iio:magnetometer:ak8975 move driver out of staging

Issues raised in last series to propose this have now been resolved
so there should be no reason this driver cannot graduate from staging.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>

3 files changed, 497 insertions, 0 deletions

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index cd29be54f643..bd1cfb666695 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -3,6 +3,17 @@
 #
 menu "Magnetometer sensors"
 
+config 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 e78672876dc2..7f328e37fbab 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -2,6 +2,7 @@
 # Makefile for industrial I/O Magnetometer sensor drivers
 #
 
+obj-$(CONFIG_AK8975)	+= ak8975.o
 obj-$(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 000000000000..af6c320a534e
--- /dev/null
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -0,0 +1,485 @@
+/*
+ * 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;
+};
+
+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;
+}
+
+/*
+ * 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 (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;
+	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;
+}
+
+/*
+ * Emits the raw flux value for the x, y, or z axis.
+ */
+static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
+{
+	struct ak8975_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = data->client;
+	u16 meas_reg;
+	s16 raw;
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	/* Set up the device for taking a sample. */
+	ret = ak8975_write_data(client,
+				AK8975_REG_CNTL,
+				AK8975_REG_CNTL_MODE_ONCE,
+				AK8975_REG_CNTL_MODE_MASK,
+				AK8975_REG_CNTL_MODE_SHIFT);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error in setting operating mode\n");
+		goto exit;
+	}
+
+	/* Wait for the conversion to complete. */
+	if (gpio_is_valid(data->eoc_gpio))
+		ret = wait_conversion_complete_gpio(data);
+	else
+		ret = wait_conversion_complete_polled(data);
+	if (ret < 0)
+		goto exit;
+
+	if (ret & AK8975_REG_ST1_DRDY_MASK) {
+		ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
+		if (ret < 0) {
+			dev_err(&client->dev, "Error in reading ST2\n");
+			goto exit;
+		}
+		if (ret & (AK8975_REG_ST2_DERR_MASK |
+			   AK8975_REG_ST2_HOFL_MASK)) {
+			dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
+			ret = -EINVAL;
+			goto exit;
+		}
+	}
+
+	/* Read the flux value from the appropriate register
+	   (the register is specified in the iio device attributes). */
+	ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
+	if (ret < 0) {
+		dev_err(&client->dev, "Read axis data fails\n");
+		goto exit;
+	}
+	meas_reg = ret;
+
+	mutex_unlock(&data->lock);
+
+	/* Endian conversion of the measured values. */
+	raw = (s16) (le16_to_cpu(meas_reg));
+
+	/* Clamp to valid range. */
+	raw = clamp_t(s16, raw, -4096, 4095);
+	*val = raw;
+	return IIO_VAL_INT;
+
+exit:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int ak8975_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2,
+			   long mask)
+{
+	struct ak8975_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return ak8975_read_axis(indio_dev, chan->address, val);
+	case IIO_CHAN_INFO_SCALE:
+		*val = 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_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			     BIT(IIO_CHAN_INFO_SCALE),			\
+		.address = index,					\
+	}
+
+static const struct iio_chan_spec ak8975_channels[] = {
+	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
+};
+
+static const struct iio_info ak8975_info = {
+	.read_raw = &ak8975_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int ak8975_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct ak8975_data *data;
+	struct iio_dev *indio_dev;
+	int eoc_gpio;
+	int err;
+
+	/* Grab and set up the supplied GPIO. */
+	if (client->dev.platform_data == 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_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@nvidia.com>");
+MODULE_DESCRIPTION("AK8975 magnetometer driver");
+MODULE_LICENSE("GPL");