[PATCH] iio:magnetometer:ak8975 move out of staging

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This driver has been clean and correct for quite some time.
It is simple and uses only straight forward standard
interfaces.

Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
---
 drivers/iio/magnetometer/Kconfig          |  11 +
 drivers/iio/magnetometer/Makefile         |   1 +
 drivers/iio/magnetometer/ak8975.c         | 520 ++++++++++++++++++++++++++++++
 drivers/staging/iio/magnetometer/Kconfig  |  11 -
 drivers/staging/iio/magnetometer/Makefile |   1 -
 drivers/staging/iio/magnetometer/ak8975.c | 520 ------------------------------
 6 files changed, 532 insertions(+), 532 deletions(-)

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index cd29be5..1087709 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -3,6 +3,17 @@
 #
 menu "Magnetometer sensors"
 
+config SENSORS_AK8975
+	tristate "Asahi Kasei AK8975 3-Axis Magnetometer"
+	depends on I2C
+	depends on GPIOLIB
+	help
+	  Say yes here to build support for Asahi Kasei AK8975 3-Axis
+	  Magnetometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ak8975.
+
 config HID_SENSOR_MAGNETOMETER_3D
 	depends on HID_SENSOR_HUB
 	select IIO_BUFFER
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index e786728..2c6fa7f 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -2,6 +2,7 @@
 # Makefile for industrial I/O Magnetometer sensor drivers
 #
 
+obj-$(CONFIG_SENSORS_AK8975) += ak8975.o
 obj-$(CONFIG_HID_SENSOR_MAGNETOMETER_3D) += hid-sensor-magn-3d.o
 
 obj-$(CONFIG_IIO_ST_MAGN_3AXIS) += st_magn.o
diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
new file mode 100644
index 0000000..28f080e
--- /dev/null
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -0,0 +1,520 @@
+/*
+ * A sensor driver for the magnetometer AK8975.
+ *
+ * Magnetic compass sensor driver for monitoring magnetic flux information.
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA	02110-1301, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+
+#include <linux/gpio.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+/*
+ * Register definitions, as well as various shifts and masks to get at the
+ * individual fields of the registers.
+ */
+#define AK8975_REG_WIA			0x00
+#define AK8975_DEVICE_ID		0x48
+
+#define AK8975_REG_INFO			0x01
+
+#define AK8975_REG_ST1			0x02
+#define AK8975_REG_ST1_DRDY_SHIFT	0
+#define AK8975_REG_ST1_DRDY_MASK	(1 << AK8975_REG_ST1_DRDY_SHIFT)
+
+#define AK8975_REG_HXL			0x03
+#define AK8975_REG_HXH			0x04
+#define AK8975_REG_HYL			0x05
+#define AK8975_REG_HYH			0x06
+#define AK8975_REG_HZL			0x07
+#define AK8975_REG_HZH			0x08
+#define AK8975_REG_ST2			0x09
+#define AK8975_REG_ST2_DERR_SHIFT	2
+#define AK8975_REG_ST2_DERR_MASK	(1 << AK8975_REG_ST2_DERR_SHIFT)
+
+#define AK8975_REG_ST2_HOFL_SHIFT	3
+#define AK8975_REG_ST2_HOFL_MASK	(1 << AK8975_REG_ST2_HOFL_SHIFT)
+
+#define AK8975_REG_CNTL			0x0A
+#define AK8975_REG_CNTL_MODE_SHIFT	0
+#define AK8975_REG_CNTL_MODE_MASK	(0xF << AK8975_REG_CNTL_MODE_SHIFT)
+#define AK8975_REG_CNTL_MODE_POWER_DOWN	0
+#define AK8975_REG_CNTL_MODE_ONCE	1
+#define AK8975_REG_CNTL_MODE_SELF_TEST	8
+#define AK8975_REG_CNTL_MODE_FUSE_ROM	0xF
+
+#define AK8975_REG_RSVC			0x0B
+#define AK8975_REG_ASTC			0x0C
+#define AK8975_REG_TS1			0x0D
+#define AK8975_REG_TS2			0x0E
+#define AK8975_REG_I2CDIS		0x0F
+#define AK8975_REG_ASAX			0x10
+#define AK8975_REG_ASAY			0x11
+#define AK8975_REG_ASAZ			0x12
+
+#define AK8975_MAX_REGS			AK8975_REG_ASAZ
+
+/*
+ * Miscellaneous values.
+ */
+#define AK8975_MAX_CONVERSION_TIMEOUT	500
+#define AK8975_CONVERSION_DONE_POLL_TIME 10
+
+/*
+ * Per-instance context data for the device.
+ */
+struct ak8975_data {
+	struct i2c_client	*client;
+	struct attribute_group	attrs;
+	struct mutex		lock;
+	u8			asa[3];
+	long			raw_to_gauss[3];
+	u8			reg_cache[AK8975_MAX_REGS];
+	int			eoc_gpio;
+	int			eoc_irq;
+};
+
+static const int ak8975_index_to_reg[] = {
+	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
+};
+
+/*
+ * Helper function to write to the I2C device's registers.
+ */
+static int ak8975_write_data(struct i2c_client *client,
+			     u8 reg, u8 val, u8 mask, u8 shift)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ak8975_data *data = iio_priv(indio_dev);
+	u8 regval;
+	int ret;
+
+	regval = (data->reg_cache[reg] & ~mask) | (val << shift);
+	ret = i2c_smbus_write_byte_data(client, reg, regval);
+	if (ret < 0) {
+		dev_err(&client->dev, "Write to device fails status %x\n", ret);
+		return ret;
+	}
+	data->reg_cache[reg] = regval;
+
+	return 0;
+}
+
+/*
+ * Helper function to read a contiguous set of the I2C device's registers.
+ */
+static int ak8975_read_data(struct i2c_client *client,
+			    u8 reg, u8 length, u8 *buffer)
+{
+	int ret;
+	struct i2c_msg msg[2] = {
+		{
+			.addr = client->addr,
+			.flags = I2C_M_NOSTART,
+			.len = 1,
+			.buf = &reg,
+		}, {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = length,
+			.buf = buffer,
+		}
+	};
+
+	ret = i2c_transfer(client->adapter, msg, 2);
+	if (ret < 0) {
+		dev_err(&client->dev, "Read from device fails\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Perform some start-of-day setup, including reading the asa calibration
+ * values and caching them.
+ */
+static int ak8975_setup(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ak8975_data *data = iio_priv(indio_dev);
+	u8 device_id;
+	int ret;
+
+	/* Confirm that the device we're talking to is really an AK8975. */
+	ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading WIA\n");
+		return ret;
+	}
+	if (device_id != AK8975_DEVICE_ID) {
+		dev_err(&client->dev, "Device ak8975 not found\n");
+		return -ENODEV;
+	}
+
+	/* Write the fused rom access mode. */
+	ret = ak8975_write_data(client,
+				AK8975_REG_CNTL,
+				AK8975_REG_CNTL_MODE_FUSE_ROM,
+				AK8975_REG_CNTL_MODE_MASK,
+				AK8975_REG_CNTL_MODE_SHIFT);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in setting fuse access mode\n");
+		return ret;
+	}
+
+	/* Get asa data and store in the device data. */
+	ret = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa);
+	if (ret < 0) {
+		dev_err(&client->dev, "Not able to read asa data\n");
+		return ret;
+	}
+
+	/* After reading fuse ROM data set power-down mode */
+	ret = ak8975_write_data(client,
+				AK8975_REG_CNTL,
+				AK8975_REG_CNTL_MODE_POWER_DOWN,
+				AK8975_REG_CNTL_MODE_MASK,
+				AK8975_REG_CNTL_MODE_SHIFT);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in setting power-down mode\n");
+		return ret;
+	}
+
+/*
+ * Precalculate scale factor (in Gauss units) for each axis and
+ * store in the device data.
+ *
+ * This scale factor is axis-dependent, and is derived from 3 calibration
+ * factors ASA(x), ASA(y), and ASA(z).
+ *
+ * These ASA values are read from the sensor device at start of day, and
+ * cached in the device context struct.
+ *
+ * Adjusting the flux value with the sensitivity adjustment value should be
+ * done via the following formula:
+ *
+ * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
+ *
+ * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
+ * is the resultant adjusted value.
+ *
+ * We reduce the formula to:
+ *
+ * Hadj = H * (ASA + 128) / 256
+ *
+ * H is in the range of -4096 to 4095.  The magnetometer has a range of
+ * +-1229uT.  To go from the raw value to uT is:
+ *
+ * HuT = H * 1229/4096, or roughly, 3/10.
+ *
+ * Since 1uT = 100 gauss, our final scale factor becomes:
+ *
+ * Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
+ * Hadj = H * ((ASA + 128) * 30 / 256
+ *
+ * Since ASA doesn't change, we cache the resultant scale factor into the
+ * device context in ak8975_setup().
+ */
+	data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
+	data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
+	data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
+
+	return 0;
+}
+
+static int wait_conversion_complete_gpio(struct ak8975_data *data)
+{
+	struct i2c_client *client = data->client;
+	u8 read_status;
+	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
+	int ret;
+
+	/* Wait for the conversion to complete. */
+	while (timeout_ms) {
+		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
+		if (gpio_get_value(data->eoc_gpio))
+			break;
+		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
+	}
+	if (!timeout_ms) {
+		dev_err(&client->dev, "Conversion timeout happened\n");
+		return -EINVAL;
+	}
+
+	ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in reading ST1\n");
+		return ret;
+	}
+	return read_status;
+}
+
+static int wait_conversion_complete_polled(struct ak8975_data *data)
+{
+	struct i2c_client *client = data->client;
+	u8 read_status;
+	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
+	int ret;
+
+	/* Wait for the conversion to complete. */
+	while (timeout_ms) {
+		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
+		ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
+		if (ret < 0) {
+			dev_err(&client->dev, "Error in reading ST1\n");
+			return ret;
+		}
+		if (read_status)
+			break;
+		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
+	}
+	if (!timeout_ms) {
+		dev_err(&client->dev, "Conversion timeout happened\n");
+		return -EINVAL;
+	}
+	return read_status;
+}
+
+/*
+ * Emits the raw flux value for the x, y, or z axis.
+ */
+static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
+{
+	struct ak8975_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+	u16 meas_reg;
+	s16 raw;
+	u8 read_status;
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	/* Set up the device for taking a sample. */
+	ret = ak8975_write_data(client,
+				AK8975_REG_CNTL,
+				AK8975_REG_CNTL_MODE_ONCE,
+				AK8975_REG_CNTL_MODE_MASK,
+				AK8975_REG_CNTL_MODE_SHIFT);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in setting operating mode\n");
+		goto exit;
+	}
+
+	/* Wait for the conversion to complete. */
+	if (gpio_is_valid(data->eoc_gpio))
+		ret = wait_conversion_complete_gpio(data);
+	else
+		ret = wait_conversion_complete_polled(data);
+	if (ret < 0)
+		goto exit;
+
+	read_status = ret;
+
+	if (read_status & AK8975_REG_ST1_DRDY_MASK) {
+		ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
+		if (ret < 0) {
+			dev_err(&client->dev, "Error in reading ST2\n");
+			goto exit;
+		}
+		if (read_status & (AK8975_REG_ST2_DERR_MASK |
+				   AK8975_REG_ST2_HOFL_MASK)) {
+			dev_err(&client->dev, "ST2 status error 0x%x\n",
+				read_status);
+			ret = -EINVAL;
+			goto exit;
+		}
+	}
+
+	/* Read the flux value from the appropriate register
+	   (the register is specified in the iio device attributes). */
+	ret = ak8975_read_data(client, ak8975_index_to_reg[index],
+			       2, (u8 *)&meas_reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "Read axis data fails\n");
+		goto exit;
+	}
+
+	mutex_unlock(&data->lock);
+
+	/* Endian conversion of the measured values. */
+	raw = (s16) (le16_to_cpu(meas_reg));
+
+	/* Clamp to valid range. */
+	raw = clamp_t(s16, raw, -4096, 4095);
+	*val = raw;
+	return IIO_VAL_INT;
+
+exit:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int ak8975_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2,
+			   long mask)
+{
+	struct ak8975_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return ak8975_read_axis(indio_dev, chan->address, val);
+	case IIO_CHAN_INFO_SCALE:
+		*val = data->raw_to_gauss[chan->address];
+		return IIO_VAL_INT;
+	}
+	return -EINVAL;
+}
+
+#define AK8975_CHANNEL(axis, index)					\
+	{								\
+		.type = IIO_MAGN,					\
+		.modified = 1,						\
+		.channel2 = IIO_MOD_##axis,				\
+		.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |		\
+			     IIO_CHAN_INFO_SCALE_SEPARATE_BIT,		\
+		.address = index,					\
+	}
+
+static const struct iio_chan_spec ak8975_channels[] = {
+	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
+};
+
+static const struct iio_info ak8975_info = {
+	.read_raw = &ak8975_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int ak8975_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct ak8975_data *data;
+	struct iio_dev *indio_dev;
+	int eoc_gpio;
+	int err;
+
+	/* Grab and set up the supplied GPIO. */
+	if (client->dev.platform_data == NULL)
+		eoc_gpio = -1;
+	else
+		eoc_gpio = *(int *)(client->dev.platform_data);
+
+	/* We may not have a GPIO based IRQ to scan, that is fine, we will
+	   poll if so */
+	if (gpio_is_valid(eoc_gpio)) {
+		err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
+		if (err < 0) {
+			dev_err(&client->dev,
+				"failed to request GPIO %d, error %d\n",
+							eoc_gpio, err);
+			goto exit;
+		}
+	}
+
+	/* Register with IIO */
+	indio_dev = iio_device_alloc(sizeof(*data));
+	if (indio_dev == NULL) {
+		err = -ENOMEM;
+		goto exit_gpio;
+	}
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	/* Perform some basic start-of-day setup of the device. */
+	err = ak8975_setup(client);
+	if (err < 0) {
+		dev_err(&client->dev, "AK8975 initialization fails\n");
+		goto exit_free_iio;
+	}
+
+	data->client = client;
+	mutex_init(&data->lock);
+	data->eoc_irq = client->irq;
+	data->eoc_gpio = eoc_gpio;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = ak8975_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
+	indio_dev->info = &ak8975_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	err = iio_device_register(indio_dev);
+	if (err < 0)
+		goto exit_free_iio;
+
+	return 0;
+
+exit_free_iio:
+	iio_device_free(indio_dev);
+exit_gpio:
+	if (gpio_is_valid(eoc_gpio))
+		gpio_free(eoc_gpio);
+exit:
+	return err;
+}
+
+static int ak8975_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ak8975_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	if (gpio_is_valid(data->eoc_gpio))
+		gpio_free(data->eoc_gpio);
+
+	iio_device_free(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id ak8975_id[] = {
+	{"ak8975", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ak8975_id);
+
+static const struct of_device_id ak8975_of_match[] = {
+	{ .compatible = "asahi-kasei,ak8975", },
+	{ .compatible = "ak8975", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ak8975_of_match);
+
+static struct i2c_driver ak8975_driver = {
+	.driver = {
+		.name	= "ak8975",
+		.of_match_table = ak8975_of_match,
+	},
+	.probe		= ak8975_probe,
+	.remove		= ak8975_remove,
+	.id_table	= ak8975_id,
+};
+module_i2c_driver(ak8975_driver);
+
+MODULE_AUTHOR("Laxman Dewangan <ldewangan@xxxxxxxxxx>");
+MODULE_DESCRIPTION("AK8975 magnetometer driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/staging/iio/magnetometer/Kconfig b/drivers/staging/iio/magnetometer/Kconfig
index df5e0d4..a3ea69e 100644
--- a/drivers/staging/iio/magnetometer/Kconfig
+++ b/drivers/staging/iio/magnetometer/Kconfig
@@ -3,17 +3,6 @@
 #
 menu "Magnetometer sensors"
 
-config SENSORS_AK8975
-	tristate "Asahi Kasei AK8975 3-Axis Magnetometer"
-	depends on I2C
-	depends on GPIOLIB
-	help
-	  Say yes here to build support for Asahi Kasei AK8975 3-Axis
-	  Magnetometer.
-
-	  To compile this driver as a module, choose M here: the module
-	  will be called ak8975.
-
 config SENSORS_HMC5843
 	tristate "Honeywell HMC5843/5883/5883L 3-Axis Magnetometer"
 	depends on I2C
diff --git a/drivers/staging/iio/magnetometer/Makefile b/drivers/staging/iio/magnetometer/Makefile
index f2a753f..f9bfb2e 100644
--- a/drivers/staging/iio/magnetometer/Makefile
+++ b/drivers/staging/iio/magnetometer/Makefile
@@ -2,5 +2,4 @@
 # Makefile for industrial I/O Magnetometer sensors
 #
 
-obj-$(CONFIG_SENSORS_AK8975)	+= ak8975.o
 obj-$(CONFIG_SENSORS_HMC5843)	+= hmc5843.o
diff --git a/drivers/staging/iio/magnetometer/ak8975.c b/drivers/staging/iio/magnetometer/ak8975.c
deleted file mode 100644
index 28f080e..0000000
--- a/drivers/staging/iio/magnetometer/ak8975.c
+++ /dev/null
@@ -1,520 +0,0 @@
-/*
- * A sensor driver for the magnetometer AK8975.
- *
- * Magnetic compass sensor driver for monitoring magnetic flux information.
- *
- * Copyright (c) 2010, NVIDIA Corporation.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA	02110-1301, USA.
- */
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/i2c.h>
-#include <linux/err.h>
-#include <linux/mutex.h>
-#include <linux/delay.h>
-
-#include <linux/gpio.h>
-
-#include <linux/iio/iio.h>
-#include <linux/iio/sysfs.h>
-/*
- * Register definitions, as well as various shifts and masks to get at the
- * individual fields of the registers.
- */
-#define AK8975_REG_WIA			0x00
-#define AK8975_DEVICE_ID		0x48
-
-#define AK8975_REG_INFO			0x01
-
-#define AK8975_REG_ST1			0x02
-#define AK8975_REG_ST1_DRDY_SHIFT	0
-#define AK8975_REG_ST1_DRDY_MASK	(1 << AK8975_REG_ST1_DRDY_SHIFT)
-
-#define AK8975_REG_HXL			0x03
-#define AK8975_REG_HXH			0x04
-#define AK8975_REG_HYL			0x05
-#define AK8975_REG_HYH			0x06
-#define AK8975_REG_HZL			0x07
-#define AK8975_REG_HZH			0x08
-#define AK8975_REG_ST2			0x09
-#define AK8975_REG_ST2_DERR_SHIFT	2
-#define AK8975_REG_ST2_DERR_MASK	(1 << AK8975_REG_ST2_DERR_SHIFT)
-
-#define AK8975_REG_ST2_HOFL_SHIFT	3
-#define AK8975_REG_ST2_HOFL_MASK	(1 << AK8975_REG_ST2_HOFL_SHIFT)
-
-#define AK8975_REG_CNTL			0x0A
-#define AK8975_REG_CNTL_MODE_SHIFT	0
-#define AK8975_REG_CNTL_MODE_MASK	(0xF << AK8975_REG_CNTL_MODE_SHIFT)
-#define AK8975_REG_CNTL_MODE_POWER_DOWN	0
-#define AK8975_REG_CNTL_MODE_ONCE	1
-#define AK8975_REG_CNTL_MODE_SELF_TEST	8
-#define AK8975_REG_CNTL_MODE_FUSE_ROM	0xF
-
-#define AK8975_REG_RSVC			0x0B
-#define AK8975_REG_ASTC			0x0C
-#define AK8975_REG_TS1			0x0D
-#define AK8975_REG_TS2			0x0E
-#define AK8975_REG_I2CDIS		0x0F
-#define AK8975_REG_ASAX			0x10
-#define AK8975_REG_ASAY			0x11
-#define AK8975_REG_ASAZ			0x12
-
-#define AK8975_MAX_REGS			AK8975_REG_ASAZ
-
-/*
- * Miscellaneous values.
- */
-#define AK8975_MAX_CONVERSION_TIMEOUT	500
-#define AK8975_CONVERSION_DONE_POLL_TIME 10
-
-/*
- * Per-instance context data for the device.
- */
-struct ak8975_data {
-	struct i2c_client	*client;
-	struct attribute_group	attrs;
-	struct mutex		lock;
-	u8			asa[3];
-	long			raw_to_gauss[3];
-	u8			reg_cache[AK8975_MAX_REGS];
-	int			eoc_gpio;
-	int			eoc_irq;
-};
-
-static const int ak8975_index_to_reg[] = {
-	AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
-};
-
-/*
- * Helper function to write to the I2C device's registers.
- */
-static int ak8975_write_data(struct i2c_client *client,
-			     u8 reg, u8 val, u8 mask, u8 shift)
-{
-	struct iio_dev *indio_dev = i2c_get_clientdata(client);
-	struct ak8975_data *data = iio_priv(indio_dev);
-	u8 regval;
-	int ret;
-
-	regval = (data->reg_cache[reg] & ~mask) | (val << shift);
-	ret = i2c_smbus_write_byte_data(client, reg, regval);
-	if (ret < 0) {
-		dev_err(&client->dev, "Write to device fails status %x\n", ret);
-		return ret;
-	}
-	data->reg_cache[reg] = regval;
-
-	return 0;
-}
-
-/*
- * Helper function to read a contiguous set of the I2C device's registers.
- */
-static int ak8975_read_data(struct i2c_client *client,
-			    u8 reg, u8 length, u8 *buffer)
-{
-	int ret;
-	struct i2c_msg msg[2] = {
-		{
-			.addr = client->addr,
-			.flags = I2C_M_NOSTART,
-			.len = 1,
-			.buf = &reg,
-		}, {
-			.addr = client->addr,
-			.flags = I2C_M_RD,
-			.len = length,
-			.buf = buffer,
-		}
-	};
-
-	ret = i2c_transfer(client->adapter, msg, 2);
-	if (ret < 0) {
-		dev_err(&client->dev, "Read from device fails\n");
-		return ret;
-	}
-
-	return 0;
-}
-
-/*
- * Perform some start-of-day setup, including reading the asa calibration
- * values and caching them.
- */
-static int ak8975_setup(struct i2c_client *client)
-{
-	struct iio_dev *indio_dev = i2c_get_clientdata(client);
-	struct ak8975_data *data = iio_priv(indio_dev);
-	u8 device_id;
-	int ret;
-
-	/* Confirm that the device we're talking to is really an AK8975. */
-	ret = ak8975_read_data(client, AK8975_REG_WIA, 1, &device_id);
-	if (ret < 0) {
-		dev_err(&client->dev, "Error reading WIA\n");
-		return ret;
-	}
-	if (device_id != AK8975_DEVICE_ID) {
-		dev_err(&client->dev, "Device ak8975 not found\n");
-		return -ENODEV;
-	}
-
-	/* Write the fused rom access mode. */
-	ret = ak8975_write_data(client,
-				AK8975_REG_CNTL,
-				AK8975_REG_CNTL_MODE_FUSE_ROM,
-				AK8975_REG_CNTL_MODE_MASK,
-				AK8975_REG_CNTL_MODE_SHIFT);
-	if (ret < 0) {
-		dev_err(&client->dev, "Error in setting fuse access mode\n");
-		return ret;
-	}
-
-	/* Get asa data and store in the device data. */
-	ret = ak8975_read_data(client, AK8975_REG_ASAX, 3, data->asa);
-	if (ret < 0) {
-		dev_err(&client->dev, "Not able to read asa data\n");
-		return ret;
-	}
-
-	/* After reading fuse ROM data set power-down mode */
-	ret = ak8975_write_data(client,
-				AK8975_REG_CNTL,
-				AK8975_REG_CNTL_MODE_POWER_DOWN,
-				AK8975_REG_CNTL_MODE_MASK,
-				AK8975_REG_CNTL_MODE_SHIFT);
-	if (ret < 0) {
-		dev_err(&client->dev, "Error in setting power-down mode\n");
-		return ret;
-	}
-
-/*
- * Precalculate scale factor (in Gauss units) for each axis and
- * store in the device data.
- *
- * This scale factor is axis-dependent, and is derived from 3 calibration
- * factors ASA(x), ASA(y), and ASA(z).
- *
- * These ASA values are read from the sensor device at start of day, and
- * cached in the device context struct.
- *
- * Adjusting the flux value with the sensitivity adjustment value should be
- * done via the following formula:
- *
- * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
- *
- * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
- * is the resultant adjusted value.
- *
- * We reduce the formula to:
- *
- * Hadj = H * (ASA + 128) / 256
- *
- * H is in the range of -4096 to 4095.  The magnetometer has a range of
- * +-1229uT.  To go from the raw value to uT is:
- *
- * HuT = H * 1229/4096, or roughly, 3/10.
- *
- * Since 1uT = 100 gauss, our final scale factor becomes:
- *
- * Hadj = H * ((ASA + 128) / 256) * 3/10 * 100
- * Hadj = H * ((ASA + 128) * 30 / 256
- *
- * Since ASA doesn't change, we cache the resultant scale factor into the
- * device context in ak8975_setup().
- */
-	data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
-	data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
-	data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
-
-	return 0;
-}
-
-static int wait_conversion_complete_gpio(struct ak8975_data *data)
-{
-	struct i2c_client *client = data->client;
-	u8 read_status;
-	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
-	int ret;
-
-	/* Wait for the conversion to complete. */
-	while (timeout_ms) {
-		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
-		if (gpio_get_value(data->eoc_gpio))
-			break;
-		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
-	}
-	if (!timeout_ms) {
-		dev_err(&client->dev, "Conversion timeout happened\n");
-		return -EINVAL;
-	}
-
-	ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
-	if (ret < 0) {
-		dev_err(&client->dev, "Error in reading ST1\n");
-		return ret;
-	}
-	return read_status;
-}
-
-static int wait_conversion_complete_polled(struct ak8975_data *data)
-{
-	struct i2c_client *client = data->client;
-	u8 read_status;
-	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
-	int ret;
-
-	/* Wait for the conversion to complete. */
-	while (timeout_ms) {
-		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
-		ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
-		if (ret < 0) {
-			dev_err(&client->dev, "Error in reading ST1\n");
-			return ret;
-		}
-		if (read_status)
-			break;
-		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
-	}
-	if (!timeout_ms) {
-		dev_err(&client->dev, "Conversion timeout happened\n");
-		return -EINVAL;
-	}
-	return read_status;
-}
-
-/*
- * Emits the raw flux value for the x, y, or z axis.
- */
-static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
-{
-	struct ak8975_data *data = iio_priv(indio_dev);
-	struct i2c_client *client = data->client;
-	u16 meas_reg;
-	s16 raw;
-	u8 read_status;
-	int ret;
-
-	mutex_lock(&data->lock);
-
-	/* Set up the device for taking a sample. */
-	ret = ak8975_write_data(client,
-				AK8975_REG_CNTL,
-				AK8975_REG_CNTL_MODE_ONCE,
-				AK8975_REG_CNTL_MODE_MASK,
-				AK8975_REG_CNTL_MODE_SHIFT);
-	if (ret < 0) {
-		dev_err(&client->dev, "Error in setting operating mode\n");
-		goto exit;
-	}
-
-	/* Wait for the conversion to complete. */
-	if (gpio_is_valid(data->eoc_gpio))
-		ret = wait_conversion_complete_gpio(data);
-	else
-		ret = wait_conversion_complete_polled(data);
-	if (ret < 0)
-		goto exit;
-
-	read_status = ret;
-
-	if (read_status & AK8975_REG_ST1_DRDY_MASK) {
-		ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
-		if (ret < 0) {
-			dev_err(&client->dev, "Error in reading ST2\n");
-			goto exit;
-		}
-		if (read_status & (AK8975_REG_ST2_DERR_MASK |
-				   AK8975_REG_ST2_HOFL_MASK)) {
-			dev_err(&client->dev, "ST2 status error 0x%x\n",
-				read_status);
-			ret = -EINVAL;
-			goto exit;
-		}
-	}
-
-	/* Read the flux value from the appropriate register
-	   (the register is specified in the iio device attributes). */
-	ret = ak8975_read_data(client, ak8975_index_to_reg[index],
-			       2, (u8 *)&meas_reg);
-	if (ret < 0) {
-		dev_err(&client->dev, "Read axis data fails\n");
-		goto exit;
-	}
-
-	mutex_unlock(&data->lock);
-
-	/* Endian conversion of the measured values. */
-	raw = (s16) (le16_to_cpu(meas_reg));
-
-	/* Clamp to valid range. */
-	raw = clamp_t(s16, raw, -4096, 4095);
-	*val = raw;
-	return IIO_VAL_INT;
-
-exit:
-	mutex_unlock(&data->lock);
-	return ret;
-}
-
-static int ak8975_read_raw(struct iio_dev *indio_dev,
-			   struct iio_chan_spec const *chan,
-			   int *val, int *val2,
-			   long mask)
-{
-	struct ak8975_data *data = iio_priv(indio_dev);
-
-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		return ak8975_read_axis(indio_dev, chan->address, val);
-	case IIO_CHAN_INFO_SCALE:
-		*val = data->raw_to_gauss[chan->address];
-		return IIO_VAL_INT;
-	}
-	return -EINVAL;
-}
-
-#define AK8975_CHANNEL(axis, index)					\
-	{								\
-		.type = IIO_MAGN,					\
-		.modified = 1,						\
-		.channel2 = IIO_MOD_##axis,				\
-		.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |		\
-			     IIO_CHAN_INFO_SCALE_SEPARATE_BIT,		\
-		.address = index,					\
-	}
-
-static const struct iio_chan_spec ak8975_channels[] = {
-	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
-};
-
-static const struct iio_info ak8975_info = {
-	.read_raw = &ak8975_read_raw,
-	.driver_module = THIS_MODULE,
-};
-
-static int ak8975_probe(struct i2c_client *client,
-			const struct i2c_device_id *id)
-{
-	struct ak8975_data *data;
-	struct iio_dev *indio_dev;
-	int eoc_gpio;
-	int err;
-
-	/* Grab and set up the supplied GPIO. */
-	if (client->dev.platform_data == NULL)
-		eoc_gpio = -1;
-	else
-		eoc_gpio = *(int *)(client->dev.platform_data);
-
-	/* We may not have a GPIO based IRQ to scan, that is fine, we will
-	   poll if so */
-	if (gpio_is_valid(eoc_gpio)) {
-		err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
-		if (err < 0) {
-			dev_err(&client->dev,
-				"failed to request GPIO %d, error %d\n",
-							eoc_gpio, err);
-			goto exit;
-		}
-	}
-
-	/* Register with IIO */
-	indio_dev = iio_device_alloc(sizeof(*data));
-	if (indio_dev == NULL) {
-		err = -ENOMEM;
-		goto exit_gpio;
-	}
-	data = iio_priv(indio_dev);
-	i2c_set_clientdata(client, indio_dev);
-	/* Perform some basic start-of-day setup of the device. */
-	err = ak8975_setup(client);
-	if (err < 0) {
-		dev_err(&client->dev, "AK8975 initialization fails\n");
-		goto exit_free_iio;
-	}
-
-	data->client = client;
-	mutex_init(&data->lock);
-	data->eoc_irq = client->irq;
-	data->eoc_gpio = eoc_gpio;
-	indio_dev->dev.parent = &client->dev;
-	indio_dev->channels = ak8975_channels;
-	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
-	indio_dev->info = &ak8975_info;
-	indio_dev->modes = INDIO_DIRECT_MODE;
-
-	err = iio_device_register(indio_dev);
-	if (err < 0)
-		goto exit_free_iio;
-
-	return 0;
-
-exit_free_iio:
-	iio_device_free(indio_dev);
-exit_gpio:
-	if (gpio_is_valid(eoc_gpio))
-		gpio_free(eoc_gpio);
-exit:
-	return err;
-}
-
-static int ak8975_remove(struct i2c_client *client)
-{
-	struct iio_dev *indio_dev = i2c_get_clientdata(client);
-	struct ak8975_data *data = iio_priv(indio_dev);
-
-	iio_device_unregister(indio_dev);
-
-	if (gpio_is_valid(data->eoc_gpio))
-		gpio_free(data->eoc_gpio);
-
-	iio_device_free(indio_dev);
-
-	return 0;
-}
-
-static const struct i2c_device_id ak8975_id[] = {
-	{"ak8975", 0},
-	{}
-};
-
-MODULE_DEVICE_TABLE(i2c, ak8975_id);
-
-static const struct of_device_id ak8975_of_match[] = {
-	{ .compatible = "asahi-kasei,ak8975", },
-	{ .compatible = "ak8975", },
-	{ }
-};
-MODULE_DEVICE_TABLE(of, ak8975_of_match);
-
-static struct i2c_driver ak8975_driver = {
-	.driver = {
-		.name	= "ak8975",
-		.of_match_table = ak8975_of_match,
-	},
-	.probe		= ak8975_probe,
-	.remove		= ak8975_remove,
-	.id_table	= ak8975_id,
-};
-module_i2c_driver(ak8975_driver);
-
-MODULE_AUTHOR("Laxman Dewangan <ldewangan@xxxxxxxxxx>");
-MODULE_DESCRIPTION("AK8975 magnetometer driver");
-MODULE_LICENSE("GPL");
-- 
1.8.1.1

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