1 /*
2 * Driver for TI BQ32000 RTC.
3 *
4 * Copyright (C) 2009 Semihalf.
5 * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * You can get hardware description at
12 * http://www.ti.com/lit/ds/symlink/bq32000.pdf
13 */
14
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/rtc.h>
18 #include <linux/init.h>
19 #include <linux/errno.h>
20 #include <linux/bcd.h>
21
22 #define BQ32K_SECONDS 0x00 /* Seconds register address */
23 #define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */
24 #define BQ32K_STOP 0x80 /* Oscillator Stop flat */
25
26 #define BQ32K_MINUTES 0x01 /* Minutes register address */
27 #define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */
28 #define BQ32K_OF 0x80 /* Oscillator Failure flag */
29
30 #define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */
31 #define BQ32K_CENT 0x40 /* Century flag */
32 #define BQ32K_CENT_EN 0x80 /* Century flag enable bit */
33
34 #define BQ32K_CALIBRATION 0x07 /* CAL_CFG1, calibration and control */
35 #define BQ32K_TCH2 0x08 /* Trickle charge enable */
36 #define BQ32K_CFG2 0x09 /* Trickle charger control */
37 #define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */
38
39 #define MAX_LEN 10 /* Maximum number of consecutive
40 * register for this particular RTC.
41 */
42
43 struct bq32k_regs {
44 uint8_t seconds;
45 uint8_t minutes;
46 uint8_t cent_hours;
47 uint8_t day;
48 uint8_t date;
49 uint8_t month;
50 uint8_t years;
51 };
52
53 static struct i2c_driver bq32k_driver;
54
bq32k_read(struct device * dev,void * data,uint8_t off,uint8_t len)55 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
56 {
57 struct i2c_client *client = to_i2c_client(dev);
58 struct i2c_msg msgs[] = {
59 {
60 .addr = client->addr,
61 .flags = 0,
62 .len = 1,
63 .buf = &off,
64 }, {
65 .addr = client->addr,
66 .flags = I2C_M_RD,
67 .len = len,
68 .buf = data,
69 }
70 };
71
72 if (i2c_transfer(client->adapter, msgs, 2) == 2)
73 return 0;
74
75 return -EIO;
76 }
77
bq32k_write(struct device * dev,void * data,uint8_t off,uint8_t len)78 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
79 {
80 struct i2c_client *client = to_i2c_client(dev);
81 uint8_t buffer[MAX_LEN + 1];
82
83 buffer[0] = off;
84 memcpy(&buffer[1], data, len);
85
86 if (i2c_master_send(client, buffer, len + 1) == len + 1)
87 return 0;
88
89 return -EIO;
90 }
91
bq32k_rtc_read_time(struct device * dev,struct rtc_time * tm)92 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
93 {
94 struct bq32k_regs regs;
95 int error;
96
97 error = bq32k_read(dev, ®s, 0, sizeof(regs));
98 if (error)
99 return error;
100
101 /*
102 * In case of oscillator failure, the register contents should be
103 * considered invalid. The flag is cleared the next time the RTC is set.
104 */
105 if (regs.minutes & BQ32K_OF)
106 return -EINVAL;
107
108 tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
109 tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
110 tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
111 tm->tm_mday = bcd2bin(regs.date);
112 tm->tm_wday = bcd2bin(regs.day) - 1;
113 tm->tm_mon = bcd2bin(regs.month) - 1;
114 tm->tm_year = bcd2bin(regs.years) +
115 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
116
117 return 0;
118 }
119
bq32k_rtc_set_time(struct device * dev,struct rtc_time * tm)120 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
121 {
122 struct bq32k_regs regs;
123
124 regs.seconds = bin2bcd(tm->tm_sec);
125 regs.minutes = bin2bcd(tm->tm_min);
126 regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
127 regs.day = bin2bcd(tm->tm_wday + 1);
128 regs.date = bin2bcd(tm->tm_mday);
129 regs.month = bin2bcd(tm->tm_mon + 1);
130
131 if (tm->tm_year >= 100) {
132 regs.cent_hours |= BQ32K_CENT;
133 regs.years = bin2bcd(tm->tm_year - 100);
134 } else
135 regs.years = bin2bcd(tm->tm_year);
136
137 return bq32k_write(dev, ®s, 0, sizeof(regs));
138 }
139
140 static const struct rtc_class_ops bq32k_rtc_ops = {
141 .read_time = bq32k_rtc_read_time,
142 .set_time = bq32k_rtc_set_time,
143 };
144
trickle_charger_of_init(struct device * dev,struct device_node * node)145 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
146 {
147 unsigned char reg;
148 int error;
149 u32 ohms = 0;
150
151 if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
152 return 0;
153
154 switch (ohms) {
155 case 180+940:
156 /*
157 * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
158 * over diode and 940ohm resistor)
159 */
160
161 if (of_property_read_bool(node, "trickle-diode-disable")) {
162 dev_err(dev, "diode and resistor mismatch\n");
163 return -EINVAL;
164 }
165 reg = 0x05;
166 break;
167
168 case 180+20000:
169 /* diode disabled */
170
171 if (!of_property_read_bool(node, "trickle-diode-disable")) {
172 dev_err(dev, "bq32k: diode and resistor mismatch\n");
173 return -EINVAL;
174 }
175 reg = 0x45;
176 break;
177
178 default:
179 dev_err(dev, "invalid resistor value (%d)\n", ohms);
180 return -EINVAL;
181 }
182
183 error = bq32k_write(dev, ®, BQ32K_CFG2, 1);
184 if (error)
185 return error;
186
187 reg = 0x20;
188 error = bq32k_write(dev, ®, BQ32K_TCH2, 1);
189 if (error)
190 return error;
191
192 dev_info(dev, "Enabled trickle RTC battery charge.\n");
193 return 0;
194 }
195
bq32k_sysfs_show_tricklecharge_bypass(struct device * dev,struct device_attribute * attr,char * buf)196 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
197 struct device_attribute *attr,
198 char *buf)
199 {
200 int reg, error;
201
202 error = bq32k_read(dev, ®, BQ32K_CFG2, 1);
203 if (error)
204 return error;
205
206 return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
207 }
208
bq32k_sysfs_store_tricklecharge_bypass(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)209 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
210 struct device_attribute *attr,
211 const char *buf, size_t count)
212 {
213 int reg, enable, error;
214
215 if (kstrtoint(buf, 0, &enable))
216 return -EINVAL;
217
218 error = bq32k_read(dev, ®, BQ32K_CFG2, 1);
219 if (error)
220 return error;
221
222 if (enable) {
223 reg |= BQ32K_TCFE;
224 error = bq32k_write(dev, ®, BQ32K_CFG2, 1);
225 if (error)
226 return error;
227
228 dev_info(dev, "Enabled trickle charge FET bypass.\n");
229 } else {
230 reg &= ~BQ32K_TCFE;
231 error = bq32k_write(dev, ®, BQ32K_CFG2, 1);
232 if (error)
233 return error;
234
235 dev_info(dev, "Disabled trickle charge FET bypass.\n");
236 }
237
238 return count;
239 }
240
241 static DEVICE_ATTR(trickle_charge_bypass, 0644,
242 bq32k_sysfs_show_tricklecharge_bypass,
243 bq32k_sysfs_store_tricklecharge_bypass);
244
bq32k_sysfs_register(struct device * dev)245 static int bq32k_sysfs_register(struct device *dev)
246 {
247 return device_create_file(dev, &dev_attr_trickle_charge_bypass);
248 }
249
bq32k_sysfs_unregister(struct device * dev)250 static void bq32k_sysfs_unregister(struct device *dev)
251 {
252 device_remove_file(dev, &dev_attr_trickle_charge_bypass);
253 }
254
bq32k_probe(struct i2c_client * client,const struct i2c_device_id * id)255 static int bq32k_probe(struct i2c_client *client,
256 const struct i2c_device_id *id)
257 {
258 struct device *dev = &client->dev;
259 struct rtc_device *rtc;
260 uint8_t reg;
261 int error;
262
263 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
264 return -ENODEV;
265
266 /* Check Oscillator Stop flag */
267 error = bq32k_read(dev, ®, BQ32K_SECONDS, 1);
268 if (!error && (reg & BQ32K_STOP)) {
269 dev_warn(dev, "Oscillator was halted. Restarting...\n");
270 reg &= ~BQ32K_STOP;
271 error = bq32k_write(dev, ®, BQ32K_SECONDS, 1);
272 }
273 if (error)
274 return error;
275
276 /* Check Oscillator Failure flag */
277 error = bq32k_read(dev, ®, BQ32K_MINUTES, 1);
278 if (error)
279 return error;
280 if (reg & BQ32K_OF)
281 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
282
283 if (client->dev.of_node)
284 trickle_charger_of_init(dev, client->dev.of_node);
285
286 rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
287 &bq32k_rtc_ops, THIS_MODULE);
288 if (IS_ERR(rtc))
289 return PTR_ERR(rtc);
290
291 error = bq32k_sysfs_register(&client->dev);
292 if (error) {
293 dev_err(&client->dev,
294 "Unable to create sysfs entries for rtc bq32000\n");
295 return error;
296 }
297
298
299 i2c_set_clientdata(client, rtc);
300
301 return 0;
302 }
303
bq32k_remove(struct i2c_client * client)304 static int bq32k_remove(struct i2c_client *client)
305 {
306 bq32k_sysfs_unregister(&client->dev);
307
308 return 0;
309 }
310
311 static const struct i2c_device_id bq32k_id[] = {
312 { "bq32000", 0 },
313 { }
314 };
315 MODULE_DEVICE_TABLE(i2c, bq32k_id);
316
317 static const struct of_device_id bq32k_of_match[] = {
318 { .compatible = "ti,bq32000" },
319 { }
320 };
321 MODULE_DEVICE_TABLE(of, bq32k_of_match);
322
323 static struct i2c_driver bq32k_driver = {
324 .driver = {
325 .name = "bq32k",
326 .of_match_table = of_match_ptr(bq32k_of_match),
327 },
328 .probe = bq32k_probe,
329 .remove = bq32k_remove,
330 .id_table = bq32k_id,
331 };
332
333 module_i2c_driver(bq32k_driver);
334
335 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
336 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
337 MODULE_LICENSE("GPL");
338