// SPDX-License-Identifier: GPL-2.0-only
  /*
   * Simple MFD - I2C
   *
   * This driver creates a single register map with the intention for it to be
   * shared by all sub-devices.  Children can use their parent's device structure
   * (dev.parent) in order to reference it.
   *
   * Once the register map has been successfully initialised, any sub-devices
   * represented by child nodes in Device Tree will be subsequently registered.
   */
  
  #include <linux/i2c.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of_platform.h>
  #include <linux/regmap.h>
  
  static const struct regmap_config simple_regmap_config = {
  	.reg_bits = 8,
  	.val_bits = 8,
  };
  
  static int simple_mfd_i2c_probe(struct i2c_client *i2c)
  {
  	const struct regmap_config *config;
  	struct regmap *regmap;
  
  	config = device_get_match_data(&i2c->dev);
  	if (!config)
  		config = &simple_regmap_config;
  
  	regmap = devm_regmap_init_i2c(i2c, config);
  	if (IS_ERR(regmap))
  		return PTR_ERR(regmap);
  
  	return devm_of_platform_populate(&i2c->dev);
  }
  
  static const struct of_device_id simple_mfd_i2c_of_match[] = {

  	{ .compatible = "kontron,sl28cpld" },

  	{}
  };
  MODULE_DEVICE_TABLE(of, simple_mfd_i2c_of_match);
  
  static struct i2c_driver simple_mfd_i2c_driver = {
  	.probe_new = simple_mfd_i2c_probe,
  	.driver = {
  		.name = "simple-mfd-i2c",
  		.of_match_table = simple_mfd_i2c_of_match,
  	},
  };
  module_i2c_driver(simple_mfd_i2c_driver);
  
  MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
  MODULE_DESCRIPTION("Simple MFD - I2C driver");
  MODULE_LICENSE("GPL v2");