pcf8563.c revision 4110a0d6206bd175419cc5503f80cc296d184cbf 
1/*
2 * PCF8563 RTC
3 *
4 * From Phillips' datasheet:
5 *
6 * The PCF8563 is a CMOS real-time clock/calendar optimized for low power
7 * consumption. A programmable clock output, interrupt output and voltage
8 * low detector are also provided. All address and data are transferred
9 * serially via two-line bidirectional I2C-bus. Maximum bus speed is
10 * 400 kbits/s. The built-in word address register is incremented
11 * automatically after each written or read byte.
12 *
13 * Copyright (c) 2002-2007, Axis Communications AB
14 * All rights reserved.
15 *
16 * Author: Tobias Anderberg <tobiasa@axis.com>.
17 *
18 */
19
20#include <linux/module.h>
21#include <linux/kernel.h>
22#include <linux/types.h>
23#include <linux/sched.h>
24#include <linux/init.h>
25#include <linux/fs.h>
26#include <linux/ioctl.h>
27#include <linux/delay.h>
28#include <linux/bcd.h>
29#include <linux/mutex.h>
30
31#include <asm/uaccess.h>
32#include <asm/system.h>
33#include <asm/io.h>
34#include <asm/rtc.h>
35
36#include "i2c.h"
37
38#define PCF8563_MAJOR 121	/* Local major number. */
39#define DEVICE_NAME "rtc"	/* Name which is registered in /proc/devices. */
40#define PCF8563_NAME "PCF8563"
41#define DRIVER_VERSION "$Revision: 1.24 $"
42
43/* I2C bus slave registers. */
44#define RTC_I2C_READ		0xa3
45#define RTC_I2C_WRITE		0xa2
46
47/* Two simple wrapper macros, saves a few keystrokes. */
48#define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
49#define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
50
51static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
52
53static const unsigned char days_in_month[] =
54	{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
55
56int pcf8563_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
57
58/* Cache VL bit value read at driver init since writing the RTC_SECOND
59 * register clears the VL status.
60 */
61static int voltage_low;
62
63static const struct file_operations pcf8563_fops = {
64	.owner = THIS_MODULE,
65	.ioctl = pcf8563_ioctl,
66};
67
68unsigned char
69pcf8563_readreg(int reg)
70{
71	unsigned char res = rtc_read(reg);
72
73	/* The PCF8563 does not return 0 for unimplemented bits. */
74	switch (reg) {
75	case RTC_SECONDS:
76	case RTC_MINUTES:
77		res &= 0x7F;
78		break;
79	case RTC_HOURS:
80	case RTC_DAY_OF_MONTH:
81		res &= 0x3F;
82		break;
83	case RTC_WEEKDAY:
84		res &= 0x07;
85		break;
86	case RTC_MONTH:
87		res &= 0x1F;
88		break;
89	case RTC_CONTROL1:
90		res &= 0xA8;
91		break;
92	case RTC_CONTROL2:
93		res &= 0x1F;
94		break;
95	case RTC_CLOCKOUT_FREQ:
96	case RTC_TIMER_CONTROL:
97		res &= 0x83;
98		break;
99	}
100	return res;
101}
102
103void
104pcf8563_writereg(int reg, unsigned char val)
105{
106	rtc_write(reg, val);
107}
108
109void
110get_rtc_time(struct rtc_time *tm)
111{
112	tm->tm_sec  = rtc_read(RTC_SECONDS);
113	tm->tm_min  = rtc_read(RTC_MINUTES);
114	tm->tm_hour = rtc_read(RTC_HOURS);
115	tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
116	tm->tm_wday = rtc_read(RTC_WEEKDAY);
117	tm->tm_mon  = rtc_read(RTC_MONTH);
118	tm->tm_year = rtc_read(RTC_YEAR);
119
120	if (tm->tm_sec & 0x80) {
121		printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
122		       "information is no longer guaranteed!\n", PCF8563_NAME);
123	}
124
125	tm->tm_year  = bcd2bin(tm->tm_year) +
126		       ((tm->tm_mon & 0x80) ? 100 : 0);
127	tm->tm_sec  &= 0x7F;
128	tm->tm_min  &= 0x7F;
129	tm->tm_hour &= 0x3F;
130	tm->tm_mday &= 0x3F;
131	tm->tm_wday &= 0x07; /* Not coded in BCD. */
132	tm->tm_mon  &= 0x1F;
133
134	tm->tm_sec = bcd2bin(tm->tm_sec);
135	tm->tm_min = bcd2bin(tm->tm_min);
136	tm->tm_hour = bcd2bin(tm->tm_hour);
137	tm->tm_mday = bcd2bin(tm->tm_mday);
138	tm->tm_mon = bcd2bin(tm->tm_mon);
139	tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
140}
141
142int __init
143pcf8563_init(void)
144{
145	static int res;
146	static int first = 1;
147
148	if (!first)
149		return res;
150	first = 0;
151
152	/* Initiate the i2c protocol. */
153	res = i2c_init();
154	if (res < 0) {
155		printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
156		return res;
157	}
158
159	/*
160	 * First of all we need to reset the chip. This is done by
161	 * clearing control1, control2 and clk freq and resetting
162	 * all alarms.
163	 */
164	if (rtc_write(RTC_CONTROL1, 0x00) < 0)
165		goto err;
166
167	if (rtc_write(RTC_CONTROL2, 0x00) < 0)
168		goto err;
169
170	if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
171		goto err;
172
173	if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
174		goto err;
175
176	/* Reset the alarms. */
177	if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
178		goto err;
179
180	if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
181		goto err;
182
183	if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
184		goto err;
185
186	if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
187		goto err;
188
189	/* Check for low voltage, and warn about it. */
190	if (rtc_read(RTC_SECONDS) & 0x80) {
191		voltage_low = 1;
192		printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
193		       "date/time information is no longer guaranteed!\n",
194		       PCF8563_NAME);
195	}
196
197	return res;
198
199err:
200	printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
201	res = -1;
202	return res;
203}
204
205void __exit
206pcf8563_exit(void)
207{
208	unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
209}
210
211/*
212 * ioctl calls for this driver. Why return -ENOTTY upon error? Because
213 * POSIX says so!
214 */
215int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
216	unsigned long arg)
217{
218	/* Some sanity checks. */
219	if (_IOC_TYPE(cmd) != RTC_MAGIC)
220		return -ENOTTY;
221
222	if (_IOC_NR(cmd) > RTC_MAX_IOCTL)
223		return -ENOTTY;
224
225	switch (cmd) {
226	case RTC_RD_TIME:
227	{
228		struct rtc_time tm;
229
230		mutex_lock(&rtc_lock);
231		memset(&tm, 0, sizeof tm);
232		get_rtc_time(&tm);
233
234		if (copy_to_user((struct rtc_time *) arg, &tm,
235				 sizeof tm)) {
236			mutex_unlock(&rtc_lock);
237			return -EFAULT;
238		}
239
240		mutex_unlock(&rtc_lock);
241
242		return 0;
243	}
244	case RTC_SET_TIME:
245	{
246		int leap;
247		int year;
248		int century;
249		struct rtc_time tm;
250
251		memset(&tm, 0, sizeof tm);
252		if (!capable(CAP_SYS_TIME))
253			return -EPERM;
254
255		if (copy_from_user(&tm, (struct rtc_time *) arg, sizeof tm))
256			return -EFAULT;
257
258		/* Convert from struct tm to struct rtc_time. */
259		tm.tm_year += 1900;
260		tm.tm_mon += 1;
261
262		/*
263		 * Check if tm.tm_year is a leap year. A year is a leap
264		 * year if it is divisible by 4 but not 100, except
265		 * that years divisible by 400 _are_ leap years.
266		 */
267		year = tm.tm_year;
268		leap = (tm.tm_mon == 2) &&
269			((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
270
271		/* Perform some sanity checks. */
272		if ((tm.tm_year < 1970) ||
273		    (tm.tm_mon > 12) ||
274		    (tm.tm_mday == 0) ||
275		    (tm.tm_mday > days_in_month[tm.tm_mon] + leap) ||
276		    (tm.tm_wday >= 7) ||
277		    (tm.tm_hour >= 24) ||
278		    (tm.tm_min >= 60) ||
279		    (tm.tm_sec >= 60))
280			return -EINVAL;
281
282		century = (tm.tm_year >= 2000) ? 0x80 : 0;
283		tm.tm_year = tm.tm_year % 100;
284
285		tm.tm_year = bin2bcd(tm.tm_year);
286		tm.tm_mon = bin2bcd(tm.tm_mon);
287		tm.tm_mday = bin2bcd(tm.tm_mday);
288		tm.tm_hour = bin2bcd(tm.tm_hour);
289		tm.tm_min = bin2bcd(tm.tm_min);
290		tm.tm_sec = bin2bcd(tm.tm_sec);
291		tm.tm_mon |= century;
292
293		mutex_lock(&rtc_lock);
294
295		rtc_write(RTC_YEAR, tm.tm_year);
296		rtc_write(RTC_MONTH, tm.tm_mon);
297		rtc_write(RTC_WEEKDAY, tm.tm_wday); /* Not coded in BCD. */
298		rtc_write(RTC_DAY_OF_MONTH, tm.tm_mday);
299		rtc_write(RTC_HOURS, tm.tm_hour);
300		rtc_write(RTC_MINUTES, tm.tm_min);
301		rtc_write(RTC_SECONDS, tm.tm_sec);
302
303		mutex_unlock(&rtc_lock);
304
305		return 0;
306	}
307	case RTC_VL_READ:
308		if (voltage_low) {
309			printk(KERN_ERR "%s: RTC Voltage Low - "
310			       "reliable date/time information is no "
311			       "longer guaranteed!\n", PCF8563_NAME);
312		}
313
314		if (copy_to_user((int *) arg, &voltage_low, sizeof(int)))
315			return -EFAULT;
316		return 0;
317
318	case RTC_VL_CLR:
319	{
320		/* Clear the VL bit in the seconds register in case
321		 * the time has not been set already (which would
322		 * have cleared it). This does not really matter
323		 * because of the cached voltage_low value but do it
324		 * anyway for consistency. */
325
326		int ret = rtc_read(RTC_SECONDS);
327
328		rtc_write(RTC_SECONDS, (ret & 0x7F));
329
330		/* Clear the cached value. */
331		voltage_low = 0;
332
333		return 0;
334	}
335	default:
336		return -ENOTTY;
337	}
338
339	return 0;
340}
341
342static int __init pcf8563_register(void)
343{
344	if (pcf8563_init() < 0) {
345		printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
346		       "Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
347		return -1;
348	}
349
350	if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
351		printk(KERN_INFO "%s: Unable to get major number %d for RTC device.\n",
352		       PCF8563_NAME, PCF8563_MAJOR);
353		return -1;
354	}
355
356	printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
357	       DRIVER_VERSION);
358
359	/* Check for low voltage, and warn about it. */
360	if (voltage_low) {
361		printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
362		       "information is no longer guaranteed!\n", PCF8563_NAME);
363	}
364
365	return 0;
366}
367
368module_init(pcf8563_register);
369module_exit(pcf8563_exit);
370