// SPDX-License-Identifier: GPL-2.0-only

  /*

   * Copyright (C) 2006 Juergen Beisert, Pengutronix
   * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix

   * Copyright (C) 2009 Wolfram Sang, Pengutronix

   *

   * Check max730x.c for further details.

   */

  #include <linux/module.h>

  #include <linux/init.h>
  #include <linux/platform_device.h>
  #include <linux/mutex.h>

  #include <linux/slab.h>

  #include <linux/spi/spi.h>
  #include <linux/spi/max7301.h>

  /* A write to the MAX7301 means one message with one transfer */
  static int max7301_spi_write(struct device *dev, unsigned int reg,
  				unsigned int val)

  {

  	struct spi_device *spi = to_spi_device(dev);

  	u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);

  	return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);

  }

  /* A read from the MAX7301 means two transfers; here, one message each */
  
  static int max7301_spi_read(struct device *dev, unsigned int reg)

  {
  	int ret;
  	u16 word;

  	struct spi_device *spi = to_spi_device(dev);

  
  	word = 0x8000 | (reg << 8);

  	ret = spi_write_then_read(spi, &word, sizeof(word), &word,
  				  sizeof(word));

  	if (ret)
  		return ret;
  	return word & 0xff;
  }

  static int max7301_probe(struct spi_device *spi)

  {
  	struct max7301 *ts;

  	int ret;

  	/* bits_per_word cannot be configured in platform data */

  	spi->bits_per_word = 16;

  	ret = spi_setup(spi);
  	if (ret < 0)
  		return ret;

  	ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);

  	if (!ts)
  		return -ENOMEM;

  	ts->read = max7301_spi_read;
  	ts->write = max7301_spi_write;
  	ts->dev = &spi->dev;

  	ret = __max730x_probe(ts);

  	return ret;
  }

  static int max7301_remove(struct spi_device *spi)

  {

  	return __max730x_remove(&spi->dev);

  }

  static const struct spi_device_id max7301_id[] = {
  	{ "max7301", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(spi, max7301_id);

  static struct spi_driver max7301_driver = {
  	.driver = {

  		.name = "max7301",

  	},

  	.probe = max7301_probe,

  	.remove = max7301_remove,

  	.id_table = max7301_id,

  };
  
  static int __init max7301_init(void)
  {
  	return spi_register_driver(&max7301_driver);
  }

  /* register after spi postcore initcall and before
   * subsys initcalls that may rely on these GPIOs
   */
  subsys_initcall(max7301_init);

  
  static void __exit max7301_exit(void)
  {
  	spi_unregister_driver(&max7301_driver);
  }

  module_exit(max7301_exit);

  MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");

  MODULE_LICENSE("GPL v2");

  MODULE_DESCRIPTION("MAX7301 GPIO-Expander");