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/io.h>
33 #include <asm/rtc.h>
34
35 #include "i2c.h"
36
37 #define PCF8563_MAJOR 121 /* Local major number. */
38 #define DEVICE_NAME "rtc" /* Name which is registered in /proc/devices. */
39 #define PCF8563_NAME "PCF8563"
40 #define DRIVER_VERSION "$Revision: 1.24 $"
41
42 /* I2C bus slave registers. */
43 #define RTC_I2C_READ 0xa3
44 #define RTC_I2C_WRITE 0xa2
45
46 /* Two simple wrapper macros, saves a few keystrokes. */
47 #define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
48 #define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
49
50 static DEFINE_MUTEX(pcf8563_mutex);
51 static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
52
53 static const unsigned char days_in_month[] =
54 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
55
56 static long pcf8563_unlocked_ioctl(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 */
61 static int voltage_low;
62
63 static const struct file_operations pcf8563_fops = {
64 .owner = THIS_MODULE,
65 .unlocked_ioctl = pcf8563_unlocked_ioctl,
66 .llseek = noop_llseek,
67 };
68
69 unsigned char
pcf8563_readreg(int reg)70 pcf8563_readreg(int reg)
71 {
72 unsigned char res = rtc_read(reg);
73
74 /* The PCF8563 does not return 0 for unimplemented bits. */
75 switch (reg) {
76 case RTC_SECONDS:
77 case RTC_MINUTES:
78 res &= 0x7F;
79 break;
80 case RTC_HOURS:
81 case RTC_DAY_OF_MONTH:
82 res &= 0x3F;
83 break;
84 case RTC_WEEKDAY:
85 res &= 0x07;
86 break;
87 case RTC_MONTH:
88 res &= 0x1F;
89 break;
90 case RTC_CONTROL1:
91 res &= 0xA8;
92 break;
93 case RTC_CONTROL2:
94 res &= 0x1F;
95 break;
96 case RTC_CLOCKOUT_FREQ:
97 case RTC_TIMER_CONTROL:
98 res &= 0x83;
99 break;
100 }
101 return res;
102 }
103
104 void
pcf8563_writereg(int reg,unsigned char val)105 pcf8563_writereg(int reg, unsigned char val)
106 {
107 rtc_write(reg, val);
108 }
109
110 void
get_rtc_time(struct rtc_time * tm)111 get_rtc_time(struct rtc_time *tm)
112 {
113 tm->tm_sec = rtc_read(RTC_SECONDS);
114 tm->tm_min = rtc_read(RTC_MINUTES);
115 tm->tm_hour = rtc_read(RTC_HOURS);
116 tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
117 tm->tm_wday = rtc_read(RTC_WEEKDAY);
118 tm->tm_mon = rtc_read(RTC_MONTH);
119 tm->tm_year = rtc_read(RTC_YEAR);
120
121 if (tm->tm_sec & 0x80) {
122 printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
123 "information is no longer guaranteed!\n", PCF8563_NAME);
124 }
125
126 tm->tm_year = bcd2bin(tm->tm_year) +
127 ((tm->tm_mon & 0x80) ? 100 : 0);
128 tm->tm_sec &= 0x7F;
129 tm->tm_min &= 0x7F;
130 tm->tm_hour &= 0x3F;
131 tm->tm_mday &= 0x3F;
132 tm->tm_wday &= 0x07; /* Not coded in BCD. */
133 tm->tm_mon &= 0x1F;
134
135 tm->tm_sec = bcd2bin(tm->tm_sec);
136 tm->tm_min = bcd2bin(tm->tm_min);
137 tm->tm_hour = bcd2bin(tm->tm_hour);
138 tm->tm_mday = bcd2bin(tm->tm_mday);
139 tm->tm_mon = bcd2bin(tm->tm_mon);
140 tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
141 }
142
143 int __init
pcf8563_init(void)144 pcf8563_init(void)
145 {
146 static int res;
147 static int first = 1;
148
149 if (!first)
150 return res;
151 first = 0;
152
153 /* Initiate the i2c protocol. */
154 res = i2c_init();
155 if (res < 0) {
156 printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
157 return res;
158 }
159
160 /*
161 * First of all we need to reset the chip. This is done by
162 * clearing control1, control2 and clk freq and resetting
163 * all alarms.
164 */
165 if (rtc_write(RTC_CONTROL1, 0x00) < 0)
166 goto err;
167
168 if (rtc_write(RTC_CONTROL2, 0x00) < 0)
169 goto err;
170
171 if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
172 goto err;
173
174 if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
175 goto err;
176
177 /* Reset the alarms. */
178 if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
179 goto err;
180
181 if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
182 goto err;
183
184 if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
185 goto err;
186
187 if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
188 goto err;
189
190 /* Check for low voltage, and warn about it. */
191 if (rtc_read(RTC_SECONDS) & 0x80) {
192 voltage_low = 1;
193 printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
194 "date/time information is no longer guaranteed!\n",
195 PCF8563_NAME);
196 }
197
198 return res;
199
200 err:
201 printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
202 res = -1;
203 return res;
204 }
205
206 void __exit
pcf8563_exit(void)207 pcf8563_exit(void)
208 {
209 unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
210 }
211
212 /*
213 * ioctl calls for this driver. Why return -ENOTTY upon error? Because
214 * POSIX says so!
215 */
pcf8563_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)216 static int pcf8563_ioctl(struct file *filp, unsigned int cmd, 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
pcf8563_unlocked_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)342 static long pcf8563_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
343 {
344 int ret;
345
346 mutex_lock(&pcf8563_mutex);
347 ret = pcf8563_ioctl(filp, cmd, arg);
348 mutex_unlock(&pcf8563_mutex);
349
350 return ret;
351 }
352
pcf8563_register(void)353 static int __init pcf8563_register(void)
354 {
355 if (pcf8563_init() < 0) {
356 printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
357 "Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
358 return -1;
359 }
360
361 if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
362 printk(KERN_INFO "%s: Unable to get major number %d for RTC device.\n",
363 PCF8563_NAME, PCF8563_MAJOR);
364 return -1;
365 }
366
367 printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
368 DRIVER_VERSION);
369
370 /* Check for low voltage, and warn about it. */
371 if (voltage_low) {
372 printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
373 "information is no longer guaranteed!\n", PCF8563_NAME);
374 }
375
376 return 0;
377 }
378
379 module_init(pcf8563_register);
380 module_exit(pcf8563_exit);
381