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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> | |
22 | ||
72f5de92 IS |
23 | /* Here are names of the chip's registers (a.k.a. commands) */ |
24 | enum ltc4215_cmd { | |
25 | LTC4215_CONTROL = 0x00, /* rw */ | |
26 | LTC4215_ALERT = 0x01, /* rw */ | |
27 | LTC4215_STATUS = 0x02, /* ro */ | |
28 | LTC4215_FAULT = 0x03, /* rw */ | |
29 | LTC4215_SENSE = 0x04, /* rw */ | |
30 | LTC4215_SOURCE = 0x05, /* rw */ | |
31 | LTC4215_ADIN = 0x06, /* rw */ | |
32 | }; | |
33 | ||
34 | struct ltc4215_data { | |
35 | struct device *hwmon_dev; | |
36 | ||
37 | struct mutex update_lock; | |
38 | bool valid; | |
39 | unsigned long last_updated; /* in jiffies */ | |
40 | ||
41 | /* Registers */ | |
42 | u8 regs[7]; | |
43 | }; | |
44 | ||
45 | static struct ltc4215_data *ltc4215_update_device(struct device *dev) | |
46 | { | |
47 | struct i2c_client *client = to_i2c_client(dev); | |
48 | struct ltc4215_data *data = i2c_get_clientdata(client); | |
49 | s32 val; | |
50 | int i; | |
51 | ||
52 | mutex_lock(&data->update_lock); | |
53 | ||
54 | /* The chip's A/D updates 10 times per second */ | |
55 | if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { | |
56 | ||
57 | dev_dbg(&client->dev, "Starting ltc4215 update\n"); | |
58 | ||
59 | /* Read all registers */ | |
60 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { | |
61 | val = i2c_smbus_read_byte_data(client, i); | |
62 | if (unlikely(val < 0)) | |
63 | data->regs[i] = 0; | |
64 | else | |
65 | data->regs[i] = val; | |
66 | } | |
67 | ||
68 | data->last_updated = jiffies; | |
69 | data->valid = 1; | |
70 | } | |
71 | ||
72 | mutex_unlock(&data->update_lock); | |
73 | ||
74 | return data; | |
75 | } | |
76 | ||
77 | /* Return the voltage from the given register in millivolts */ | |
78 | static int ltc4215_get_voltage(struct device *dev, u8 reg) | |
79 | { | |
80 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
81 | const u8 regval = data->regs[reg]; | |
82 | u32 voltage = 0; | |
83 | ||
84 | switch (reg) { | |
85 | case LTC4215_SENSE: | |
86 | /* 151 uV per increment */ | |
87 | voltage = regval * 151 / 1000; | |
88 | break; | |
89 | case LTC4215_SOURCE: | |
90 | /* 60.5 mV per increment */ | |
91 | voltage = regval * 605 / 10; | |
92 | break; | |
93 | case LTC4215_ADIN: | |
94 | /* The ADIN input is divided by 12.5, and has 4.82 mV | |
95 | * per increment, so we have the additional multiply */ | |
96 | voltage = regval * 482 * 125 / 1000; | |
97 | break; | |
98 | default: | |
99 | /* If we get here, the developer messed up */ | |
100 | WARN_ON_ONCE(1); | |
101 | break; | |
102 | } | |
103 | ||
104 | return voltage; | |
105 | } | |
106 | ||
107 | /* Return the current from the sense resistor in mA */ | |
108 | static unsigned int ltc4215_get_current(struct device *dev) | |
109 | { | |
110 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
111 | ||
112 | /* The strange looking conversions that follow are fixed-point | |
113 | * math, since we cannot do floating point in the kernel. | |
114 | * | |
115 | * Step 1: convert sense register to microVolts | |
116 | * Step 2: convert voltage to milliAmperes | |
117 | * | |
118 | * If you play around with the V=IR equation, you come up with | |
119 | * the following: X uV / Y mOhm == Z mA | |
120 | * | |
121 | * With the resistors that are fractions of a milliOhm, we multiply | |
122 | * the voltage and resistance by 10, to shift the decimal point. | |
123 | * Now we can use the normal division operator again. | |
124 | */ | |
125 | ||
126 | /* Calculate voltage in microVolts (151 uV per increment) */ | |
127 | const unsigned int voltage = data->regs[LTC4215_SENSE] * 151; | |
128 | ||
129 | /* Calculate current in milliAmperes (4 milliOhm sense resistor) */ | |
130 | const unsigned int curr = voltage / 4; | |
131 | ||
132 | return curr; | |
133 | } | |
134 | ||
135 | static ssize_t ltc4215_show_voltage(struct device *dev, | |
136 | struct device_attribute *da, | |
137 | char *buf) | |
138 | { | |
139 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
140 | const int voltage = ltc4215_get_voltage(dev, attr->index); | |
141 | ||
142 | return snprintf(buf, PAGE_SIZE, "%d\n", voltage); | |
143 | } | |
144 | ||
145 | static ssize_t ltc4215_show_current(struct device *dev, | |
146 | struct device_attribute *da, | |
147 | char *buf) | |
148 | { | |
149 | const unsigned int curr = ltc4215_get_current(dev); | |
150 | ||
151 | return snprintf(buf, PAGE_SIZE, "%u\n", curr); | |
152 | } | |
153 | ||
154 | static ssize_t ltc4215_show_power(struct device *dev, | |
155 | struct device_attribute *da, | |
156 | char *buf) | |
157 | { | |
158 | const unsigned int curr = ltc4215_get_current(dev); | |
159 | const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN); | |
160 | ||
161 | /* current in mA * voltage in mV == power in uW */ | |
162 | const unsigned int power = abs(output_voltage * curr); | |
163 | ||
164 | return snprintf(buf, PAGE_SIZE, "%u\n", power); | |
165 | } | |
166 | ||
167 | static ssize_t ltc4215_show_alarm(struct device *dev, | |
168 | struct device_attribute *da, | |
169 | char *buf) | |
170 | { | |
171 | struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da); | |
172 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
173 | const u8 reg = data->regs[attr->index]; | |
174 | const u32 mask = attr->nr; | |
175 | ||
176 | return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0); | |
177 | } | |
178 | ||
179 | /* These macros are used below in constructing device attribute objects | |
180 | * for use with sysfs_create_group() to make a sysfs device file | |
181 | * for each register. | |
182 | */ | |
183 | ||
184 | #define LTC4215_VOLTAGE(name, ltc4215_cmd_idx) \ | |
185 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ | |
186 | ltc4215_show_voltage, NULL, ltc4215_cmd_idx) | |
187 | ||
188 | #define LTC4215_CURRENT(name) \ | |
189 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ | |
190 | ltc4215_show_current, NULL, 0); | |
191 | ||
192 | #define LTC4215_POWER(name) \ | |
193 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ | |
194 | ltc4215_show_power, NULL, 0); | |
195 | ||
196 | #define LTC4215_ALARM(name, mask, reg) \ | |
197 | static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \ | |
198 | ltc4215_show_alarm, NULL, (mask), reg) | |
199 | ||
200 | /* Construct a sensor_device_attribute structure for each register */ | |
201 | ||
202 | /* Current */ | |
203 | LTC4215_CURRENT(curr1_input); | |
204 | LTC4215_ALARM(curr1_max_alarm, (1 << 2), LTC4215_STATUS); | |
205 | ||
206 | /* Power (virtual) */ | |
207 | LTC4215_POWER(power1_input); | |
72f5de92 IS |
208 | |
209 | /* Input Voltage */ | |
210 | LTC4215_VOLTAGE(in1_input, LTC4215_ADIN); | |
211 | LTC4215_ALARM(in1_max_alarm, (1 << 0), LTC4215_STATUS); | |
212 | LTC4215_ALARM(in1_min_alarm, (1 << 1), LTC4215_STATUS); | |
213 | ||
214 | /* Output Voltage */ | |
215 | LTC4215_VOLTAGE(in2_input, LTC4215_SOURCE); | |
0a6bf658 | 216 | LTC4215_ALARM(in2_min_alarm, (1 << 3), LTC4215_STATUS); |
72f5de92 IS |
217 | |
218 | /* Finally, construct an array of pointers to members of the above objects, | |
219 | * as required for sysfs_create_group() | |
220 | */ | |
221 | static struct attribute *ltc4215_attributes[] = { | |
222 | &sensor_dev_attr_curr1_input.dev_attr.attr, | |
223 | &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, | |
224 | ||
225 | &sensor_dev_attr_power1_input.dev_attr.attr, | |
72f5de92 IS |
226 | |
227 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
228 | &sensor_dev_attr_in1_max_alarm.dev_attr.attr, | |
229 | &sensor_dev_attr_in1_min_alarm.dev_attr.attr, | |
230 | ||
231 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
0a6bf658 | 232 | &sensor_dev_attr_in2_min_alarm.dev_attr.attr, |
72f5de92 IS |
233 | |
234 | NULL, | |
235 | }; | |
236 | ||
237 | static const struct attribute_group ltc4215_group = { | |
238 | .attrs = ltc4215_attributes, | |
239 | }; | |
240 | ||
241 | static int ltc4215_probe(struct i2c_client *client, | |
242 | const struct i2c_device_id *id) | |
243 | { | |
2d2a7cff | 244 | struct i2c_adapter *adapter = client->adapter; |
72f5de92 IS |
245 | struct ltc4215_data *data; |
246 | int ret; | |
247 | ||
2d2a7cff JD |
248 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
249 | return -ENODEV; | |
250 | ||
72f5de92 IS |
251 | data = kzalloc(sizeof(*data), GFP_KERNEL); |
252 | if (!data) { | |
253 | ret = -ENOMEM; | |
254 | goto out_kzalloc; | |
255 | } | |
256 | ||
257 | i2c_set_clientdata(client, data); | |
258 | mutex_init(&data->update_lock); | |
259 | ||
260 | /* Initialize the LTC4215 chip */ | |
b6b9d696 | 261 | i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00); |
72f5de92 IS |
262 | |
263 | /* Register sysfs hooks */ | |
264 | ret = sysfs_create_group(&client->dev.kobj, <c4215_group); | |
265 | if (ret) | |
266 | goto out_sysfs_create_group; | |
267 | ||
268 | data->hwmon_dev = hwmon_device_register(&client->dev); | |
269 | if (IS_ERR(data->hwmon_dev)) { | |
270 | ret = PTR_ERR(data->hwmon_dev); | |
271 | goto out_hwmon_device_register; | |
272 | } | |
273 | ||
274 | return 0; | |
275 | ||
276 | out_hwmon_device_register: | |
277 | sysfs_remove_group(&client->dev.kobj, <c4215_group); | |
278 | out_sysfs_create_group: | |
279 | kfree(data); | |
280 | out_kzalloc: | |
281 | return ret; | |
282 | } | |
283 | ||
284 | static int ltc4215_remove(struct i2c_client *client) | |
285 | { | |
286 | struct ltc4215_data *data = i2c_get_clientdata(client); | |
287 | ||
288 | hwmon_device_unregister(data->hwmon_dev); | |
289 | sysfs_remove_group(&client->dev.kobj, <c4215_group); | |
290 | ||
291 | kfree(data); | |
292 | ||
293 | return 0; | |
294 | } | |
295 | ||
72f5de92 | 296 | static const struct i2c_device_id ltc4215_id[] = { |
2d2a7cff | 297 | { "ltc4215", 0 }, |
72f5de92 IS |
298 | { } |
299 | }; | |
300 | MODULE_DEVICE_TABLE(i2c, ltc4215_id); | |
301 | ||
302 | /* This is the driver that will be inserted */ | |
303 | static struct i2c_driver ltc4215_driver = { | |
72f5de92 IS |
304 | .driver = { |
305 | .name = "ltc4215", | |
306 | }, | |
307 | .probe = ltc4215_probe, | |
308 | .remove = ltc4215_remove, | |
309 | .id_table = ltc4215_id, | |
72f5de92 IS |
310 | }; |
311 | ||
312 | static int __init ltc4215_init(void) | |
313 | { | |
314 | return i2c_add_driver(<c4215_driver); | |
315 | } | |
316 | ||
317 | static void __exit ltc4215_exit(void) | |
318 | { | |
319 | i2c_del_driver(<c4215_driver); | |
320 | } | |
321 | ||
322 | MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); | |
323 | MODULE_DESCRIPTION("LTC4215 driver"); | |
324 | MODULE_LICENSE("GPL"); | |
325 | ||
326 | module_init(ltc4215_init); | |
327 | module_exit(ltc4215_exit); |