drivers/char/ds1302.c

   1 /*!***************************************************************************
   2 *!
   3 *! FILE NAME  : ds1302.c
   4 *!
   5 *! DESCRIPTION: Implements an interface for the DS1302 RTC
   6 *!
   7 *! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init, get_rtc_status
   8 *!
   9 *! ---------------------------------------------------------------------------
  10 *!
  11 *! (C) Copyright 1999, 2000, 2001  Axis Communications AB, LUND, SWEDEN
  12 *!
  13 *!***************************************************************************/
  14
  15
  16 #include <linux/fs.h>
  17 #include <linux/init.h>
  18 #include <linux/mm.h>
  19 #include <linux/module.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/delay.h>
  22 #include <linux/bcd.h>
  23 #include <linux/mutex.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/io.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/rtc.h>
  29 #if defined(CONFIG_M32R)
  30 #include <asm/m32r.h>
  31 #endif
  32
  33 #define RTC_MAJOR_NR 121 /* local major, change later */
  34
  35 static DEFINE_MUTEX(rtc_mutex);
  36 static const char ds1302_name[] = "ds1302";
  37
  38 /* Send 8 bits. */
  39 static void
  40 out_byte_rtc(unsigned int reg_addr, unsigned char x)
  41 {
  42         //RST H
  43         outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  44         //write data
  45         outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
  46         //WE
  47         outw(0x0002,(unsigned long)PLD_RTCCR);
  48         //wait
  49         while(inw((unsigned long)PLD_RTCCR));
  50
  51         //RST L
  52         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  53
  54 }
  55
  56 static unsigned char
  57 in_byte_rtc(unsigned int reg_addr)
  58 {
  59         unsigned char retval;
  60
  61         //RST H
  62         outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  63         //write data
  64         outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
  65         //RE
  66         outw(0x0001,(unsigned long)PLD_RTCCR);
  67         //wait
  68         while(inw((unsigned long)PLD_RTCCR));
  69
  70         //read data
  71         retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;
  72
  73         //RST L
  74         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  75
  76         return retval;
  77 }
  78
  79 /* Enable writing. */
  80
  81 static void
  82 ds1302_wenable(void)
  83 {
  84         out_byte_rtc(0x8e,0x00);
  85 }
  86
  87 /* Disable writing. */
  88
  89 static void
  90 ds1302_wdisable(void)
  91 {
  92         out_byte_rtc(0x8e,0x80);
  93 }
  94
  95
  96
  97 /* Read a byte from the selected register in the DS1302. */
  98
  99 unsigned char
 100 ds1302_readreg(int reg)
 101 {
 102         unsigned char x;
 103
 104         x=in_byte_rtc((0x81 | (reg << 1))); /* read register */
 105
 106         return x;
 107 }
 108
 109 /* Write a byte to the selected register. */
 110
 111 void
 112 ds1302_writereg(int reg, unsigned char val)
 113 {
 114         ds1302_wenable();
 115         out_byte_rtc((0x80 | (reg << 1)),val);
 116         ds1302_wdisable();
 117 }
 118
 119 void
 120 get_rtc_time(struct rtc_time *rtc_tm)
 121 {
 122         unsigned long flags;
 123
 124         local_irq_save(flags);
 125
 126         rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 127         rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 128         rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 129         rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 130         rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 131         rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
 132
 133         local_irq_restore(flags);
 134
 135         rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 136         rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 137         rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 138         rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 139         rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 140         rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 141
 142         /*
 143          * Account for differences between how the RTC uses the values
 144          * and how they are defined in a struct rtc_time;
 145          */
 146
 147         if (rtc_tm->tm_year <= 69)
 148                 rtc_tm->tm_year += 100;
 149
 150         rtc_tm->tm_mon--;
 151 }
 152
 153 static unsigned char days_in_mo[] =
 154     {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 155
 156 /* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
 157
 158 static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 159 {
 160         unsigned long flags;
 161
 162         switch(cmd) {
 163                 case RTC_RD_TIME:       /* read the time/date from RTC  */
 164                 {
 165                         struct rtc_time rtc_tm;
 166
 167                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
 168                         mutex_lock(&rtc_mutex);
 169                         get_rtc_time(&rtc_tm);
 170                         mutex_unlock(&rtc_mutex);
 171                         if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 172                                 return -EFAULT;
 173                         return 0;
 174                 }
 175
 176                 case RTC_SET_TIME:      /* set the RTC */
 177                 {
 178                         struct rtc_time rtc_tm;
 179                         unsigned char mon, day, hrs, min, sec, leap_yr;
 180                         unsigned int yrs;
 181
 182                         if (!capable(CAP_SYS_TIME))
 183                                 return -EPERM;
 184
 185                         if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 186                                 return -EFAULT;
 187
 188                         yrs = rtc_tm.tm_year + 1900;
 189                         mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 190                         day = rtc_tm.tm_mday;
 191                         hrs = rtc_tm.tm_hour;
 192                         min = rtc_tm.tm_min;
 193                         sec = rtc_tm.tm_sec;
 194
 195
 196                         if ((yrs < 1970) || (yrs > 2069))
 197                                 return -EINVAL;
 198
 199                         leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 200
 201                         if ((mon > 12) || (day == 0))
 202                                 return -EINVAL;
 203
 204                         if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 205                                 return -EINVAL;
 206
 207                         if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 208                                 return -EINVAL;
 209
 210                         if (yrs >= 2000)
 211                                 yrs -= 2000;    /* RTC (0, 1, ... 69) */
 212                         else
 213                                 yrs -= 1900;    /* RTC (70, 71, ... 99) */
 214
 215                         sec = bin2bcd(sec);
 216                         min = bin2bcd(min);
 217                         hrs = bin2bcd(hrs);
 218                         day = bin2bcd(day);
 219                         mon = bin2bcd(mon);
 220                         yrs = bin2bcd(yrs);
 221
 222                         mutex_lock(&rtc_mutex);
 223                         local_irq_save(flags);
 224                         CMOS_WRITE(yrs, RTC_YEAR);
 225                         CMOS_WRITE(mon, RTC_MONTH);
 226                         CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 227                         CMOS_WRITE(hrs, RTC_HOURS);
 228                         CMOS_WRITE(min, RTC_MINUTES);
 229                         CMOS_WRITE(sec, RTC_SECONDS);
 230                         local_irq_restore(flags);
 231                         mutex_unlock(&rtc_mutex);
 232
 233                         /* Notice that at this point, the RTC is updated but
 234                          * the kernel is still running with the old time.
 235                          * You need to set that separately with settimeofday
 236                          * or adjtimex.
 237                          */
 238                         return 0;
 239                 }
 240
 241                 case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 242                 {
 243                         int tcs_val;
 244
 245                         if (!capable(CAP_SYS_TIME))
 246                                 return -EPERM;
 247
 248                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 249                                 return -EFAULT;
 250
 251                         mutex_lock(&rtc_mutex);
 252                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 253                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 254                         mutex_unlock(&rtc_mutex);
 255                         return 0;
 256                 }
 257                 default:
 258                         return -EINVAL;
 259         }
 260 }
 261
 262 int
 263 get_rtc_status(char *buf)
 264 {
 265         char *p;
 266         struct rtc_time tm;
 267
 268         p = buf;
 269
 270         get_rtc_time(&tm);
 271
 272         /*
 273          * There is no way to tell if the luser has the RTC set for local
 274          * time or for Universal Standard Time (GMT). Probably local though.
 275          */
 276
 277         p += sprintf(p,
 278                 "rtc_time\t: %02d:%02d:%02d\n"
 279                 "rtc_date\t: %04d-%02d-%02d\n",
 280                 tm.tm_hour, tm.tm_min, tm.tm_sec,
 281                 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 282
 283         return  p - buf;
 284 }
 285
 286
 287 /* The various file operations we support. */
 288
 289 static const struct file_operations rtc_fops = {
 290         .owner          = THIS_MODULE,
 291         .unlocked_ioctl = rtc_ioctl,
 292 };
 293
 294 /* Probe for the chip by writing something to its RAM and try reading it back. */
 295
 296 #define MAGIC_PATTERN 0x42
 297
 298 static int __init
 299 ds1302_probe(void)
 300 {
 301         int retval, res, baur;
 302
 303         baur=(boot_cpu_data.bus_clock/(2*1000*1000));
 304
 305         printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);
 306
 307         outw(0x0000,(unsigned long)PLD_RTCCR);
 308         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
 309         outw(baur,(unsigned long)PLD_RTCBAUR);
 310
 311         /* Try to talk to timekeeper. */
 312
 313         ds1302_wenable();
 314         /* write RAM byte 0 */
 315         /* write something magic */
 316         out_byte_rtc(0xc0,MAGIC_PATTERN);
 317
 318         /* read RAM byte 0 */
 319         if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
 320                 char buf[100];
 321                 ds1302_wdisable();
 322                 printk("%s: RTC found.\n", ds1302_name);
 323                 get_rtc_status(buf);
 324                 printk(buf);
 325                 retval = 1;
 326         } else {
 327                 printk("%s: RTC not found.\n", ds1302_name);
 328                 retval = 0;
 329         }
 330
 331         return retval;
 332 }
 333
 334
 335 /* Just probe for the RTC and register the device to handle the ioctl needed. */
 336
 337 int __init
 338 ds1302_init(void)
 339 {
 340         if (!ds1302_probe()) {
 341                 return -1;
 342         }
 343         return 0;
 344 }
 345
 346 static int __init ds1302_register(void)
 347 {
 348         ds1302_init();
 349         if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 350                 printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 351                        ds1302_name, RTC_MAJOR_NR);
 352                 return -1;
 353         }
 354         return 0;
 355 }
 356
 357 module_init(ds1302_register);