--- /dev/null
+/*
+ * 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, ®);
+ 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");
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