Staging: iio: add digital compass hmc5843 driver

Adding support for the Honeywell HMC5843. The interface to the device is
i2c

TODO:
Adding the documentation
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Kconfig

@@ -44,6 +44,7 @@ source "drivers/staging/iio/adc/Kconfig"
 source "drivers/staging/iio/gyro/Kconfig"
 source "drivers/staging/iio/imu/Kconfig"
 source "drivers/staging/iio/light/Kconfig"
+source "drivers/staging/iio/magnetometer/Kconfig"
 
 source "drivers/staging/iio/trigger/Kconfig"
 

drivers/staging/iio/Makefile

@@ -15,3 +15,4 @@ obj-y += gyro/
 obj-y += imu/
 obj-y += light/
 obj-y += trigger/
+obj-y += magnetometer/

drivers/staging/iio/magnetometer/Kconfig

+#
+# Magnetometer sensors
+#
+comment "Magnetometer sensors"
+
+config SENSORS_HMC5843
+	tristate "Honeywell HMC5843 3-Axis Magnetometer"
+	depends on I2C
+	help
+	  Say Y here to add support for the Honeywell HMC 5843 3-Axis
+	  Magnetometer (digital compass).
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hmc5843
+

drivers/staging/iio/magnetometer/Makefile

+#
+# Makefile for industrial I/O Magnetometer sensors
+#
+
+obj-$(CONFIG_SENSORS_HMC5843)	+= hmc5843.o

drivers/staging/iio/magnetometer/hmc5843.c

+/*  Copyright (C) 2010 Texas Instruments
+    Author: Shubhrajyoti Datta <shubhrajyoti@ti.com>
+    Acknowledgement: Jonathan Cameron <jic23@cam.ac.uk> for valuable inputs.
+
+    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., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include "../iio.h"
+#include "../sysfs.h"
+#include "magnet.h"
+
+#define HMC5843_I2C_ADDRESS			0x1E
+
+#define HMC5843_CONFIG_REG_A			0x00
+#define HMC5843_CONFIG_REG_B			0x01
+#define HMC5843_MODE_REG			0x02
+#define HMC5843_DATA_OUT_X_MSB_REG		0x03
+#define HMC5843_DATA_OUT_X_LSB_REG		0x04
+#define HMC5843_DATA_OUT_Y_MSB_REG		0x05
+#define HMC5843_DATA_OUT_Y_LSB_REG		0x06
+#define HMC5843_DATA_OUT_Z_MSB_REG		0x07
+#define HMC5843_DATA_OUT_Z_LSB_REG		0x08
+#define HMC5843_STATUS_REG			0x09
+#define HMC5843_ID_REG_A			0x0A
+#define HMC5843_ID_REG_B			0x0B
+#define HMC5843_ID_REG_C			0x0C
+
+#define HMC5843_ID_REG_LENGTH			0x03
+#define HMC5843_ID_STRING			"H43"
+
+/*
+ * Range settings in  (+-)Ga
+ * */
+#define RANGE_GAIN_OFFSET			0x05
+
+#define	RANGE_0_7				0x00
+#define	RANGE_1_0				0x01 /* default */
+#define	RANGE_1_5				0x02
+#define	RANGE_2_0				0x03
+#define	RANGE_3_2				0x04
+#define	RANGE_3_8				0x05
+#define	RANGE_4_5				0x06
+#define	RANGE_6_5				0x07 /* Not recommended */
+
+/*
+ * Device status
+ */
+#define	DATA_READY  				0x01
+#define	DATA_OUTPUT_LOCK  			0x02
+#define	VOLTAGE_REGULATOR_ENABLED  		0x04
+
+/*
+ * Mode register configuration
+ */
+#define	MODE_CONVERSION_CONTINUOUS		0x00
+#define	MODE_CONVERSION_SINGLE			0x01
+#define	MODE_IDLE				0x02
+#define	MODE_SLEEP				0x03
+
+/* Minimum Data Output Rate in 1/10 Hz  */
+#define RATE_OFFSET				0x02
+#define RATE_BITMASK				0x1C
+#define	RATE_5					0x00
+#define	RATE_10					0x01
+#define	RATE_20					0x02
+#define	RATE_50					0x03
+#define	RATE_100				0x04
+#define	RATE_200				0x05
+#define	RATE_500				0x06
+#define	RATE_NOT_USED				0x07
+
+/*
+ * Device Configutration
+ */
+#define	CONF_NORMAL  				0x00
+#define	CONF_POSITIVE_BIAS			0x01
+#define	CONF_NEGATIVE_BIAS			0x02
+#define	CONF_NOT_USED				0x03
+#define	MEAS_CONF_MASK				0x03
+
+static const int regval_to_counts_per_mg[] = {
+	1620,
+	1300,
+	970,
+	780,
+	530,
+	460,
+	390,
+	280
+};
+static const int regval_to_input_field_mg[] = {
+	700,
+	1000,
+	1500,
+	2000,
+	3200,
+	3800,
+	4500,
+	6500
+};
+static const char *regval_to_samp_freq[] = {
+	"0.5",
+	"1",
+	"2",
+	"5",
+	"10",
+	"20",
+	"50",
+};
+
+/* Addresses to scan: 0x1E */
+static const unsigned short normal_i2c[] = { HMC5843_I2C_ADDRESS,
+							I2C_CLIENT_END };
+
+/* Each client has this additional data */
+struct hmc5843_data {
+	struct iio_dev	*indio_dev;
+	struct mutex lock;
+	u8		rate;
+	u8		meas_conf;
+	u8		operating_mode;
+	u8		range;
+};
+
+static void hmc5843_init_client(struct i2c_client *client);
+
+static s32 hmc5843_configure(struct i2c_client *client,
+				       u8 operating_mode)
+{
+	/* The lower two bits contain the current conversion mode */
+	return i2c_smbus_write_byte_data(client,
+					HMC5843_MODE_REG,
+					(operating_mode & 0x03));
+}
+
+/* Return the measurement value from the  specified channel */
+static ssize_t hmc5843_read_measurement(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	s16 coordinate_val;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	s32 result;
+
+	mutex_lock(&data->lock);
+
+	result = i2c_smbus_read_byte_data(client, HMC5843_STATUS_REG);
+	while (!(result & DATA_READY))
+		result = i2c_smbus_read_byte_data(client, HMC5843_STATUS_REG);
+
+	result = i2c_smbus_read_word_data(client, this_attr->address);
+	mutex_unlock(&data->lock);
+	if (result < 0)
+		return -EINVAL;
+
+	coordinate_val	= (s16)swab16((u16)result);
+	return sprintf(buf, "%d\n", coordinate_val);
+}
+static IIO_DEV_ATTR_MAGN_X(hmc5843_read_measurement,
+		HMC5843_DATA_OUT_X_MSB_REG);
+static IIO_DEV_ATTR_MAGN_Y(hmc5843_read_measurement,
+		HMC5843_DATA_OUT_Y_MSB_REG);
+static IIO_DEV_ATTR_MAGN_Z(hmc5843_read_measurement,
+		HMC5843_DATA_OUT_Z_MSB_REG);
+
+/*
+ * From the datasheet
+ * 0 - Continuous-Conversion Mode: In continuous-conversion mode, the
+ * device continuously performs conversions an places the result in the
+ * data register.
+ *
+ * 1 - Single-Conversion Mode : device performs a single measurement,
+ *  sets RDY high and returned to sleep mode
+ *
+ * 2 - Idle Mode :  Device is placed in idle mode.
+ *
+ * 3 - Sleep Mode. Device is placed in sleep mode.
+ *
+ */
+static ssize_t hmc5843_show_operating_mode(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	return sprintf(buf, "%d\n", data->operating_mode);
+}
+
+static ssize_t hmc5843_set_operating_mode(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf,
+				size_t count)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	unsigned long operating_mode = 0;
+	s32 status;
+	int error;
+	mutex_lock(&data->lock);
+	error = strict_strtoul(buf, 10, &operating_mode);
+	if (error)
+		return error;
+	dev_dbg(dev, "set Conversion mode to %lu\n", operating_mode);
+	if (operating_mode > MODE_SLEEP)
+			return -EINVAL;
+
+	status = i2c_smbus_write_byte_data(client, this_attr->address,
+					operating_mode);
+	if (status) {
+		count = -EINVAL;
+		goto exit;
+	}
+	data->operating_mode = operating_mode;
+
+exit:
+	mutex_unlock(&data->lock);
+	return count;
+}
+static IIO_DEVICE_ATTR(operating_mode,
+			S_IWUSR | S_IRUGO,
+			hmc5843_show_operating_mode,
+			hmc5843_set_operating_mode,
+			HMC5843_MODE_REG);
+
+/*
+ * API for setting the measurement configuration to
+ * Normal, Positive bias and Negative bias
+ * From the datasheet
+ *
+ * Normal measurement configuration (default): In normal measurement
+ * configuration the device follows normal measurement flow. Pins BP and BN
+ * are left floating and high impedance.
+ *
+ * Positive bias configuration: In positive bias configuration, a positive
+ * current is forced across the resistive load on pins BP and BN.
+ *
+ * Negative bias configuration. In negative bias configuration, a negative
+ * current is forced across the resistive load on pins BP and BN.
+ *
+ */
+static s32 hmc5843_set_meas_conf(struct i2c_client *client,
+				      u8 meas_conf)
+{
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	u8 reg_val;
+	reg_val = (meas_conf & MEAS_CONF_MASK) |  (data->rate << RATE_OFFSET);
+	return i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_A, reg_val);
+}
+
+static ssize_t hmc5843_show_measurement_configuration(struct device *dev,
+						struct device_attribute *attr,
+						char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	return sprintf(buf, "%d\n", data->meas_conf);
+}
+
+static ssize_t hmc5843_set_measurement_configuration(struct device *dev,
+						struct device_attribute *attr,
+						const char *buf,
+						size_t count)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	unsigned long meas_conf = 0;
+	int error = strict_strtoul(buf, 10, &meas_conf);
+	if (error)
+		return error;
+	mutex_lock(&data->lock);
+
+	dev_dbg(dev, "set mode to %lu\n", meas_conf);
+	if (hmc5843_set_meas_conf(client, meas_conf)) {
+		count = -EINVAL;
+		goto exit;
+	}
+	data->meas_conf = meas_conf;
+
+exit:
+	mutex_unlock(&data->lock);
+	return count;
+}
+static IIO_DEVICE_ATTR(meas_conf,
+			S_IWUSR | S_IRUGO,
+			hmc5843_show_measurement_configuration,
+			hmc5843_set_measurement_configuration,
+			0);
+
+/*
+ * From Datasheet
+ * The table shows the minimum data output
+ * Value	| Minimum data output rate(Hz)
+ * 0		| 0.5
+ * 1		| 1
+ * 2		| 2
+ * 3		| 5
+ * 4		| 10 (default)
+ * 5		| 20
+ * 6		| 50
+ * 7		| Not used
+ */
+static IIO_CONST_ATTR_AVAIL_SAMP_FREQ("0.5 1 2 5 10 20 50");
+
+static s32 hmc5843_set_rate(struct i2c_client *client,
+				u8 rate)
+{
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	u8 reg_val;
+
+	reg_val = (data->meas_conf) |  (rate << RATE_OFFSET);
+	if (rate >= RATE_NOT_USED) {
+		dev_err(&client->dev,
+			"This data output rate is not supported \n");
+		return -EINVAL;
+	}
+	return i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_A, reg_val);
+}
+
+static ssize_t set_sampling_frequency(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	unsigned long rate = 0;
+
+	if (strncmp(buf, "0.5" , 3) == 0)
+		rate = RATE_5;
+	else if (strncmp(buf, "1" , 1) == 0)
+		rate = RATE_10;
+	else if (strncmp(buf, "2", 1) == 0)
+		rate = RATE_20;
+	else if (strncmp(buf, "5", 1) == 0)
+		rate = RATE_50;
+	else if (strncmp(buf, "10", 2) == 0)
+		rate = RATE_100;
+	else if (strncmp(buf, "20" , 2) == 0)
+		rate = RATE_200;
+	else if (strncmp(buf, "50" , 2) == 0)
+		rate = RATE_500;
+	else
+		return -EINVAL;
+
+	mutex_lock(&data->lock);
+	dev_dbg(dev, "set rate to %lu\n", rate);
+	if (hmc5843_set_rate(client, rate)) {
+		count = -EINVAL;
+		goto exit;
+	}
+	data->rate = rate;
+
+exit:
+	mutex_unlock(&data->lock);
+	return count;
+}
+
+static ssize_t show_sampling_frequency(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	u32 rate;
+
+	rate = i2c_smbus_read_byte_data(client,  this_attr->address);
+	if (rate < 0)
+		return -EINVAL;
+	rate = (rate & RATE_BITMASK) >> RATE_OFFSET;
+	return sprintf(buf, "%s\n", regval_to_samp_freq[rate]);
+}
+static IIO_DEVICE_ATTR(sampling_frequency,
+			S_IWUSR | S_IRUGO,
+			show_sampling_frequency,
+			set_sampling_frequency,
+			HMC5843_CONFIG_REG_A);
+
+/*
+ * From Datasheet
+ *	Nominal gain settings
+ * Value	| Sensor Input Field Range(Ga)	| Gain(counts/ milli-gauss)
+ *0		|(+-)0.7			|1620
+ *1		|(+-)1.0			|1300
+ *2		|(+-)1.5			|970
+ *3		|(+-)2.0			|780
+ *4		|(+-)3.2			|530
+ *5		|(+-)3.8			|460
+ *6		|(+-)4.5			|390
+ *7		|(+-)6.5			|280
+ */
+static ssize_t show_range(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	u8 range;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct hmc5843_data *data = indio_dev->dev_data;
+
+	range = data->range;
+	return sprintf(buf, "%d\n", regval_to_input_field_mg[range]);
+}
+
+static ssize_t set_range(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf,
+			size_t count)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	unsigned long range = 0;
+	int error;
+	mutex_lock(&data->lock);
+	error = strict_strtoul(buf, 10, &range);
+	if (error)
+		return error;
+	dev_dbg(dev, "set range to %lu\n", range);
+
+	if (range > RANGE_6_5)
+		return -EINVAL;
+
+	data->range = range;
+	range = range << RANGE_GAIN_OFFSET;
+	if (i2c_smbus_write_byte_data(client, this_attr->address, range))
+		count = -EINVAL;
+
+	mutex_unlock(&data->lock);
+	return count;
+
+}
+static IIO_DEVICE_ATTR(magn_range,
+			S_IWUSR | S_IRUGO,
+			show_range,
+			set_range,
+			HMC5843_CONFIG_REG_B);
+
+static ssize_t show_gain(struct device *dev,
+			struct device_attribute *attr,
+			char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct hmc5843_data *data = indio_dev->dev_data;
+	return sprintf(buf, "%d\n", regval_to_counts_per_mg[data->range]);
+}
+static IIO_DEVICE_ATTR(magn_gain,
+			S_IRUGO,
+			show_gain,
+			NULL , 0);
+
+static struct attribute *hmc5843_attributes[] = {
+	&iio_dev_attr_meas_conf.dev_attr.attr,
+	&iio_dev_attr_operating_mode.dev_attr.attr,
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_dev_attr_magn_range.dev_attr.attr,
+	&iio_dev_attr_magn_gain.dev_attr.attr,
+	&iio_dev_attr_magn_x_raw.dev_attr.attr,
+	&iio_dev_attr_magn_y_raw.dev_attr.attr,
+	&iio_dev_attr_magn_z_raw.dev_attr.attr,
+	&iio_const_attr_available_sampling_frequency.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group hmc5843_group = {
+	.attrs = hmc5843_attributes,
+};
+
+static int hmc5843_detect(struct i2c_client *client,
+			  struct i2c_board_info *info)
+{
+	unsigned char id_str[HMC5843_ID_REG_LENGTH];
+
+	if (client->addr != HMC5843_I2C_ADDRESS)
+		return -ENODEV;
+
+	if (i2c_smbus_read_i2c_block_data(client, HMC5843_ID_REG_A,
+				HMC5843_ID_REG_LENGTH, id_str)
+			!= HMC5843_ID_REG_LENGTH)
+		return -ENODEV;
+
+	if (0 != strncmp(id_str, HMC5843_ID_STRING, HMC5843_ID_REG_LENGTH))
+		return -ENODEV;
+
+	return 0;
+}
+
+/* Called when we have found a new HMC5843. */
+static void hmc5843_init_client(struct i2c_client *client)
+{
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	hmc5843_set_meas_conf(client, data->meas_conf);
+	hmc5843_set_rate(client, data->rate);
+	hmc5843_configure(client, data->operating_mode);
+	i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_B, data->range);
+	mutex_init(&data->lock);
+	pr_info("HMC5843 initialized\n");
+}
+
+static int hmc5843_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct hmc5843_data *data;
+	int err = 0;
+
+	data = kzalloc(sizeof(struct hmc5843_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	/* default settings at probe */
+
+	data->meas_conf = CONF_NORMAL;
+	data->range = RANGE_1_0;
+	data->operating_mode = MODE_CONVERSION_CONTINUOUS;
+
+	i2c_set_clientdata(client, data);
+
+	/* Initialize the HMC5843 chip */
+	hmc5843_init_client(client);
+
+	data->indio_dev = iio_allocate_device();
+	if (!data->indio_dev) {
+		err = -ENOMEM;
+		goto exit_free1;
+	}
+	data->indio_dev->attrs = &hmc5843_group;
+	data->indio_dev->dev.parent = &client->dev;
+	data->indio_dev->dev_data = (void *)(data);
+	data->indio_dev->driver_module = THIS_MODULE;
+	data->indio_dev->modes = INDIO_DIRECT_MODE;
+	err = iio_device_register(data->indio_dev);
+	if (err)
+		goto exit_free2;
+	return 0;
+exit_free2:
+	iio_free_device(data->indio_dev);
+exit_free1:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int hmc5843_remove(struct i2c_client *client)
+{
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	 /*  sleep mode to save power */
+	hmc5843_configure(client, MODE_SLEEP);
+	iio_device_unregister(data->indio_dev);
+	kfree(i2c_get_clientdata(client));
+	return 0;
+}
+
+static int hmc5843_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+	hmc5843_configure(client, MODE_SLEEP);
+	return 0;
+}
+
+static int hmc5843_resume(struct i2c_client *client)
+{
+	struct hmc5843_data *data = i2c_get_clientdata(client);
+	hmc5843_configure(client, data->operating_mode);
+	return 0;
+}
+
+static const struct i2c_device_id hmc5843_id[] = {
+	{ "hmc5843", 0 },
+	{ }
+};
+
+static struct i2c_driver hmc5843_driver = {
+	.driver = {
+		.name	= "hmc5843",
+	},
+	.id_table	= hmc5843_id,
+	.probe		= hmc5843_probe,
+	.remove		= hmc5843_remove,
+	.detect		= hmc5843_detect,
+	.address_list	= normal_i2c,
+	.suspend	= hmc5843_suspend,
+	.resume		= hmc5843_resume,
+};
+
+static int __init hmc5843_init(void)
+{
+	return i2c_add_driver(&hmc5843_driver);
+}
+
+static void __exit hmc5843_exit(void)
+{
+	i2c_del_driver(&hmc5843_driver);
+}
+
+MODULE_AUTHOR("Shubhrajyoti Datta <shubhrajyoti@ti.com");
+MODULE_DESCRIPTION("HMC5843 driver");
+MODULE_LICENSE("GPL");
+
+module_init(hmc5843_init);
+module_exit(hmc5843_exit);