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 */
ltc4260_get_value(struct device * dev,u8 reg)37 static 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
ltc4260_value_show(struct device * dev,struct device_attribute * da,char * buf)73 static 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
ltc4260_bool_show(struct device * dev,struct device_attribute * da,char * buf)85 static 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 */
105 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4260_value, LTC4260_SOURCE);
106 static 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 */
113 static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4260_bool, FAULT_UV);
114 static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4260_bool, FAULT_OV);
115 static SENSOR_DEVICE_ATTR_RO(in2_alarm, ltc4260_bool,
116 FAULT_POWER_BAD | FAULT_FET_SHORT);
117
118 /* Current (via sense resistor) */
119 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4260_value, LTC4260_SENSE);
120
121 /* Overcurrent alarm */
122 static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4260_bool, FAULT_OC);
123
124 static 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 };
136 ATTRIBUTE_GROUPS(ltc4260);
137
138 static const struct regmap_config ltc4260_regmap_config = {
139 .reg_bits = 8,
140 .val_bits = 8,
141 .max_register = LTC4260_ADIN,
142 };
143
ltc4260_probe(struct i2c_client * client)144 static 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, <c4260_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
165 static const struct i2c_device_id ltc4260_id[] = {
166 {"ltc4260", 0},
167 { }
168 };
169
170 MODULE_DEVICE_TABLE(i2c, ltc4260_id);
171
172 static struct i2c_driver ltc4260_driver = {
173 .driver = {
174 .name = "ltc4260",
175 },
176 .probe_new = ltc4260_probe,
177 .id_table = ltc4260_id,
178 };
179
180 module_i2c_driver(ltc4260_driver);
181
182 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
183 MODULE_DESCRIPTION("LTC4260 driver");
184 MODULE_LICENSE("GPL");
185