1/*
2 * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
3 *
4 * Copyright (c) 2014 Guenter Roeck
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/err.h>
20#include <linux/slab.h>
21#include <linux/i2c.h>
22#include <linux/hwmon.h>
23#include <linux/hwmon-sysfs.h>
24#include <linux/jiffies.h>
25#include <linux/regmap.h>
26
27/* chip registers */
28#define LTC4260_CONTROL 0x00
29#define LTC4260_ALERT 0x01
30#define LTC4260_STATUS 0x02
31#define LTC4260_FAULT 0x03
32#define LTC4260_SENSE 0x04
33#define LTC4260_SOURCE 0x05
34#define LTC4260_ADIN 0x06
35
36/*
37 * Fault register bits
38 */
39#define FAULT_OV (1 << 0)
40#define FAULT_UV (1 << 1)
41#define FAULT_OC (1 << 2)
42#define FAULT_POWER_BAD (1 << 3)
43#define FAULT_FET_SHORT (1 << 5)
44
45/* Return the voltage from the given register in mV or mA */
46static int ltc4260_get_value(struct device *dev, u8 reg)
47{
48 struct regmap *regmap = dev_get_drvdata(dev);
49 unsigned int val;
50 int ret;
51
52 ret = regmap_read(regmap, reg, &val);
53 if (ret < 0)
54 return ret;
55
56 switch (reg) {
57 case LTC4260_ADIN:
58 /* 10 mV resolution. Convert to mV. */
59 val = val * 10;
60 break;
61 case LTC4260_SOURCE:
62 /* 400 mV resolution. Convert to mV. */
63 val = val * 400;
64 break;
65 case LTC4260_SENSE:
66 /*
67 * 300 uV resolution. Convert to current as measured with
68 * an 1 mOhm sense resistor, in mA. If a different sense
69 * resistor is installed, calculate the actual current by
70 * dividing the reported current by the sense resistor value
71 * in mOhm.
72 */
73 val = val * 300;
74 break;
75 default:
76 return -EINVAL;
77 }
78
79 return val;
80}
81
82static ssize_t ltc4260_value_show(struct device *dev,
83 struct device_attribute *da, char *buf)
84{
85 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
86 int value;
87
88 value = ltc4260_get_value(dev, attr->index);
89 if (value < 0)
90 return value;
91 return snprintf(buf, PAGE_SIZE, "%d\n", value);
92}
93
94static ssize_t ltc4260_bool_show(struct device *dev,
95 struct device_attribute *da, char *buf)
96{
97 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
98 struct regmap *regmap = dev_get_drvdata(dev);
99 unsigned int fault;
100 int ret;
101
102 ret = regmap_read(regmap, LTC4260_FAULT, &fault);
103 if (ret < 0)
104 return ret;
105
106 fault &= attr->index;
107 if (fault) /* Clear reported faults in chip register */
108 regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
109
110 return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
111}
112
113/* Voltages */
114static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4260_value, LTC4260_SOURCE);
115static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4260_value, LTC4260_ADIN);
116
117/*
118 * Voltage alarms
119 * UV/OV faults are associated with the input voltage, and the POWER BAD and
120 * FET SHORT faults are associated with the output voltage.
121 */
122static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4260_bool, FAULT_UV);
123static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4260_bool, FAULT_OV);
124static SENSOR_DEVICE_ATTR_RO(in2_alarm, ltc4260_bool,
125 FAULT_POWER_BAD | FAULT_FET_SHORT);
126
127/* Current (via sense resistor) */
128static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4260_value, LTC4260_SENSE);
129
130/* Overcurrent alarm */
131static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4260_bool, FAULT_OC);
132
133static struct attribute *ltc4260_attrs[] = {
134 &sensor_dev_attr_in1_input.dev_attr.attr,
135 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
136 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
137 &sensor_dev_attr_in2_input.dev_attr.attr,
138 &sensor_dev_attr_in2_alarm.dev_attr.attr,
139
140 &sensor_dev_attr_curr1_input.dev_attr.attr,
141 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
142
143 NULL,
144};
145ATTRIBUTE_GROUPS(ltc4260);
146
147static const struct regmap_config ltc4260_regmap_config = {
148 .reg_bits = 8,
149 .val_bits = 8,
150 .max_register = LTC4260_ADIN,
151};
152
153static int ltc4260_probe(struct i2c_client *client,
154 const struct i2c_device_id *id)
155{
156 struct device *dev = &client->dev;
157 struct device *hwmon_dev;
158 struct regmap *regmap;
159
160 regmap = devm_regmap_init_i2c(client, &ltc4260_regmap_config);
161 if (IS_ERR(regmap)) {
162 dev_err(dev, "failed to allocate register map\n");
163 return PTR_ERR(regmap);
164 }
165
166 /* Clear faults */
167 regmap_write(regmap, LTC4260_FAULT, 0x00);
168
169 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
170 regmap,
171 ltc4260_groups);
172 return PTR_ERR_OR_ZERO(hwmon_dev);
173}
174
175static const struct i2c_device_id ltc4260_id[] = {
176 {"ltc4260", 0},
177 { }
178};
179
180MODULE_DEVICE_TABLE(i2c, ltc4260_id);
181
182static struct i2c_driver ltc4260_driver = {
183 .driver = {
184 .name = "ltc4260",
185 },
186 .probe = ltc4260_probe,
187 .id_table = ltc4260_id,
188};
189
190module_i2c_driver(ltc4260_driver);
191
192MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
193MODULE_DESCRIPTION("LTC4260 driver");
194MODULE_LICENSE("GPL");
195