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: 1.17 $"
42
43 /* Two simple wrapper macros, saves a few keystrokes. */
44 #define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
45 #define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
46
47 static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
48
49 static const unsigned char days_in_month[] =
50 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
51
52 int pcf8563_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
53
54 /* Cache VL bit value read at driver init since writing the RTC_SECOND
55 * register clears the VL status.
56 */
57 static int voltage_low;
58
59 static const struct file_operations pcf8563_fops = {
60 .owner = THIS_MODULE,
61 .ioctl = pcf8563_ioctl
62 };
63
64 unsigned char
pcf8563_readreg(int reg)65 pcf8563_readreg(int reg)
66 {
67 unsigned char res = rtc_read(reg);
68
69 /* The PCF8563 does not return 0 for unimplemented bits. */
70 switch (reg) {
71 case RTC_SECONDS:
72 case RTC_MINUTES:
73 res &= 0x7F;
74 break;
75 case RTC_HOURS:
76 case RTC_DAY_OF_MONTH:
77 res &= 0x3F;
78 break;
79 case RTC_WEEKDAY:
80 res &= 0x07;
81 break;
82 case RTC_MONTH:
83 res &= 0x1F;
84 break;
85 case RTC_CONTROL1:
86 res &= 0xA8;
87 break;
88 case RTC_CONTROL2:
89 res &= 0x1F;
90 break;
91 case RTC_CLOCKOUT_FREQ:
92 case RTC_TIMER_CONTROL:
93 res &= 0x83;
94 break;
95 }
96 return res;
97 }
98
99 void
pcf8563_writereg(int reg,unsigned char val)100 pcf8563_writereg(int reg, unsigned char val)
101 {
102 rtc_write(reg, val);
103 }
104
105 void
get_rtc_time(struct rtc_time * tm)106 get_rtc_time(struct rtc_time *tm)
107 {
108 tm->tm_sec = rtc_read(RTC_SECONDS);
109 tm->tm_min = rtc_read(RTC_MINUTES);
110 tm->tm_hour = rtc_read(RTC_HOURS);
111 tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
112 tm->tm_wday = rtc_read(RTC_WEEKDAY);
113 tm->tm_mon = rtc_read(RTC_MONTH);
114 tm->tm_year = rtc_read(RTC_YEAR);
115
116 if (tm->tm_sec & 0x80) {
117 printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
118 "information is no longer guaranteed!\n", PCF8563_NAME);
119 }
120
121 tm->tm_year = bcd2bin(tm->tm_year) +
122 ((tm->tm_mon & 0x80) ? 100 : 0);
123 tm->tm_sec &= 0x7F;
124 tm->tm_min &= 0x7F;
125 tm->tm_hour &= 0x3F;
126 tm->tm_mday &= 0x3F;
127 tm->tm_wday &= 0x07; /* Not coded in BCD. */
128 tm->tm_mon &= 0x1F;
129
130 tm->tm_sec = bcd2bin(tm->tm_sec);
131 tm->tm_min = bcd2bin(tm->tm_min);
132 tm->tm_hour = bcd2bin(tm->tm_hour);
133 tm->tm_mday = bcd2bin(tm->tm_mday);
134 tm->tm_mon = bcd2bin(tm->tm_mon);
135 tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
136 }
137
138 int __init
pcf8563_init(void)139 pcf8563_init(void)
140 {
141 static int res;
142 static int first = 1;
143
144 if (!first)
145 return res;
146 first = 0;
147
148 /* Initiate the i2c protocol. */
149 res = i2c_init();
150 if (res < 0) {
151 printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
152 return res;
153 }
154
155 /*
156 * First of all we need to reset the chip. This is done by
157 * clearing control1, control2 and clk freq and resetting
158 * all alarms.
159 */
160 if (rtc_write(RTC_CONTROL1, 0x00) < 0)
161 goto err;
162
163 if (rtc_write(RTC_CONTROL2, 0x00) < 0)
164 goto err;
165
166 if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
167 goto err;
168
169 if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
170 goto err;
171
172 /* Reset the alarms. */
173 if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
174 goto err;
175
176 if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
177 goto err;
178
179 if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
180 goto err;
181
182 if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
183 goto err;
184
185 /* Check for low voltage, and warn about it. */
186 if (rtc_read(RTC_SECONDS) & 0x80) {
187 voltage_low = 1;
188 printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
189 "date/time information is no longer guaranteed!\n",
190 PCF8563_NAME);
191 }
192
193 return res;
194
195 err:
196 printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
197 res = -1;
198 return res;
199 }
200
201 void __exit
pcf8563_exit(void)202 pcf8563_exit(void)
203 {
204 unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
205 }
206
207 /*
208 * ioctl calls for this driver. Why return -ENOTTY upon error? Because
209 * POSIX says so!
210 */
pcf8563_ioctl(struct inode * inode,struct file * filp,unsigned int cmd,unsigned long arg)211 int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
212 unsigned long arg)
213 {
214 /* Some sanity checks. */
215 if (_IOC_TYPE(cmd) != RTC_MAGIC)
216 return -ENOTTY;
217
218 if (_IOC_NR(cmd) > RTC_MAX_IOCTL)
219 return -ENOTTY;
220
221 switch (cmd) {
222 case RTC_RD_TIME:
223 {
224 struct rtc_time tm;
225
226 mutex_lock(&rtc_lock);
227 memset(&tm, 0, sizeof tm);
228 get_rtc_time(&tm);
229
230 if (copy_to_user((struct rtc_time *) arg, &tm,
231 sizeof tm)) {
232 mutex_unlock(&rtc_lock);
233 return -EFAULT;
234 }
235
236 mutex_unlock(&rtc_lock);
237
238 return 0;
239 }
240 case RTC_SET_TIME:
241 {
242 int leap;
243 int year;
244 int century;
245 struct rtc_time tm;
246
247 memset(&tm, 0, sizeof tm);
248 if (!capable(CAP_SYS_TIME))
249 return -EPERM;
250
251 if (copy_from_user(&tm, (struct rtc_time *) arg,
252 sizeof tm))
253 return -EFAULT;
254
255 /* Convert from struct tm to struct rtc_time. */
256 tm.tm_year += 1900;
257 tm.tm_mon += 1;
258
259 /*
260 * Check if tm.tm_year is a leap year. A year is a leap
261 * year if it is divisible by 4 but not 100, except
262 * that years divisible by 400 _are_ leap years.
263 */
264 year = tm.tm_year;
265 leap = (tm.tm_mon == 2) &&
266 ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
267
268 /* Perform some sanity checks. */
269 if ((tm.tm_year < 1970) ||
270 (tm.tm_mon > 12) ||
271 (tm.tm_mday == 0) ||
272 (tm.tm_mday > days_in_month[tm.tm_mon] + leap) ||
273 (tm.tm_wday >= 7) ||
274 (tm.tm_hour >= 24) ||
275 (tm.tm_min >= 60) ||
276 (tm.tm_sec >= 60))
277 return -EINVAL;
278
279 century = (tm.tm_year >= 2000) ? 0x80 : 0;
280 tm.tm_year = tm.tm_year % 100;
281
282 tm.tm_year = bin2bcd(tm.tm_year);
283 tm.tm_mon = bin2bcd(tm.tm_mon);
284 tm.tm_mday = bin2bcd(tm.tm_mday);
285 tm.tm_hour = bin2bcd(tm.tm_hour);
286 tm.tm_min = bin2bcd(tm.tm_min);
287 tm.tm_sec = bin2bcd(tm.tm_sec);
288 tm.tm_mon |= century;
289
290 mutex_lock(&rtc_lock);
291
292 rtc_write(RTC_YEAR, tm.tm_year);
293 rtc_write(RTC_MONTH, tm.tm_mon);
294 rtc_write(RTC_WEEKDAY, tm.tm_wday); /* Not coded in BCD. */
295 rtc_write(RTC_DAY_OF_MONTH, tm.tm_mday);
296 rtc_write(RTC_HOURS, tm.tm_hour);
297 rtc_write(RTC_MINUTES, tm.tm_min);
298 rtc_write(RTC_SECONDS, tm.tm_sec);
299
300 mutex_unlock(&rtc_lock);
301
302 return 0;
303 }
304 case RTC_VL_READ:
305 if (voltage_low)
306 printk(KERN_ERR "%s: RTC Voltage Low - "
307 "reliable date/time information is no "
308 "longer guaranteed!\n", PCF8563_NAME);
309
310 if (copy_to_user((int *) arg, &voltage_low, sizeof(int)))
311 return -EFAULT;
312 return 0;
313
314 case RTC_VL_CLR:
315 {
316 /* Clear the VL bit in the seconds register in case
317 * the time has not been set already (which would
318 * have cleared it). This does not really matter
319 * because of the cached voltage_low value but do it
320 * anyway for consistency. */
321
322 int ret = rtc_read(RTC_SECONDS);
323
324 rtc_write(RTC_SECONDS, (ret & 0x7F));
325
326 /* Clear the cached value. */
327 voltage_low = 0;
328
329 return 0;
330 }
331 default:
332 return -ENOTTY;
333 }
334
335 return 0;
336 }
337
pcf8563_register(void)338 static int __init pcf8563_register(void)
339 {
340 if (pcf8563_init() < 0) {
341 printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
342 "Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
343 return -1;
344 }
345
346 if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
347 printk(KERN_INFO "%s: Unable to get major numer %d for RTC "
348 "device.\n", PCF8563_NAME, PCF8563_MAJOR);
349 return -1;
350 }
351
352 printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
353 DRIVER_VERSION);
354
355 /* Check for low voltage, and warn about it. */
356 if (voltage_low) {
357 printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
358 "information is no longer guaranteed!\n", PCF8563_NAME);
359 }
360
361 return 0;
362 }
363
364 module_init(pcf8563_register);
365 module_exit(pcf8563_exit);
366