pcf8563.c revision 6038f373a3dc1f1c26496e60b6c40b164716f07e 
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#include <linux/smp_lock.h>
31
32#include <asm/uaccess.h>
33#include <asm/system.h>
34#include <asm/io.h>
35#include <asm/rtc.h>
36
37#include "i2c.h"
38
39#define PCF8563_MAJOR 121	/* Local major number. */
40#define DEVICE_NAME "rtc"	/* Name which is registered in /proc/devices. */
41#define PCF8563_NAME "PCF8563"
42#define DRIVER_VERSION "$Revision: 1.24 $"
43
44/* I2C bus slave registers. */
45#define RTC_I2C_READ		0xa3
46#define RTC_I2C_WRITE		0xa2
47
48/* Two simple wrapper macros, saves a few keystrokes. */
49#define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
50#define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
51
52static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
53
54static const unsigned char days_in_month[] =
55	{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
56
57static long pcf8563_unlocked_ioctl(struct file *, unsigned int, unsigned long);
58
59/* Cache VL bit value read at driver init since writing the RTC_SECOND
60 * register clears the VL status.
61 */
62static int voltage_low;
63
64static const struct file_operations pcf8563_fops = {
65	.owner = THIS_MODULE,
66	.unlocked_ioctl = pcf8563_unlocked_ioctl,
67	.llseek		= noop_llseek,
68};
69
70unsigned char
71pcf8563_readreg(int reg)
72{
73	unsigned char res = rtc_read(reg);
74
75	/* The PCF8563 does not return 0 for unimplemented bits. */
76	switch (reg) {
77	case RTC_SECONDS:
78	case RTC_MINUTES:
79		res &= 0x7F;
80		break;
81	case RTC_HOURS:
82	case RTC_DAY_OF_MONTH:
83		res &= 0x3F;
84		break;
85	case RTC_WEEKDAY:
86		res &= 0x07;
87		break;
88	case RTC_MONTH:
89		res &= 0x1F;
90		break;
91	case RTC_CONTROL1:
92		res &= 0xA8;
93		break;
94	case RTC_CONTROL2:
95		res &= 0x1F;
96		break;
97	case RTC_CLOCKOUT_FREQ:
98	case RTC_TIMER_CONTROL:
99		res &= 0x83;
100		break;
101	}
102	return res;
103}
104
105void
106pcf8563_writereg(int reg, unsigned char val)
107{
108	rtc_write(reg, val);
109}
110
111void
112get_rtc_time(struct rtc_time *tm)
113{
114	tm->tm_sec  = rtc_read(RTC_SECONDS);
115	tm->tm_min  = rtc_read(RTC_MINUTES);
116	tm->tm_hour = rtc_read(RTC_HOURS);
117	tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
118	tm->tm_wday = rtc_read(RTC_WEEKDAY);
119	tm->tm_mon  = rtc_read(RTC_MONTH);
120	tm->tm_year = rtc_read(RTC_YEAR);
121
122	if (tm->tm_sec & 0x80) {
123		printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
124		       "information is no longer guaranteed!\n", PCF8563_NAME);
125	}
126
127	tm->tm_year  = bcd2bin(tm->tm_year) +
128		       ((tm->tm_mon & 0x80) ? 100 : 0);
129	tm->tm_sec  &= 0x7F;
130	tm->tm_min  &= 0x7F;
131	tm->tm_hour &= 0x3F;
132	tm->tm_mday &= 0x3F;
133	tm->tm_wday &= 0x07; /* Not coded in BCD. */
134	tm->tm_mon  &= 0x1F;
135
136	tm->tm_sec = bcd2bin(tm->tm_sec);
137	tm->tm_min = bcd2bin(tm->tm_min);
138	tm->tm_hour = bcd2bin(tm->tm_hour);
139	tm->tm_mday = bcd2bin(tm->tm_mday);
140	tm->tm_mon = bcd2bin(tm->tm_mon);
141	tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
142}
143
144int __init
145pcf8563_init(void)
146{
147	static int res;
148	static int first = 1;
149
150	if (!first)
151		return res;
152	first = 0;
153
154	/* Initiate the i2c protocol. */
155	res = i2c_init();
156	if (res < 0) {
157		printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
158		return res;
159	}
160
161	/*
162	 * First of all we need to reset the chip. This is done by
163	 * clearing control1, control2 and clk freq and resetting
164	 * all alarms.
165	 */
166	if (rtc_write(RTC_CONTROL1, 0x00) < 0)
167		goto err;
168
169	if (rtc_write(RTC_CONTROL2, 0x00) < 0)
170		goto err;
171
172	if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
173		goto err;
174
175	if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
176		goto err;
177
178	/* Reset the alarms. */
179	if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
180		goto err;
181
182	if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
183		goto err;
184
185	if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
186		goto err;
187
188	if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
189		goto err;
190
191	/* Check for low voltage, and warn about it. */
192	if (rtc_read(RTC_SECONDS) & 0x80) {
193		voltage_low = 1;
194		printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
195		       "date/time information is no longer guaranteed!\n",
196		       PCF8563_NAME);
197	}
198
199	return res;
200
201err:
202	printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
203	res = -1;
204	return res;
205}
206
207void __exit
208pcf8563_exit(void)
209{
210	unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
211}
212
213/*
214 * ioctl calls for this driver. Why return -ENOTTY upon error? Because
215 * POSIX says so!
216 */
217static int pcf8563_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
218{
219	/* Some sanity checks. */
220	if (_IOC_TYPE(cmd) != RTC_MAGIC)
221		return -ENOTTY;
222
223	if (_IOC_NR(cmd) > RTC_MAX_IOCTL)
224		return -ENOTTY;
225
226	switch (cmd) {
227	case RTC_RD_TIME:
228	{
229		struct rtc_time tm;
230
231		mutex_lock(&rtc_lock);
232		memset(&tm, 0, sizeof tm);
233		get_rtc_time(&tm);
234
235		if (copy_to_user((struct rtc_time *) arg, &tm,
236				 sizeof tm)) {
237			mutex_unlock(&rtc_lock);
238			return -EFAULT;
239		}
240
241		mutex_unlock(&rtc_lock);
242
243		return 0;
244	}
245	case RTC_SET_TIME:
246	{
247		int leap;
248		int year;
249		int century;
250		struct rtc_time tm;
251
252		memset(&tm, 0, sizeof tm);
253		if (!capable(CAP_SYS_TIME))
254			return -EPERM;
255
256		if (copy_from_user(&tm, (struct rtc_time *) arg, sizeof tm))
257			return -EFAULT;
258
259		/* Convert from struct tm to struct rtc_time. */
260		tm.tm_year += 1900;
261		tm.tm_mon += 1;
262
263		/*
264		 * Check if tm.tm_year is a leap year. A year is a leap
265		 * year if it is divisible by 4 but not 100, except
266		 * that years divisible by 400 _are_ leap years.
267		 */
268		year = tm.tm_year;
269		leap = (tm.tm_mon == 2) &&
270			((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
271
272		/* Perform some sanity checks. */
273		if ((tm.tm_year < 1970) ||
274		    (tm.tm_mon > 12) ||
275		    (tm.tm_mday == 0) ||
276		    (tm.tm_mday > days_in_month[tm.tm_mon] + leap) ||
277		    (tm.tm_wday >= 7) ||
278		    (tm.tm_hour >= 24) ||
279		    (tm.tm_min >= 60) ||
280		    (tm.tm_sec >= 60))
281			return -EINVAL;
282
283		century = (tm.tm_year >= 2000) ? 0x80 : 0;
284		tm.tm_year = tm.tm_year % 100;
285
286		tm.tm_year = bin2bcd(tm.tm_year);
287		tm.tm_mon = bin2bcd(tm.tm_mon);
288		tm.tm_mday = bin2bcd(tm.tm_mday);
289		tm.tm_hour = bin2bcd(tm.tm_hour);
290		tm.tm_min = bin2bcd(tm.tm_min);
291		tm.tm_sec = bin2bcd(tm.tm_sec);
292		tm.tm_mon |= century;
293
294		mutex_lock(&rtc_lock);
295
296		rtc_write(RTC_YEAR, tm.tm_year);
297		rtc_write(RTC_MONTH, tm.tm_mon);
298		rtc_write(RTC_WEEKDAY, tm.tm_wday); /* Not coded in BCD. */
299		rtc_write(RTC_DAY_OF_MONTH, tm.tm_mday);
300		rtc_write(RTC_HOURS, tm.tm_hour);
301		rtc_write(RTC_MINUTES, tm.tm_min);
302		rtc_write(RTC_SECONDS, tm.tm_sec);
303
304		mutex_unlock(&rtc_lock);
305
306		return 0;
307	}
308	case RTC_VL_READ:
309		if (voltage_low) {
310			printk(KERN_ERR "%s: RTC Voltage Low - "
311			       "reliable date/time information is no "
312			       "longer guaranteed!\n", PCF8563_NAME);
313		}
314
315		if (copy_to_user((int *) arg, &voltage_low, sizeof(int)))
316			return -EFAULT;
317		return 0;
318
319	case RTC_VL_CLR:
320	{
321		/* Clear the VL bit in the seconds register in case
322		 * the time has not been set already (which would
323		 * have cleared it). This does not really matter
324		 * because of the cached voltage_low value but do it
325		 * anyway for consistency. */
326
327		int ret = rtc_read(RTC_SECONDS);
328
329		rtc_write(RTC_SECONDS, (ret & 0x7F));
330
331		/* Clear the cached value. */
332		voltage_low = 0;
333
334		return 0;
335	}
336	default:
337		return -ENOTTY;
338	}
339
340	return 0;
341}
342
343static long pcf8563_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
344{
345	int ret;
346
347	lock_kernel();
348	return pcf8563_ioctl(filp, cmd, arg);
349	unlock_kernel();
350
351	return ret;
352}
353
354static int __init pcf8563_register(void)
355{
356	if (pcf8563_init() < 0) {
357		printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
358		       "Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
359		return -1;
360	}
361
362	if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
363		printk(KERN_INFO "%s: Unable to get major number %d for RTC device.\n",
364		       PCF8563_NAME, PCF8563_MAJOR);
365		return -1;
366	}
367
368	printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
369	       DRIVER_VERSION);
370
371	/* Check for low voltage, and warn about it. */
372	if (voltage_low) {
373		printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
374		       "information is no longer guaranteed!\n", PCF8563_NAME);
375	}
376
377	return 0;
378}
379
380module_init(pcf8563_register);
381module_exit(pcf8563_exit);
382