2 * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
4 * Copyright (C) 2005 James Chapman (ds1337 core)
5 * Copyright (C) 2006 David Brownell
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.
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/slab.h>
15 #include <linux/i2c.h>
16 #include <linux/string.h>
17 #include <linux/rtc.h>
18 #include <linux/bcd.h>
22 /* We can't determine type by probing, but if we expect pre-Linux code
23 * to have set the chip up as a clock (turning on the oscillator and
24 * setting the date and time), Linux can ignore the non-clock features.
25 * That's a natural job for a factory or repair bench.
27 * This is currently a simple no-alarms driver. If your board has the
28 * alarm irq wired up on a ds1337 or ds1339, and you want to use that,
29 * then look at the rtc-rs5c372 driver for code to steal...
38 // rs5c372 too? different address...
42 /* RTC registers don't differ much, except for the century flag */
43 #define DS1307_REG_SECS 0x00 /* 00-59 */
44 # define DS1307_BIT_CH 0x80
45 # define DS1340_BIT_nEOSC 0x80
46 #define DS1307_REG_MIN 0x01 /* 00-59 */
47 #define DS1307_REG_HOUR 0x02 /* 00-23, or 1-12{am,pm} */
48 # define DS1307_BIT_12HR 0x40 /* in REG_HOUR */
49 # define DS1307_BIT_PM 0x20 /* in REG_HOUR */
50 # define DS1340_BIT_CENTURY_EN 0x80 /* in REG_HOUR */
51 # define DS1340_BIT_CENTURY 0x40 /* in REG_HOUR */
52 #define DS1307_REG_WDAY 0x03 /* 01-07 */
53 #define DS1307_REG_MDAY 0x04 /* 01-31 */
54 #define DS1307_REG_MONTH 0x05 /* 01-12 */
55 # define DS1337_BIT_CENTURY 0x80 /* in REG_MONTH */
56 #define DS1307_REG_YEAR 0x06 /* 00-99 */
58 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
59 * start at 7, and they differ a LOT. Only control and status matter for
60 * basic RTC date and time functionality; be careful using them.
62 #define DS1307_REG_CONTROL 0x07 /* or ds1338 */
63 # define DS1307_BIT_OUT 0x80
64 # define DS1338_BIT_OSF 0x20
65 # define DS1307_BIT_SQWE 0x10
66 # define DS1307_BIT_RS1 0x02
67 # define DS1307_BIT_RS0 0x01
68 #define DS1337_REG_CONTROL 0x0e
69 # define DS1337_BIT_nEOSC 0x80
70 # define DS1337_BIT_RS2 0x10
71 # define DS1337_BIT_RS1 0x08
72 # define DS1337_BIT_INTCN 0x04
73 # define DS1337_BIT_A2IE 0x02
74 # define DS1337_BIT_A1IE 0x01
75 #define DS1340_REG_CONTROL 0x07
76 # define DS1340_BIT_OUT 0x80
77 # define DS1340_BIT_FT 0x40
78 # define DS1340_BIT_CALIB_SIGN 0x20
79 # define DS1340_M_CALIBRATION 0x1f
80 #define DS1340_REG_FLAG 0x09
81 # define DS1340_BIT_OSF 0x80
82 #define DS1337_REG_STATUS 0x0f
83 # define DS1337_BIT_OSF 0x80
84 # define DS1337_BIT_A2I 0x02
85 # define DS1337_BIT_A1I 0x01
86 #define DS1339_REG_TRICKLE 0x10
94 struct i2c_msg msg
[2];
95 struct i2c_client
*client
;
96 struct i2c_client dev
;
97 struct rtc_device
*rtc
;
107 static const struct chip_desc chips
[] = { {
131 static inline const struct chip_desc
*find_chip(const char *s
)
135 for (i
= 0; i
< ARRAY_SIZE(chips
); i
++)
136 if (strnicmp(s
, chips
[i
].name
, sizeof chips
[i
].name
) == 0)
141 static int ds1307_get_time(struct device
*dev
, struct rtc_time
*t
)
143 struct ds1307
*ds1307
= dev_get_drvdata(dev
);
146 /* read the RTC date and time registers all at once */
147 ds1307
->msg
[1].flags
= I2C_M_RD
;
148 ds1307
->msg
[1].len
= 7;
150 tmp
= i2c_transfer(to_i2c_adapter(ds1307
->client
->dev
.parent
),
153 dev_err(dev
, "%s error %d\n", "read", tmp
);
157 dev_dbg(dev
, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
159 ds1307
->regs
[0], ds1307
->regs
[1],
160 ds1307
->regs
[2], ds1307
->regs
[3],
161 ds1307
->regs
[4], ds1307
->regs
[5],
164 t
->tm_sec
= BCD2BIN(ds1307
->regs
[DS1307_REG_SECS
] & 0x7f);
165 t
->tm_min
= BCD2BIN(ds1307
->regs
[DS1307_REG_MIN
] & 0x7f);
166 tmp
= ds1307
->regs
[DS1307_REG_HOUR
] & 0x3f;
167 t
->tm_hour
= BCD2BIN(tmp
);
168 t
->tm_wday
= BCD2BIN(ds1307
->regs
[DS1307_REG_WDAY
] & 0x07) - 1;
169 t
->tm_mday
= BCD2BIN(ds1307
->regs
[DS1307_REG_MDAY
] & 0x3f);
170 tmp
= ds1307
->regs
[DS1307_REG_MONTH
] & 0x1f;
171 t
->tm_mon
= BCD2BIN(tmp
) - 1;
173 /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
174 t
->tm_year
= BCD2BIN(ds1307
->regs
[DS1307_REG_YEAR
]) + 100;
176 dev_dbg(dev
, "%s secs=%d, mins=%d, "
177 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
178 "read", t
->tm_sec
, t
->tm_min
,
179 t
->tm_hour
, t
->tm_mday
,
180 t
->tm_mon
, t
->tm_year
, t
->tm_wday
);
182 /* initial clock setting can be undefined */
183 return rtc_valid_tm(t
);
186 static int ds1307_set_time(struct device
*dev
, struct rtc_time
*t
)
188 struct ds1307
*ds1307
= dev_get_drvdata(dev
);
191 u8
*buf
= ds1307
->regs
;
193 dev_dbg(dev
, "%s secs=%d, mins=%d, "
194 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
195 "write", t
->tm_sec
, t
->tm_min
,
196 t
->tm_hour
, t
->tm_mday
,
197 t
->tm_mon
, t
->tm_year
, t
->tm_wday
);
199 *buf
++ = 0; /* first register addr */
200 buf
[DS1307_REG_SECS
] = BIN2BCD(t
->tm_sec
);
201 buf
[DS1307_REG_MIN
] = BIN2BCD(t
->tm_min
);
202 buf
[DS1307_REG_HOUR
] = BIN2BCD(t
->tm_hour
);
203 buf
[DS1307_REG_WDAY
] = BIN2BCD(t
->tm_wday
+ 1);
204 buf
[DS1307_REG_MDAY
] = BIN2BCD(t
->tm_mday
);
205 buf
[DS1307_REG_MONTH
] = BIN2BCD(t
->tm_mon
+ 1);
207 /* assume 20YY not 19YY */
208 tmp
= t
->tm_year
- 100;
209 buf
[DS1307_REG_YEAR
] = BIN2BCD(tmp
);
211 switch (ds1307
->type
) {
214 buf
[DS1307_REG_MONTH
] |= DS1337_BIT_CENTURY
;
217 buf
[DS1307_REG_HOUR
] |= DS1340_BIT_CENTURY_EN
218 | DS1340_BIT_CENTURY
;
224 ds1307
->msg
[1].flags
= 0;
225 ds1307
->msg
[1].len
= 8;
227 dev_dbg(dev
, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
228 "write", buf
[0], buf
[1], buf
[2], buf
[3],
229 buf
[4], buf
[5], buf
[6]);
231 result
= i2c_transfer(to_i2c_adapter(ds1307
->client
->dev
.parent
),
234 dev_err(dev
, "%s error %d\n", "write", tmp
);
240 static const struct rtc_class_ops ds13xx_rtc_ops
= {
241 .read_time
= ds1307_get_time
,
242 .set_time
= ds1307_set_time
,
245 static struct i2c_driver ds1307_driver
;
247 static int __devinit
ds1307_probe(struct i2c_client
*client
)
249 struct ds1307
*ds1307
;
252 const struct chip_desc
*chip
;
253 struct i2c_adapter
*adapter
= to_i2c_adapter(client
->dev
.parent
);
255 chip
= find_chip(client
->name
);
257 dev_err(&client
->dev
, "unknown chip type '%s'\n",
262 if (!i2c_check_functionality(adapter
,
263 I2C_FUNC_I2C
| I2C_FUNC_SMBUS_WRITE_BYTE_DATA
))
266 if (!(ds1307
= kzalloc(sizeof(struct ds1307
), GFP_KERNEL
)))
269 ds1307
->client
= client
;
270 i2c_set_clientdata(client
, ds1307
);
272 ds1307
->msg
[0].addr
= client
->addr
;
273 ds1307
->msg
[0].flags
= 0;
274 ds1307
->msg
[0].len
= 1;
275 ds1307
->msg
[0].buf
= &ds1307
->reg_addr
;
277 ds1307
->msg
[1].addr
= client
->addr
;
278 ds1307
->msg
[1].flags
= I2C_M_RD
;
279 ds1307
->msg
[1].len
= sizeof(ds1307
->regs
);
280 ds1307
->msg
[1].buf
= ds1307
->regs
;
282 ds1307
->type
= chip
->type
;
284 switch (ds1307
->type
) {
287 ds1307
->reg_addr
= DS1337_REG_CONTROL
;
288 ds1307
->msg
[1].len
= 2;
290 /* get registers that the "rtc" read below won't read... */
291 tmp
= i2c_transfer(adapter
, ds1307
->msg
, 2);
293 pr_debug("read error %d\n", tmp
);
298 ds1307
->reg_addr
= 0;
299 ds1307
->msg
[1].len
= sizeof(ds1307
->regs
);
301 /* oscillator off? turn it on, so clock can tick. */
302 if (ds1307
->regs
[0] & DS1337_BIT_nEOSC
)
303 i2c_smbus_write_byte_data(client
, DS1337_REG_CONTROL
,
304 ds1307
->regs
[0] & ~DS1337_BIT_nEOSC
);
306 /* oscillator fault? clear flag, and warn */
307 if (ds1307
->regs
[1] & DS1337_BIT_OSF
) {
308 i2c_smbus_write_byte_data(client
, DS1337_REG_STATUS
,
309 ds1307
->regs
[1] & ~DS1337_BIT_OSF
);
310 dev_warn(&client
->dev
, "SET TIME!\n");
318 /* read RTC registers */
320 tmp
= i2c_transfer(adapter
, ds1307
->msg
, 2);
322 pr_debug("read error %d\n", tmp
);
327 /* minimal sanity checking; some chips (like DS1340) don't
328 * specify the extra bits as must-be-zero, but there are
329 * still a few values that are clearly out-of-range.
331 tmp
= ds1307
->regs
[DS1307_REG_SECS
];
332 switch (ds1307
->type
) {
334 /* FIXME read register with DS1340_BIT_OSF, use that to
335 * trigger the "set time" warning (*after* restarting the
336 * oscillator!) instead of this weaker ds1307/m41t00 test.
340 /* clock halted? turn it on, so clock can tick. */
341 if (tmp
& DS1307_BIT_CH
) {
342 i2c_smbus_write_byte_data(client
, DS1307_REG_SECS
, 0);
343 dev_warn(&client
->dev
, "SET TIME!\n");
348 /* clock halted? turn it on, so clock can tick. */
349 if (tmp
& DS1307_BIT_CH
)
350 i2c_smbus_write_byte_data(client
, DS1307_REG_SECS
, 0);
352 /* oscillator fault? clear flag, and warn */
353 if (ds1307
->regs
[DS1307_REG_CONTROL
] & DS1338_BIT_OSF
) {
354 i2c_smbus_write_byte_data(client
, DS1307_REG_CONTROL
,
355 ds1307
->regs
[DS1337_REG_CONTROL
]
357 dev_warn(&client
->dev
, "SET TIME!\n");
366 tmp
= ds1307
->regs
[DS1307_REG_SECS
];
367 tmp
= BCD2BIN(tmp
& 0x7f);
370 tmp
= BCD2BIN(ds1307
->regs
[DS1307_REG_MIN
] & 0x7f);
374 tmp
= BCD2BIN(ds1307
->regs
[DS1307_REG_MDAY
] & 0x3f);
375 if (tmp
== 0 || tmp
> 31)
378 tmp
= BCD2BIN(ds1307
->regs
[DS1307_REG_MONTH
] & 0x1f);
379 if (tmp
== 0 || tmp
> 12)
382 tmp
= ds1307
->regs
[DS1307_REG_HOUR
];
383 switch (ds1307
->type
) {
386 /* NOTE: ignores century bits; fix before deploying
387 * systems that will run through year 2100.
391 if (!(tmp
& DS1307_BIT_12HR
))
394 /* Be sure we're in 24 hour mode. Multi-master systems
397 tmp
= BCD2BIN(tmp
& 0x1f);
400 if (ds1307
->regs
[DS1307_REG_HOUR
] & DS1307_BIT_PM
)
402 i2c_smbus_write_byte_data(client
,
407 ds1307
->rtc
= rtc_device_register(client
->name
, &client
->dev
,
408 &ds13xx_rtc_ops
, THIS_MODULE
);
409 if (IS_ERR(ds1307
->rtc
)) {
410 err
= PTR_ERR(ds1307
->rtc
);
411 dev_err(&client
->dev
,
412 "unable to register the class device\n");
419 dev_dbg(&client
->dev
, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
421 ds1307
->regs
[0], ds1307
->regs
[1],
422 ds1307
->regs
[2], ds1307
->regs
[3],
423 ds1307
->regs
[4], ds1307
->regs
[5],
431 static int __devexit
ds1307_remove(struct i2c_client
*client
)
433 struct ds1307
*ds1307
= i2c_get_clientdata(client
);
435 rtc_device_unregister(ds1307
->rtc
);
440 static struct i2c_driver ds1307_driver
= {
442 .name
= "rtc-ds1307",
443 .owner
= THIS_MODULE
,
445 .probe
= ds1307_probe
,
446 .remove
= __devexit_p(ds1307_remove
),
449 static int __init
ds1307_init(void)
451 return i2c_add_driver(&ds1307_driver
);
453 module_init(ds1307_init
);
455 static void __exit
ds1307_exit(void)
457 i2c_del_driver(&ds1307_driver
);
459 module_exit(ds1307_exit
);
461 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
462 MODULE_LICENSE("GPL");