1/*
2 * Driver for Linear Technology LTC4222 Dual 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/bitops.h>
22#include <linux/i2c.h>
23#include <linux/hwmon.h>
24#include <linux/hwmon-sysfs.h>
25#include <linux/jiffies.h>
26#include <linux/regmap.h>
27
28/* chip registers */
29
30#define LTC4222_CONTROL1 0xd0
31#define LTC4222_ALERT1 0xd1
32#define LTC4222_STATUS1 0xd2
33#define LTC4222_FAULT1 0xd3
34#define LTC4222_CONTROL2 0xd4
35#define LTC4222_ALERT2 0xd5
36#define LTC4222_STATUS2 0xd6
37#define LTC4222_FAULT2 0xd7
38#define LTC4222_SOURCE1 0xd8
39#define LTC4222_SOURCE2 0xda
40#define LTC4222_ADIN1 0xdc
41#define LTC4222_ADIN2 0xde
42#define LTC4222_SENSE1 0xe0
43#define LTC4222_SENSE2 0xe2
44#define LTC4222_ADC_CONTROL 0xe4
45
46/*
47 * Fault register bits
48 */
49#define FAULT_OV BIT(0)
50#define FAULT_UV BIT(1)
51#define FAULT_OC BIT(2)
52#define FAULT_POWER_BAD BIT(3)
53#define FAULT_FET_BAD BIT(5)
54
55/* Return the voltage from the given register in mV or mA */
56static int ltc4222_get_value(struct device *dev, u8 reg)
57{
58 struct regmap *regmap = dev_get_drvdata(dev);
59 unsigned int val;
60 u8 buf[2];
61 int ret;
62
63 ret = regmap_bulk_read(regmap, reg, buf, 2);
64 if (ret < 0)
65 return ret;
66
67 val = ((buf[0] << 8) + buf[1]) >> 6;
68
69 switch (reg) {
70 case LTC4222_ADIN1:
71 case LTC4222_ADIN2:
72 /* 1.25 mV resolution. Convert to mV. */
73 val = DIV_ROUND_CLOSEST(val * 5, 4);
74 break;
75 case LTC4222_SOURCE1:
76 case LTC4222_SOURCE2:
77 /* 31.25 mV resolution. Convert to mV. */
78 val = DIV_ROUND_CLOSEST(val * 125, 4);
79 break;
80 case LTC4222_SENSE1:
81 case LTC4222_SENSE2:
82 /*
83 * 62.5 uV resolution. Convert to current as measured with
84 * an 1 mOhm sense resistor, in mA. If a different sense
85 * resistor is installed, calculate the actual current by
86 * dividing the reported current by the sense resistor value
87 * in mOhm.
88 */
89 val = DIV_ROUND_CLOSEST(val * 125, 2);
90 break;
91 default:
92 return -EINVAL;
93 }
94 return val;
95}
96
97static ssize_t ltc4222_value_show(struct device *dev,
98 struct device_attribute *da, char *buf)
99{
100 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
101 int value;
102
103 value = ltc4222_get_value(dev, attr->index);
104 if (value < 0)
105 return value;
106 return snprintf(buf, PAGE_SIZE, "%d\n", value);
107}
108
109static ssize_t ltc4222_bool_show(struct device *dev,
110 struct device_attribute *da, char *buf)
111{
112 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
113 struct regmap *regmap = dev_get_drvdata(dev);
114 unsigned int fault;
115 int ret;
116
117 ret = regmap_read(regmap, attr->nr, &fault);
118 if (ret < 0)
119 return ret;
120 fault &= attr->index;
121 if (fault) /* Clear reported faults in chip register */
122 regmap_update_bits(regmap, attr->nr, attr->index, 0);
123
124 return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
125}
126
127/* Voltages */
128static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4222_value, LTC4222_SOURCE1);
129static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4222_value, LTC4222_ADIN1);
130static SENSOR_DEVICE_ATTR_RO(in3_input, ltc4222_value, LTC4222_SOURCE2);
131static SENSOR_DEVICE_ATTR_RO(in4_input, ltc4222_value, LTC4222_ADIN2);
132
133/*
134 * Voltage alarms
135 * UV/OV faults are associated with the input voltage, and power bad and fet
136 * faults are associated with the output voltage.
137 */
138static SENSOR_DEVICE_ATTR_2_RO(in1_min_alarm, ltc4222_bool, LTC4222_FAULT1,
139 FAULT_UV);
140static SENSOR_DEVICE_ATTR_2_RO(in1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
141 FAULT_OV);
142static SENSOR_DEVICE_ATTR_2_RO(in2_alarm, ltc4222_bool, LTC4222_FAULT1,
143 FAULT_POWER_BAD | FAULT_FET_BAD);
144
145static SENSOR_DEVICE_ATTR_2_RO(in3_min_alarm, ltc4222_bool, LTC4222_FAULT2,
146 FAULT_UV);
147static SENSOR_DEVICE_ATTR_2_RO(in3_max_alarm, ltc4222_bool, LTC4222_FAULT2,
148 FAULT_OV);
149static SENSOR_DEVICE_ATTR_2_RO(in4_alarm, ltc4222_bool, LTC4222_FAULT2,
150 FAULT_POWER_BAD | FAULT_FET_BAD);
151
152/* Current (via sense resistor) */
153static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4222_value, LTC4222_SENSE1);
154static SENSOR_DEVICE_ATTR_RO(curr2_input, ltc4222_value, LTC4222_SENSE2);
155
156/* Overcurrent alarm */
157static SENSOR_DEVICE_ATTR_2_RO(curr1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
158 FAULT_OC);
159static SENSOR_DEVICE_ATTR_2_RO(curr2_max_alarm, ltc4222_bool, LTC4222_FAULT2,
160 FAULT_OC);
161
162static struct attribute *ltc4222_attrs[] = {
163 &sensor_dev_attr_in1_input.dev_attr.attr,
164 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
165 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
166 &sensor_dev_attr_in2_input.dev_attr.attr,
167 &sensor_dev_attr_in2_alarm.dev_attr.attr,
168 &sensor_dev_attr_in3_input.dev_attr.attr,
169 &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
170 &sensor_dev_attr_in3_max_alarm.dev_attr.attr,
171 &sensor_dev_attr_in4_input.dev_attr.attr,
172 &sensor_dev_attr_in4_alarm.dev_attr.attr,
173
174 &sensor_dev_attr_curr1_input.dev_attr.attr,
175 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
176 &sensor_dev_attr_curr2_input.dev_attr.attr,
177 &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
178
179 NULL,
180};
181ATTRIBUTE_GROUPS(ltc4222);
182
183static const struct regmap_config ltc4222_regmap_config = {
184 .reg_bits = 8,
185 .val_bits = 8,
186 .max_register = LTC4222_ADC_CONTROL,
187};
188
189static int ltc4222_probe(struct i2c_client *client,
190 const struct i2c_device_id *id)
191{
192 struct device *dev = &client->dev;
193 struct device *hwmon_dev;
194 struct regmap *regmap;
195
196 regmap = devm_regmap_init_i2c(client, &ltc4222_regmap_config);
197 if (IS_ERR(regmap)) {
198 dev_err(dev, "failed to allocate register map\n");
199 return PTR_ERR(regmap);
200 }
201
202 /* Clear faults */
203 regmap_write(regmap, LTC4222_FAULT1, 0x00);
204 regmap_write(regmap, LTC4222_FAULT2, 0x00);
205
206 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
207 regmap,
208 ltc4222_groups);
209 return PTR_ERR_OR_ZERO(hwmon_dev);
210}
211
212static const struct i2c_device_id ltc4222_id[] = {
213 {"ltc4222", 0},
214 { }
215};
216
217MODULE_DEVICE_TABLE(i2c, ltc4222_id);
218
219static struct i2c_driver ltc4222_driver = {
220 .driver = {
221 .name = "ltc4222",
222 },
223 .probe = ltc4222_probe,
224 .id_table = ltc4222_id,
225};
226
227module_i2c_driver(ltc4222_driver);
228
229MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
230MODULE_DESCRIPTION("LTC4222 driver");
231MODULE_LICENSE("GPL");
232