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