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72f5de92 IS |
1 | /* |
2 | * Driver for Linear Technology LTC4215 I2C Hot Swap Controller | |
3 | * | |
4 | * Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu> | |
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; version 2 of the License. | |
9 | * | |
10 | * Datasheet: | |
11 | * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697 | |
12 | */ | |
13 | ||
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/i2c.h> | |
20 | #include <linux/hwmon.h> | |
21 | #include <linux/hwmon-sysfs.h> | |
dcd8f392 | 22 | #include <linux/jiffies.h> |
72f5de92 | 23 | |
72f5de92 IS |
24 | /* Here are names of the chip's registers (a.k.a. commands) */ |
25 | enum ltc4215_cmd { | |
26 | LTC4215_CONTROL = 0x00, /* rw */ | |
27 | LTC4215_ALERT = 0x01, /* rw */ | |
28 | LTC4215_STATUS = 0x02, /* ro */ | |
29 | LTC4215_FAULT = 0x03, /* rw */ | |
30 | LTC4215_SENSE = 0x04, /* rw */ | |
31 | LTC4215_SOURCE = 0x05, /* rw */ | |
32 | LTC4215_ADIN = 0x06, /* rw */ | |
33 | }; | |
34 | ||
35 | struct ltc4215_data { | |
6c588b45 | 36 | struct i2c_client *client; |
72f5de92 IS |
37 | |
38 | struct mutex update_lock; | |
39 | bool valid; | |
40 | unsigned long last_updated; /* in jiffies */ | |
41 | ||
42 | /* Registers */ | |
43 | u8 regs[7]; | |
44 | }; | |
45 | ||
46 | static struct ltc4215_data *ltc4215_update_device(struct device *dev) | |
47 | { | |
6c588b45 GR |
48 | struct ltc4215_data *data = dev_get_drvdata(dev); |
49 | struct i2c_client *client = data->client; | |
72f5de92 IS |
50 | s32 val; |
51 | int i; | |
52 | ||
53 | mutex_lock(&data->update_lock); | |
54 | ||
55 | /* The chip's A/D updates 10 times per second */ | |
56 | if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { | |
57 | ||
58 | dev_dbg(&client->dev, "Starting ltc4215 update\n"); | |
59 | ||
60 | /* Read all registers */ | |
61 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { | |
62 | val = i2c_smbus_read_byte_data(client, i); | |
63 | if (unlikely(val < 0)) | |
64 | data->regs[i] = 0; | |
65 | else | |
66 | data->regs[i] = val; | |
67 | } | |
68 | ||
69 | data->last_updated = jiffies; | |
70 | data->valid = 1; | |
71 | } | |
72 | ||
73 | mutex_unlock(&data->update_lock); | |
74 | ||
75 | return data; | |
76 | } | |
77 | ||
78 | /* Return the voltage from the given register in millivolts */ | |
79 | static int ltc4215_get_voltage(struct device *dev, u8 reg) | |
80 | { | |
81 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
82 | const u8 regval = data->regs[reg]; | |
83 | u32 voltage = 0; | |
84 | ||
85 | switch (reg) { | |
86 | case LTC4215_SENSE: | |
87 | /* 151 uV per increment */ | |
88 | voltage = regval * 151 / 1000; | |
89 | break; | |
90 | case LTC4215_SOURCE: | |
91 | /* 60.5 mV per increment */ | |
92 | voltage = regval * 605 / 10; | |
93 | break; | |
94 | case LTC4215_ADIN: | |
790fa38c GR |
95 | /* |
96 | * The ADIN input is divided by 12.5, and has 4.82 mV | |
97 | * per increment, so we have the additional multiply | |
98 | */ | |
72f5de92 IS |
99 | voltage = regval * 482 * 125 / 1000; |
100 | break; | |
101 | default: | |
102 | /* If we get here, the developer messed up */ | |
103 | WARN_ON_ONCE(1); | |
104 | break; | |
105 | } | |
106 | ||
107 | return voltage; | |
108 | } | |
109 | ||
110 | /* Return the current from the sense resistor in mA */ | |
111 | static unsigned int ltc4215_get_current(struct device *dev) | |
112 | { | |
113 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
114 | ||
790fa38c GR |
115 | /* |
116 | * The strange looking conversions that follow are fixed-point | |
72f5de92 IS |
117 | * math, since we cannot do floating point in the kernel. |
118 | * | |
119 | * Step 1: convert sense register to microVolts | |
120 | * Step 2: convert voltage to milliAmperes | |
121 | * | |
122 | * If you play around with the V=IR equation, you come up with | |
123 | * the following: X uV / Y mOhm == Z mA | |
124 | * | |
125 | * With the resistors that are fractions of a milliOhm, we multiply | |
126 | * the voltage and resistance by 10, to shift the decimal point. | |
127 | * Now we can use the normal division operator again. | |
128 | */ | |
129 | ||
130 | /* Calculate voltage in microVolts (151 uV per increment) */ | |
131 | const unsigned int voltage = data->regs[LTC4215_SENSE] * 151; | |
132 | ||
133 | /* Calculate current in milliAmperes (4 milliOhm sense resistor) */ | |
134 | const unsigned int curr = voltage / 4; | |
135 | ||
136 | return curr; | |
137 | } | |
138 | ||
d7f2a8f5 GR |
139 | static ssize_t ltc4215_voltage_show(struct device *dev, |
140 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
141 | { |
142 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
143 | const int voltage = ltc4215_get_voltage(dev, attr->index); | |
144 | ||
145 | return snprintf(buf, PAGE_SIZE, "%d\n", voltage); | |
146 | } | |
147 | ||
d7f2a8f5 GR |
148 | static ssize_t ltc4215_current_show(struct device *dev, |
149 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
150 | { |
151 | const unsigned int curr = ltc4215_get_current(dev); | |
152 | ||
153 | return snprintf(buf, PAGE_SIZE, "%u\n", curr); | |
154 | } | |
155 | ||
d7f2a8f5 GR |
156 | static ssize_t ltc4215_power_show(struct device *dev, |
157 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
158 | { |
159 | const unsigned int curr = ltc4215_get_current(dev); | |
160 | const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN); | |
161 | ||
162 | /* current in mA * voltage in mV == power in uW */ | |
163 | const unsigned int power = abs(output_voltage * curr); | |
164 | ||
165 | return snprintf(buf, PAGE_SIZE, "%u\n", power); | |
166 | } | |
167 | ||
d7f2a8f5 GR |
168 | static ssize_t ltc4215_alarm_show(struct device *dev, |
169 | struct device_attribute *da, char *buf) | |
72f5de92 | 170 | { |
b5f0f1ea | 171 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
72f5de92 | 172 | struct ltc4215_data *data = ltc4215_update_device(dev); |
b5f0f1ea GR |
173 | const u8 reg = data->regs[LTC4215_STATUS]; |
174 | const u32 mask = attr->index; | |
72f5de92 | 175 | |
b5f0f1ea | 176 | return snprintf(buf, PAGE_SIZE, "%u\n", !!(reg & mask)); |
72f5de92 IS |
177 | } |
178 | ||
790fa38c GR |
179 | /* |
180 | * These macros are used below in constructing device attribute objects | |
72f5de92 IS |
181 | * for use with sysfs_create_group() to make a sysfs device file |
182 | * for each register. | |
183 | */ | |
184 | ||
72f5de92 IS |
185 | /* Construct a sensor_device_attribute structure for each register */ |
186 | ||
187 | /* Current */ | |
d7f2a8f5 GR |
188 | static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4215_current, 0); |
189 | static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4215_alarm, 1 << 2); | |
72f5de92 IS |
190 | |
191 | /* Power (virtual) */ | |
d7f2a8f5 | 192 | static SENSOR_DEVICE_ATTR_RO(power1_input, ltc4215_power, 0); |
72f5de92 IS |
193 | |
194 | /* Input Voltage */ | |
d7f2a8f5 GR |
195 | static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4215_voltage, LTC4215_ADIN); |
196 | static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4215_alarm, 1 << 0); | |
197 | static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4215_alarm, 1 << 1); | |
72f5de92 IS |
198 | |
199 | /* Output Voltage */ | |
d7f2a8f5 GR |
200 | static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4215_voltage, LTC4215_SOURCE); |
201 | static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4215_alarm, 1 << 3); | |
72f5de92 | 202 | |
790fa38c GR |
203 | /* |
204 | * Finally, construct an array of pointers to members of the above objects, | |
72f5de92 IS |
205 | * as required for sysfs_create_group() |
206 | */ | |
6c588b45 | 207 | static struct attribute *ltc4215_attrs[] = { |
72f5de92 IS |
208 | &sensor_dev_attr_curr1_input.dev_attr.attr, |
209 | &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, | |
210 | ||
211 | &sensor_dev_attr_power1_input.dev_attr.attr, | |
72f5de92 IS |
212 | |
213 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
214 | &sensor_dev_attr_in1_max_alarm.dev_attr.attr, | |
215 | &sensor_dev_attr_in1_min_alarm.dev_attr.attr, | |
216 | ||
217 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
0a6bf658 | 218 | &sensor_dev_attr_in2_min_alarm.dev_attr.attr, |
72f5de92 IS |
219 | |
220 | NULL, | |
221 | }; | |
6c588b45 | 222 | ATTRIBUTE_GROUPS(ltc4215); |
72f5de92 IS |
223 | |
224 | static int ltc4215_probe(struct i2c_client *client, | |
225 | const struct i2c_device_id *id) | |
226 | { | |
2d2a7cff | 227 | struct i2c_adapter *adapter = client->adapter; |
6c588b45 | 228 | struct device *dev = &client->dev; |
72f5de92 | 229 | struct ltc4215_data *data; |
6c588b45 | 230 | struct device *hwmon_dev; |
72f5de92 | 231 | |
2d2a7cff JD |
232 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
233 | return -ENODEV; | |
234 | ||
6c588b45 | 235 | data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); |
d2b95e58 GR |
236 | if (!data) |
237 | return -ENOMEM; | |
72f5de92 | 238 | |
6c588b45 | 239 | data->client = client; |
72f5de92 IS |
240 | mutex_init(&data->update_lock); |
241 | ||
242 | /* Initialize the LTC4215 chip */ | |
b6b9d696 | 243 | i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00); |
72f5de92 | 244 | |
6c588b45 GR |
245 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, |
246 | data, | |
247 | ltc4215_groups); | |
248 | return PTR_ERR_OR_ZERO(hwmon_dev); | |
72f5de92 IS |
249 | } |
250 | ||
72f5de92 | 251 | static const struct i2c_device_id ltc4215_id[] = { |
2d2a7cff | 252 | { "ltc4215", 0 }, |
72f5de92 IS |
253 | { } |
254 | }; | |
255 | MODULE_DEVICE_TABLE(i2c, ltc4215_id); | |
256 | ||
257 | /* This is the driver that will be inserted */ | |
258 | static struct i2c_driver ltc4215_driver = { | |
72f5de92 IS |
259 | .driver = { |
260 | .name = "ltc4215", | |
261 | }, | |
262 | .probe = ltc4215_probe, | |
72f5de92 | 263 | .id_table = ltc4215_id, |
72f5de92 IS |
264 | }; |
265 | ||
f0967eea | 266 | module_i2c_driver(ltc4215_driver); |
72f5de92 IS |
267 | |
268 | MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); | |
269 | MODULE_DESCRIPTION("LTC4215 driver"); | |
270 | MODULE_LICENSE("GPL"); |