drivers/char/ip27-rtc.c

   1 /*
   2  *      Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
   3  *
   4  *      Real Time Clock interface for Linux
   5  *
   6  *      TODO: Implement periodic interrupts.
   7  *
   8  *      Copyright (C) 2000 Silicon Graphics, Inc.
   9  *      Written by Ulf Carlsson (ulfc@engr.sgi.com)
  10  *
  11  *      Based on code written by Paul Gortmaker.
  12  *
  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.
  17  *
  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.
  22  *
  23  */
  24
  25 #define RTC_VERSION             "1.09b"
  26
  27 #include <linux/bcd.h>
  28 #include <linux/module.h>
  29 #include <linux/kernel.h>
  30 #include <linux/smp_lock.h>
  31 #include <linux/types.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/ioport.h>
  34 #include <linux/fcntl.h>
  35 #include <linux/rtc.h>
  36 #include <linux/init.h>
  37 #include <linux/poll.h>
  38 #include <linux/proc_fs.h>
  39
  40 #include <asm/m48t35.h>
  41 #include <asm/sn/ioc3.h>
  42 #include <asm/io.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>
  49
  50 static long rtc_ioctl(struct file *filp, unsigned int cmd,
  51                         unsigned long arg);
  52
  53 static int rtc_read_proc(char *page, char **start, off_t off,
  54                          int count, int *eof, void *data);
  55
  56 static void get_rtc_time(struct rtc_time *rtc_tm);
  57
  58 /*
  59  *      Bits in rtc_status. (6 bits of room for future expansion)
  60  */
  61
  62 #define RTC_IS_OPEN             0x01    /* means /dev/rtc is in use     */
  63 #define RTC_TIMER_ON            0x02    /* missed irq timer active      */
  64
  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;
  68
  69 /*
  70  *      If this driver ever becomes modularised, it will be really nice
  71  *      to make the epoch retain its value across module reload...
  72  */
  73
  74 static unsigned long epoch = 1970;      /* year corresponding to 0x00   */
  75
  76 static const unsigned char days_in_mo[] =
  77 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  78
  79 static long rtc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  80 {
  81
  82         struct rtc_time wtime;
  83
  84         switch (cmd) {
  85         case RTC_RD_TIME:       /* Read the time/date from RTC  */
  86         {
  87                 get_rtc_time(&wtime);
  88                 break;
  89         }
  90         case RTC_SET_TIME:      /* Set the RTC */
  91         {
  92                 struct rtc_time rtc_tm;
  93                 unsigned char mon, day, hrs, min, sec, leap_yr;
  94                 unsigned int yrs;
  95
  96                 if (!capable(CAP_SYS_TIME))
  97                         return -EACCES;
  98
  99                 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
 100                                    sizeof(struct rtc_time)))
 101                         return -EFAULT;
 102
 103                 yrs = rtc_tm.tm_year + 1900;
 104                 mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 105                 day = rtc_tm.tm_mday;
 106                 hrs = rtc_tm.tm_hour;
 107                 min = rtc_tm.tm_min;
 108                 sec = rtc_tm.tm_sec;
 109
 110                 if (yrs < 1970)
 111                         return -EINVAL;
 112
 113                 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 114
 115                 if ((mon > 12) || (day == 0))
 116                         return -EINVAL;
 117
 118                 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 119                         return -EINVAL;
 120
 121                 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 122                         return -EINVAL;
 123
 124                 if ((yrs -= epoch) > 255)    /* They are unsigned */
 125                         return -EINVAL;
 126
 127                 if (yrs > 169)
 128                         return -EINVAL;
 129
 130                 if (yrs >= 100)
 131                         yrs -= 100;
 132
 133                 sec = BIN2BCD(sec);
 134                 min = BIN2BCD(min);
 135                 hrs = BIN2BCD(hrs);
 136                 day = BIN2BCD(day);
 137                 mon = BIN2BCD(mon);
 138                 yrs = BIN2BCD(yrs);
 139
 140                 spin_lock_irq(&rtc_lock);
 141                 rtc->control |= M48T35_RTC_SET;
 142                 rtc->year = yrs;
 143                 rtc->month = mon;
 144                 rtc->date = day;
 145                 rtc->hour = hrs;
 146                 rtc->min = min;
 147                 rtc->sec = sec;
 148                 rtc->control &= ~M48T35_RTC_SET;
 149                 spin_unlock_irq(&rtc_lock);
 150
 151                 return 0;
 152         }
 153         default:
 154                 return -EINVAL;
 155         }
 156         return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
 157 }
 158
 159 /*
 160  *      We enforce only one user at a time here with the open/close.
 161  *      Also clear the previous interrupt data on an open, and clean
 162  *      up things on a close.
 163  */
 164
 165 static int rtc_open(struct inode *inode, struct file *file)
 166 {
 167         lock_kernel();
 168         spin_lock_irq(&rtc_lock);
 169
 170         if (rtc_status & RTC_IS_OPEN) {
 171                 spin_unlock_irq(&rtc_lock);
 172                 unlock_kernel();
 173                 return -EBUSY;
 174         }
 175
 176         rtc_status |= RTC_IS_OPEN;
 177         spin_unlock_irq(&rtc_lock);
 178         unlock_kernel();
 179
 180         return 0;
 181 }
 182
 183 static int rtc_release(struct inode *inode, struct file *file)
 184 {
 185         /*
 186          * Turn off all interrupts once the device is no longer
 187          * in use, and clear the data.
 188          */
 189
 190         spin_lock_irq(&rtc_lock);
 191         rtc_status &= ~RTC_IS_OPEN;
 192         spin_unlock_irq(&rtc_lock);
 193
 194         return 0;
 195 }
 196
 197 /*
 198  *      The various file operations we support.
 199  */
 200
 201 static const struct file_operations rtc_fops = {
 202         .owner          = THIS_MODULE,
 203         .unlocked_ioctl = rtc_ioctl,
 204         .open           = rtc_open,
 205         .release        = rtc_release,
 206 };
 207
 208 static struct miscdevice rtc_dev=
 209 {
 210         RTC_MINOR,
 211         "rtc",
 212         &rtc_fops
 213 };
 214
 215 static int __init rtc_init(void)
 216 {
 217         rtc = (struct m48t35_rtc *)
 218         (KL_CONFIG_CH_CONS_INFO(master_nasid)->memory_base + IOC3_BYTEBUS_DEV0);
 219
 220         printk(KERN_INFO "Real Time Clock Driver v%s\n", RTC_VERSION);
 221         if (misc_register(&rtc_dev)) {
 222                 printk(KERN_ERR "rtc: cannot register misc device.\n");
 223                 return -ENODEV;
 224         }
 225         if (!create_proc_read_entry("driver/rtc", 0, NULL, rtc_read_proc, NULL)) {
 226                 printk(KERN_ERR "rtc: cannot create /proc/rtc.\n");
 227                 misc_deregister(&rtc_dev);
 228                 return -ENOENT;
 229         }
 230
 231         rtc_freq = 1024;
 232
 233         return 0;
 234 }
 235
 236 static void __exit rtc_exit (void)
 237 {
 238         /* interrupts and timer disabled at this point by rtc_release */
 239
 240         remove_proc_entry ("rtc", NULL);
 241         misc_deregister(&rtc_dev);
 242 }
 243
 244 module_init(rtc_init);
 245 module_exit(rtc_exit);
 246
 247 /*
 248  *      Info exported via "/proc/rtc".
 249  */
 250
 251 static int rtc_get_status(char *buf)
 252 {
 253         char *p;
 254         struct rtc_time tm;
 255
 256         /*
 257          * Just emulate the standard /proc/rtc
 258          */
 259
 260         p = buf;
 261
 262         get_rtc_time(&tm);
 263
 264         /*
 265          * There is no way to tell if the luser has the RTC set for local
 266          * time or for Universal Standard Time (GMT). Probably local though.
 267          */
 268         p += sprintf(p,
 269                      "rtc_time\t: %02d:%02d:%02d\n"
 270                      "rtc_date\t: %04d-%02d-%02d\n"
 271                      "rtc_epoch\t: %04lu\n"
 272                      "24hr\t\t: yes\n",
 273                      tm.tm_hour, tm.tm_min, tm.tm_sec,
 274                      tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
 275
 276         return  p - buf;
 277 }
 278
 279 static int rtc_read_proc(char *page, char **start, off_t off,
 280                                  int count, int *eof, void *data)
 281 {
 282         int len = rtc_get_status(page);
 283         if (len <= off+count) *eof = 1;
 284         *start = page + off;
 285         len -= off;
 286         if (len>count) len = count;
 287         if (len<0) len = 0;
 288         return len;
 289 }
 290
 291 static void get_rtc_time(struct rtc_time *rtc_tm)
 292 {
 293         /*
 294          * Do we need to wait for the last update to finish?
 295          */
 296
 297         /*
 298          * Only the values that we read from the RTC are set. We leave
 299          * tm_wday, tm_yday and tm_isdst untouched. Even though the
 300          * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
 301          * by the RTC when initially set to a non-zero value.
 302          */
 303         spin_lock_irq(&rtc_lock);
 304         rtc->control |= M48T35_RTC_READ;
 305         rtc_tm->tm_sec = rtc->sec;
 306         rtc_tm->tm_min = rtc->min;
 307         rtc_tm->tm_hour = rtc->hour;
 308         rtc_tm->tm_mday = rtc->date;
 309         rtc_tm->tm_mon = rtc->month;
 310         rtc_tm->tm_year = rtc->year;
 311         rtc->control &= ~M48T35_RTC_READ;
 312         spin_unlock_irq(&rtc_lock);
 313
 314         rtc_tm->tm_sec = BCD2BIN(rtc_tm->tm_sec);
 315         rtc_tm->tm_min = BCD2BIN(rtc_tm->tm_min);
 316         rtc_tm->tm_hour = BCD2BIN(rtc_tm->tm_hour);
 317         rtc_tm->tm_mday = BCD2BIN(rtc_tm->tm_mday);
 318         rtc_tm->tm_mon = BCD2BIN(rtc_tm->tm_mon);
 319         rtc_tm->tm_year = BCD2BIN(rtc_tm->tm_year);
 320
 321         /*
 322          * Account for differences between how the RTC uses the values
 323          * and how they are defined in a struct rtc_time;
 324          */
 325         if ((rtc_tm->tm_year += (epoch - 1900)) <= 69)
 326                 rtc_tm->tm_year += 100;
 327
 328         rtc_tm->tm_mon--;
 329 }