Date:	Wed, 15 Apr 2015 14:02:04 +0300
From:	Daniel Baluta <daniel.baluta@...el.com>
To:	jic23@...nel.org
Cc:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	daniel.baluta@...el.com, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org
Subject: [PATCH 1/3] iio: magnetometer: Add support for MEMSIC MMC35240 sensor

Minimal implementation for MMC35240 3-axis magnetometer
sensor. It provides processed readings and possiblity to change
the sampling frequency.

Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
---
 drivers/iio/magnetometer/Kconfig    |  11 +
 drivers/iio/magnetometer/Makefile   |   1 +
 drivers/iio/magnetometer/mmc35240.c | 476 ++++++++++++++++++++++++++++++++++++
 3 files changed, 488 insertions(+)
 create mode 100644 drivers/iio/magnetometer/mmc35240.c

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index a5d6de7..7aba685 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -47,6 +47,17 @@ config HID_SENSOR_MAGNETOMETER_3D
 	  Say yes here to build support for the HID SENSOR
 	  Magnetometer 3D.
 
+config MMC35240
+	tristate "MEMSIC MMC35240 3-axis magnetic sensor"
+	select REGMAP_I2C
+	depends on I2C
+	help
+	  Say yes here to build support for the MEMSIC MMC35240 3-axis
+	  magnetic sensor.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mmc35240.
+
 config IIO_ST_MAGN_3AXIS
 	tristate "STMicroelectronics magnetometers 3-Axis Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 0f5d3c9..696a429 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_AK8975)	+= ak8975.o
 obj-$(CONFIG_MAG3110)	+= mag3110.o
 obj-$(CONFIG_HID_SENSOR_MAGNETOMETER_3D) += hid-sensor-magn-3d.o
+obj-$(CONFIG_MMC35240)	+= mmc35240.o
 
 obj-$(CONFIG_IIO_ST_MAGN_3AXIS) += st_magn.o
 st_magn-y := st_magn_core.o
diff --git a/drivers/iio/magnetometer/mmc35240.c b/drivers/iio/magnetometer/mmc35240.c
new file mode 100644
index 0000000..c46c1f7
--- /dev/null
+++ b/drivers/iio/magnetometer/mmc35240.c
@@ -0,0 +1,476 @@
+/*
+ * MMC35240 - MEMSIC 3-axis Magnetic Sensor
+ *
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
+ *
+ * TODO: offset, ACPI, continuous measurement mode, PM
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MMC35240_DRV_NAME "mmc35240"
+#define MMC35240_REGMAP_NAME "mmc35240_regmap"
+
+#define MMC35240_REG_XOUT_L	0x00
+#define MMC35240_REG_XOUT_H	0x01
+#define MMC35240_REG_YOUT_L	0x02
+#define MMC35240_REG_YOUT_H	0x03
+#define MMC35240_REG_ZOUT_L	0x04
+#define MMC35240_REG_ZOUT_H	0x05
+
+#define MMC35240_REG_STATUS	0x06
+#define MMC35240_REG_CTRL0	0x07
+#define MMC35240_REG_CTRL1	0x08
+
+#define MMC35240_REG_ID		0x20
+
+#define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)
+
+#define MMC35240_CTRL0_REFILL_BIT	BIT(7)
+#define MMC35240_CTRL0_RESET_BIT	BIT(6)
+#define MMC35240_CTRL0_SET_BIT		BIT(5)
+#define MMC35240_CTRL0_CMM_BIT		BIT(1)
+#define MMC35240_CTRL0_TM_BIT		BIT(0)
+
+/* output resolution bits */
+#define MMC35240_CTRL1_BW0_BIT		BIT(0)
+#define MMC35240_CTRL1_BW1_BIT		BIT(1)
+
+#define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
+		 MMC35240_CTRL1_BW1_BIT)
+#define MMC35240_CTRL1_BW_SHIFT		0
+
+#define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
+#define MMC53240_WAIT_SET_RESET		1000	/* us */
+
+enum mmc35240_resolution {
+	MMC35240_16_BITS_SLOW = 0, /* 100 Hz */
+	MMC35240_16_BITS_FAST,     /* 200 Hz */
+	MMC35240_14_BITS,          /* 333 Hz */
+	MMC35240_12_BITS,          /* 666 Hz */
+	MMC35240_MAX_BITS /* this must be last */
+};
+
+enum mmc35240_axis {
+	AXIS_X = 0,
+	AXIS_Y,
+	AXIS_Z,
+};
+
+static const struct {
+	int sens[3]; /* sensitivity per X, Y, Z axis */
+	int nfo; /* null field output */
+} mmc35240_props_table[] = {
+	/* 16 bits, 100Hz ODR */
+	{
+		{1024, 1024, 770},
+		32768,
+	},
+	/* 16 bits, 200Hz ODR */
+	{
+		{1024, 1024, 770},
+		32768,
+	},
+	/* 14 bits, 333Hz ODR */
+	{
+		{256, 256, 193},
+		8192,
+	},
+	/* 12 bits, 666Hz ODR */
+	{
+		{64, 64, 48},
+		2048,
+	},
+};
+
+struct mmc35240_data {
+	struct i2c_client *client;
+	struct mutex mutex;
+	struct regmap *regmap;
+	enum mmc35240_resolution res;
+};
+
+int mmc35240_samp_freq[] = {100, 200, 333, 666};
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("100 200 333 666");
+
+#define MMC35240_CHANNEL(_axis) { \
+	.type = IIO_MAGN, \
+	.modified = 1, \
+	.channel2 = IIO_MOD_ ## _axis, \
+	.address = AXIS_ ## _axis, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+}
+
+static const struct iio_chan_spec mmc35240_channels[] = {
+	MMC35240_CHANNEL(X),
+	MMC35240_CHANNEL(Y),
+	MMC35240_CHANNEL(Z),
+};
+
+static struct attribute *mmc35240_attributes[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+};
+
+static const struct attribute_group mmc35240_attribute_group = {
+	.attrs = mmc35240_attributes,
+};
+
+static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
+					int val, int val2)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
+		if (mmc35240_samp_freq[i] == val)
+			return i;
+	return -EINVAL;
+}
+
+static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
+{
+	int ret;
+	u8 coil_bit;
+
+	/*
+	 * Recharge the capacitor at VCAP pin, requested to be issued
+	 * before a SET/RESET command.
+	 */
+	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
+				 MMC35240_CTRL0_REFILL_BIT,
+				 MMC35240_CTRL0_REFILL_BIT);
+	if (ret < 0)
+		return ret;
+	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);
+
+	if (set)
+		coil_bit = MMC35240_CTRL0_SET_BIT;
+	else
+		coil_bit = MMC35240_CTRL0_RESET_BIT;
+
+	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
+				  MMC35240_CTRL0_REFILL_BIT,
+				  coil_bit);
+}
+
+static int mmc35240_init(struct mmc35240_data *data)
+{
+	int ret;
+	unsigned int reg_id;
+
+	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Error reading product id\n");
+		return ret;
+	}
+
+	dev_info(&data->client->dev, "MMC35240 chip id %x\n", reg_id);
+
+	/*
+	 * make sure we restore sensor characteristics, by doing
+	 * a RESET/SET sequence
+	 */
+	ret = mmc35240_hw_set(data, false);
+	if (ret < 0)
+		return ret;
+	usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);
+
+	ret = mmc35240_hw_set(data, true);
+	if (ret < 0)
+		return ret;
+
+	/* set default sampling frequency */
+	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
+				  MMC35240_CTRL1_BW_MASK,
+				  data->res << MMC35240_CTRL1_BW_SHIFT);
+}
+
+static int mmc35240_take_measurement(struct mmc35240_data *data)
+{
+	int ret, tries = 100;
+	unsigned int reg_status;
+
+	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
+			   MMC35240_CTRL0_TM_BIT);
+	if (ret < 0)
+		return ret;
+
+	while (tries-- > 0) {
+		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
+				  &reg_status);
+		if (ret < 0)
+			return ret;
+		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
+			break;
+		msleep(20);
+	}
+
+	if (tries < 0) {
+		dev_err(&data->client->dev, "data not ready\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
+{
+	int ret;
+
+	ret = mmc35240_take_measurement(data);
+	if (ret < 0)
+		return ret;
+
+	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
+				3 * sizeof(__be16));
+}
+
+int mmc35240_raw_to_gauss(struct mmc35240_data *data, int index, __le16 buf[],
+			  int *val, int *val2)
+{
+	int raw_x, raw_y, raw_z;
+	int sens_x, sens_y, sens_z;
+	int nfo;
+
+	raw_x = le16_to_cpu(buf[AXIS_X]);
+	raw_y = le16_to_cpu(buf[AXIS_Y]);
+	raw_z = le16_to_cpu(buf[AXIS_Z]);
+
+	sens_x = mmc35240_props_table[data->res].sens[AXIS_X];
+	sens_y = mmc35240_props_table[data->res].sens[AXIS_Y];
+	sens_z = mmc35240_props_table[data->res].sens[AXIS_Z];
+
+	nfo = mmc35240_props_table[data->res].nfo;
+
+	switch (index) {
+	case AXIS_X:
+		*val = (raw_x - nfo) / sens_x;
+		*val2 = ((raw_x - nfo) % sens_x) * 1000000;
+		break;
+	case AXIS_Y:
+		*val = (raw_y - nfo) / sens_y - (raw_z - nfo) / sens_z;
+		*val2 = (((raw_y - nfo) % sens_y - (raw_z - nfo) % sens_z))
+			* 1000000;
+		break;
+	case AXIS_Z:
+		*val = (raw_y - nfo) / sens_y + (raw_z - nfo) / sens_z;
+		*val2 = (((raw_y - nfo) % sens_y + (raw_z - nfo) % sens_z))
+			* 1000000;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int mmc35240_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int *val,
+			     int *val2, long mask)
+{
+	struct mmc35240_data *data = iio_priv(indio_dev);
+	int ret, i;
+	unsigned int reg;
+	__le16 buf[3];
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		mutex_lock(&data->mutex);
+		ret = mmc35240_read_measurement(data, buf);
+		mutex_unlock(&data->mutex);
+		if (ret < 0)
+			return ret;
+		ret = mmc35240_raw_to_gauss(data, chan->address,
+					    buf, val, val2);
+		if (ret < 0)
+			return ret;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		mutex_lock(&data->mutex);
+		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
+		mutex_unlock(&data->mutex);
+		if (ret < 0)
+			return ret;
+
+		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
+		if (i < 0 || i > ARRAY_SIZE(mmc35240_samp_freq))
+			return -EINVAL;
+
+		*val = mmc35240_samp_freq[i];
+		*val2 = 0;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mmc35240_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan, int val,
+			      int val2, long mask)
+{
+	struct mmc35240_data *data = iio_priv(indio_dev);
+	int i, ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		i = mmc35240_get_samp_freq_index(data, val, val2);
+		if (i < 0)
+			return -EINVAL;
+		mutex_lock(&data->mutex);
+		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
+					 MMC35240_CTRL1_BW_MASK,
+					 i << MMC35240_CTRL1_BW_SHIFT);
+		mutex_unlock(&data->mutex);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mmc35240_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= mmc35240_read_raw,
+	.write_raw	= mmc35240_write_raw,
+	.attrs		= &mmc35240_attribute_group,
+};
+
+static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MMC35240_REG_CTRL0:
+	case MMC35240_REG_CTRL1:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MMC35240_REG_XOUT_L:
+	case MMC35240_REG_XOUT_H:
+	case MMC35240_REG_YOUT_L:
+	case MMC35240_REG_YOUT_H:
+	case MMC35240_REG_ZOUT_L:
+	case MMC35240_REG_ZOUT_H:
+	case MMC35240_REG_STATUS:
+	case MMC35240_REG_ID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MMC35240_REG_CTRL0:
+	case MMC35240_REG_CTRL1:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static struct reg_default mmc35240_reg_defaults[] = {
+	{ MMC35240_REG_CTRL0,  0x00 },
+	{ MMC35240_REG_CTRL1,  0x00 },
+};
+
+static const struct regmap_config mmc35240_regmap_config = {
+	.name = MMC35240_REGMAP_NAME,
+
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = MMC35240_REG_ID,
+	.cache_type = REGCACHE_FLAT,
+
+	.writeable_reg = mmc35240_is_writeable_reg,
+	.readable_reg = mmc35240_is_readable_reg,
+	.volatile_reg = mmc35240_is_volatile_reg,
+
+	.reg_defaults = mmc35240_reg_defaults,
+	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
+};
+
+static int mmc35240_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct mmc35240_data *data;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "regmap initialization failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	data->regmap = regmap;
+	data->res = MMC35240_16_BITS_SLOW;
+
+	mutex_init(&data->mutex);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &mmc35240_info;
+	indio_dev->name = MMC35240_DRV_NAME;
+	indio_dev->channels = mmc35240_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = mmc35240_init(data);
+	if (ret < 0) {
+		dev_err(&client->dev, "mmc35240 chip init failed\n");
+		return ret;
+	}
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static int mmc35240_remove(struct i2c_client *client)
+{
+	return 0;
+}
+
+static const struct i2c_device_id mmc35240_id[] = {
+	{"MMC35240", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, mmc35240_id);
+
+static struct i2c_driver mmc35240_driver = {
+	.driver = {
+		.name = MMC35240_DRV_NAME,
+	},
+	.probe		= mmc35240_probe,
+	.remove		= mmc35240_remove,
+	.id_table	= mmc35240_id,
+};
+
+module_i2c_driver(mmc35240_driver);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@...el.com>");
+MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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