1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
  4 *
  5 * Copyright (c) 2014 Guenter Roeck
  6 */
  7
  8#include <linux/kernel.h>
  9#include <linux/module.h>
 10#include <linux/err.h>
 11#include <linux/slab.h>
 12#include <linux/i2c.h>
 13#include <linux/hwmon.h>
 14#include <linux/hwmon-sysfs.h>
 15#include <linux/jiffies.h>
 16#include <linux/regmap.h>
 17
 18/* chip registers */
 19#define LTC4260_CONTROL	0x00
 20#define LTC4260_ALERT	0x01
 21#define LTC4260_STATUS	0x02
 22#define LTC4260_FAULT	0x03
 23#define LTC4260_SENSE	0x04
 24#define LTC4260_SOURCE	0x05
 25#define LTC4260_ADIN	0x06
 26
 27/*
 28 * Fault register bits
 29 */
 30#define FAULT_OV	(1 << 0)
 31#define FAULT_UV	(1 << 1)
 32#define FAULT_OC	(1 << 2)
 33#define FAULT_POWER_BAD	(1 << 3)
 34#define FAULT_FET_SHORT	(1 << 5)
 35
 36/* Return the voltage from the given register in mV or mA */
 37static int ltc4260_get_value(struct device *dev, u8 reg)
 38{
 39	struct regmap *regmap = dev_get_drvdata(dev);
 40	unsigned int val;
 41	int ret;
 42
 43	ret = regmap_read(regmap, reg, &val);
 44	if (ret < 0)
 45		return ret;
 46
 47	switch (reg) {
 48	case LTC4260_ADIN:
 49		/* 10 mV resolution. Convert to mV. */
 50		val = val * 10;
 51		break;
 52	case LTC4260_SOURCE:
 53		/* 400 mV resolution. Convert to mV. */
 54		val = val * 400;
 55		break;
 56	case LTC4260_SENSE:
 57		/*
 58		 * 300 uV resolution. Convert to current as measured with
 59		 * an 1 mOhm sense resistor, in mA. If a different sense
 60		 * resistor is installed, calculate the actual current by
 61		 * dividing the reported current by the sense resistor value
 62		 * in mOhm.
 63		 */
 64		val = val * 300;
 65		break;
 66	default:
 67		return -EINVAL;
 68	}
 69
 70	return val;
 71}
 72
 73static ssize_t ltc4260_value_show(struct device *dev,
 74				  struct device_attribute *da, char *buf)
 75{
 76	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 77	int value;
 78
 79	value = ltc4260_get_value(dev, attr->index);
 80	if (value < 0)
 81		return value;
 82	return sysfs_emit(buf, "%d\n", value);
 83}
 84
 85static ssize_t ltc4260_bool_show(struct device *dev,
 86				 struct device_attribute *da, char *buf)
 87{
 88	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 89	struct regmap *regmap = dev_get_drvdata(dev);
 90	unsigned int fault;
 91	int ret;
 92
 93	ret = regmap_read(regmap, LTC4260_FAULT, &fault);
 94	if (ret < 0)
 95		return ret;
 96
 97	fault &= attr->index;
 98	if (fault)		/* Clear reported faults in chip register */
 99		regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
100
101	return sysfs_emit(buf, "%d\n", !!fault);
102}
103
104/* Voltages */
105static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4260_value, LTC4260_SOURCE);
106static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4260_value, LTC4260_ADIN);
107
108/*
109 * Voltage alarms
110 * UV/OV faults are associated with the input voltage, and the POWER BAD and
111 * FET SHORT faults are associated with the output voltage.
112 */
113static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4260_bool, FAULT_UV);
114static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4260_bool, FAULT_OV);
115static SENSOR_DEVICE_ATTR_RO(in2_alarm, ltc4260_bool,
116			     FAULT_POWER_BAD | FAULT_FET_SHORT);
117
118/* Current (via sense resistor) */
119static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4260_value, LTC4260_SENSE);
120
121/* Overcurrent alarm */
122static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4260_bool, FAULT_OC);
123
124static struct attribute *ltc4260_attrs[] = {
125	&sensor_dev_attr_in1_input.dev_attr.attr,
126	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
127	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
128	&sensor_dev_attr_in2_input.dev_attr.attr,
129	&sensor_dev_attr_in2_alarm.dev_attr.attr,
130
131	&sensor_dev_attr_curr1_input.dev_attr.attr,
132	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
133
134	NULL,
135};
136ATTRIBUTE_GROUPS(ltc4260);
137
138static const struct regmap_config ltc4260_regmap_config = {
139	.reg_bits = 8,
140	.val_bits = 8,
141	.max_register = LTC4260_ADIN,
142};
143
144static int ltc4260_probe(struct i2c_client *client)
145{
146	struct device *dev = &client->dev;
147	struct device *hwmon_dev;
148	struct regmap *regmap;
149
150	regmap = devm_regmap_init_i2c(client, &ltc4260_regmap_config);
151	if (IS_ERR(regmap)) {
152		dev_err(dev, "failed to allocate register map\n");
153		return PTR_ERR(regmap);
154	}
155
156	/* Clear faults */
157	regmap_write(regmap, LTC4260_FAULT, 0x00);
158
159	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
160							   regmap,
161							   ltc4260_groups);
162	return PTR_ERR_OR_ZERO(hwmon_dev);
163}
164
165static const struct i2c_device_id ltc4260_id[] = {
166	{"ltc4260"},
167	{ }
168};
169
170MODULE_DEVICE_TABLE(i2c, ltc4260_id);
171
172static struct i2c_driver ltc4260_driver = {
173	.driver = {
174		   .name = "ltc4260",
175		   },
176	.probe = ltc4260_probe,
177	.id_table = ltc4260_id,
178};
179
180module_i2c_driver(ltc4260_driver);
181
182MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
183MODULE_DESCRIPTION("LTC4260 driver");
184MODULE_LICENSE("GPL");