rtc: add support for Epson RTC-9701JE V2
[linux-2.6.git] / drivers / rtc / rtc-pcf8583.c
1 /*
2  *  drivers/rtc/rtc-pcf8583.c
3  *
4  *  Copyright (C) 2000 Russell King
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 version 2 as
8  * published by the Free Software Foundation.
9  *
10  *  Driver for PCF8583 RTC & RAM chip
11  *
12  *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
13  */
14 #include <linux/module.h>
15 #include <linux/i2c.h>
16 #include <linux/slab.h>
17 #include <linux/string.h>
18 #include <linux/mc146818rtc.h>
19 #include <linux/init.h>
20 #include <linux/errno.h>
21 #include <linux/bcd.h>
22
23 struct rtc_mem {
24         unsigned int    loc;
25         unsigned int    nr;
26         unsigned char   *data;
27 };
28
29 struct pcf8583 {
30         struct i2c_client client;
31         struct rtc_device *rtc;
32         unsigned char ctrl;
33 };
34
35 #define CTRL_STOP       0x80
36 #define CTRL_HOLD       0x40
37 #define CTRL_32KHZ      0x00
38 #define CTRL_MASK       0x08
39 #define CTRL_ALARMEN    0x04
40 #define CTRL_ALARM      0x02
41 #define CTRL_TIMER      0x01
42
43 static const unsigned short normal_i2c[] = { 0x50, I2C_CLIENT_END };
44
45 /* Module parameters */
46 I2C_CLIENT_INSMOD;
47
48 static struct i2c_driver pcf8583_driver;
49
50 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
51 #define set_ctrl(x, v) get_ctrl(x) = v
52
53 #define CMOS_YEAR       (64 + 128)
54 #define CMOS_CHECKSUM   (63)
55
56 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
57 {
58         unsigned char buf[8], addr[1] = { 1 };
59         struct i2c_msg msgs[2] = {
60                 {
61                         .addr = client->addr,
62                         .flags = 0,
63                         .len = 1,
64                         .buf = addr,
65                 }, {
66                         .addr = client->addr,
67                         .flags = I2C_M_RD,
68                         .len = 6,
69                         .buf = buf,
70                 }
71         };
72         int ret;
73
74         memset(buf, 0, sizeof(buf));
75
76         ret = i2c_transfer(client->adapter, msgs, 2);
77         if (ret == 2) {
78                 dt->tm_year = buf[4] >> 6;
79                 dt->tm_wday = buf[5] >> 5;
80
81                 buf[4] &= 0x3f;
82                 buf[5] &= 0x1f;
83
84                 dt->tm_sec = BCD2BIN(buf[1]);
85                 dt->tm_min = BCD2BIN(buf[2]);
86                 dt->tm_hour = BCD2BIN(buf[3]);
87                 dt->tm_mday = BCD2BIN(buf[4]);
88                 dt->tm_mon = BCD2BIN(buf[5]) - 1;
89         }
90
91         return ret == 2 ? 0 : -EIO;
92 }
93
94 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
95 {
96         unsigned char buf[8];
97         int ret, len = 6;
98
99         buf[0] = 0;
100         buf[1] = get_ctrl(client) | 0x80;
101         buf[2] = 0;
102         buf[3] = BIN2BCD(dt->tm_sec);
103         buf[4] = BIN2BCD(dt->tm_min);
104         buf[5] = BIN2BCD(dt->tm_hour);
105
106         if (datetoo) {
107                 len = 8;
108                 buf[6] = BIN2BCD(dt->tm_mday) | (dt->tm_year << 6);
109                 buf[7] = BIN2BCD(dt->tm_mon + 1)  | (dt->tm_wday << 5);
110         }
111
112         ret = i2c_master_send(client, (char *)buf, len);
113         if (ret != len)
114                 return -EIO;
115
116         buf[1] = get_ctrl(client);
117         ret = i2c_master_send(client, (char *)buf, 2);
118
119         return ret == 2 ? 0 : -EIO;
120 }
121
122 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
123 {
124         *ctrl = get_ctrl(client);
125         return 0;
126 }
127
128 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
129 {
130         unsigned char buf[2];
131
132         buf[0] = 0;
133         buf[1] = *ctrl;
134         set_ctrl(client, *ctrl);
135
136         return i2c_master_send(client, (char *)buf, 2);
137 }
138
139 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
140 {
141         unsigned char addr[1];
142         struct i2c_msg msgs[2] = {
143                 {
144                         .addr = client->addr,
145                         .flags = 0,
146                         .len = 1,
147                         .buf = addr,
148                 }, {
149                         .addr = client->addr,
150                         .flags = I2C_M_RD,
151                         .len = mem->nr,
152                         .buf = mem->data,
153                 }
154         };
155
156         if (mem->loc < 8)
157                 return -EINVAL;
158
159         addr[0] = mem->loc;
160
161         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
162 }
163
164 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
165 {
166         unsigned char buf[9];
167         int ret;
168
169         if (mem->loc < 8 || mem->nr > 8)
170                 return -EINVAL;
171
172         buf[0] = mem->loc;
173         memcpy(buf + 1, mem->data, mem->nr);
174
175         ret = i2c_master_send(client, buf, mem->nr + 1);
176         return ret == mem->nr + 1 ? 0 : -EIO;
177 }
178
179 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
180 {
181         struct i2c_client *client = to_i2c_client(dev);
182         unsigned char ctrl, year[2];
183         struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year };
184         int real_year, year_offset, err;
185
186         /*
187          * Ensure that the RTC is running.
188          */
189         pcf8583_get_ctrl(client, &ctrl);
190         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
191                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
192
193                 printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
194                        ctrl, new_ctrl);
195
196                 if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0)
197                         return err;
198         }
199
200         if (pcf8583_get_datetime(client, tm) ||
201             pcf8583_read_mem(client, &mem))
202                 return -EIO;
203
204         real_year = year[0];
205
206         /*
207          * The RTC year holds the LSB two bits of the current
208          * year, which should reflect the LSB two bits of the
209          * CMOS copy of the year.  Any difference indicates
210          * that we have to correct the CMOS version.
211          */
212         year_offset = tm->tm_year - (real_year & 3);
213         if (year_offset < 0)
214                 /*
215                  * RTC year wrapped.  Adjust it appropriately.
216                  */
217                 year_offset += 4;
218
219         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
220
221         return 0;
222 }
223
224 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
225 {
226         struct i2c_client *client = to_i2c_client(dev);
227         unsigned char year[2], chk;
228         struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
229         struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
230         unsigned int proper_year = tm->tm_year + 1900;
231         int ret;
232
233         /*
234          * The RTC's own 2-bit year must reflect the least
235          * significant two bits of the CMOS year.
236          */
237
238         ret = pcf8583_set_datetime(client, tm, 1);
239         if (ret)
240                 return ret;
241
242         ret = pcf8583_read_mem(client, &cmos_check);
243         if (ret)
244                 return ret;
245
246         ret = pcf8583_read_mem(client, &cmos_year);
247         if (ret)
248                 return ret;
249
250         chk -= year[1] + year[0];
251
252         year[1] = proper_year / 100;
253         year[0] = proper_year % 100;
254
255         chk += year[1] + year[0];
256
257         ret = pcf8583_write_mem(client, &cmos_year);
258
259         if (ret)
260                 return ret;
261
262         ret = pcf8583_write_mem(client, &cmos_check);
263
264         return ret;
265 }
266
267 static const struct rtc_class_ops pcf8583_rtc_ops = {
268         .read_time      = pcf8583_rtc_read_time,
269         .set_time       = pcf8583_rtc_set_time,
270 };
271
272 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind);
273
274 static int pcf8583_attach(struct i2c_adapter *adap)
275 {
276         return i2c_probe(adap, &addr_data, pcf8583_probe);
277 }
278
279 static int pcf8583_detach(struct i2c_client *client)
280 {
281         int err;
282         struct pcf8583 *pcf = i2c_get_clientdata(client);
283         struct rtc_device *rtc = pcf->rtc;
284
285         if (rtc)
286                 rtc_device_unregister(rtc);
287
288         if ((err = i2c_detach_client(client)))
289                 return err;
290
291         kfree(pcf);
292         return 0;
293 }
294
295 static struct i2c_driver pcf8583_driver = {
296         .driver = {
297                 .name   = "pcf8583",
298         },
299         .id             = I2C_DRIVERID_PCF8583,
300         .attach_adapter = pcf8583_attach,
301         .detach_client  = pcf8583_detach,
302 };
303
304 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind)
305 {
306         struct pcf8583 *pcf;
307         struct i2c_client *client;
308         struct rtc_device *rtc;
309         unsigned char buf[1], ad[1] = { 0 };
310         int err;
311         struct i2c_msg msgs[2] = {
312                 {
313                         .addr = addr,
314                         .flags = 0,
315                         .len = 1,
316                         .buf = ad,
317                 }, {
318                         .addr = addr,
319                         .flags = I2C_M_RD,
320                         .len = 1,
321                         .buf = buf,
322                 }
323         };
324
325         if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
326                 return 0;
327
328         pcf = kzalloc(sizeof(*pcf), GFP_KERNEL);
329         if (!pcf)
330                 return -ENOMEM;
331
332         client = &pcf->client;
333
334         client->addr            = addr;
335         client->adapter = adap;
336         client->driver  = &pcf8583_driver;
337
338         strlcpy(client->name, pcf8583_driver.driver.name, I2C_NAME_SIZE);
339
340         if (i2c_transfer(client->adapter, msgs, 2) != 2) {
341                 err = -EIO;
342                 goto exit_kfree;
343         }
344
345         err = i2c_attach_client(client);
346
347         if (err)
348                 goto exit_kfree;
349
350         rtc = rtc_device_register(pcf8583_driver.driver.name, &client->dev,
351                                   &pcf8583_rtc_ops, THIS_MODULE);
352
353         if (IS_ERR(rtc)) {
354                 err = PTR_ERR(rtc);
355                 goto exit_detach;
356         }
357
358         pcf->rtc = rtc;
359         i2c_set_clientdata(client, pcf);
360         set_ctrl(client, buf[0]);
361
362         return 0;
363
364 exit_detach:
365         i2c_detach_client(client);
366
367 exit_kfree:
368         kfree(pcf);
369
370         return err;
371 }
372
373 static __init int pcf8583_init(void)
374 {
375         return i2c_add_driver(&pcf8583_driver);
376 }
377
378 static __exit void pcf8583_exit(void)
379 {
380         i2c_del_driver(&pcf8583_driver);
381 }
382
383 module_init(pcf8583_init);
384 module_exit(pcf8583_exit);
385
386 MODULE_AUTHOR("Russell King");
387 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
388 MODULE_LICENSE("GPL");