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
51 static DEFINE_MUTEX(pcf8563_mutex);
52 static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
53
54 static const unsigned char days_in_month[] =
55 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
56
57 static 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 */
62 static int voltage_low;
63
64 static const struct file_operations pcf8563_fops = {
65 .owner = THIS_MODULE,
66 .unlocked_ioctl = pcf8563_unlocked_ioctl,
67 .llseek = noop_llseek,
68 };
69
70 unsigned char
pcf8563_readreg(int reg)71 pcf8563_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
105 void
pcf8563_writereg(int reg,unsigned char val)106 pcf8563_writereg(int reg, unsigned char val)
107 {
108 rtc_write(reg, val);
109 }
110
111 void
get_rtc_time(struct rtc_time * tm)112 get_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
144 int __init
pcf8563_init(void)145 pcf8563_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
201 err:
202 printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
203 res = -1;
204 return res;
205 }
206
207 void __exit
pcf8563_exit(void)208 pcf8563_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 */
pcf8563_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)217 static 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
pcf8563_unlocked_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)343 static long pcf8563_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
344 {
345 int ret;
346
347 mutex_lock(&pcf8563_mutex);
348 ret = pcf8563_ioctl(filp, cmd, arg);
349 mutex_unlock(&pcf8563_mutex);
350
351 return ret;
352 }
353
pcf8563_register(void)354 static 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
380 module_init(pcf8563_register);
381 module_exit(pcf8563_exit);
382