text: #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/i2c-mux.h>
  #include <linux/iio/iio.h>
  #include <linux/module.h>
  #include <linux/regmap.h>
  #include <linux/pm_runtime.h>
  
  #include "mpu3050.h"
  
  static const struct regmap_config mpu3050_i2c_regmap_config = {
  	.reg_bits = 8,
  	.val_bits = 8,
  };
  
  static int mpu3050_i2c_bypass_select(struct i2c_mux_core *mux, u32 chan_id)
  {
  	struct mpu3050 *mpu3050 = i2c_mux_priv(mux);
  
  	/* Just power up the device, that is all that is needed */
  	pm_runtime_get_sync(mpu3050->dev);
  	return 0;
  }
  
  static int mpu3050_i2c_bypass_deselect(struct i2c_mux_core *mux, u32 chan_id)
  {
  	struct mpu3050 *mpu3050 = i2c_mux_priv(mux);
  
  	pm_runtime_mark_last_busy(mpu3050->dev);
  	pm_runtime_put_autosuspend(mpu3050->dev);
  	return 0;
  }
  
  static int mpu3050_i2c_probe(struct i2c_client *client,
  			     const struct i2c_device_id *id)
  {
  	struct regmap *regmap;
  	const char *name;
  	struct mpu3050 *mpu3050;
  	int ret;
  
  	if (!i2c_check_functionality(client->adapter,
  				     I2C_FUNC_SMBUS_I2C_BLOCK))
  		return -EOPNOTSUPP;
  
  	if (id)
  		name = id->name;
  	else
  		return -ENODEV;
  
  	regmap = devm_regmap_init_i2c(client, &mpu3050_i2c_regmap_config);
  	if (IS_ERR(regmap)) {
  		dev_err(&client->dev, "Failed to register i2c regmap %d\n",
  			(int)PTR_ERR(regmap));
  		return PTR_ERR(regmap);
  	}
  
  	ret = mpu3050_common_probe(&client->dev, regmap, client->irq, name);
  	if (ret)
  		return ret;
  
  	/* The main driver is up, now register the I2C mux */
  	mpu3050 = iio_priv(dev_get_drvdata(&client->dev));
  	mpu3050->i2cmux = i2c_mux_alloc(client->adapter, &client->dev,
  					1, 0, I2C_MUX_LOCKED | I2C_MUX_GATE,
  					mpu3050_i2c_bypass_select,
  					mpu3050_i2c_bypass_deselect);
  	/* Just fail the mux, there is no point in killing the driver */
  	if (!mpu3050->i2cmux)
  		dev_err(&client->dev, "failed to allocate I2C mux\n");
  	else {
  		mpu3050->i2cmux->priv = mpu3050;
  		ret = i2c_mux_add_adapter(mpu3050->i2cmux, 0, 0, 0);
  		if (ret)
  			dev_err(&client->dev, "failed to add I2C mux\n");
  	}
  
  	return 0;
  }
  
  static int mpu3050_i2c_remove(struct i2c_client *client)
  {
  	struct iio_dev *indio_dev = dev_get_drvdata(&client->dev);
  	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
  
  	if (mpu3050->i2cmux)
  		i2c_mux_del_adapters(mpu3050->i2cmux);
  
  	return mpu3050_common_remove(&client->dev);
  }
  
  /*
   * device id table is used to identify what device can be
   * supported by this driver
   */
  static const struct i2c_device_id mpu3050_i2c_id[] = {
  	{ "mpu3050" },
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, mpu3050_i2c_id);
  
  static const struct of_device_id mpu3050_i2c_of_match[] = {
  	{ .compatible = "invensense,mpu3050", .data = "mpu3050" },
  	/* Deprecated vendor ID from the Input driver */
  	{ .compatible = "invn,mpu3050", .data = "mpu3050" },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, mpu3050_i2c_of_match);
  
  static struct i2c_driver mpu3050_i2c_driver = {
  	.probe = mpu3050_i2c_probe,
  	.remove = mpu3050_i2c_remove,
  	.id_table = mpu3050_i2c_id,
  	.driver = {
  		.of_match_table = mpu3050_i2c_of_match,
  		.name = "mpu3050-i2c",
  		.pm = &mpu3050_dev_pm_ops,
  	},
  };
  module_i2c_driver(mpu3050_i2c_driver);
  
  MODULE_AUTHOR("Linus Walleij");
  MODULE_DESCRIPTION("Invensense MPU3050 gyroscope driver");
  MODULE_LICENSE("GPL");
  