Initial import

1 files changed, 850 insertions, 0 deletions

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
new file mode 100644
index 000000000..b13936dac
--- /dev/null
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -0,0 +1,850 @@
+/*
+ * 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	0x00
+#define AK8975_REG_CNTL_MODE_ONCE	0x01
+#define AK8975_REG_CNTL_MODE_SELF_TEST	0x08
+#define AK8975_REG_CNTL_MODE_FUSE_ROM	0x0F
+
+#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
+
+/*
+ * AK09912 Register definitions
+ */
+#define AK09912_REG_WIA1		0x00
+#define AK09912_REG_WIA2		0x01
+#define AK09912_DEVICE_ID		0x04
+#define AK09911_DEVICE_ID		0x05
+
+#define AK09911_REG_INFO1		0x02
+#define AK09911_REG_INFO2		0x03
+
+#define AK09912_REG_ST1			0x10
+
+#define AK09912_REG_ST1_DRDY_SHIFT	0
+#define AK09912_REG_ST1_DRDY_MASK	(1 << AK09912_REG_ST1_DRDY_SHIFT)
+
+#define AK09912_REG_HXL			0x11
+#define AK09912_REG_HXH			0x12
+#define AK09912_REG_HYL			0x13
+#define AK09912_REG_HYH			0x14
+#define AK09912_REG_HZL			0x15
+#define AK09912_REG_HZH			0x16
+#define AK09912_REG_TMPS		0x17
+
+#define AK09912_REG_ST2			0x18
+#define AK09912_REG_ST2_HOFL_SHIFT	3
+#define AK09912_REG_ST2_HOFL_MASK	(1 << AK09912_REG_ST2_HOFL_SHIFT)
+
+#define AK09912_REG_CNTL1		0x30
+
+#define AK09912_REG_CNTL2		0x31
+#define AK09912_REG_CNTL_MODE_POWER_DOWN	0x00
+#define AK09912_REG_CNTL_MODE_ONCE	0x01
+#define AK09912_REG_CNTL_MODE_SELF_TEST	0x10
+#define AK09912_REG_CNTL_MODE_FUSE_ROM	0x1F
+#define AK09912_REG_CNTL2_MODE_SHIFT	0
+#define AK09912_REG_CNTL2_MODE_MASK	(0x1F << AK09912_REG_CNTL2_MODE_SHIFT)
+
+#define AK09912_REG_CNTL3		0x32
+
+#define AK09912_REG_TS1			0x33
+#define AK09912_REG_TS2			0x34
+#define AK09912_REG_TS3			0x35
+#define AK09912_REG_I2CDIS		0x36
+#define AK09912_REG_TS4			0x37
+
+#define AK09912_REG_ASAX		0x60
+#define AK09912_REG_ASAY		0x61
+#define AK09912_REG_ASAZ		0x62
+
+#define AK09912_MAX_REGS		AK09912_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)
+
+/*
+ * 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().
+ *
+ * Given we use IIO_VAL_INT_PLUS_MICRO bit when displaying the scale, we
+ * multiply the stored scale value by 1e6.
+ */
+static long ak8975_raw_to_gauss(u16 data)
+{
+	return (((long)data + 128) * 3000) / 256;
+}
+
+/*
+ * For AK8963 and AK09911, same calculation, but the device is less sensitive:
+ *
+ * H is in the range of +-8190.  The magnetometer has a range of
+ * +-4912uT.  To go from the raw value to uT is:
+ *
+ * HuT = H * 4912/8190, or roughly, 6/10, instead of 3/10.
+ */
+
+static long ak8963_09911_raw_to_gauss(u16 data)
+{
+	return (((long)data + 128) * 6000) / 256;
+}
+
+/*
+ * For AK09912, same calculation, except the device is more sensitive:
+ *
+ * H is in the range of -32752 to 32752.  The magnetometer has a range of
+ * +-4912uT.  To go from the raw value to uT is:
+ *
+ * HuT = H * 4912/32752, or roughly, 3/20, instead of 3/10.
+ */
+static long ak09912_raw_to_gauss(u16 data)
+{
+	return (((long)data + 128) * 1500) / 256;
+}
+
+/* Compatible Asahi Kasei Compass parts */
+enum asahi_compass_chipset {
+	AK8975,
+	AK8963,
+	AK09911,
+	AK09912,
+	AK_MAX_TYPE
+};
+
+enum ak_ctrl_reg_addr {
+	ST1,
+	ST2,
+	CNTL,
+	ASA_BASE,
+	MAX_REGS,
+	REGS_END,
+};
+
+enum ak_ctrl_reg_mask {
+	ST1_DRDY,
+	ST2_HOFL,
+	ST2_DERR,
+	CNTL_MODE,
+	MASK_END,
+};
+
+enum ak_ctrl_mode {
+	POWER_DOWN,
+	MODE_ONCE,
+	SELF_TEST,
+	FUSE_ROM,
+	MODE_END,
+};
+
+struct ak_def {
+	enum asahi_compass_chipset type;
+	long (*raw_to_gauss)(u16 data);
+	u16 range;
+	u8 ctrl_regs[REGS_END];
+	u8 ctrl_masks[MASK_END];
+	u8 ctrl_modes[MODE_END];
+	u8 data_regs[3];
+};
+
+static struct ak_def ak_def_array[AK_MAX_TYPE] = {
+	{
+		.type = AK8975,
+		.raw_to_gauss = ak8975_raw_to_gauss,
+		.range = 4096,
+		.ctrl_regs = {
+			AK8975_REG_ST1,
+			AK8975_REG_ST2,
+			AK8975_REG_CNTL,
+			AK8975_REG_ASAX,
+			AK8975_MAX_REGS},
+		.ctrl_masks = {
+			AK8975_REG_ST1_DRDY_MASK,
+			AK8975_REG_ST2_HOFL_MASK,
+			AK8975_REG_ST2_DERR_MASK,
+			AK8975_REG_CNTL_MODE_MASK},
+		.ctrl_modes = {
+			AK8975_REG_CNTL_MODE_POWER_DOWN,
+			AK8975_REG_CNTL_MODE_ONCE,
+			AK8975_REG_CNTL_MODE_SELF_TEST,
+			AK8975_REG_CNTL_MODE_FUSE_ROM},
+		.data_regs = {
+			AK8975_REG_HXL,
+			AK8975_REG_HYL,
+			AK8975_REG_HZL},
+	},
+	{
+		.type = AK8963,
+		.raw_to_gauss = ak8963_09911_raw_to_gauss,
+		.range = 8190,
+		.ctrl_regs = {
+			AK8975_REG_ST1,
+			AK8975_REG_ST2,
+			AK8975_REG_CNTL,
+			AK8975_REG_ASAX,
+			AK8975_MAX_REGS},
+		.ctrl_masks = {
+			AK8975_REG_ST1_DRDY_MASK,
+			AK8975_REG_ST2_HOFL_MASK,
+			0,
+			AK8975_REG_CNTL_MODE_MASK},
+		.ctrl_modes = {
+			AK8975_REG_CNTL_MODE_POWER_DOWN,
+			AK8975_REG_CNTL_MODE_ONCE,
+			AK8975_REG_CNTL_MODE_SELF_TEST,
+			AK8975_REG_CNTL_MODE_FUSE_ROM},
+		.data_regs = {
+			AK8975_REG_HXL,
+			AK8975_REG_HYL,
+			AK8975_REG_HZL},
+	},
+	{
+		.type = AK09911,
+		.raw_to_gauss = ak8963_09911_raw_to_gauss,
+		.range = 8192,
+		.ctrl_regs = {
+			AK09912_REG_ST1,
+			AK09912_REG_ST2,
+			AK09912_REG_CNTL2,
+			AK09912_REG_ASAX,
+			AK09912_MAX_REGS},
+		.ctrl_masks = {
+			AK09912_REG_ST1_DRDY_MASK,
+			AK09912_REG_ST2_HOFL_MASK,
+			0,
+			AK09912_REG_CNTL2_MODE_MASK},
+		.ctrl_modes = {
+			AK09912_REG_CNTL_MODE_POWER_DOWN,
+			AK09912_REG_CNTL_MODE_ONCE,
+			AK09912_REG_CNTL_MODE_SELF_TEST,
+			AK09912_REG_CNTL_MODE_FUSE_ROM},
+		.data_regs = {
+			AK09912_REG_HXL,
+			AK09912_REG_HYL,
+			AK09912_REG_HZL},
+	},
+	{
+		.type = AK09912,
+		.raw_to_gauss = ak09912_raw_to_gauss,
+		.range = 32752,
+		.ctrl_regs = {
+			AK09912_REG_ST1,
+			AK09912_REG_ST2,
+			AK09912_REG_CNTL2,
+			AK09912_REG_ASAX,
+			AK09912_MAX_REGS},
+		.ctrl_masks = {
+			AK09912_REG_ST1_DRDY_MASK,
+			AK09912_REG_ST2_HOFL_MASK,
+			0,
+			AK09912_REG_CNTL2_MODE_MASK},
+		.ctrl_modes = {
+			AK09912_REG_CNTL_MODE_POWER_DOWN,
+			AK09912_REG_CNTL_MODE_ONCE,
+			AK09912_REG_CNTL_MODE_SELF_TEST,
+			AK09912_REG_CNTL_MODE_FUSE_ROM},
+		.data_regs = {
+			AK09912_REG_HXL,
+			AK09912_REG_HYL,
+			AK09912_REG_HZL},
+	}
+};
+
+/*
+ * Per-instance context data for the device.
+ */
+struct ak8975_data {
+	struct i2c_client	*client;
+	struct ak_def		*def;
+	struct attribute_group	attrs;
+	struct mutex		lock;
+	u8			asa[3];
+	long			raw_to_gauss[3];
+	int			eoc_gpio;
+	int			eoc_irq;
+	wait_queue_head_t	data_ready_queue;
+	unsigned long		flags;
+	u8			cntl_cache;
+};
+
+/*
+ * Return 0 if the i2c device is the one we expect.
+ * return a negative error number otherwise
+ */
+static int ak8975_who_i_am(struct i2c_client *client,
+			   enum asahi_compass_chipset type)
+{
+	u8 wia_val[2];
+	int ret;
+
+	/*
+	 * Signature for each device:
+	 * Device   |  WIA1      |  WIA2
+	 * AK09912  |  DEVICE_ID |  AK09912_DEVICE_ID
+	 * AK09911  |  DEVICE_ID |  AK09911_DEVICE_ID
+	 * AK8975   |  DEVICE_ID |  NA
+	 * AK8963   |  DEVICE_ID |  NA
+	 */
+	ret = i2c_smbus_read_i2c_block_data(client, AK09912_REG_WIA1,
+					    2, wia_val);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading WIA\n");
+		return ret;
+	}
+
+	if (wia_val[0] != AK8975_DEVICE_ID)
+		return -ENODEV;
+
+	switch (type) {
+	case AK8975:
+	case AK8963:
+		return 0;
+	case AK09911:
+		if (wia_val[1] == AK09911_DEVICE_ID)
+			return 0;
+		break;
+	case AK09912:
+		if (wia_val[1] == AK09912_DEVICE_ID)
+			return 0;
+		break;
+	default:
+		dev_err(&client->dev, "Type %d unknown\n", type);
+	}
+	return -ENODEV;
+}
+
+/*
+ * Helper function to write to CNTL register.
+ */
+static int ak8975_set_mode(struct ak8975_data *data, enum ak_ctrl_mode mode)
+{
+	u8 regval;
+	int ret;
+
+	regval = (data->cntl_cache & ~data->def->ctrl_masks[CNTL_MODE]) |
+		 data->def->ctrl_modes[mode];
+	ret = i2c_smbus_write_byte_data(data->client,
+					data->def->ctrl_regs[CNTL], regval);
+	if (ret < 0) {
+		return ret;
+	}
+	data->cntl_cache = regval;
+	/* After mode change wait atleast 100us */
+	usleep_range(100, 500);
+
+	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);
+	int ret;
+
+	/* Write the fused rom access mode. */
+	ret = ak8975_set_mode(data, FUSE_ROM);
+	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,
+					    data->def->ctrl_regs[ASA_BASE],
+					    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_set_mode(data, POWER_DOWN);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in setting power-down mode\n");
+		return ret;
+	}
+
+	if (data->eoc_gpio > 0 || client->irq > 0) {
+		ret = ak8975_setup_irq(data);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"Error setting data ready interrupt\n");
+			return ret;
+		}
+	}
+
+	data->raw_to_gauss[0] = data->def->raw_to_gauss(data->asa[0]);
+	data->raw_to_gauss[1] = data->def->raw_to_gauss(data->asa[1]);
+	data->raw_to_gauss[2] = data->def->raw_to_gauss(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, data->def->ctrl_regs[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,
+					       data->def->ctrl_regs[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_set_mode(data, MODE_ONCE);
+	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 & data->def->ctrl_masks[ST1_DRDY]) {
+		ret = i2c_smbus_read_byte_data(client,
+					       data->def->ctrl_regs[ST2]);
+		if (ret < 0) {
+			dev_err(&client->dev, "Error in reading ST2\n");
+			goto exit;
+		}
+		if (ret & (data->def->ctrl_masks[ST2_DERR] |
+			   data->def->ctrl_masks[ST2_HOFL])) {
+			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, data->def->data_regs[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, -data->def->range, data->def->range);
+	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},
+	{"AK09911", AK09911},
+	{"AK09912", AK09912},
+	{ },
+};
+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;
+	enum asahi_compass_chipset chipset;
+
+	/* 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) {
+		chipset = (enum asahi_compass_chipset)(id->driver_data);
+		name = id->name;
+	} else if (ACPI_HANDLE(&client->dev))
+		name = ak8975_match_acpi_device(&client->dev, &chipset);
+	else
+		return -ENOSYS;
+
+	if (chipset >= AK_MAX_TYPE) {
+		dev_err(&client->dev, "AKM device type unsupported: %d\n",
+			chipset);
+		return -ENODEV;
+	}
+
+	data->def = &ak_def_array[chipset];
+	err = ak8975_who_i_am(client, data->def->type);
+	if (err < 0) {
+		dev_err(&client->dev, "Unexpected device\n");
+		return err;
+	}
+	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, "%s initialization fails\n", name);
+		return err;
+	}
+
+	mutex_init(&data->lock);
+	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;
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id ak8975_id[] = {
+	{"ak8975", AK8975},
+	{"ak8963", AK8963},
+	{"AK8963", AK8963},
+	{"ak09911", AK09911},
+	{"ak09912", AK09912},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ak8975_id);
+
+static const struct of_device_id ak8975_of_match[] = {
+	{ .compatible = "asahi-kasei,ak8975", },
+	{ .compatible = "ak8975", },
+	{ .compatible = "asahi-kasei,ak8963", },
+	{ .compatible = "ak8963", },
+	{ .compatible = "asahi-kasei,ak09911", },
+	{ .compatible = "ak09911", },
+	{ .compatible = "asahi-kasei,ak09912", },
+	{ .compatible = "ak09912", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ak8975_of_match);
+
+static struct i2c_driver ak8975_driver = {
+	.driver = {
+		.name	= "ak8975",
+		.of_match_table = of_match_ptr(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");