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1 | /* |
2 | * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller | |
3 | * | |
4 | * Copyright (C) 2010 Ericsson AB. | |
5 | * | |
6 | * Derived from: | |
7 | * | |
8 | * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller | |
9 | * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu> | |
10 | * | |
11 | * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf | |
12 | * | |
13 | * This program is free software; you can redistribute it and/or modify | |
14 | * it under the terms of the GNU General Public License as published by | |
15 | * the Free Software Foundation; either version 2 of the License, or | |
16 | * (at your option) any later version. | |
17 | * | |
18 | * This program is distributed in the hope that it will be useful, | |
19 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
20 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
21 | * GNU General Public License for more details. | |
22 | * | |
23 | * You should have received a copy of the GNU General Public License | |
24 | * along with this program; if not, write to the Free Software | |
25 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
26 | */ | |
27 | ||
28 | #include <linux/kernel.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/init.h> | |
31 | #include <linux/err.h> | |
32 | #include <linux/slab.h> | |
33 | #include <linux/i2c.h> | |
34 | #include <linux/hwmon.h> | |
35 | #include <linux/hwmon-sysfs.h> | |
36 | ||
37 | /* chip registers */ | |
38 | #define LTC4261_STATUS 0x00 /* readonly */ | |
39 | #define LTC4261_FAULT 0x01 | |
40 | #define LTC4261_ALERT 0x02 | |
41 | #define LTC4261_CONTROL 0x03 | |
42 | #define LTC4261_SENSE_H 0x04 | |
43 | #define LTC4261_SENSE_L 0x05 | |
44 | #define LTC4261_ADIN2_H 0x06 | |
45 | #define LTC4261_ADIN2_L 0x07 | |
46 | #define LTC4261_ADIN_H 0x08 | |
47 | #define LTC4261_ADIN_L 0x09 | |
48 | ||
49 | /* | |
50 | * Fault register bits | |
51 | */ | |
52 | #define FAULT_OV (1<<0) | |
53 | #define FAULT_UV (1<<1) | |
54 | #define FAULT_OC (1<<2) | |
55 | ||
56 | struct ltc4261_data { | |
57 | struct device *hwmon_dev; | |
58 | ||
59 | struct mutex update_lock; | |
60 | bool valid; | |
61 | unsigned long last_updated; /* in jiffies */ | |
62 | ||
63 | /* Registers */ | |
64 | u8 regs[10]; | |
65 | }; | |
66 | ||
67 | static struct ltc4261_data *ltc4261_update_device(struct device *dev) | |
68 | { | |
69 | struct i2c_client *client = to_i2c_client(dev); | |
70 | struct ltc4261_data *data = i2c_get_clientdata(client); | |
71 | struct ltc4261_data *ret = data; | |
72 | ||
73 | mutex_lock(&data->update_lock); | |
74 | ||
75 | if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) { | |
76 | int i; | |
77 | ||
78 | /* Read registers -- 0x00 to 0x09 */ | |
79 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { | |
80 | int val; | |
81 | ||
82 | val = i2c_smbus_read_byte_data(client, i); | |
83 | if (unlikely(val < 0)) { | |
84 | dev_dbg(dev, | |
69f8b741 | 85 | "Failed to read ADC value: error %d\n", |
e5f5c99a GR |
86 | val); |
87 | ret = ERR_PTR(val); | |
88 | goto abort; | |
89 | } | |
90 | data->regs[i] = val; | |
91 | } | |
92 | data->last_updated = jiffies; | |
93 | data->valid = 1; | |
94 | } | |
95 | abort: | |
96 | mutex_unlock(&data->update_lock); | |
97 | return ret; | |
98 | } | |
99 | ||
100 | /* Return the voltage from the given register in mV or mA */ | |
101 | static int ltc4261_get_value(struct ltc4261_data *data, u8 reg) | |
102 | { | |
103 | u32 val; | |
104 | ||
105 | val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6); | |
106 | ||
107 | switch (reg) { | |
108 | case LTC4261_ADIN_H: | |
109 | case LTC4261_ADIN2_H: | |
110 | /* 2.5mV resolution. Convert to mV. */ | |
111 | val = val * 25 / 10; | |
112 | break; | |
113 | case LTC4261_SENSE_H: | |
114 | /* | |
115 | * 62.5uV resolution. Convert to current as measured with | |
116 | * an 1 mOhm sense resistor, in mA. If a different sense | |
117 | * resistor is installed, calculate the actual current by | |
118 | * dividing the reported current by the sense resistor value | |
119 | * in mOhm. | |
120 | */ | |
121 | val = val * 625 / 10; | |
122 | break; | |
123 | default: | |
124 | /* If we get here, the developer messed up */ | |
125 | WARN_ON_ONCE(1); | |
126 | val = 0; | |
127 | break; | |
128 | } | |
129 | ||
130 | return val; | |
131 | } | |
132 | ||
133 | static ssize_t ltc4261_show_value(struct device *dev, | |
134 | struct device_attribute *da, char *buf) | |
135 | { | |
136 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
137 | struct ltc4261_data *data = ltc4261_update_device(dev); | |
138 | int value; | |
139 | ||
140 | if (IS_ERR(data)) | |
141 | return PTR_ERR(data); | |
142 | ||
143 | value = ltc4261_get_value(data, attr->index); | |
144 | return snprintf(buf, PAGE_SIZE, "%d\n", value); | |
145 | } | |
146 | ||
147 | static ssize_t ltc4261_show_bool(struct device *dev, | |
148 | struct device_attribute *da, char *buf) | |
149 | { | |
150 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
151 | struct i2c_client *client = to_i2c_client(dev); | |
152 | struct ltc4261_data *data = ltc4261_update_device(dev); | |
153 | u8 fault; | |
154 | ||
155 | if (IS_ERR(data)) | |
156 | return PTR_ERR(data); | |
157 | ||
158 | fault = data->regs[LTC4261_FAULT] & attr->index; | |
159 | if (fault) /* Clear reported faults in chip register */ | |
160 | i2c_smbus_write_byte_data(client, LTC4261_FAULT, ~fault); | |
161 | ||
162 | return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0); | |
163 | } | |
164 | ||
165 | /* | |
166 | * These macros are used below in constructing device attribute objects | |
167 | * for use with sysfs_create_group() to make a sysfs device file | |
168 | * for each register. | |
169 | */ | |
170 | ||
171 | #define LTC4261_VALUE(name, ltc4261_cmd_idx) \ | |
172 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ | |
173 | ltc4261_show_value, NULL, ltc4261_cmd_idx) | |
174 | ||
175 | #define LTC4261_BOOL(name, mask) \ | |
176 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ | |
177 | ltc4261_show_bool, NULL, (mask)) | |
178 | ||
179 | /* | |
180 | * Input voltages. | |
181 | */ | |
182 | LTC4261_VALUE(in1_input, LTC4261_ADIN_H); | |
183 | LTC4261_VALUE(in2_input, LTC4261_ADIN2_H); | |
184 | ||
185 | /* | |
186 | * Voltage alarms. The chip has only one set of voltage alarm status bits, | |
187 | * triggered by input voltage alarms. In many designs, those alarms are | |
188 | * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin | |
189 | * to the OV pin. ADIN2 is, however, not available on all chip variants. | |
190 | * To ensure that the alarm condition is reported to the user, report it | |
191 | * with both voltage sensors. | |
192 | */ | |
193 | LTC4261_BOOL(in1_min_alarm, FAULT_UV); | |
194 | LTC4261_BOOL(in1_max_alarm, FAULT_OV); | |
195 | LTC4261_BOOL(in2_min_alarm, FAULT_UV); | |
196 | LTC4261_BOOL(in2_max_alarm, FAULT_OV); | |
197 | ||
198 | /* Currents (via sense resistor) */ | |
199 | LTC4261_VALUE(curr1_input, LTC4261_SENSE_H); | |
200 | ||
201 | /* Overcurrent alarm */ | |
202 | LTC4261_BOOL(curr1_max_alarm, FAULT_OC); | |
203 | ||
204 | static struct attribute *ltc4261_attributes[] = { | |
205 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
206 | &sensor_dev_attr_in1_min_alarm.dev_attr.attr, | |
207 | &sensor_dev_attr_in1_max_alarm.dev_attr.attr, | |
208 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
209 | &sensor_dev_attr_in2_min_alarm.dev_attr.attr, | |
210 | &sensor_dev_attr_in2_max_alarm.dev_attr.attr, | |
211 | ||
212 | &sensor_dev_attr_curr1_input.dev_attr.attr, | |
213 | &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, | |
214 | ||
215 | NULL, | |
216 | }; | |
217 | ||
218 | static const struct attribute_group ltc4261_group = { | |
219 | .attrs = ltc4261_attributes, | |
220 | }; | |
221 | ||
222 | static int ltc4261_probe(struct i2c_client *client, | |
223 | const struct i2c_device_id *id) | |
224 | { | |
225 | struct i2c_adapter *adapter = client->adapter; | |
226 | struct ltc4261_data *data; | |
227 | int ret; | |
228 | ||
229 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) | |
230 | return -ENODEV; | |
231 | ||
232 | if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { | |
475200c0 | 233 | dev_err(&client->dev, "Failed to read status register\n"); |
e5f5c99a GR |
234 | return -ENODEV; |
235 | } | |
236 | ||
237 | data = kzalloc(sizeof(*data), GFP_KERNEL); | |
238 | if (!data) { | |
239 | ret = -ENOMEM; | |
240 | goto out_kzalloc; | |
241 | } | |
242 | ||
243 | i2c_set_clientdata(client, data); | |
244 | mutex_init(&data->update_lock); | |
245 | ||
246 | /* Clear faults */ | |
247 | i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); | |
248 | ||
249 | /* Register sysfs hooks */ | |
250 | ret = sysfs_create_group(&client->dev.kobj, <c4261_group); | |
251 | if (ret) | |
252 | goto out_sysfs_create_group; | |
253 | ||
254 | data->hwmon_dev = hwmon_device_register(&client->dev); | |
255 | if (IS_ERR(data->hwmon_dev)) { | |
256 | ret = PTR_ERR(data->hwmon_dev); | |
257 | goto out_hwmon_device_register; | |
258 | } | |
259 | ||
260 | return 0; | |
261 | ||
262 | out_hwmon_device_register: | |
263 | sysfs_remove_group(&client->dev.kobj, <c4261_group); | |
264 | out_sysfs_create_group: | |
265 | kfree(data); | |
266 | out_kzalloc: | |
267 | return ret; | |
268 | } | |
269 | ||
270 | static int ltc4261_remove(struct i2c_client *client) | |
271 | { | |
272 | struct ltc4261_data *data = i2c_get_clientdata(client); | |
273 | ||
274 | hwmon_device_unregister(data->hwmon_dev); | |
275 | sysfs_remove_group(&client->dev.kobj, <c4261_group); | |
276 | ||
277 | kfree(data); | |
278 | ||
279 | return 0; | |
280 | } | |
281 | ||
282 | static const struct i2c_device_id ltc4261_id[] = { | |
283 | {"ltc4261", 0}, | |
284 | {} | |
285 | }; | |
286 | ||
287 | MODULE_DEVICE_TABLE(i2c, ltc4261_id); | |
288 | ||
289 | /* This is the driver that will be inserted */ | |
290 | static struct i2c_driver ltc4261_driver = { | |
291 | .driver = { | |
292 | .name = "ltc4261", | |
293 | }, | |
294 | .probe = ltc4261_probe, | |
295 | .remove = ltc4261_remove, | |
296 | .id_table = ltc4261_id, | |
297 | }; | |
298 | ||
299 | static int __init ltc4261_init(void) | |
300 | { | |
301 | return i2c_add_driver(<c4261_driver); | |
302 | } | |
303 | ||
304 | static void __exit ltc4261_exit(void) | |
305 | { | |
306 | i2c_del_driver(<c4261_driver); | |
307 | } | |
308 | ||
309 | MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); | |
310 | MODULE_DESCRIPTION("LTC4261 driver"); | |
311 | MODULE_LICENSE("GPL"); | |
312 | ||
313 | module_init(ltc4261_init); | |
314 | module_exit(ltc4261_exit); |