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>

3 files changed, 367 insertions, 0 deletions

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index a59047d7657e..69302bed2860 100644
--- a/drivers/iio/accel/Kconfig
+++ b/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
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index ebd2675b2a02..020dda0ae508 100644
--- a/drivers/iio/accel/Makefile
+++ b/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
 
diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
new file mode 100644
index 000000000000..e15c1bd26bd1
--- /dev/null
+++ b/drivers/iio/accel/mxc4005.c
@@ -0,0 +1,354 @@
+/*
+ * 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");