iio: accel: add support for Memsic MXC6255XC sensor

This patch adds a minimal implementation for the Memsic MXC6255XC
orientation sensing accelerometer. The supported operations are reading
raw acceleration values for X/Y axis that can be scaled using the
exposed scale.

Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 969428dd63299af04e4200ae309f971463f3f5eb..75ac08790bc5ad572dd93b6b49efed8c35bf9d1e 100644 (file)
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -158,6 +158,17 @@ config MXC4005
          To compile this driver as a module, choose M. The module will be
          called mxc4005.
 
+config MXC6255
+       tristate "Memsic MXC6255 Orientation Sensing Accelerometer Driver"
+       depends on I2C
+       select REGMAP_I2C
+       help
+         Say yes here to build support for the Memsic MXC6255 Orientation
+         Sensing Accelerometer Driver.
+
+         To compile this driver as a module, choose M here: the module will be
+         called mxc6255.
+
 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 7925f166e6e957c76cf7acc9862ea603f23d9ea0..525ed52fab52fafcb8425f80281208fd0a9f2c2c 100644 (file)
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_MMA9551)         += mma9551.o
 obj-$(CONFIG_MMA9553)          += mma9553.o
 
 obj-$(CONFIG_MXC4005)          += mxc4005.o
+obj-$(CONFIG_MXC6255)          += mxc6255.o
 
 obj-$(CONFIG_STK8312)          += stk8312.o
 obj-$(CONFIG_STK8BA50)         += stk8ba50.o

diff --git a/drivers/iio/accel/mxc6255.c b/drivers/iio/accel/mxc6255.c
new file mode 100644 (file)
index 0000000..97ccde7
--- /dev/null
+++ b/drivers/iio/accel/mxc6255.c
@@ -0,0 +1,198 @@
+/*
+ * MXC6255 - MEMSIC orientation sensing accelerometer
+ *
+ * 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 MXC6255 (7-bit I2C slave address 0x15).
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/iio/iio.h>
+#include <linux/delay.h>
+#include <linux/acpi.h>
+#include <linux/regmap.h>
+#include <linux/iio/sysfs.h>
+
+#define MXC6255_DRV_NAME               "mxc6255"
+#define MXC6255_REGMAP_NAME            "mxc6255_regmap"
+
+#define MXC6255_REG_XOUT               0x00
+#define MXC6255_REG_YOUT               0x01
+#define MXC6255_REG_CHIP_ID            0x08
+
+#define MXC6255_CHIP_ID                        0x05
+
+/*
+ * MXC6255 has only one measurement range: +/- 2G.
+ * The acceleration output is an 8-bit value.
+ *
+ * Scale is calculated as follows:
+ * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
+ *
+ * Scale value for +/- 2G measurement range
+ */
+#define MXC6255_SCALE                  153829
+
+enum mxc6255_axis {
+       AXIS_X,
+       AXIS_Y,
+};
+
+struct mxc6255_data {
+       struct i2c_client *client;
+       struct regmap *regmap;
+};
+
+static int mxc6255_read_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan,
+                           int *val, int *val2, long mask)
+{
+       struct mxc6255_data *data = iio_priv(indio_dev);
+       unsigned int reg;
+       int ret;
+
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+               ret = regmap_read(data->regmap, chan->address, &reg);
+               if (ret < 0) {
+                       dev_err(&data->client->dev,
+                               "Error reading reg %lu\n", chan->address);
+                       return ret;
+               }
+
+               *val = sign_extend32(reg, 7);
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_SCALE:
+               *val = 0;
+               *val2 = MXC6255_SCALE;
+               return IIO_VAL_INT_PLUS_MICRO;
+       default:
+               return -EINVAL;
+       }
+}
+
+static const struct iio_info mxc6255_info = {
+       .driver_module  = THIS_MODULE,
+       .read_raw       = mxc6255_read_raw,
+};
+
+#define MXC6255_CHANNEL(_axis, reg) {                          \
+       .type = IIO_ACCEL,                                      \
+       .modified = 1,                                          \
+       .channel2 = IIO_MOD_##_axis,                            \
+       .address = reg,                                         \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
+       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
+}
+
+static const struct iio_chan_spec mxc6255_channels[] = {
+       MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
+       MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
+};
+
+static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
+{
+       switch (reg) {
+       case MXC6255_REG_XOUT:
+       case MXC6255_REG_YOUT:
+       case MXC6255_REG_CHIP_ID:
+               return true;
+       default:
+               return false;
+       }
+}
+
+static const struct regmap_config mxc6255_regmap_config = {
+       .name = MXC6255_REGMAP_NAME,
+
+       .reg_bits = 8,
+       .val_bits = 8,
+
+       .readable_reg = mxc6255_is_readable_reg,
+};
+
+static int mxc6255_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+       struct mxc6255_data *data;
+       struct iio_dev *indio_dev;
+       struct regmap *regmap;
+       unsigned int chip_id;
+       int ret;
+
+       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+       if (!indio_dev)
+               return -ENOMEM;
+
+       regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
+       if (IS_ERR(regmap)) {
+               dev_err(&client->dev, "Error initializing regmap\n");
+               return PTR_ERR(regmap);
+       }
+
+       data = iio_priv(indio_dev);
+       i2c_set_clientdata(client, indio_dev);
+       data->client = client;
+       data->regmap = regmap;
+
+       indio_dev->name = MXC6255_DRV_NAME;
+       indio_dev->dev.parent = &client->dev;
+       indio_dev->channels = mxc6255_channels;
+       indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
+       indio_dev->modes = INDIO_DIRECT_MODE;
+       indio_dev->info = &mxc6255_info;
+
+       ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
+       if (ret < 0) {
+               dev_err(&client->dev, "Error reading chip id %d\n", ret);
+               return ret;
+       }
+
+       if (chip_id != MXC6255_CHIP_ID) {
+               dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
+               return -ENODEV;
+       }
+
+       dev_dbg(&client->dev, "Chip id %x\n", chip_id);
+
+       ret = devm_iio_device_register(&client->dev, indio_dev);
+       if (ret < 0) {
+               dev_err(&client->dev, "Could not register IIO device\n");
+               return ret;
+       }
+
+       return 0;
+}
+
+static const struct acpi_device_id mxc6255_acpi_match[] = {
+       {"MXC6255",     0},
+       { }
+};
+MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
+
+static const struct i2c_device_id mxc6255_id[] = {
+       {"mxc6255",     0},
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, mxc6255_id);
+
+static struct i2c_driver mxc6255_driver = {
+       .driver = {
+               .name = MXC6255_DRV_NAME,
+               .acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
+       },
+       .probe          = mxc6255_probe,
+       .id_table       = mxc6255_id,
+};
+
+module_i2c_driver(mxc6255_driver);
+
+MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
+MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
+MODULE_LICENSE("GPL v2");