1 /*
2 * Driver for Linear Technology LTC4151 High Voltage I2C Current
3 * and Voltage Monitor
4 *
5 * Copyright (C) 2011 AppearTV AS
6 *
7 * Derived from:
8 *
9 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
10 * Swap Controller
11 * Copyright (C) 2010 Ericsson AB.
12 *
13 * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
14 *
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 *
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 *
29 */
30
31 #include <linux/kernel.h>
32 #include <linux/module.h>
33 #include <linux/init.h>
34 #include <linux/err.h>
35 #include <linux/slab.h>
36 #include <linux/i2c.h>
37 #include <linux/hwmon.h>
38 #include <linux/hwmon-sysfs.h>
39 #include <linux/jiffies.h>
40
41 /* chip registers */
42 #define LTC4151_SENSE_H 0x00
43 #define LTC4151_SENSE_L 0x01
44 #define LTC4151_VIN_H 0x02
45 #define LTC4151_VIN_L 0x03
46 #define LTC4151_ADIN_H 0x04
47 #define LTC4151_ADIN_L 0x05
48
49 struct ltc4151_data {
50 struct i2c_client *client;
51
52 struct mutex update_lock;
53 bool valid;
54 unsigned long last_updated; /* in jiffies */
55
56 /* Registers */
57 u8 regs[6];
58 };
59
ltc4151_update_device(struct device * dev)60 static struct ltc4151_data *ltc4151_update_device(struct device *dev)
61 {
62 struct ltc4151_data *data = dev_get_drvdata(dev);
63 struct i2c_client *client = data->client;
64 struct ltc4151_data *ret = data;
65
66 mutex_lock(&data->update_lock);
67
68 /*
69 * The chip's A/D updates 6 times per second
70 * (Conversion Rate 6 - 9 Hz)
71 */
72 if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
73 int i;
74
75 dev_dbg(&client->dev, "Starting ltc4151 update\n");
76
77 /* Read all registers */
78 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
79 int val;
80
81 val = i2c_smbus_read_byte_data(client, i);
82 if (unlikely(val < 0)) {
83 dev_dbg(dev,
84 "Failed to read ADC value: error %d\n",
85 val);
86 ret = ERR_PTR(val);
87 goto abort;
88 }
89 data->regs[i] = val;
90 }
91 data->last_updated = jiffies;
92 data->valid = 1;
93 }
94 abort:
95 mutex_unlock(&data->update_lock);
96 return ret;
97 }
98
99 /* Return the voltage from the given register in mV */
ltc4151_get_value(struct ltc4151_data * data,u8 reg)100 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
101 {
102 u32 val;
103
104 val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
105
106 switch (reg) {
107 case LTC4151_ADIN_H:
108 /* 500uV resolution. Convert to mV. */
109 val = val * 500 / 1000;
110 break;
111 case LTC4151_SENSE_H:
112 /*
113 * 20uV resolution. Convert to current as measured with
114 * an 1 mOhm sense resistor, in mA.
115 */
116 val = val * 20;
117 break;
118 case LTC4151_VIN_H:
119 /* 25 mV per increment */
120 val = val * 25;
121 break;
122 default:
123 /* If we get here, the developer messed up */
124 WARN_ON_ONCE(1);
125 val = 0;
126 break;
127 }
128
129 return val;
130 }
131
ltc4151_show_value(struct device * dev,struct device_attribute * da,char * buf)132 static ssize_t ltc4151_show_value(struct device *dev,
133 struct device_attribute *da, char *buf)
134 {
135 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
136 struct ltc4151_data *data = ltc4151_update_device(dev);
137 int value;
138
139 if (IS_ERR(data))
140 return PTR_ERR(data);
141
142 value = ltc4151_get_value(data, attr->index);
143 return snprintf(buf, PAGE_SIZE, "%d\n", value);
144 }
145
146 /*
147 * Input voltages.
148 */
149 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4151_show_value, NULL,
150 LTC4151_VIN_H);
151 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4151_show_value, NULL,
152 LTC4151_ADIN_H);
153
154 /* Currents (via sense resistor) */
155 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4151_show_value, NULL,
156 LTC4151_SENSE_H);
157
158 /*
159 * Finally, construct an array of pointers to members of the above objects,
160 * as required for sysfs_create_group()
161 */
162 static struct attribute *ltc4151_attrs[] = {
163 &sensor_dev_attr_in1_input.dev_attr.attr,
164 &sensor_dev_attr_in2_input.dev_attr.attr,
165
166 &sensor_dev_attr_curr1_input.dev_attr.attr,
167
168 NULL,
169 };
170 ATTRIBUTE_GROUPS(ltc4151);
171
ltc4151_probe(struct i2c_client * client,const struct i2c_device_id * id)172 static int ltc4151_probe(struct i2c_client *client,
173 const struct i2c_device_id *id)
174 {
175 struct i2c_adapter *adapter = client->adapter;
176 struct device *dev = &client->dev;
177 struct ltc4151_data *data;
178 struct device *hwmon_dev;
179
180 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
181 return -ENODEV;
182
183 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
184 if (!data)
185 return -ENOMEM;
186
187 data->client = client;
188 mutex_init(&data->update_lock);
189
190 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
191 data,
192 ltc4151_groups);
193 return PTR_ERR_OR_ZERO(hwmon_dev);
194 }
195
196 static const struct i2c_device_id ltc4151_id[] = {
197 { "ltc4151", 0 },
198 { }
199 };
200 MODULE_DEVICE_TABLE(i2c, ltc4151_id);
201
202 /* This is the driver that will be inserted */
203 static struct i2c_driver ltc4151_driver = {
204 .driver = {
205 .name = "ltc4151",
206 },
207 .probe = ltc4151_probe,
208 .id_table = ltc4151_id,
209 };
210
211 module_i2c_driver(ltc4151_driver);
212
213 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
214 MODULE_DESCRIPTION("LTC4151 driver");
215 MODULE_LICENSE("GPL");
216