2 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
4 * Real Time Clock interface for Linux
6 * TODO: Implement periodic interrupts.
8 * Copyright (C) 2000 Silicon Graphics, Inc.
9 * Written by Ulf Carlsson (ulfc@engr.sgi.com)
11 * Based on code written by Paul Gortmaker.
13 * This driver allows use of the real time clock (built into
14 * nearly all computers) from user space. It exports the /dev/rtc
15 * interface supporting various ioctl() and also the /proc/rtc
16 * pseudo-file for status information.
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
25 #define RTC_VERSION "1.09b"
27 #include <linux/bcd.h>
28 #include <linux/module.h>
29 #include <linux/kernel.h>
30 #include <linux/types.h>
31 #include <linux/miscdevice.h>
32 #include <linux/ioport.h>
33 #include <linux/fcntl.h>
34 #include <linux/rtc.h>
35 #include <linux/init.h>
36 #include <linux/poll.h>
37 #include <linux/proc_fs.h>
38 #include <linux/smp_lock.h>
40 #include <asm/m48t35.h>
41 #include <asm/sn/ioc3.h>
43 #include <asm/uaccess.h>
44 #include <asm/system.h>
45 #include <asm/sn/klconfig.h>
46 #include <asm/sn/sn0/ip27.h>
47 #include <asm/sn/sn0/hub.h>
48 #include <asm/sn/sn_private.h>
50 static int rtc_ioctl(struct inode
*inode
, struct file
*file
,
51 unsigned int cmd
, unsigned long arg
);
53 static int rtc_read_proc(char *page
, char **start
, off_t off
,
54 int count
, int *eof
, void *data
);
56 static void get_rtc_time(struct rtc_time
*rtc_tm
);
59 * Bits in rtc_status. (6 bits of room for future expansion)
62 #define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
63 #define RTC_TIMER_ON 0x02 /* missed irq timer active */
65 static unsigned char rtc_status
; /* bitmapped status byte. */
66 static unsigned long rtc_freq
; /* Current periodic IRQ rate */
67 static struct m48t35_rtc
*rtc
;
70 * If this driver ever becomes modularised, it will be really nice
71 * to make the epoch retain its value across module reload...
74 static unsigned long epoch
= 1970; /* year corresponding to 0x00 */
76 static const unsigned char days_in_mo
[] =
77 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
79 static int rtc_ioctl(struct inode
*inode
, struct file
*file
, unsigned int cmd
,
83 struct rtc_time wtime
;
86 case RTC_RD_TIME
: /* Read the time/date from RTC */
91 case RTC_SET_TIME
: /* Set the RTC */
93 struct rtc_time rtc_tm
;
94 unsigned char mon
, day
, hrs
, min
, sec
, leap_yr
;
97 if (!capable(CAP_SYS_TIME
))
100 if (copy_from_user(&rtc_tm
, (struct rtc_time
*)arg
,
101 sizeof(struct rtc_time
)))
104 yrs
= rtc_tm
.tm_year
+ 1900;
105 mon
= rtc_tm
.tm_mon
+ 1; /* tm_mon starts at zero */
106 day
= rtc_tm
.tm_mday
;
107 hrs
= rtc_tm
.tm_hour
;
114 leap_yr
= ((!(yrs
% 4) && (yrs
% 100)) || !(yrs
% 400));
116 if ((mon
> 12) || (day
== 0))
119 if (day
> (days_in_mo
[mon
] + ((mon
== 2) && leap_yr
)))
122 if ((hrs
>= 24) || (min
>= 60) || (sec
>= 60))
125 if ((yrs
-= epoch
) > 255) /* They are unsigned */
141 spin_lock_irq(&rtc_lock
);
142 rtc
->control
|= M48T35_RTC_SET
;
149 rtc
->control
&= ~M48T35_RTC_SET
;
150 spin_unlock_irq(&rtc_lock
);
157 return copy_to_user((void *)arg
, &wtime
, sizeof wtime
) ? -EFAULT
: 0;
161 * We enforce only one user at a time here with the open/close.
162 * Also clear the previous interrupt data on an open, and clean
163 * up things on a close.
166 static int rtc_open(struct inode
*inode
, struct file
*file
)
168 spin_lock_irq(&rtc_lock
);
170 if (rtc_status
& RTC_IS_OPEN
) {
171 spin_unlock_irq(&rtc_lock
);
175 rtc_status
|= RTC_IS_OPEN
;
176 spin_unlock_irq(&rtc_lock
);
181 static int rtc_release(struct inode
*inode
, struct file
*file
)
184 * Turn off all interrupts once the device is no longer
185 * in use, and clear the data.
188 spin_lock_irq(&rtc_lock
);
189 rtc_status
&= ~RTC_IS_OPEN
;
190 spin_unlock_irq(&rtc_lock
);
196 * The various file operations we support.
199 static const struct file_operations rtc_fops
= {
200 .owner
= THIS_MODULE
,
203 .release
= rtc_release
,
206 static struct miscdevice rtc_dev
=
213 static int __init
rtc_init(void)
215 rtc
= (struct m48t35_rtc
*)
216 (KL_CONFIG_CH_CONS_INFO(master_nasid
)->memory_base
+ IOC3_BYTEBUS_DEV0
);
218 printk(KERN_INFO
"Real Time Clock Driver v%s\n", RTC_VERSION
);
219 if (misc_register(&rtc_dev
)) {
220 printk(KERN_ERR
"rtc: cannot register misc device.\n");
223 if (!create_proc_read_entry("driver/rtc", 0, NULL
, rtc_read_proc
, NULL
)) {
224 printk(KERN_ERR
"rtc: cannot create /proc/rtc.\n");
225 misc_deregister(&rtc_dev
);
234 static void __exit
rtc_exit (void)
236 /* interrupts and timer disabled at this point by rtc_release */
238 remove_proc_entry ("rtc", NULL
);
239 misc_deregister(&rtc_dev
);
242 module_init(rtc_init
);
243 module_exit(rtc_exit
);
246 * Info exported via "/proc/rtc".
249 static int rtc_get_status(char *buf
)
255 * Just emulate the standard /proc/rtc
263 * There is no way to tell if the luser has the RTC set for local
264 * time or for Universal Standard Time (GMT). Probably local though.
267 "rtc_time\t: %02d:%02d:%02d\n"
268 "rtc_date\t: %04d-%02d-%02d\n"
269 "rtc_epoch\t: %04lu\n"
271 tm
.tm_hour
, tm
.tm_min
, tm
.tm_sec
,
272 tm
.tm_year
+ 1900, tm
.tm_mon
+ 1, tm
.tm_mday
, epoch
);
277 static int rtc_read_proc(char *page
, char **start
, off_t off
,
278 int count
, int *eof
, void *data
)
280 int len
= rtc_get_status(page
);
281 if (len
<= off
+count
) *eof
= 1;
284 if (len
>count
) len
= count
;
289 static void get_rtc_time(struct rtc_time
*rtc_tm
)
292 * Do we need to wait for the last update to finish?
296 * Only the values that we read from the RTC are set. We leave
297 * tm_wday, tm_yday and tm_isdst untouched. Even though the
298 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
299 * by the RTC when initially set to a non-zero value.
301 spin_lock_irq(&rtc_lock
);
302 rtc
->control
|= M48T35_RTC_READ
;
303 rtc_tm
->tm_sec
= rtc
->sec
;
304 rtc_tm
->tm_min
= rtc
->min
;
305 rtc_tm
->tm_hour
= rtc
->hour
;
306 rtc_tm
->tm_mday
= rtc
->date
;
307 rtc_tm
->tm_mon
= rtc
->month
;
308 rtc_tm
->tm_year
= rtc
->year
;
309 rtc
->control
&= ~M48T35_RTC_READ
;
310 spin_unlock_irq(&rtc_lock
);
312 rtc_tm
->tm_sec
= BCD2BIN(rtc_tm
->tm_sec
);
313 rtc_tm
->tm_min
= BCD2BIN(rtc_tm
->tm_min
);
314 rtc_tm
->tm_hour
= BCD2BIN(rtc_tm
->tm_hour
);
315 rtc_tm
->tm_mday
= BCD2BIN(rtc_tm
->tm_mday
);
316 rtc_tm
->tm_mon
= BCD2BIN(rtc_tm
->tm_mon
);
317 rtc_tm
->tm_year
= BCD2BIN(rtc_tm
->tm_year
);
320 * Account for differences between how the RTC uses the values
321 * and how they are defined in a struct rtc_time;
323 if ((rtc_tm
->tm_year
+= (epoch
- 1900)) <= 69)
324 rtc_tm
->tm_year
+= 100;
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