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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 device *hwmon_dev; |
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 | |
60 | static struct ltc4151_data *ltc4151_update_device(struct device *dev) |
61 | { |
62 | struct i2c_client *client = to_i2c_client(dev); |
63 | struct ltc4151_data *data = i2c_get_clientdata(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 */ |
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 | |
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, \ |
150 | ltc4151_show_value, NULL, LTC4151_VIN_H); |
151 | static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \ |
152 | ltc4151_show_value, NULL, LTC4151_ADIN_H); |
153 | |
154 | /* Currents (via sense resistor) */ |
155 | static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \ |
156 | ltc4151_show_value, NULL, 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_attributes[] = { |
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 | |
171 | static const struct attribute_group ltc4151_group = { |
172 | .attrs = ltc4151_attributes, |
173 | }; |
174 | |
175 | static int ltc4151_probe(struct i2c_client *client, |
176 | const struct i2c_device_id *id) |
177 | { |
178 | struct i2c_adapter *adapter = client->adapter; |
179 | struct ltc4151_data *data; |
180 | int ret; |
181 | |
182 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
183 | return -ENODEV; |
184 | |
185 | data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); |
186 | if (!data) |
187 | return -ENOMEM; |
188 | |
189 | i2c_set_clientdata(client, data); |
190 | mutex_init(&data->update_lock); |
191 | |
192 | /* Register sysfs hooks */ |
193 | ret = sysfs_create_group(&client->dev.kobj, <c4151_group); |
194 | if (ret) |
195 | return ret; |
196 | |
197 | data->hwmon_dev = hwmon_device_register(&client->dev); |
198 | if (IS_ERR(data->hwmon_dev)) { |
199 | ret = PTR_ERR(data->hwmon_dev); |
200 | goto out_hwmon_device_register; |
201 | } |
202 | |
203 | return 0; |
204 | |
205 | out_hwmon_device_register: |
206 | sysfs_remove_group(&client->dev.kobj, <c4151_group); |
207 | return ret; |
208 | } |
209 | |
210 | static int ltc4151_remove(struct i2c_client *client) |
211 | { |
212 | struct ltc4151_data *data = i2c_get_clientdata(client); |
213 | |
214 | hwmon_device_unregister(data->hwmon_dev); |
215 | sysfs_remove_group(&client->dev.kobj, <c4151_group); |
216 | |
217 | return 0; |
218 | } |
219 | |
220 | static const struct i2c_device_id ltc4151_id[] = { |
221 | { "ltc4151", 0 }, |
222 | { } |
223 | }; |
224 | MODULE_DEVICE_TABLE(i2c, ltc4151_id); |
225 | |
226 | /* This is the driver that will be inserted */ |
227 | static struct i2c_driver ltc4151_driver = { |
228 | .driver = { |
229 | .name = "ltc4151", |
230 | }, |
231 | .probe = ltc4151_probe, |
232 | .remove = ltc4151_remove, |
233 | .id_table = ltc4151_id, |
234 | }; |
235 | |
236 | module_i2c_driver(ltc4151_driver); |
237 | |
238 | MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); |
239 | MODULE_DESCRIPTION("LTC4151 driver"); |
240 | MODULE_LICENSE("GPL"); |
241 |
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