// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * mcp3021.c - driver for Microchip MCP3021 and MCP3221

   *
   * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
   * Author: Mingkai Hu <Mingkai.hu@freescale.com>

   * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>

   * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>

   *
   * This driver export the value of analog input voltage to sysfs, the
   * voltage unit is mV. Through the sysfs interface, lm-sensors tool
   * can also display the input voltage.

   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/hwmon.h>
  #include <linux/slab.h>
  #include <linux/i2c.h>
  #include <linux/err.h>
  #include <linux/device.h>

  #include <linux/of.h>
  #include <linux/of_device.h>

  /* Vdd / reference voltage in millivolt */
  #define MCP3021_VDD_REF_MAX	5500
  #define MCP3021_VDD_REF_MIN	2700
  #define MCP3021_VDD_REF_DEFAULT	3300

  
  /* output format */
  #define MCP3021_SAR_SHIFT	2
  #define MCP3021_SAR_MASK	0x3ff

  #define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */

  #define MCP3221_SAR_SHIFT	0
  #define MCP3221_SAR_MASK	0xfff
  #define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */

  enum chips {

  	mcp3021,
  	mcp3221

  };

  /*
   * Client data (each client gets its own)
   */
  struct mcp3021_data {
  	struct device *hwmon_dev;

  	u32 vdd;        /* supply and reference voltage in millivolt */

  	u16 sar_shift;
  	u16 sar_mask;
  	u8 output_res;

  };
  
  static int mcp3021_read16(struct i2c_client *client)
  {

  	struct mcp3021_data *data = i2c_get_clientdata(client);

  	int ret;
  	u16 reg;
  	__be16 buf;
  
  	ret = i2c_master_recv(client, (char *)&buf, 2);
  	if (ret < 0)
  		return ret;
  	if (ret != 2)
  		return -EIO;
  
  	/* The output code of the MCP3021 is transmitted with MSB first. */
  	reg = be16_to_cpu(buf);
  
  	/*
  	 * The ten-bit output code is composed of the lower 4-bit of the
  	 * first byte and the upper 6-bit of the second byte.
  	 */

  	reg = (reg >> data->sar_shift) & data->sar_mask;

  
  	return reg;
  }

  static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)

  {

  	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);

  }

  static ssize_t in0_input_show(struct device *dev,
  			      struct device_attribute *attr, char *buf)

  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct mcp3021_data *data = i2c_get_clientdata(client);
  	int reg, in_input;
  
  	reg = mcp3021_read16(client);
  	if (reg < 0)
  		return reg;

  	in_input = volts_from_reg(data, reg);

  	return sprintf(buf, "%d
  ", in_input);
  }

  static DEVICE_ATTR_RO(in0_input);

  static const struct i2c_device_id mcp3021_id[];
  
  static int mcp3021_probe(struct i2c_client *client)

  {
  	int err;
  	struct mcp3021_data *data = NULL;

  	struct device_node *np = client->dev.of_node;

  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  		return -ENODEV;

  	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
  			    GFP_KERNEL);

  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);

  	if (np) {
  		if (!of_property_read_u32(np, "reference-voltage-microvolt",
  					  &data->vdd))
  			data->vdd /= 1000;
  		else
  			data->vdd = MCP3021_VDD_REF_DEFAULT;
  	} else {
  		u32 *pdata = dev_get_platdata(&client->dev);
  
  		if (pdata)
  			data->vdd = *pdata;
  		else
  			data->vdd = MCP3021_VDD_REF_DEFAULT;
  	}

  	switch (i2c_match_id(mcp3021_id, client)->driver_data) {

  	case mcp3021:
  		data->sar_shift = MCP3021_SAR_SHIFT;
  		data->sar_mask = MCP3021_SAR_MASK;
  		data->output_res = MCP3021_OUTPUT_RES;

  		break;

  
  	case mcp3221:
  		data->sar_shift = MCP3221_SAR_SHIFT;
  		data->sar_mask = MCP3221_SAR_MASK;
  		data->output_res = MCP3221_OUTPUT_RES;

  		break;

  	}

  	if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
  		return -EINVAL;

  
  	err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
  	if (err)

  		return err;

  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_remove;
  	}
  
  	return 0;
  
  exit_remove:
  	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);

  	return err;
  }
  
  static int mcp3021_remove(struct i2c_client *client)
  {
  	struct mcp3021_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);

  
  	return 0;
  }
  
  static const struct i2c_device_id mcp3021_id[] = {

  	{ "mcp3021", mcp3021 },

  	{ "mcp3221", mcp3221 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, mcp3021_id);

  #ifdef CONFIG_OF
  static const struct of_device_id of_mcp3021_match[] = {
  	{ .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
  	{ .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, of_mcp3021_match);
  #endif

  static struct i2c_driver mcp3021_driver = {
  	.driver = {
  		.name = "mcp3021",

  		.of_match_table = of_match_ptr(of_mcp3021_match),

  	},

  	.probe_new = mcp3021_probe,

  	.remove = mcp3021_remove,
  	.id_table = mcp3021_id,
  };
  
  module_i2c_driver(mcp3021_driver);
  
  MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");

  MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");

  MODULE_LICENSE("GPL");