drivers/char/ds1302.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*!***************************************************************************
   3 *!
   4 *! FILE NAME  : ds1302.c
   5 *!
   6 *! DESCRIPTION: Implements an interface for the DS1302 RTC
   7 *!
   8 *! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init, get_rtc_status
   9 *!
  10 *! ---------------------------------------------------------------------------
  11 *!
  12 *! (C) Copyright 1999, 2000, 2001  Axis Communications AB, LUND, SWEDEN
  13 *!
  14 *!***************************************************************************/
  15
  16
  17 #include <linux/fs.h>
  18 #include <linux/init.h>
  19 #include <linux/mm.h>
  20 #include <linux/module.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/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 DEFINE_MUTEX(rtc_mutex);
  35 static const char ds1302_name[] = "ds1302";
  36
  37 /* Send 8 bits. */
  38 static void
  39 out_byte_rtc(unsigned int reg_addr, unsigned char x)
  40 {
  41         //RST H
  42         outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  43         //write data
  44         outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
  45         //WE
  46         outw(0x0002,(unsigned long)PLD_RTCCR);
  47         //wait
  48         while(inw((unsigned long)PLD_RTCCR));
  49
  50         //RST L
  51         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  52
  53 }
  54
  55 static unsigned char
  56 in_byte_rtc(unsigned int reg_addr)
  57 {
  58         unsigned char retval;
  59
  60         //RST H
  61         outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  62         //write data
  63         outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
  64         //RE
  65         outw(0x0001,(unsigned long)PLD_RTCCR);
  66         //wait
  67         while(inw((unsigned long)PLD_RTCCR));
  68
  69         //read data
  70         retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;
  71
  72         //RST L
  73         outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  74
  75         return retval;
  76 }
  77
  78 /* Enable writing. */
  79
  80 static void
  81 ds1302_wenable(void)
  82 {
  83         out_byte_rtc(0x8e,0x00);
  84 }
  85
  86 /* Disable writing. */
  87
  88 static void
  89 ds1302_wdisable(void)
  90 {
  91         out_byte_rtc(0x8e,0x80);
  92 }
  93
  94
  95
  96 /* Read a byte from the selected register in the DS1302. */
  97
  98 unsigned char
  99 ds1302_readreg(int reg)
 100 {
 101         unsigned char x;
 102
 103         x=in_byte_rtc((0x81 | (reg << 1))); /* read register */
 104
 105         return x;
 106 }
 107
 108 /* Write a byte to the selected register. */
 109
 110 void
 111 ds1302_writereg(int reg, unsigned char val)
 112 {
 113         ds1302_wenable();
 114         out_byte_rtc((0x80 | (reg << 1)),val);
 115         ds1302_wdisable();
 116 }
 117
 118 void
 119 get_rtc_time(struct rtc_time *rtc_tm)
 120 {
 121         unsigned long flags;
 122
 123         local_irq_save(flags);
 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         rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 135         rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 136         rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 137         rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 138         rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 139         rtc_tm->tm_year = bcd2bin(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 long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 158 {
 159         unsigned long flags;
 160
 161         switch(cmd) {
 162                 case RTC_RD_TIME:       /* read the time/date from RTC  */
 163                 {
 164                         struct rtc_time rtc_tm;
 165
 166                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
 167                         mutex_lock(&rtc_mutex);
 168                         get_rtc_time(&rtc_tm);
 169                         mutex_unlock(&rtc_mutex);
 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                         sec = bin2bcd(sec);
 215                         min = bin2bcd(min);
 216                         hrs = bin2bcd(hrs);
 217                         day = bin2bcd(day);
 218                         mon = bin2bcd(mon);
 219                         yrs = bin2bcd(yrs);
 220
 221                         mutex_lock(&rtc_mutex);
 222                         local_irq_save(flags);
 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                         mutex_unlock(&rtc_mutex);
 231
 232                         /* Notice that at this point, the RTC is updated but
 233                          * the kernel is still running with the old time.
 234                          * You need to set that separately with settimeofday
 235                          * or adjtimex.
 236                          */
 237                         return 0;
 238                 }
 239
 240                 case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 241                 {
 242                         int tcs_val;
 243
 244                         if (!capable(CAP_SYS_TIME))
 245                                 return -EPERM;
 246
 247                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 248                                 return -EFAULT;
 249
 250                         mutex_lock(&rtc_mutex);
 251                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 252                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 253                         mutex_unlock(&rtc_mutex);
 254                         return 0;
 255                 }
 256                 default:
 257                         return -EINVAL;
 258         }
 259 }
 260
 261 int
 262 get_rtc_status(char *buf)
 263 {
 264         char *p;
 265         struct rtc_time tm;
 266
 267         p = buf;
 268
 269         get_rtc_time(&tm);
 270
 271         /*
 272          * There is no way to tell if the luser has the RTC set for local
 273          * time or for Universal Standard Time (GMT). Probably local though.
 274          */
 275
 276         p += sprintf(p,
 277                 "rtc_time\t: %02d:%02d:%02d\n"
 278                 "rtc_date\t: %04d-%02d-%02d\n",
 279                 tm.tm_hour, tm.tm_min, tm.tm_sec,
 280                 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 281
 282         return  p - buf;
 283 }
 284
 285
 286 /* The various file operations we support. */
 287
 288 static const struct file_operations rtc_fops = {
 289         .owner          = THIS_MODULE,
 290         .unlocked_ioctl = rtc_ioctl,
 291         .llseek         = noop_llseek,
 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);