1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Driver for Linear Technology LTC4151 High Voltage I2C Current |
4 | * and Voltage Monitor |
5 | * |
6 | * Copyright (C) 2011 AppearTV AS |
7 | * |
8 | * Derived from: |
9 | * |
10 | * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot |
11 | * Swap Controller |
12 | * Copyright (C) 2010 Ericsson AB. |
13 | * |
14 | * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf |
15 | */ |
16 | |
17 | #include <linux/kernel.h> |
18 | #include <linux/module.h> |
19 | #include <linux/of.h> |
20 | #include <linux/init.h> |
21 | #include <linux/err.h> |
22 | #include <linux/slab.h> |
23 | #include <linux/i2c.h> |
24 | #include <linux/hwmon.h> |
25 | #include <linux/hwmon-sysfs.h> |
26 | #include <linux/jiffies.h> |
27 | |
28 | /* chip registers */ |
29 | #define LTC4151_SENSE_H 0x00 |
30 | #define LTC4151_SENSE_L 0x01 |
31 | #define LTC4151_VIN_H 0x02 |
32 | #define LTC4151_VIN_L 0x03 |
33 | #define LTC4151_ADIN_H 0x04 |
34 | #define LTC4151_ADIN_L 0x05 |
35 | |
36 | struct ltc4151_data { |
37 | struct i2c_client *client; |
38 | |
39 | struct mutex update_lock; |
40 | bool valid; |
41 | unsigned long last_updated; /* in jiffies */ |
42 | unsigned int shunt; /* in micro ohms */ |
43 | |
44 | /* Registers */ |
45 | u8 regs[6]; |
46 | }; |
47 | |
48 | static struct ltc4151_data *ltc4151_update_device(struct device *dev) |
49 | { |
50 | struct ltc4151_data *data = dev_get_drvdata(dev); |
51 | struct i2c_client *client = data->client; |
52 | struct ltc4151_data *ret = data; |
53 | |
54 | mutex_lock(&data->update_lock); |
55 | |
56 | /* |
57 | * The chip's A/D updates 6 times per second |
58 | * (Conversion Rate 6 - 9 Hz) |
59 | */ |
60 | if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { |
61 | int i; |
62 | |
63 | dev_dbg(&client->dev, "Starting ltc4151 update\n" ); |
64 | |
65 | /* Read all registers */ |
66 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { |
67 | int val; |
68 | |
69 | val = i2c_smbus_read_byte_data(client, command: i); |
70 | if (unlikely(val < 0)) { |
71 | dev_dbg(dev, |
72 | "Failed to read ADC value: error %d\n" , |
73 | val); |
74 | ret = ERR_PTR(error: val); |
75 | goto abort; |
76 | } |
77 | data->regs[i] = val; |
78 | } |
79 | data->last_updated = jiffies; |
80 | data->valid = true; |
81 | } |
82 | abort: |
83 | mutex_unlock(lock: &data->update_lock); |
84 | return ret; |
85 | } |
86 | |
87 | /* Return the voltage from the given register in mV */ |
88 | static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) |
89 | { |
90 | u32 val; |
91 | |
92 | val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); |
93 | |
94 | switch (reg) { |
95 | case LTC4151_ADIN_H: |
96 | /* 500uV resolution. Convert to mV. */ |
97 | val = val * 500 / 1000; |
98 | break; |
99 | case LTC4151_SENSE_H: |
100 | /* |
101 | * 20uV resolution. Convert to current as measured with |
102 | * a given sense resistor, in mA. |
103 | */ |
104 | val = val * 20 * 1000 / data->shunt; |
105 | break; |
106 | case LTC4151_VIN_H: |
107 | /* 25 mV per increment */ |
108 | val = val * 25; |
109 | break; |
110 | default: |
111 | /* If we get here, the developer messed up */ |
112 | WARN_ON_ONCE(1); |
113 | val = 0; |
114 | break; |
115 | } |
116 | |
117 | return val; |
118 | } |
119 | |
120 | static ssize_t ltc4151_value_show(struct device *dev, |
121 | struct device_attribute *da, char *buf) |
122 | { |
123 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
124 | struct ltc4151_data *data = ltc4151_update_device(dev); |
125 | int value; |
126 | |
127 | if (IS_ERR(ptr: data)) |
128 | return PTR_ERR(ptr: data); |
129 | |
130 | value = ltc4151_get_value(data, reg: attr->index); |
131 | return sysfs_emit(buf, fmt: "%d\n" , value); |
132 | } |
133 | |
134 | /* |
135 | * Input voltages. |
136 | */ |
137 | static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H); |
138 | static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H); |
139 | |
140 | /* Currents (via sense resistor) */ |
141 | static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H); |
142 | |
143 | /* |
144 | * Finally, construct an array of pointers to members of the above objects, |
145 | * as required for sysfs_create_group() |
146 | */ |
147 | static struct attribute *ltc4151_attrs[] = { |
148 | &sensor_dev_attr_in1_input.dev_attr.attr, |
149 | &sensor_dev_attr_in2_input.dev_attr.attr, |
150 | |
151 | &sensor_dev_attr_curr1_input.dev_attr.attr, |
152 | |
153 | NULL, |
154 | }; |
155 | ATTRIBUTE_GROUPS(ltc4151); |
156 | |
157 | static int ltc4151_probe(struct i2c_client *client) |
158 | { |
159 | struct i2c_adapter *adapter = client->adapter; |
160 | struct device *dev = &client->dev; |
161 | struct ltc4151_data *data; |
162 | struct device *hwmon_dev; |
163 | u32 shunt; |
164 | |
165 | if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
166 | return -ENODEV; |
167 | |
168 | data = devm_kzalloc(dev, size: sizeof(*data), GFP_KERNEL); |
169 | if (!data) |
170 | return -ENOMEM; |
171 | |
172 | if (of_property_read_u32(np: client->dev.of_node, |
173 | propname: "shunt-resistor-micro-ohms" , out_value: &shunt)) |
174 | shunt = 1000; /* 1 mOhm if not set via DT */ |
175 | |
176 | if (shunt == 0) |
177 | return -EINVAL; |
178 | |
179 | data->shunt = shunt; |
180 | |
181 | data->client = client; |
182 | mutex_init(&data->update_lock); |
183 | |
184 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, name: client->name, |
185 | drvdata: data, |
186 | groups: ltc4151_groups); |
187 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
188 | } |
189 | |
190 | static const struct i2c_device_id ltc4151_id[] = { |
191 | { "ltc4151" , 0 }, |
192 | { } |
193 | }; |
194 | MODULE_DEVICE_TABLE(i2c, ltc4151_id); |
195 | |
196 | static const struct of_device_id __maybe_unused ltc4151_match[] = { |
197 | { .compatible = "lltc,ltc4151" }, |
198 | {}, |
199 | }; |
200 | MODULE_DEVICE_TABLE(of, ltc4151_match); |
201 | |
202 | /* This is the driver that will be inserted */ |
203 | static struct i2c_driver ltc4151_driver = { |
204 | .driver = { |
205 | .name = "ltc4151" , |
206 | .of_match_table = of_match_ptr(ltc4151_match), |
207 | }, |
208 | .probe = ltc4151_probe, |
209 | .id_table = ltc4151_id, |
210 | }; |
211 | |
212 | module_i2c_driver(ltc4151_driver); |
213 | |
214 | MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>" ); |
215 | MODULE_DESCRIPTION("LTC4151 driver" ); |
216 | MODULE_LICENSE("GPL" ); |
217 | |