chip->users_lock);
+	if (chip->users > 0)
+		ak8974_enable(chip, AK8974_PWR_OFF);
+	mutex_unlock(&chip->users_lock);
+	return 0;
+}
+
+static int ak8974_resume(struct i2c_client *client)
+{
+	struct ak8974_chip *chip = i2c_get_clientdata(client);
+	mutex_lock(&chip->users_lock);
+	if (chip->users > 0)
+		ak8974_enable(chip, AK8974_PWR_ON);
+	mutex_unlock(&chip->users_lock);
+	return 0;
+}
+
+static void ak8974_shutdown(struct i2c_client *client)
+{
+	struct ak8974_chip *chip = i2c_get_clientdata(client);
+
+	mutex_lock(&chip->users_lock);
+	if (chip->users > 0)
+		ak8974_enable(chip, AK8974_PWR_OFF);
+
+	mutex_unlock(&chip->users_lock);
+}
+
+#else
+#define ak8974_suspend	NULL
+#define ak8974_shutdown NULL
+#define ak8974_resume	NULL
+#endif
+
+static const struct i2c_device_id ak8974_id[] = {
+	{"ami305", 0 },
+	{"ak8974", 0 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ak8974_id);
+
+static struct i2c_driver ak8974_driver = {
+	.driver	 = {
+		.name	= "ak8974",
+		.owner	= THIS_MODULE,
+	},
+	.suspend  = ak8974_suspend,
+	.shutdown = ak8974_shutdown,
+	.resume	  = ak8974_resume,
+	.probe	  = ak8974_probe,
+	.remove	  = __devexit_p(ak8974_remove),
+	.id_table = ak8974_id,
+};
+
+static int __init ak8974_init(void)
+{
+	return i2c_add_driver(&ak8974_driver);
+}
+
+static void __exit ak8974_exit(void)
+{
+	i2c_del_driver(&ak8974_driver);
+}
+
+
+MODULE_DESCRIPTION("AK8974/5 and AMI305 3-axis magnetometer driver");
+MODULE_AUTHOR("Samu Onkalo, Nokia Corporation");
+MODULE_LICENSE("GPL v2");
+
+module_init(ak8974_init);
+module_exit(ak8974_exit);
diff --git a/include/linux/i2c/ak8974.h b/include/linux/i2c/ak8974.h
new file mode 100644
index 0000000..b991404
--- /dev/null
+++ b/include/linux/i2c/ak8974.h
@@ -0,0 +1,50 @@
+/*
+ * Driver for ak8974 (Asahi Kasei EMD Corporation)
+ * and ami305 (Aichi Steel) magnetometer chip.
+ *
+ * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+ *
+ * Contact: Samu Onkalo <samu.p.onkalo@...ia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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 St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ */
+
+#ifndef __LINUX_I2C_AK8974_H
+#define __LINUX_I2C_AK8974_H
+
+#define AK8974_NO_MAP		  0
+#define AK8974_DEV_X		  1
+#define AK8974_DEV_Y		  2
+#define AK8974_DEV_Z		  3
+#define AK8974_INV_DEV_X	 -1
+#define AK8974_INV_DEV_Y	 -2
+#define AK8974_INV_DEV_Z	 -3
+
+struct ak8974_platform_data {
+	s8 axis_x;
+	s8 axis_y;
+	s8 axis_z;
+};
+
+/* Device name: /dev/ak8974n, where n is a running number */
+struct ak8974_data {
+	__s16 x;
+	__s16 y;
+	__s16 z;
+	__u16 valid;
+} __attribute__((packed));
+
+#endif
-- 
1.6.3.3

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