1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
4 *
5 * Copyright (C) 2010 Ericsson AB.
6 *
7 * Derived from:
8 *
9 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
10 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
11 *
12 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
13 */
14
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/err.h>
19 #include <linux/slab.h>
20 #include <linux/i2c.h>
21 #include <linux/hwmon.h>
22 #include <linux/hwmon-sysfs.h>
23 #include <linux/jiffies.h>
24
25 /* chip registers */
26 #define LTC4261_STATUS 0x00 /* readonly */
27 #define LTC4261_FAULT 0x01
28 #define LTC4261_ALERT 0x02
29 #define LTC4261_CONTROL 0x03
30 #define LTC4261_SENSE_H 0x04
31 #define LTC4261_SENSE_L 0x05
32 #define LTC4261_ADIN2_H 0x06
33 #define LTC4261_ADIN2_L 0x07
34 #define LTC4261_ADIN_H 0x08
35 #define LTC4261_ADIN_L 0x09
36
37 /*
38 * Fault register bits
39 */
40 #define FAULT_OV (1<<0)
41 #define FAULT_UV (1<<1)
42 #define FAULT_OC (1<<2)
43
44 struct ltc4261_data {
45 struct i2c_client *client;
46
47 struct mutex update_lock;
48 bool valid;
49 unsigned long last_updated; /* in jiffies */
50
51 /* Registers */
52 u8 regs[10];
53 };
54
ltc4261_update_device(struct device * dev)55 static struct ltc4261_data *ltc4261_update_device(struct device *dev)
56 {
57 struct ltc4261_data *data = dev_get_drvdata(dev);
58 struct i2c_client *client = data->client;
59 struct ltc4261_data *ret = data;
60
61 mutex_lock(&data->update_lock);
62
63 if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
64 int i;
65
66 /* Read registers -- 0x00 to 0x09 */
67 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
68 int val;
69
70 val = i2c_smbus_read_byte_data(client, i);
71 if (unlikely(val < 0)) {
72 dev_dbg(dev,
73 "Failed to read ADC value: error %d\n",
74 val);
75 ret = ERR_PTR(val);
76 data->valid = false;
77 goto abort;
78 }
79 data->regs[i] = val;
80 }
81 data->last_updated = jiffies;
82 data->valid = true;
83 }
84 abort:
85 mutex_unlock(&data->update_lock);
86 return ret;
87 }
88
89 /* Return the voltage from the given register in mV or mA */
ltc4261_get_value(struct ltc4261_data * data,u8 reg)90 static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
91 {
92 u32 val;
93
94 val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
95
96 switch (reg) {
97 case LTC4261_ADIN_H:
98 case LTC4261_ADIN2_H:
99 /* 2.5mV resolution. Convert to mV. */
100 val = val * 25 / 10;
101 break;
102 case LTC4261_SENSE_H:
103 /*
104 * 62.5uV resolution. Convert to current as measured with
105 * an 1 mOhm sense resistor, in mA. If a different sense
106 * resistor is installed, calculate the actual current by
107 * dividing the reported current by the sense resistor value
108 * in mOhm.
109 */
110 val = val * 625 / 10;
111 break;
112 default:
113 /* If we get here, the developer messed up */
114 WARN_ON_ONCE(1);
115 val = 0;
116 break;
117 }
118
119 return val;
120 }
121
ltc4261_value_show(struct device * dev,struct device_attribute * da,char * buf)122 static ssize_t ltc4261_value_show(struct device *dev,
123 struct device_attribute *da, char *buf)
124 {
125 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
126 struct ltc4261_data *data = ltc4261_update_device(dev);
127 int value;
128
129 if (IS_ERR(data))
130 return PTR_ERR(data);
131
132 value = ltc4261_get_value(data, attr->index);
133 return sysfs_emit(buf, "%d\n", value);
134 }
135
ltc4261_bool_show(struct device * dev,struct device_attribute * da,char * buf)136 static ssize_t ltc4261_bool_show(struct device *dev,
137 struct device_attribute *da, char *buf)
138 {
139 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
140 struct ltc4261_data *data = ltc4261_update_device(dev);
141 u8 fault;
142
143 if (IS_ERR(data))
144 return PTR_ERR(data);
145
146 fault = data->regs[LTC4261_FAULT] & attr->index;
147 if (fault) /* Clear reported faults in chip register */
148 i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);
149
150 return sysfs_emit(buf, "%d\n", fault ? 1 : 0);
151 }
152
153 /*
154 * Input voltages.
155 */
156 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H);
157 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H);
158
159 /*
160 * Voltage alarms. The chip has only one set of voltage alarm status bits,
161 * triggered by input voltage alarms. In many designs, those alarms are
162 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
163 * to the OV pin. ADIN2 is, however, not available on all chip variants.
164 * To ensure that the alarm condition is reported to the user, report it
165 * with both voltage sensors.
166 */
167 static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV);
168 static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV);
169 static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV);
170 static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV);
171
172 /* Currents (via sense resistor) */
173 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H);
174
175 /* Overcurrent alarm */
176 static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC);
177
178 static struct attribute *ltc4261_attrs[] = {
179 &sensor_dev_attr_in1_input.dev_attr.attr,
180 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
181 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
182 &sensor_dev_attr_in2_input.dev_attr.attr,
183 &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
184 &sensor_dev_attr_in2_max_alarm.dev_attr.attr,
185
186 &sensor_dev_attr_curr1_input.dev_attr.attr,
187 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
188
189 NULL,
190 };
191 ATTRIBUTE_GROUPS(ltc4261);
192
ltc4261_probe(struct i2c_client * client)193 static int ltc4261_probe(struct i2c_client *client)
194 {
195 struct i2c_adapter *adapter = client->adapter;
196 struct device *dev = &client->dev;
197 struct ltc4261_data *data;
198 struct device *hwmon_dev;
199
200 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
201 return -ENODEV;
202
203 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
204 dev_err(dev, "Failed to read status register\n");
205 return -ENODEV;
206 }
207
208 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
209 if (!data)
210 return -ENOMEM;
211
212 data->client = client;
213 mutex_init(&data->update_lock);
214
215 /* Clear faults */
216 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
217
218 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
219 data,
220 ltc4261_groups);
221 return PTR_ERR_OR_ZERO(hwmon_dev);
222 }
223
224 static const struct i2c_device_id ltc4261_id[] = {
225 {"ltc4261", 0},
226 {}
227 };
228
229 MODULE_DEVICE_TABLE(i2c, ltc4261_id);
230
231 /* This is the driver that will be inserted */
232 static struct i2c_driver ltc4261_driver = {
233 .driver = {
234 .name = "ltc4261",
235 },
236 .probe = ltc4261_probe,
237 .id_table = ltc4261_id,
238 };
239
240 module_i2c_driver(ltc4261_driver);
241
242 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
243 MODULE_DESCRIPTION("LTC4261 driver");
244 MODULE_LICENSE("GPL");
245
