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

  /*
   * Driver for Linear Technology LTC4222 Dual Hot Swap controller
   *
   * Copyright (c) 2014 Guenter Roeck

   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/bitops.h>
  #include <linux/i2c.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/jiffies.h>
  #include <linux/regmap.h>
  
  /* chip registers */
  
  #define LTC4222_CONTROL1	0xd0
  #define LTC4222_ALERT1		0xd1
  #define LTC4222_STATUS1		0xd2
  #define LTC4222_FAULT1		0xd3
  #define LTC4222_CONTROL2	0xd4
  #define LTC4222_ALERT2		0xd5
  #define LTC4222_STATUS2		0xd6
  #define LTC4222_FAULT2		0xd7
  #define LTC4222_SOURCE1		0xd8
  #define LTC4222_SOURCE2		0xda
  #define LTC4222_ADIN1		0xdc
  #define LTC4222_ADIN2		0xde
  #define LTC4222_SENSE1		0xe0
  #define LTC4222_SENSE2		0xe2
  #define LTC4222_ADC_CONTROL	0xe4
  
  /*
   * Fault register bits
   */
  #define FAULT_OV	BIT(0)
  #define FAULT_UV	BIT(1)
  #define FAULT_OC	BIT(2)
  #define FAULT_POWER_BAD	BIT(3)
  #define FAULT_FET_BAD	BIT(5)
  
  /* Return the voltage from the given register in mV or mA */
  static int ltc4222_get_value(struct device *dev, u8 reg)
  {
  	struct regmap *regmap = dev_get_drvdata(dev);
  	unsigned int val;
  	u8 buf[2];
  	int ret;
  
  	ret = regmap_bulk_read(regmap, reg, buf, 2);
  	if (ret < 0)
  		return ret;
  
  	val = ((buf[0] << 8) + buf[1]) >> 6;
  
  	switch (reg) {
  	case LTC4222_ADIN1:
  	case LTC4222_ADIN2:
  		/* 1.25 mV resolution. Convert to mV. */
  		val = DIV_ROUND_CLOSEST(val * 5, 4);
  		break;
  	case LTC4222_SOURCE1:
  	case LTC4222_SOURCE2:
  		/* 31.25 mV resolution. Convert to mV. */
  		val = DIV_ROUND_CLOSEST(val * 125, 4);
  		break;
  	case LTC4222_SENSE1:
  	case LTC4222_SENSE2:
  		/*
  		 * 62.5 uV resolution. Convert to current as measured with
  		 * an 1 mOhm sense resistor, in mA. If a different sense
  		 * resistor is installed, calculate the actual current by
  		 * dividing the reported current by the sense resistor value
  		 * in mOhm.
  		 */
  		val = DIV_ROUND_CLOSEST(val * 125, 2);
  		break;
  	default:
  		return -EINVAL;
  	}
  	return val;
  }

  static ssize_t ltc4222_value_show(struct device *dev,

  				  struct device_attribute *da, char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	int value;
  
  	value = ltc4222_get_value(dev, attr->index);
  	if (value < 0)
  		return value;
  	return snprintf(buf, PAGE_SIZE, "%d
  ", value);
  }

  static ssize_t ltc4222_bool_show(struct device *dev,

  				 struct device_attribute *da, char *buf)
  {
  	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
  	struct regmap *regmap = dev_get_drvdata(dev);
  	unsigned int fault;
  	int ret;
  
  	ret = regmap_read(regmap, attr->nr, &fault);
  	if (ret < 0)
  		return ret;
  	fault &= attr->index;
  	if (fault)		/* Clear reported faults in chip register */
  		regmap_update_bits(regmap, attr->nr, attr->index, 0);
  
  	return snprintf(buf, PAGE_SIZE, "%d
  ", !!fault);
  }
  
  /* Voltages */

  static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4222_value, LTC4222_SOURCE1);
  static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4222_value, LTC4222_ADIN1);
  static SENSOR_DEVICE_ATTR_RO(in3_input, ltc4222_value, LTC4222_SOURCE2);
  static SENSOR_DEVICE_ATTR_RO(in4_input, ltc4222_value, LTC4222_ADIN2);

  
  /*
   * Voltage alarms
   * UV/OV faults are associated with the input voltage, and power bad and fet
   * faults are associated with the output voltage.
   */

  static SENSOR_DEVICE_ATTR_2_RO(in1_min_alarm, ltc4222_bool, LTC4222_FAULT1,
  			       FAULT_UV);
  static SENSOR_DEVICE_ATTR_2_RO(in1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
  			       FAULT_OV);
  static SENSOR_DEVICE_ATTR_2_RO(in2_alarm, ltc4222_bool, LTC4222_FAULT1,
  			       FAULT_POWER_BAD | FAULT_FET_BAD);
  
  static SENSOR_DEVICE_ATTR_2_RO(in3_min_alarm, ltc4222_bool, LTC4222_FAULT2,
  			       FAULT_UV);
  static SENSOR_DEVICE_ATTR_2_RO(in3_max_alarm, ltc4222_bool, LTC4222_FAULT2,
  			       FAULT_OV);
  static SENSOR_DEVICE_ATTR_2_RO(in4_alarm, ltc4222_bool, LTC4222_FAULT2,
  			       FAULT_POWER_BAD | FAULT_FET_BAD);

  
  /* Current (via sense resistor) */

  static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4222_value, LTC4222_SENSE1);
  static SENSOR_DEVICE_ATTR_RO(curr2_input, ltc4222_value, LTC4222_SENSE2);

  
  /* Overcurrent alarm */

  static SENSOR_DEVICE_ATTR_2_RO(curr1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
  			       FAULT_OC);
  static SENSOR_DEVICE_ATTR_2_RO(curr2_max_alarm, ltc4222_bool, LTC4222_FAULT2,
  			       FAULT_OC);

  
  static struct attribute *ltc4222_attrs[] = {
  	&sensor_dev_attr_in1_input.dev_attr.attr,
  	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_in2_input.dev_attr.attr,
  	&sensor_dev_attr_in2_alarm.dev_attr.attr,
  	&sensor_dev_attr_in3_input.dev_attr.attr,
  	&sensor_dev_attr_in3_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_in3_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_in4_input.dev_attr.attr,
  	&sensor_dev_attr_in4_alarm.dev_attr.attr,
  
  	&sensor_dev_attr_curr1_input.dev_attr.attr,
  	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_curr2_input.dev_attr.attr,
  	&sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
  
  	NULL,
  };
  ATTRIBUTE_GROUPS(ltc4222);

  static const struct regmap_config ltc4222_regmap_config = {

  	.reg_bits = 8,
  	.val_bits = 8,
  	.max_register = LTC4222_ADC_CONTROL,
  };

  static int ltc4222_probe(struct i2c_client *client)

  {
  	struct device *dev = &client->dev;
  	struct device *hwmon_dev;
  	struct regmap *regmap;
  
  	regmap = devm_regmap_init_i2c(client, &ltc4222_regmap_config);
  	if (IS_ERR(regmap)) {
  		dev_err(dev, "failed to allocate register map
  ");
  		return PTR_ERR(regmap);
  	}
  
  	/* Clear faults */
  	regmap_write(regmap, LTC4222_FAULT1, 0x00);
  	regmap_write(regmap, LTC4222_FAULT2, 0x00);
  
  	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
  							   regmap,
  							   ltc4222_groups);
  	return PTR_ERR_OR_ZERO(hwmon_dev);
  }
  
  static const struct i2c_device_id ltc4222_id[] = {
  	{"ltc4222", 0},
  	{ }
  };
  
  MODULE_DEVICE_TABLE(i2c, ltc4222_id);
  
  static struct i2c_driver ltc4222_driver = {
  	.driver = {
  		   .name = "ltc4222",
  		   },

  	.probe_new = ltc4222_probe,

  	.id_table = ltc4222_id,
  };
  
  module_i2c_driver(ltc4222_driver);
  
  MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
  MODULE_DESCRIPTION("LTC4222 driver");
  MODULE_LICENSE("GPL");