arch/ppc64/kernel/rtc.c

   1 /*
   2  *      Real Time Clock interface for PPC64.
   3  *
   4  *      Based on rtc.c by Paul Gortmaker
   5  *
   6  *      This driver allows use of the real time clock
   7  *      from user space. It exports the /dev/rtc
   8  *      interface supporting various ioctl() and also the
   9  *      /proc/driver/rtc pseudo-file for status information.
  10  *
  11  *      Interface does not support RTC interrupts nor an alarm.
  12  *
  13  *      This program is free software; you can redistribute it and/or
  14  *      modify it under the terms of the GNU General Public License
  15  *      as published by the Free Software Foundation; either version
  16  *      2 of the License, or (at your option) any later version.
  17  *
  18  *      1.0     Mike Corrigan:    IBM iSeries rtc support
  19  *      1.1     Dave Engebretsen: IBM pSeries rtc support
  20  */
  21
  22 #define RTC_VERSION             "1.1"
  23
  24 #include <linux/config.h>
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/types.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/ioport.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/mc146818rtc.h>
  32 #include <linux/init.h>
  33 #include <linux/poll.h>
  34 #include <linux/proc_fs.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/bcd.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/delay.h>
  39
  40 #include <asm/io.h>
  41 #include <asm/uaccess.h>
  42 #include <asm/system.h>
  43 #include <asm/time.h>
  44 #include <asm/rtas.h>
  45
  46 #include <asm/machdep.h>
  47
  48 /*
  49  *      We sponge a minor off of the misc major. No need slurping
  50  *      up another valuable major dev number for this. If you add
  51  *      an ioctl, make sure you don't conflict with SPARC's RTC
  52  *      ioctls.
  53  */
  54
  55 static ssize_t rtc_read(struct file *file, char __user *buf,
  56                         size_t count, loff_t *ppos);
  57
  58 static int rtc_ioctl(struct inode *inode, struct file *file,
  59                      unsigned int cmd, unsigned long arg);
  60
  61 static int rtc_read_proc(char *page, char **start, off_t off,
  62                          int count, int *eof, void *data);
  63
  64 /*
  65  *      If this driver ever becomes modularised, it will be really nice
  66  *      to make the epoch retain its value across module reload...
  67  */
  68
  69 static unsigned long epoch = 1900;      /* year corresponding to 0x00   */
  70
  71 static const unsigned char days_in_mo[] =
  72 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  73
  74 /*
  75  *      Now all the various file operations that we export.
  76  */
  77
  78 static ssize_t rtc_read(struct file *file, char __user *buf,
  79                         size_t count, loff_t *ppos)
  80 {
  81         return -EIO;
  82 }
  83
  84 static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
  85                      unsigned long arg)
  86 {
  87         struct rtc_time wtime;
  88
  89         switch (cmd) {
  90         case RTC_RD_TIME:       /* Read the time/date from RTC  */
  91         {
  92                 memset(&wtime, 0, sizeof(struct rtc_time));
  93                 ppc_md.get_rtc_time(&wtime);
  94                 break;
  95         }
  96         case RTC_SET_TIME:      /* Set the RTC */
  97         {
  98                 struct rtc_time rtc_tm;
  99                 unsigned char mon, day, hrs, min, sec, leap_yr;
 100                 unsigned int yrs;
 101
 102                 if (!capable(CAP_SYS_TIME))
 103                         return -EACCES;
 104
 105                 if (copy_from_user(&rtc_tm, (struct rtc_time __user *)arg,
 106                                    sizeof(struct rtc_time)))
 107                         return -EFAULT;
 108
 109                 yrs = rtc_tm.tm_year;
 110                 mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 111                 day = rtc_tm.tm_mday;
 112                 hrs = rtc_tm.tm_hour;
 113                 min = rtc_tm.tm_min;
 114                 sec = rtc_tm.tm_sec;
 115
 116                 if (yrs < 70)
 117                         return -EINVAL;
 118
 119                 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 120
 121                 if ((mon > 12) || (day == 0))
 122                         return -EINVAL;
 123
 124                 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 125                         return -EINVAL;
 126
 127                 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 128                         return -EINVAL;
 129
 130                 if ( yrs > 169 )
 131                         return -EINVAL;
 132
 133                 ppc_md.set_rtc_time(&rtc_tm);
 134
 135                 return 0;
 136         }
 137         case RTC_EPOCH_READ:    /* Read the epoch.      */
 138         {
 139                 return put_user (epoch, (unsigned long __user *)arg);
 140         }
 141         case RTC_EPOCH_SET:     /* Set the epoch.       */
 142         {
 143                 /*
 144                  * There were no RTC clocks before 1900.
 145                  */
 146                 if (arg < 1900)
 147                         return -EINVAL;
 148
 149                 if (!capable(CAP_SYS_TIME))
 150                         return -EACCES;
 151
 152                 epoch = arg;
 153                 return 0;
 154         }
 155         default:
 156                 return -EINVAL;
 157         }
 158         return copy_to_user((void __user *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
 159 }
 160
 161 static int rtc_open(struct inode *inode, struct file *file)
 162 {
 163         nonseekable_open(inode, file);
 164         return 0;
 165 }
 166
 167 static int rtc_release(struct inode *inode, struct file *file)
 168 {
 169         return 0;
 170 }
 171
 172 /*
 173  *      The various file operations we support.
 174  */
 175 static struct file_operations rtc_fops = {
 176         .owner =        THIS_MODULE,
 177         .llseek =       no_llseek,
 178         .read =         rtc_read,
 179         .ioctl =        rtc_ioctl,
 180         .open =         rtc_open,
 181         .release =      rtc_release,
 182 };
 183
 184 static struct miscdevice rtc_dev = {
 185         .minor =        RTC_MINOR,
 186         .name =         "rtc",
 187         .fops =         &rtc_fops
 188 };
 189
 190 static int __init rtc_init(void)
 191 {
 192         int retval;
 193
 194         retval = misc_register(&rtc_dev);
 195         if(retval < 0)
 196                 return retval;
 197
 198 #ifdef CONFIG_PROC_FS
 199         if (create_proc_read_entry("driver/rtc", 0, NULL, rtc_read_proc, NULL)
 200                         == NULL) {
 201                 misc_deregister(&rtc_dev);
 202                 return -ENOMEM;
 203         }
 204 #endif
 205
 206         printk(KERN_INFO "i/pSeries Real Time Clock Driver v" RTC_VERSION "\n");
 207
 208         return 0;
 209 }
 210
 211 static void __exit rtc_exit (void)
 212 {
 213         remove_proc_entry ("driver/rtc", NULL);
 214         misc_deregister(&rtc_dev);
 215 }
 216
 217 module_init(rtc_init);
 218 module_exit(rtc_exit);
 219
 220 /*
 221  *      Info exported via "/proc/driver/rtc".
 222  */
 223
 224 static int rtc_proc_output (char *buf)
 225 {
 226
 227         char *p;
 228         struct rtc_time tm;
 229
 230         p = buf;
 231
 232         ppc_md.get_rtc_time(&tm);
 233
 234         /*
 235          * There is no way to tell if the luser has the RTC set for local
 236          * time or for Universal Standard Time (GMT). Probably local though.
 237          */
 238         p += sprintf(p,
 239                      "rtc_time\t: %02d:%02d:%02d\n"
 240                      "rtc_date\t: %04d-%02d-%02d\n"
 241                      "rtc_epoch\t: %04lu\n",
 242                      tm.tm_hour, tm.tm_min, tm.tm_sec,
 243                      tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch);
 244
 245         p += sprintf(p,
 246                      "DST_enable\t: no\n"
 247                      "BCD\t\t: yes\n"
 248                      "24hr\t\t: yes\n" );
 249
 250         return  p - buf;
 251 }
 252
 253 static int rtc_read_proc(char *page, char **start, off_t off,
 254                          int count, int *eof, void *data)
 255 {
 256         int len = rtc_proc_output (page);
 257         if (len <= off+count) *eof = 1;
 258         *start = page + off;
 259         len -= off;
 260         if (len>count) len = count;
 261         if (len<0) len = 0;
 262         return len;
 263 }
 264
 265 #ifdef CONFIG_PPC_RTAS
 266 #define MAX_RTC_WAIT 5000       /* 5 sec */
 267 #define RTAS_CLOCK_BUSY (-2)
 268 unsigned long rtas_get_boot_time(void)
 269 {
 270         int ret[8];
 271         int error, wait_time;
 272         unsigned long max_wait_tb;
 273
 274         max_wait_tb = __get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 275         do {
 276                 error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
 277                 if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
 278                         wait_time = rtas_extended_busy_delay_time(error);
 279                         /* This is boot time so we spin. */
 280                         udelay(wait_time*1000);
 281                         error = RTAS_CLOCK_BUSY;
 282                 }
 283         } while (error == RTAS_CLOCK_BUSY && (__get_tb() < max_wait_tb));
 284
 285         if (error != 0 && printk_ratelimit()) {
 286                 printk(KERN_WARNING "error: reading the clock failed (%d)\n",
 287                         error);
 288                 return 0;
 289         }
 290
 291         return mktime(ret[0], ret[1], ret[2], ret[3], ret[4], ret[5]);
 292 }
 293
 294 /* NOTE: get_rtc_time will get an error if executed in interrupt context
 295  * and if a delay is needed to read the clock.  In this case we just
 296  * silently return without updating rtc_tm.
 297  */
 298 void rtas_get_rtc_time(struct rtc_time *rtc_tm)
 299 {
 300         int ret[8];
 301         int error, wait_time;
 302         unsigned long max_wait_tb;
 303
 304         max_wait_tb = __get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 305         do {
 306                 error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
 307                 if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
 308                         if (in_interrupt() && printk_ratelimit()) {
 309                                 printk(KERN_WARNING "error: reading clock would delay interrupt\n");
 310                                 return; /* delay not allowed */
 311                         }
 312                         wait_time = rtas_extended_busy_delay_time(error);
 313                         msleep_interruptible(wait_time);
 314                         error = RTAS_CLOCK_BUSY;
 315                 }
 316         } while (error == RTAS_CLOCK_BUSY && (__get_tb() < max_wait_tb));
 317
 318         if (error != 0 && printk_ratelimit()) {
 319                 printk(KERN_WARNING "error: reading the clock failed (%d)\n",
 320                        error);
 321                 return;
 322         }
 323
 324         rtc_tm->tm_sec = ret[5];
 325         rtc_tm->tm_min = ret[4];
 326         rtc_tm->tm_hour = ret[3];
 327         rtc_tm->tm_mday = ret[2];
 328         rtc_tm->tm_mon = ret[1] - 1;
 329         rtc_tm->tm_year = ret[0] - 1900;
 330 }
 331
 332 int rtas_set_rtc_time(struct rtc_time *tm)
 333 {
 334         int error, wait_time;
 335         unsigned long max_wait_tb;
 336
 337         max_wait_tb = __get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 338         do {
 339                 error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL,
 340                                   tm->tm_year + 1900, tm->tm_mon + 1,
 341                                   tm->tm_mday, tm->tm_hour, tm->tm_min,
 342                                   tm->tm_sec, 0);
 343                 if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
 344                         if (in_interrupt())
 345                                 return 1;       /* probably decrementer */
 346                         wait_time = rtas_extended_busy_delay_time(error);
 347                         msleep_interruptible(wait_time);
 348                         error = RTAS_CLOCK_BUSY;
 349                 }
 350         } while (error == RTAS_CLOCK_BUSY && (__get_tb() < max_wait_tb));
 351
 352         if (error != 0 && printk_ratelimit())
 353                 printk(KERN_WARNING "error: setting the clock failed (%d)\n",
 354                        error);
 355
 356         return 0;
 357 }
 358 #endif