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         local_irq_disable();
 124
 125         rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 126         rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 127         rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 128         rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 129         rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 130         rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
 131
 132         local_irq_restore(flags);
 133
 134         BCD_TO_BIN(rtc_tm->tm_sec);
 135         BCD_TO_BIN(rtc_tm->tm_min);
 136         BCD_TO_BIN(rtc_tm->tm_hour);
 137         BCD_TO_BIN(rtc_tm->tm_mday);
 138         BCD_TO_BIN(rtc_tm->tm_mon);
 139         BCD_TO_BIN(rtc_tm->tm_year);
 140
 141         /*
 142          * Account for differences between how the RTC uses the values
 143          * and how they are defined in a struct rtc_time;
 144          */
 145
 146         if (rtc_tm->tm_year <= 69)
 147                 rtc_tm->tm_year += 100;
 148
 149         rtc_tm->tm_mon--;
 150 }
 151
 152 static unsigned char days_in_mo[] =
 153     {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 154
 155 /* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
 156
 157 static int
 158 rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 159           unsigned long arg)
 160 {
 161         unsigned long flags;
 162
 163         switch(cmd) {
 164                 case RTC_RD_TIME:       /* read the time/date from RTC  */
 165                 {
 166                         struct rtc_time rtc_tm;
 167
 168                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
 169                         get_rtc_time(&rtc_tm);
 170                         if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 171                                 return -EFAULT;
 172                         return 0;
 173                 }
 174
 175                 case RTC_SET_TIME:      /* set the RTC */
 176                 {
 177                         struct rtc_time rtc_tm;
 178                         unsigned char mon, day, hrs, min, sec, leap_yr;
 179                         unsigned int yrs;
 180
 181                         if (!capable(CAP_SYS_TIME))
 182                                 return -EPERM;
 183
 184                         if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 185                                 return -EFAULT;
 186
 187                         yrs = rtc_tm.tm_year + 1900;
 188                         mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 189                         day = rtc_tm.tm_mday;
 190                         hrs = rtc_tm.tm_hour;
 191                         min = rtc_tm.tm_min;
 192                         sec = rtc_tm.tm_sec;
 193
 194
 195                         if ((yrs < 1970) || (yrs > 2069))
 196                                 return -EINVAL;
 197
 198                         leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 199
 200                         if ((mon > 12) || (day == 0))
 201                                 return -EINVAL;
 202
 203                         if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 204                                 return -EINVAL;
 205
 206                         if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 207                                 return -EINVAL;
 208
 209                         if (yrs >= 2000)
 210                                 yrs -= 2000;    /* RTC (0, 1, ... 69) */
 211                         else
 212                                 yrs -= 1900;    /* RTC (70, 71, ... 99) */
 213
 214                         BIN_TO_BCD(sec);
 215                         BIN_TO_BCD(min);
 216                         BIN_TO_BCD(hrs);
 217                         BIN_TO_BCD(day);
 218                         BIN_TO_BCD(mon);
 219                         BIN_TO_BCD(yrs);
 220
 221                         local_irq_save(flags);
 222                         local_irq_disable();
 223                         CMOS_WRITE(yrs, RTC_YEAR);
 224                         CMOS_WRITE(mon, RTC_MONTH);
 225                         CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 226                         CMOS_WRITE(hrs, RTC_HOURS);
 227                         CMOS_WRITE(min, RTC_MINUTES);
 228                         CMOS_WRITE(sec, RTC_SECONDS);
 229                         local_irq_restore(flags);
 230
 231                         /* Notice that at this point, the RTC is updated but
 232                          * the kernel is still running with the old time.
 233                          * You need to set that separately with settimeofday
 234                          * or adjtimex.
 235                          */
 236                         return 0;
 237                 }
 238
 239                 case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 240                 {
 241                         int tcs_val;
 242
 243                         if (!capable(CAP_SYS_TIME))
 244                                 return -EPERM;
 245
 246                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 247                                 return -EFAULT;
 248
 249                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 250                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 251                         return 0;
 252                 }
 253                 default:
 254                         return -EINVAL;
 255         }
 256 }
 257
 258 int
 259 get_rtc_status(char *buf)
 260 {
 261         char *p;
 262         struct rtc_time tm;
 263
 264         p = buf;
 265
 266         get_rtc_time(&tm);
 267
 268         /*
 269          * There is no way to tell if the luser has the RTC set for local
 270          * time or for Universal Standard Time (GMT). Probably local though.
 271          */
 272
 273         p += sprintf(p,
 274                 "rtc_time\t: %02d:%02d:%02d\n"
 275                 "rtc_date\t: %04d-%02d-%02d\n",
 276                 tm.tm_hour, tm.tm_min, tm.tm_sec,
 277                 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 278
 279         return  p - buf;
 280 }
 281
 282
 283 /* The various file operations we support. */
 284
 285 static struct file_operations rtc_fops = {
 286         .owner          = THIS_MODULE,
 287         .ioctl          = rtc_ioctl,
 288 };
 289
 290 /* Probe for the chip by writing something to its RAM and try reading it back. */
 291
 292 #define MAGIC_PATTERN 0x42
 293
 294 static int __init
 295 ds1302_probe(void)
 296 {
 297         int retval, res, baur;
 298
 299         baur=(boot_cpu_data.bus_clock/(2*1000*1000));
 300
 301         printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);
 302
 303         outw(0x0000,(unsigned long)PLD_RTCCR);
 304         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
 305         outw(baur,(unsigned long)PLD_RTCBAUR);
 306
 307         /* Try to talk to timekeeper. */
 308
 309         ds1302_wenable();
 310         /* write RAM byte 0 */
 311         /* write something magic */
 312         out_byte_rtc(0xc0,MAGIC_PATTERN);
 313
 314         /* read RAM byte 0 */
 315         if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
 316                 char buf[100];
 317                 ds1302_wdisable();
 318                 printk("%s: RTC found.\n", ds1302_name);
 319                 get_rtc_status(buf);
 320                 printk(buf);
 321                 retval = 1;
 322         } else {
 323                 printk("%s: RTC not found.\n", ds1302_name);
 324                 retval = 0;
 325         }
 326
 327         return retval;
 328 }
 329
 330
 331 /* Just probe for the RTC and register the device to handle the ioctl needed. */
 332
 333 int __init
 334 ds1302_init(void)
 335 {
 336         if (!ds1302_probe()) {
 337                 return -1;
 338         }
 339         return 0;
 340 }
 341
 342 static int __init ds1302_register(void)
 343 {
 344         ds1302_init();
 345         if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 346                 printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 347                        ds1302_name, RTC_MAJOR_NR);
 348                 return -1;
 349         }
 350         return 0;
 351 }
 352
 353 module_init(ds1302_register);