iio: accel: add support for mxc4005 accelerometer

This patch adds support for Memsic MXC4005XC 3-axis accelerometer. The
current implementation is a minimal one as it adds raw readings for the
three axes and setting scale from userspace.
Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/Kconfig

@@ -137,6 +137,17 @@ config MMA9553
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma9553.
 
+config MXC4005
+	tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say yes here to build support for the Memsic MXC4005XC 3-axis
+	  accelerometer.
+
+	  To compile this driver as a module, choose M. The module will be
+	  called mxc4005.
+
 config STK8312
 	tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
 	depends on I2C

drivers/iio/accel/Makefile

@@ -14,6 +14,8 @@ obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o
 obj-$(CONFIG_MMA9551)		+= mma9551.o
 obj-$(CONFIG_MMA9553)		+= mma9553.o
 
+obj-$(CONFIG_MXC4005)		+= mxc4005.o
+
 obj-$(CONFIG_STK8312)		+= stk8312.o
 obj-$(CONFIG_STK8BA50)		+= stk8ba50.o
 

drivers/iio/accel/mxc4005.c

+/*
+ * 3-axis accelerometer driver for MXC4005XC Memsic sensor
+ *
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/acpi.h>
+#include <linux/regmap.h>
+#include <linux/iio/sysfs.h>
+
+#define MXC4005_DRV_NAME		"mxc4005"
+#define MXC4005_REGMAP_NAME		"mxc4005_regmap"
+
+#define MXC4005_REG_XOUT_UPPER		0x03
+#define MXC4005_REG_XOUT_LOWER		0x04
+#define MXC4005_REG_YOUT_UPPER		0x05
+#define MXC4005_REG_YOUT_LOWER		0x06
+#define MXC4005_REG_ZOUT_UPPER		0x07
+#define MXC4005_REG_ZOUT_LOWER		0x08
+
+#define MXC4005_REG_CONTROL		0x0D
+#define MXC4005_REG_CONTROL_MASK_FSR	GENMASK(6, 5)
+#define MXC4005_CONTROL_FSR_SHIFT	5
+
+#define MXC4005_REG_DEVICE_ID		0x0E
+
+enum mxc4005_axis {
+	AXIS_X,
+	AXIS_Y,
+	AXIS_Z,
+};
+
+enum mxc4005_range {
+	MXC4005_RANGE_2G,
+	MXC4005_RANGE_4G,
+	MXC4005_RANGE_8G,
+};
+
+struct mxc4005_data {
+	struct device *dev;
+	struct mutex mutex;
+	struct regmap *regmap;
+};
+
+/*
+ * MXC4005 can operate in the following ranges:
+ * +/- 2G, 4G, 8G (the default +/-2G)
+ *
+ * (2 + 2) * 9.81 / (2^12 - 1) = 0.009582
+ * (4 + 4) * 9.81 / (2^12 - 1) = 0.019164
+ * (8 + 8) * 9.81 / (2^12 - 1) = 0.038329
+ */
+static const struct {
+	u8 range;
+	int scale;
+} mxc4005_scale_table[] = {
+	{MXC4005_RANGE_2G, 9582},
+	{MXC4005_RANGE_4G, 19164},
+	{MXC4005_RANGE_8G, 38329},
+};
+
+
+static IIO_CONST_ATTR(in_accel_scale_available, "0.009582 0.019164 0.038329");
+
+static struct attribute *mxc4005_attributes[] = {
+	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group mxc4005_attrs_group = {
+	.attrs = mxc4005_attributes,
+};
+
+static bool mxc4005_is_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MXC4005_REG_XOUT_UPPER:
+	case MXC4005_REG_XOUT_LOWER:
+	case MXC4005_REG_YOUT_UPPER:
+	case MXC4005_REG_YOUT_LOWER:
+	case MXC4005_REG_ZOUT_UPPER:
+	case MXC4005_REG_ZOUT_LOWER:
+	case MXC4005_REG_DEVICE_ID:
+	case MXC4005_REG_CONTROL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool mxc4005_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MXC4005_REG_CONTROL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config mxc4005_regmap_config = {
+	.name = MXC4005_REGMAP_NAME,
+
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = MXC4005_REG_DEVICE_ID,
+
+	.readable_reg = mxc4005_is_readable_reg,
+	.writeable_reg = mxc4005_is_writeable_reg,
+};
+
+static int mxc4005_read_axis(struct mxc4005_data *data,
+			     unsigned int addr)
+{
+	__be16 reg;
+	int ret;
+
+	ret = regmap_bulk_read(data->regmap, addr, (u8 *) &reg, sizeof(reg));
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read reg %02x\n", addr);
+		return ret;
+	}
+
+	return be16_to_cpu(reg);
+}
+
+static int mxc4005_read_scale(struct mxc4005_data *data)
+{
+	unsigned int reg;
+	int ret;
+	int i;
+
+	ret = regmap_read(data->regmap, MXC4005_REG_CONTROL, &reg);
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read reg_control\n");
+		return ret;
+	}
+
+	i = reg >> MXC4005_CONTROL_FSR_SHIFT;
+
+	if (i < 0 || i >= ARRAY_SIZE(mxc4005_scale_table))
+		return -EINVAL;
+
+	return mxc4005_scale_table[i].scale;
+}
+
+static int mxc4005_set_scale(struct mxc4005_data *data, int val)
+{
+	unsigned int reg;
+	int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(mxc4005_scale_table); i++) {
+		if (mxc4005_scale_table[i].scale == val) {
+			reg = i << MXC4005_CONTROL_FSR_SHIFT;
+			ret = regmap_update_bits(data->regmap,
+						 MXC4005_REG_CONTROL,
+						 MXC4005_REG_CONTROL_MASK_FSR,
+						 reg);
+			if (ret < 0)
+				dev_err(data->dev,
+					"failed to write reg_control\n");
+			return ret;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int mxc4005_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mxc4005_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_ACCEL:
+			if (iio_buffer_enabled(indio_dev))
+				return -EBUSY;
+
+			ret = mxc4005_read_axis(data, chan->address);
+			if (ret < 0)
+				return ret;
+			*val = sign_extend32(ret >> 4, 11);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		ret = mxc4005_read_scale(data);
+		if (ret < 0)
+			return ret;
+
+		*val = 0;
+		*val2 = ret;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mxc4005_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct mxc4005_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		if (val != 0)
+			return -EINVAL;
+
+		return mxc4005_set_scale(data, val2);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mxc4005_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= mxc4005_read_raw,
+	.write_raw	= mxc4005_write_raw,
+	.attrs		= &mxc4005_attrs_group,
+};
+
+#define MXC4005_CHANNEL(_axis, _addr) {				\
+	.type = IIO_ACCEL,					\
+	.modified = 1,						\
+	.channel2 = IIO_MOD_##_axis,				\
+	.address = _addr,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+}
+
+static const struct iio_chan_spec mxc4005_channels[] = {
+	MXC4005_CHANNEL(X, MXC4005_REG_XOUT_UPPER),
+	MXC4005_CHANNEL(Y, MXC4005_REG_YOUT_UPPER),
+	MXC4005_CHANNEL(Z, MXC4005_REG_ZOUT_UPPER),
+};
+
+static int mxc4005_chip_init(struct mxc4005_data *data)
+{
+	int ret;
+	unsigned int reg;
+
+	ret = regmap_read(data->regmap, MXC4005_REG_DEVICE_ID, &reg);
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read chip id\n");
+		return ret;
+	}
+
+	dev_dbg(data->dev, "MXC4005 chip id %02x\n", reg);
+
+	return 0;
+}
+
+static int mxc4005_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct mxc4005_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, &mxc4005_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "failed to initialize regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->dev = &client->dev;
+	data->regmap = regmap;
+
+	ret = mxc4005_chip_init(data);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to initialize chip\n");
+		return ret;
+	}
+
+	mutex_init(&data->mutex);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = mxc4005_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mxc4005_channels);
+	indio_dev->name = MXC4005_DRV_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &mxc4005_info;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"unable to register iio device %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mxc4005_remove(struct i2c_client *client)
+{
+	iio_device_unregister(i2c_get_clientdata(client));
+
+	return 0;
+}
+
+static const struct acpi_device_id mxc4005_acpi_match[] = {
+	{"MXC4005",	0},
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, mxc4005_acpi_match);
+
+static const struct i2c_device_id mxc4005_id[] = {
+	{"mxc4005",	0},
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, mxc4005_id);
+
+static struct i2c_driver mxc4005_driver = {
+	.driver = {
+		.name = MXC4005_DRV_NAME,
+		.acpi_match_table = ACPI_PTR(mxc4005_acpi_match),
+	},
+	.probe		= mxc4005_probe,
+	.remove		= mxc4005_remove,
+	.id_table	= mxc4005_id,
+};
+
+module_i2c_driver(mxc4005_driver);
+
+MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MXC4005 3-axis accelerometer driver");