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bfdb46ce RM |
1 | /* |
2 | * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC | |
3 | * | |
4 | * Copyright (C) 2009 Bluewater Systems Ltd | |
5 | * | |
6 | * Author: Ryan Mallon <ryan@bluewatersys.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | */ | |
13 | ||
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/types.h> | |
17 | #include <linux/errno.h> | |
18 | #include <linux/swab.h> | |
19 | #include <linux/i2c.h> | |
20 | #include <linux/idr.h> | |
21 | #include <linux/power_supply.h> | |
5a0e3ad6 | 22 | #include <linux/slab.h> |
bfdb46ce RM |
23 | |
24 | #define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */ | |
25 | ||
26 | #define DS2782_REG_VOLT_MSB 0x0c | |
27 | #define DS2782_REG_TEMP_MSB 0x0a | |
28 | #define DS2782_REG_CURRENT_MSB 0x0e | |
29 | ||
30 | /* EEPROM Block */ | |
31 | #define DS2782_REG_RSNSP 0x69 /* Sense resistor value */ | |
32 | ||
33 | /* Current unit measurement in uA for a 1 milli-ohm sense resistor */ | |
34 | #define DS2782_CURRENT_UNITS 1563 | |
35 | ||
36 | #define to_ds2782_info(x) container_of(x, struct ds2782_info, battery) | |
37 | ||
38 | struct ds2782_info { | |
39 | struct i2c_client *client; | |
40 | struct power_supply battery; | |
41 | int id; | |
42 | }; | |
43 | ||
44 | static DEFINE_IDR(battery_id); | |
45 | static DEFINE_MUTEX(battery_lock); | |
46 | ||
47 | static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val) | |
48 | { | |
49 | int ret; | |
50 | ||
51 | ret = i2c_smbus_read_byte_data(info->client, reg); | |
52 | if (ret < 0) { | |
53 | dev_err(&info->client->dev, "register read failed\n"); | |
54 | return ret; | |
55 | } | |
56 | ||
57 | *val = ret; | |
58 | return 0; | |
59 | } | |
60 | ||
61 | static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb, | |
62 | s16 *val) | |
63 | { | |
64 | int ret; | |
65 | ||
66 | ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb)); | |
67 | if (ret < 0) { | |
68 | dev_err(&info->client->dev, "register read failed\n"); | |
69 | return ret; | |
70 | } | |
71 | ||
72 | *val = ret; | |
73 | return 0; | |
74 | } | |
75 | ||
76 | static int ds2782_get_temp(struct ds2782_info *info, int *temp) | |
77 | { | |
78 | s16 raw; | |
79 | int err; | |
80 | ||
81 | /* | |
82 | * Temperature is measured in units of 0.125 degrees celcius, the | |
83 | * power_supply class measures temperature in tenths of degrees | |
84 | * celsius. The temperature value is stored as a 10 bit number, plus | |
85 | * sign in the upper bits of a 16 bit register. | |
86 | */ | |
87 | err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw); | |
88 | if (err) | |
89 | return err; | |
90 | *temp = ((raw / 32) * 125) / 100; | |
91 | return 0; | |
92 | } | |
93 | ||
94 | static int ds2782_get_current(struct ds2782_info *info, int *current_uA) | |
95 | { | |
96 | int sense_res; | |
97 | int err; | |
98 | u8 sense_res_raw; | |
99 | s16 raw; | |
100 | ||
101 | /* | |
102 | * The units of measurement for current are dependent on the value of | |
103 | * the sense resistor. | |
104 | */ | |
105 | err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw); | |
106 | if (err) | |
107 | return err; | |
108 | if (sense_res_raw == 0) { | |
109 | dev_err(&info->client->dev, "sense resistor value is 0\n"); | |
110 | return -ENXIO; | |
111 | } | |
112 | sense_res = 1000 / sense_res_raw; | |
113 | ||
114 | dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n", | |
115 | sense_res); | |
116 | err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw); | |
117 | if (err) | |
118 | return err; | |
119 | *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res); | |
120 | return 0; | |
121 | } | |
122 | ||
123 | static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA) | |
124 | { | |
125 | s16 raw; | |
126 | int err; | |
127 | ||
128 | /* | |
129 | * Voltage is measured in units of 4.88mV. The voltage is stored as | |
130 | * a 10-bit number plus sign, in the upper bits of a 16-bit register | |
131 | */ | |
132 | err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw); | |
133 | if (err) | |
134 | return err; | |
135 | *voltage_uA = (raw / 32) * 4800; | |
136 | return 0; | |
137 | } | |
138 | ||
139 | static int ds2782_get_capacity(struct ds2782_info *info, int *capacity) | |
140 | { | |
141 | int err; | |
142 | u8 raw; | |
143 | ||
144 | err = ds2782_read_reg(info, DS2782_REG_RARC, &raw); | |
145 | if (err) | |
146 | return err; | |
147 | *capacity = raw; | |
148 | return raw; | |
149 | } | |
150 | ||
151 | static int ds2782_get_status(struct ds2782_info *info, int *status) | |
152 | { | |
153 | int err; | |
154 | int current_uA; | |
155 | int capacity; | |
156 | ||
157 | err = ds2782_get_current(info, ¤t_uA); | |
158 | if (err) | |
159 | return err; | |
160 | ||
161 | err = ds2782_get_capacity(info, &capacity); | |
162 | if (err) | |
163 | return err; | |
164 | ||
165 | if (capacity == 100) | |
166 | *status = POWER_SUPPLY_STATUS_FULL; | |
167 | else if (current_uA == 0) | |
168 | *status = POWER_SUPPLY_STATUS_NOT_CHARGING; | |
169 | else if (current_uA < 0) | |
170 | *status = POWER_SUPPLY_STATUS_DISCHARGING; | |
171 | else | |
172 | *status = POWER_SUPPLY_STATUS_CHARGING; | |
173 | ||
174 | return 0; | |
175 | } | |
176 | ||
177 | static int ds2782_battery_get_property(struct power_supply *psy, | |
178 | enum power_supply_property prop, | |
179 | union power_supply_propval *val) | |
180 | { | |
181 | struct ds2782_info *info = to_ds2782_info(psy); | |
182 | int ret; | |
183 | ||
184 | switch (prop) { | |
185 | case POWER_SUPPLY_PROP_STATUS: | |
186 | ret = ds2782_get_status(info, &val->intval); | |
187 | break; | |
188 | ||
189 | case POWER_SUPPLY_PROP_CAPACITY: | |
190 | ret = ds2782_get_capacity(info, &val->intval); | |
191 | break; | |
192 | ||
193 | case POWER_SUPPLY_PROP_VOLTAGE_NOW: | |
194 | ret = ds2782_get_voltage(info, &val->intval); | |
195 | break; | |
196 | ||
197 | case POWER_SUPPLY_PROP_CURRENT_NOW: | |
198 | ret = ds2782_get_current(info, &val->intval); | |
199 | break; | |
200 | ||
201 | case POWER_SUPPLY_PROP_TEMP: | |
202 | ret = ds2782_get_temp(info, &val->intval); | |
203 | break; | |
204 | ||
205 | default: | |
206 | ret = -EINVAL; | |
207 | } | |
208 | ||
209 | return ret; | |
210 | } | |
211 | ||
212 | static enum power_supply_property ds2782_battery_props[] = { | |
213 | POWER_SUPPLY_PROP_STATUS, | |
214 | POWER_SUPPLY_PROP_CAPACITY, | |
215 | POWER_SUPPLY_PROP_VOLTAGE_NOW, | |
216 | POWER_SUPPLY_PROP_CURRENT_NOW, | |
217 | POWER_SUPPLY_PROP_TEMP, | |
218 | }; | |
219 | ||
220 | static void ds2782_power_supply_init(struct power_supply *battery) | |
221 | { | |
222 | battery->type = POWER_SUPPLY_TYPE_BATTERY; | |
223 | battery->properties = ds2782_battery_props; | |
224 | battery->num_properties = ARRAY_SIZE(ds2782_battery_props); | |
225 | battery->get_property = ds2782_battery_get_property; | |
226 | battery->external_power_changed = NULL; | |
227 | } | |
228 | ||
229 | static int ds2782_battery_remove(struct i2c_client *client) | |
230 | { | |
231 | struct ds2782_info *info = i2c_get_clientdata(client); | |
232 | ||
233 | power_supply_unregister(&info->battery); | |
234 | kfree(info->battery.name); | |
235 | ||
236 | mutex_lock(&battery_lock); | |
237 | idr_remove(&battery_id, info->id); | |
238 | mutex_unlock(&battery_lock); | |
239 | ||
240 | i2c_set_clientdata(client, info); | |
241 | ||
242 | kfree(info); | |
243 | return 0; | |
244 | } | |
245 | ||
246 | static int ds2782_battery_probe(struct i2c_client *client, | |
247 | const struct i2c_device_id *id) | |
248 | { | |
249 | struct ds2782_info *info; | |
250 | int ret; | |
251 | int num; | |
252 | ||
253 | /* Get an ID for this battery */ | |
254 | ret = idr_pre_get(&battery_id, GFP_KERNEL); | |
255 | if (ret == 0) { | |
256 | ret = -ENOMEM; | |
257 | goto fail_id; | |
258 | } | |
259 | ||
260 | mutex_lock(&battery_lock); | |
261 | ret = idr_get_new(&battery_id, client, &num); | |
262 | mutex_unlock(&battery_lock); | |
263 | if (ret < 0) | |
264 | goto fail_id; | |
265 | ||
266 | info = kzalloc(sizeof(*info), GFP_KERNEL); | |
267 | if (!info) { | |
268 | ret = -ENOMEM; | |
269 | goto fail_info; | |
270 | } | |
271 | ||
272 | info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num); | |
273 | if (!info->battery.name) { | |
274 | ret = -ENOMEM; | |
275 | goto fail_name; | |
276 | } | |
277 | ||
278 | i2c_set_clientdata(client, info); | |
279 | info->client = client; | |
280 | ds2782_power_supply_init(&info->battery); | |
281 | ||
282 | ret = power_supply_register(&client->dev, &info->battery); | |
283 | if (ret) { | |
284 | dev_err(&client->dev, "failed to register battery\n"); | |
285 | goto fail_register; | |
286 | } | |
287 | ||
288 | return 0; | |
289 | ||
290 | fail_register: | |
291 | kfree(info->battery.name); | |
292 | fail_name: | |
293 | i2c_set_clientdata(client, info); | |
294 | kfree(info); | |
295 | fail_info: | |
296 | mutex_lock(&battery_lock); | |
297 | idr_remove(&battery_id, num); | |
298 | mutex_unlock(&battery_lock); | |
299 | fail_id: | |
300 | return ret; | |
301 | } | |
302 | ||
303 | static const struct i2c_device_id ds2782_id[] = { | |
304 | {"ds2782", 0}, | |
305 | {}, | |
306 | }; | |
307 | ||
308 | static struct i2c_driver ds2782_battery_driver = { | |
309 | .driver = { | |
310 | .name = "ds2782-battery", | |
311 | }, | |
312 | .probe = ds2782_battery_probe, | |
313 | .remove = ds2782_battery_remove, | |
314 | .id_table = ds2782_id, | |
315 | }; | |
316 | ||
317 | static int __init ds2782_init(void) | |
318 | { | |
319 | return i2c_add_driver(&ds2782_battery_driver); | |
320 | } | |
321 | module_init(ds2782_init); | |
322 | ||
323 | static void __exit ds2782_exit(void) | |
324 | { | |
325 | i2c_del_driver(&ds2782_battery_driver); | |
326 | } | |
327 | module_exit(ds2782_exit); | |
328 | ||
329 | MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>"); | |
330 | MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver"); | |
331 | MODULE_LICENSE("GPL"); |