GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / rtc / rtc-isl12022.c
1 /*
2  * An I2C driver for the Intersil ISL 12022
3  *
4  * Author: Roman Fietze <roman.fietze@telemotive.de>
5  *
6  * Based on the Philips PCF8563 RTC
7  * by Alessandro Zummo <a.zummo@towertech.it>.
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License version
11  * 2 as published by the Free Software Foundation.
12  */
13
14 #include <linux/i2c.h>
15 #include <linux/bcd.h>
16 #include <linux/rtc.h>
17 #include <linux/slab.h>
18 #include <linux/module.h>
19 #include <linux/err.h>
20 #include <linux/of.h>
21 #include <linux/of_device.h>
22
23 #define DRV_VERSION "0.1"
24
25 /* ISL register offsets */
26 #define ISL12022_REG_SC         0x00
27 #define ISL12022_REG_MN         0x01
28 #define ISL12022_REG_HR         0x02
29 #define ISL12022_REG_DT         0x03
30 #define ISL12022_REG_MO         0x04
31 #define ISL12022_REG_YR         0x05
32 #define ISL12022_REG_DW         0x06
33
34 #define ISL12022_REG_SR         0x07
35 #define ISL12022_REG_INT        0x08
36
37 /* ISL register bits */
38 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
39
40 #define ISL12022_SR_LBAT85      (1 << 2)
41 #define ISL12022_SR_LBAT75      (1 << 1)
42
43 #define ISL12022_INT_WRTC       (1 << 6)
44
45
46 static struct i2c_driver isl12022_driver;
47
48 struct isl12022 {
49         struct rtc_device *rtc;
50
51         bool write_enabled;     /* true if write enable is set */
52 };
53
54
55 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
56                               uint8_t *data, size_t n)
57 {
58         struct i2c_msg msgs[] = {
59                 {
60                         .addr   = client->addr,
61                         .flags  = 0,
62                         .len    = 1,
63                         .buf    = data
64                 },              /* setup read ptr */
65                 {
66                         .addr   = client->addr,
67                         .flags  = I2C_M_RD,
68                         .len    = n,
69                         .buf    = data
70                 }
71         };
72
73         int ret;
74
75         data[0] = reg;
76         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
77         if (ret != ARRAY_SIZE(msgs)) {
78                 dev_err(&client->dev, "%s: read error, ret=%d\n",
79                         __func__, ret);
80                 return -EIO;
81         }
82
83         return 0;
84 }
85
86
87 static int isl12022_write_reg(struct i2c_client *client,
88                               uint8_t reg, uint8_t val)
89 {
90         uint8_t data[2] = { reg, val };
91         int err;
92
93         err = i2c_master_send(client, data, sizeof(data));
94         if (err != sizeof(data)) {
95                 dev_err(&client->dev,
96                         "%s: err=%d addr=%02x, data=%02x\n",
97                         __func__, err, data[0], data[1]);
98                 return -EIO;
99         }
100
101         return 0;
102 }
103
104
105 /*
106  * In the routines that deal directly with the isl12022 hardware, we use
107  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
108  */
109 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
110 {
111         uint8_t buf[ISL12022_REG_INT + 1];
112         int ret;
113
114         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
115         if (ret)
116                 return ret;
117
118         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
119                 dev_warn(&client->dev,
120                          "voltage dropped below %u%%, "
121                          "date and time is not reliable.\n",
122                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
123         }
124
125         dev_dbg(&client->dev,
126                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
127                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
128                 "sr=%02x, int=%02x",
129                 __func__,
130                 buf[ISL12022_REG_SC],
131                 buf[ISL12022_REG_MN],
132                 buf[ISL12022_REG_HR],
133                 buf[ISL12022_REG_DT],
134                 buf[ISL12022_REG_MO],
135                 buf[ISL12022_REG_YR],
136                 buf[ISL12022_REG_DW],
137                 buf[ISL12022_REG_SR],
138                 buf[ISL12022_REG_INT]);
139
140         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
141         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
142         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
143         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
144         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
145         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
146         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
147
148         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
149                 "mday=%d, mon=%d, year=%d, wday=%d\n",
150                 __func__,
151                 tm->tm_sec, tm->tm_min, tm->tm_hour,
152                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
153
154         return rtc_valid_tm(tm);
155 }
156
157 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
158 {
159         struct isl12022 *isl12022 = i2c_get_clientdata(client);
160         size_t i;
161         int ret;
162         uint8_t buf[ISL12022_REG_DW + 1];
163
164         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
165                 "mday=%d, mon=%d, year=%d, wday=%d\n",
166                 __func__,
167                 tm->tm_sec, tm->tm_min, tm->tm_hour,
168                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
169
170         if (!isl12022->write_enabled) {
171
172                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
173                 if (ret)
174                         return ret;
175
176                 /* Check if WRTC (write rtc enable) is set factory default is
177                  * 0 (not set) */
178                 if (!(buf[0] & ISL12022_INT_WRTC)) {
179                         dev_info(&client->dev,
180                                  "init write enable and 24 hour format\n");
181
182                         /* Set the write enable bit. */
183                         ret = isl12022_write_reg(client,
184                                                  ISL12022_REG_INT,
185                                                  buf[0] | ISL12022_INT_WRTC);
186                         if (ret)
187                                 return ret;
188
189                         /* Write to any RTC register to start RTC, we use the
190                          * HR register, setting the MIL bit to use the 24 hour
191                          * format. */
192                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
193                                                  buf, 1);
194                         if (ret)
195                                 return ret;
196
197                         ret = isl12022_write_reg(client,
198                                                  ISL12022_REG_HR,
199                                                  buf[0] | ISL12022_HR_MIL);
200                         if (ret)
201                                 return ret;
202                 }
203
204                 isl12022->write_enabled = 1;
205         }
206
207         /* hours, minutes and seconds */
208         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
209         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
210         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
211
212         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
213
214         /* month, 1 - 12 */
215         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
216
217         /* year and century */
218         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
219
220         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
221
222         /* write register's data */
223         for (i = 0; i < ARRAY_SIZE(buf); i++) {
224                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
225                                          buf[ISL12022_REG_SC + i]);
226                 if (ret)
227                         return -EIO;
228         }
229
230         return 0;
231 }
232
233 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
234 {
235         return isl12022_get_datetime(to_i2c_client(dev), tm);
236 }
237
238 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
239 {
240         return isl12022_set_datetime(to_i2c_client(dev), tm);
241 }
242
243 static const struct rtc_class_ops isl12022_rtc_ops = {
244         .read_time      = isl12022_rtc_read_time,
245         .set_time       = isl12022_rtc_set_time,
246 };
247
248 static int isl12022_probe(struct i2c_client *client,
249                           const struct i2c_device_id *id)
250 {
251         struct isl12022 *isl12022;
252
253         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
254                 return -ENODEV;
255
256         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
257                                 GFP_KERNEL);
258         if (!isl12022)
259                 return -ENOMEM;
260
261         dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
262
263         i2c_set_clientdata(client, isl12022);
264
265         isl12022->rtc = devm_rtc_device_register(&client->dev,
266                                         isl12022_driver.driver.name,
267                                         &isl12022_rtc_ops, THIS_MODULE);
268         return PTR_ERR_OR_ZERO(isl12022->rtc);
269 }
270
271 #ifdef CONFIG_OF
272 static const struct of_device_id isl12022_dt_match[] = {
273         { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
274         { .compatible = "isil,isl12022" },
275         { },
276 };
277 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
278 #endif
279
280 static const struct i2c_device_id isl12022_id[] = {
281         { "isl12022", 0 },
282         { }
283 };
284 MODULE_DEVICE_TABLE(i2c, isl12022_id);
285
286 static struct i2c_driver isl12022_driver = {
287         .driver         = {
288                 .name   = "rtc-isl12022",
289 #ifdef CONFIG_OF
290                 .of_match_table = of_match_ptr(isl12022_dt_match),
291 #endif
292         },
293         .probe          = isl12022_probe,
294         .id_table       = isl12022_id,
295 };
296
297 module_i2c_driver(isl12022_driver);
298
299 MODULE_AUTHOR("roman.fietze@telemotive.de");
300 MODULE_DESCRIPTION("ISL 12022 RTC driver");
301 MODULE_LICENSE("GPL");
302 MODULE_VERSION(DRV_VERSION);