arch/cris/arch-v10/drivers/ds1302.c

   1 /*!***************************************************************************
   2 *!
   3 *! FILE NAME  : ds1302.c
   4 *!
   5 *! DESCRIPTION: Implements an interface for the DS1302 RTC through Etrax I/O
   6 *!
   7 *! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init
   8 *!
   9 *! $Log: ds1302.c,v $
  10 *! Revision 1.18  2005/01/24 09:11:26  mikaelam
  11 *! Minor changes to get DS1302 RTC chip driver to work
  12 *!
  13 *! Revision 1.17  2005/01/05 06:11:22  starvik
  14 *! No need to do local_irq_disable after local_irq_save.
  15 *!
  16 *! Revision 1.16  2004/12/13 12:21:52  starvik
  17 *! Added I/O and DMA allocators from Linux 2.4
  18 *!
  19 *! Revision 1.14  2004/08/24 06:48:43  starvik
  20 *! Whitespace cleanup
  21 *!
  22 *! Revision 1.13  2004/05/28 09:26:59  starvik
  23 *! Modified I2C initialization to work in 2.6.
  24 *!
  25 *! Revision 1.12  2004/05/14 07:58:03  starvik
  26 *! Merge of changes from 2.4
  27 *!
  28 *! Revision 1.10  2004/02/04 09:25:12  starvik
  29 *! Merge of Linux 2.6.2
  30 *!
  31 *! Revision 1.9  2003/07/04 08:27:37  starvik
  32 *! Merge of Linux 2.5.74
  33 *!
  34 *! Revision 1.8  2003/04/09 05:20:47  starvik
  35 *! Merge of Linux 2.5.67
  36 *!
  37 *! Revision 1.6  2003/01/09 14:42:51  starvik
  38 *! Merge of Linux 2.5.55
  39 *!
  40 *! Revision 1.4  2002/12/11 13:13:57  starvik
  41 *! Added arch/ to v10 specific includes
  42 *! Added fix from Linux 2.4 in serial.c (flush_to_flip_buffer)
  43 *!
  44 *! Revision 1.3  2002/11/20 11:56:10  starvik
  45 *! Merge of Linux 2.5.48
  46 *!
  47 *! Revision 1.2  2002/11/18 13:16:06  starvik
  48 *! Linux 2.5 port of latest 2.4 drivers
  49 *!
  50 *! Revision 1.15  2002/10/11 16:14:33  johana
  51 *! Added CONFIG_ETRAX_DS1302_TRICKLE_CHARGE and initial setting of the
  52 *! trcklecharge register.
  53 *!
  54 *! Revision 1.14  2002/10/10 12:15:38  magnusmn
  55 *! Added support for having the RST signal on bit g0
  56 *!
  57 *! Revision 1.13  2002/05/29 15:16:08  johana
  58 *! Removed unused variables.
  59 *!
  60 *! Revision 1.12  2002/04/10 15:35:25  johana
  61 *! Moved probe function closer to init function and marked it __init.
  62 *!
  63 *! Revision 1.11  2001/06/14 12:35:52  jonashg
  64 *! The ATA hack is back. It is unfortunately the only way to set g27 to output.
  65 *!
  66 *! Revision 1.9  2001/06/14 10:00:14  jonashg
  67 *! No need for tempudelay to be inline anymore (had to adjust the usec to
  68 *! loops conversion because of this to make it slow enough to be a udelay).
  69 *!
  70 *! Revision 1.8  2001/06/14 08:06:32  jonashg
  71 *! Made tempudelay delay usecs (well, just a tad more).
  72 *!
  73 *! Revision 1.7  2001/06/13 14:18:11  jonashg
  74 *! Only allow processes with SYS_TIME capability to set time and charge.
  75 *!
  76 *! Revision 1.6  2001/06/12 15:22:07  jonashg
  77 *! * Made init function __init.
  78 *! * Parameter to out_byte() is unsigned char.
  79 *! * The magic number 42 has got a name.
  80 *! * Removed comment about /proc (nothing is exported there).
  81 *!
  82 *! Revision 1.5  2001/06/12 14:35:13  jonashg
  83 *! Gave the module a name and added it to printk's.
  84 *!
  85 *! Revision 1.4  2001/05/31 14:53:40  jonashg
  86 *! Made tempudelay() inline so that the watchdog doesn't reset (see
  87 *! function comment).
  88 *!
  89 *! Revision 1.3  2001/03/26 16:03:06  bjornw
  90 *! Needs linux/config.h
  91 *!
  92 *! Revision 1.2  2001/03/20 19:42:00  bjornw
  93 *! Use the ETRAX prefix on the DS1302 options
  94 *!
  95 *! Revision 1.1  2001/03/20 09:13:50  magnusmn
  96 *! Linux 2.4 port
  97 *!
  98 *! Revision 1.10  2000/07/05 15:38:23  bjornw
  99 *! Dont update kernel time when a RTC_SET_TIME is done
 100 *!
 101 *! Revision 1.9  2000/03/02 15:42:59  macce
 102 *! * Hack to make RTC work on all 2100/2400
 103 *!
 104 *! Revision 1.8  2000/02/23 16:59:18  torbjore
 105 *! added setup of R_GEN_CONFIG when RTC is connected to the generic port.
 106 *!
 107 *! Revision 1.7  2000/01/17 15:51:43  johana
 108 *! Added RTC_SET_CHARGE ioctl to enable trickle charger.
 109 *!
 110 *! Revision 1.6  1999/10/27 13:19:47  bjornw
 111 *! Added update_xtime_from_cmos which reads back the updated RTC into the kernel.
 112 *! /dev/rtc calls it now.
 113 *!
 114 *! Revision 1.5  1999/10/27 12:39:37  bjornw
 115 *! Disabled superuser check. Anyone can now set the time.
 116 *!
 117 *! Revision 1.4  1999/09/02 13:27:46  pkj
 118 *! Added shadow for R_PORT_PB_CONFIG.
 119 *! Renamed port_g_shadow to port_g_data_shadow.
 120 *!
 121 *! Revision 1.3  1999/09/02 08:28:06  pkj
 122 *! Made it possible to select either port PB or the generic port for the RST
 123 *! signal line to the DS1302 RTC.
 124 *! Also make sure the RST bit is configured as output on Port PB (if used).
 125 *!
 126 *! Revision 1.2  1999/09/01 14:47:20  bjornw
 127 *! Added support for /dev/rtc operations with ioctl RD_TIME and SET_TIME to read
 128 *! and set the date. Register as major 121.
 129 *!
 130 *! Revision 1.1  1999/09/01 09:45:29  bjornw
 131 *! Implemented a DS1302 RTC driver.
 132 *!
 133 *!
 134 *! ---------------------------------------------------------------------------
 135 *!
 136 *! (C) Copyright 1999, 2000, 2001, 2002, 2003, 2004  Axis Communications AB, LUND, SWEDEN
 137 *!
 138 *! $Id: ds1302.c,v 1.18 2005/01/24 09:11:26 mikaelam Exp $
 139 *!
 140 *!***************************************************************************/
 141
 142
 143 #include <linux/fs.h>
 144 #include <linux/init.h>
 145 #include <linux/mm.h>
 146 #include <linux/module.h>
 147 #include <linux/miscdevice.h>
 148 #include <linux/delay.h>
 149 #include <linux/bcd.h>
 150 #include <linux/capability.h>
 151
 152 #include <asm/uaccess.h>
 153 #include <asm/system.h>
 154 #include <asm/arch/svinto.h>
 155 #include <asm/io.h>
 156 #include <asm/rtc.h>
 157 #include <asm/arch/io_interface_mux.h>
 158
 159 #define RTC_MAJOR_NR 121 /* local major, change later */
 160
 161 static const char ds1302_name[] = "ds1302";
 162
 163 /* The DS1302 might be connected to different bits on different products.
 164  * It has three signals - SDA, SCL and RST. RST and SCL are always outputs,
 165  * but SDA can have a selected direction.
 166  * For now, only PORT_PB is hardcoded.
 167  */
 168
 169 /* The RST bit may be on either the Generic Port or Port PB. */
 170 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 171 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_G_DATA,  port_g_data_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
 172 #define TK_RST_DIR(x)
 173 #else
 174 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
 175 #define TK_RST_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
 176 #endif
 177
 178
 179 #define TK_SDA_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SDABIT, x)
 180 #define TK_SCL_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SCLBIT, x)
 181
 182 #define TK_SDA_IN()   ((*R_PORT_PB_READ >> CONFIG_ETRAX_DS1302_SDABIT) & 1)
 183 /* 1 is out, 0 is in */
 184 #define TK_SDA_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SDABIT, x)
 185 #define TK_SCL_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SCLBIT, x)
 186
 187
 188 /*
 189  * The reason for tempudelay and not udelay is that loops_per_usec
 190  * (used in udelay) is not set when functions here are called from time.c
 191  */
 192
 193 static void tempudelay(int usecs)
 194 {
 195         volatile int loops;
 196
 197         for(loops = usecs * 12; loops > 0; loops--)
 198                 /* nothing */;
 199 }
 200
 201
 202 /* Send 8 bits. */
 203 static void
 204 out_byte(unsigned char x)
 205 {
 206         int i;
 207         TK_SDA_DIR(1);
 208         for (i = 8; i--;) {
 209                 /* The chip latches incoming bits on the rising edge of SCL. */
 210                 TK_SCL_OUT(0);
 211                 TK_SDA_OUT(x & 1);
 212                 tempudelay(1);
 213                 TK_SCL_OUT(1);
 214                 tempudelay(1);
 215                 x >>= 1;
 216         }
 217         TK_SDA_DIR(0);
 218 }
 219
 220 static unsigned char
 221 in_byte(void)
 222 {
 223         unsigned char x = 0;
 224         int i;
 225
 226         /* Read byte. Bits come LSB first, on the falling edge of SCL.
 227          * Assume SDA is in input direction already.
 228          */
 229         TK_SDA_DIR(0);
 230
 231         for (i = 8; i--;) {
 232                 TK_SCL_OUT(0);
 233                 tempudelay(1);
 234                 x >>= 1;
 235                 x |= (TK_SDA_IN() << 7);
 236                 TK_SCL_OUT(1);
 237                 tempudelay(1);
 238         }
 239
 240         return x;
 241 }
 242
 243 /* Prepares for a transaction by de-activating RST (active-low). */
 244
 245 static void
 246 start(void)
 247 {
 248         TK_SCL_OUT(0);
 249         tempudelay(1);
 250         TK_RST_OUT(0);
 251         tempudelay(5);
 252         TK_RST_OUT(1);
 253 }
 254
 255 /* Ends a transaction by taking RST active again. */
 256
 257 static void
 258 stop(void)
 259 {
 260         tempudelay(2);
 261         TK_RST_OUT(0);
 262 }
 263
 264 /* Enable writing. */
 265
 266 static void
 267 ds1302_wenable(void)
 268 {
 269         start();
 270         out_byte(0x8e); /* Write control register  */
 271         out_byte(0x00); /* Disable write protect bit 7 = 0 */
 272         stop();
 273 }
 274
 275 /* Disable writing. */
 276
 277 static void
 278 ds1302_wdisable(void)
 279 {
 280         start();
 281         out_byte(0x8e); /* Write control register  */
 282         out_byte(0x80); /* Disable write protect bit 7 = 0 */
 283         stop();
 284 }
 285
 286
 287
 288 /* Read a byte from the selected register in the DS1302. */
 289
 290 unsigned char
 291 ds1302_readreg(int reg)
 292 {
 293         unsigned char x;
 294
 295         start();
 296         out_byte(0x81 | (reg << 1)); /* read register */
 297         x = in_byte();
 298         stop();
 299
 300         return x;
 301 }
 302
 303 /* Write a byte to the selected register. */
 304
 305 void
 306 ds1302_writereg(int reg, unsigned char val)
 307 {
 308 #ifndef CONFIG_ETRAX_RTC_READONLY
 309         int do_writereg = 1;
 310 #else
 311         int do_writereg = 0;
 312
 313         if (reg == RTC_TRICKLECHARGER)
 314                 do_writereg = 1;
 315 #endif
 316
 317         if (do_writereg) {
 318                 ds1302_wenable();
 319                 start();
 320                 out_byte(0x80 | (reg << 1)); /* write register */
 321                 out_byte(val);
 322                 stop();
 323                 ds1302_wdisable();
 324         }
 325 }
 326
 327 void
 328 get_rtc_time(struct rtc_time *rtc_tm)
 329 {
 330         unsigned long flags;
 331
 332         local_irq_save(flags);
 333
 334         rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 335         rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 336         rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 337         rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 338         rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 339         rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
 340
 341         local_irq_restore(flags);
 342
 343         BCD_TO_BIN(rtc_tm->tm_sec);
 344         BCD_TO_BIN(rtc_tm->tm_min);
 345         BCD_TO_BIN(rtc_tm->tm_hour);
 346         BCD_TO_BIN(rtc_tm->tm_mday);
 347         BCD_TO_BIN(rtc_tm->tm_mon);
 348         BCD_TO_BIN(rtc_tm->tm_year);
 349
 350         /*
 351          * Account for differences between how the RTC uses the values
 352          * and how they are defined in a struct rtc_time;
 353          */
 354
 355         if (rtc_tm->tm_year <= 69)
 356                 rtc_tm->tm_year += 100;
 357
 358         rtc_tm->tm_mon--;
 359 }
 360
 361 static unsigned char days_in_mo[] =
 362     {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 363
 364 /* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
 365
 366 static int
 367 rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 368           unsigned long arg)
 369 {
 370         unsigned long flags;
 371
 372         switch(cmd) {
 373                 case RTC_RD_TIME:       /* read the time/date from RTC  */
 374                 {
 375                         struct rtc_time rtc_tm;
 376
 377                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
 378                         get_rtc_time(&rtc_tm);
 379                         if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 380                                 return -EFAULT;
 381                         return 0;
 382                 }
 383
 384                 case RTC_SET_TIME:      /* set the RTC */
 385                 {
 386                         struct rtc_time rtc_tm;
 387                         unsigned char mon, day, hrs, min, sec, leap_yr;
 388                         unsigned int yrs;
 389
 390                         if (!capable(CAP_SYS_TIME))
 391                                 return -EPERM;
 392
 393                         if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 394                                 return -EFAULT;
 395
 396                         yrs = rtc_tm.tm_year + 1900;
 397                         mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 398                         day = rtc_tm.tm_mday;
 399                         hrs = rtc_tm.tm_hour;
 400                         min = rtc_tm.tm_min;
 401                         sec = rtc_tm.tm_sec;
 402
 403
 404                         if ((yrs < 1970) || (yrs > 2069))
 405                                 return -EINVAL;
 406
 407                         leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 408
 409                         if ((mon > 12) || (day == 0))
 410                                 return -EINVAL;
 411
 412                         if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 413                                 return -EINVAL;
 414
 415                         if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 416                                 return -EINVAL;
 417
 418                         if (yrs >= 2000)
 419                                 yrs -= 2000;    /* RTC (0, 1, ... 69) */
 420                         else
 421                                 yrs -= 1900;    /* RTC (70, 71, ... 99) */
 422
 423                         BIN_TO_BCD(sec);
 424                         BIN_TO_BCD(min);
 425                         BIN_TO_BCD(hrs);
 426                         BIN_TO_BCD(day);
 427                         BIN_TO_BCD(mon);
 428                         BIN_TO_BCD(yrs);
 429
 430                         local_irq_save(flags);
 431                         CMOS_WRITE(yrs, RTC_YEAR);
 432                         CMOS_WRITE(mon, RTC_MONTH);
 433                         CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 434                         CMOS_WRITE(hrs, RTC_HOURS);
 435                         CMOS_WRITE(min, RTC_MINUTES);
 436                         CMOS_WRITE(sec, RTC_SECONDS);
 437                         local_irq_restore(flags);
 438
 439                         /* Notice that at this point, the RTC is updated but
 440                          * the kernel is still running with the old time.
 441                          * You need to set that separately with settimeofday
 442                          * or adjtimex.
 443                          */
 444                         return 0;
 445                 }
 446
 447                 case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 448                 {
 449                         int tcs_val;
 450
 451                         if (!capable(CAP_SYS_TIME))
 452                                 return -EPERM;
 453
 454                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 455                                 return -EFAULT;
 456
 457                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 458                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 459                         return 0;
 460                 }
 461                 case RTC_VLOW_RD:
 462                 {
 463                         /* TODO:
 464                          * Implement voltage low detection support
 465                          */
 466                         printk(KERN_WARNING "DS1302: RTC Voltage Low detection"
 467                                " is not supported\n");
 468                         return 0;
 469                 }
 470                 case RTC_VLOW_SET:
 471                 {
 472                         /* TODO:
 473                          * Nothing to do since Voltage Low detection is not supported
 474                          */
 475                         return 0;
 476                 }
 477                 default:
 478                         return -ENOIOCTLCMD;
 479         }
 480 }
 481
 482 static void
 483 print_rtc_status(void)
 484 {
 485         struct rtc_time tm;
 486
 487         get_rtc_time(&tm);
 488
 489         /*
 490          * There is no way to tell if the luser has the RTC set for local
 491          * time or for Universal Standard Time (GMT). Probably local though.
 492          */
 493
 494         printk(KERN_INFO "rtc_time\t: %02d:%02d:%02d\n",
 495                tm.tm_hour, tm.tm_min, tm.tm_sec);
 496         printk(KERN_INFO "rtc_date\t: %04d-%02d-%02d\n",
 497                tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 498 }
 499
 500 /* The various file operations we support. */
 501
 502 static const struct file_operations rtc_fops = {
 503         .owner =        THIS_MODULE,
 504         .ioctl =        rtc_ioctl,
 505 };
 506
 507 /* Probe for the chip by writing something to its RAM and try reading it back. */
 508
 509 #define MAGIC_PATTERN 0x42
 510
 511 static int __init
 512 ds1302_probe(void)
 513 {
 514         int retval, res;
 515
 516         TK_RST_DIR(1);
 517         TK_SCL_DIR(1);
 518         TK_SDA_DIR(0);
 519
 520         /* Try to talk to timekeeper. */
 521
 522         ds1302_wenable();
 523         start();
 524         out_byte(0xc0); /* write RAM byte 0 */
 525         out_byte(MAGIC_PATTERN); /* write something magic */
 526         start();
 527         out_byte(0xc1); /* read RAM byte 0 */
 528
 529         if((res = in_byte()) == MAGIC_PATTERN) {
 530                 stop();
 531                 ds1302_wdisable();
 532                 printk(KERN_INFO "%s: RTC found.\n", ds1302_name);
 533                 printk(KERN_INFO "%s: SDA, SCL, RST on PB%i, PB%i, %s%i\n",
 534                        ds1302_name,
 535                        CONFIG_ETRAX_DS1302_SDABIT,
 536                        CONFIG_ETRAX_DS1302_SCLBIT,
 537 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 538                        "GENIO",
 539 #else
 540                        "PB",
 541 #endif
 542                        CONFIG_ETRAX_DS1302_RSTBIT);
 543                        print_rtc_status();
 544                 retval = 1;
 545         } else {
 546                 stop();
 547                 retval = 0;
 548         }
 549
 550         return retval;
 551 }
 552
 553
 554 /* Just probe for the RTC and register the device to handle the ioctl needed. */
 555
 556 int __init
 557 ds1302_init(void)
 558 {
 559 #ifdef CONFIG_ETRAX_I2C
 560         i2c_init();
 561 #endif
 562
 563         if (!ds1302_probe()) {
 564 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 565 #if CONFIG_ETRAX_DS1302_RSTBIT == 27
 566                 /*
 567                  * The only way to set g27 to output is to enable ATA.
 568                  *
 569                  * Make sure that R_GEN_CONFIG is setup correct.
 570                  */
 571                 /* Allocating the ATA interface will grab almost all
 572                  * pins in I/O groups a, b, c and d.  A consequence of
 573                  * allocating the ATA interface is that the fixed
 574                  * interfaces shared RAM, parallel port 0, parallel
 575                  * port 1, parallel port W, SCSI-8 port 0, SCSI-8 port
 576                  * 1, SCSI-W, serial port 2, serial port 3,
 577                  * synchronous serial port 3 and USB port 2 and almost
 578                  * all GPIO pins on port g cannot be used.
 579                  */
 580                 if (cris_request_io_interface(if_ata, "ds1302/ATA")) {
 581                         printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 582                         return -1;
 583                 }
 584
 585 #elif CONFIG_ETRAX_DS1302_RSTBIT == 0
 586                 if (cris_io_interface_allocate_pins(if_gpio_grp_a,
 587                                                     'g',
 588                                                     CONFIG_ETRAX_DS1302_RSTBIT,
 589                                                     CONFIG_ETRAX_DS1302_RSTBIT)) {
 590                         printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 591                         return -1;
 592                 }
 593
 594                 /* Set the direction of this bit to out. */
 595                 genconfig_shadow = ((genconfig_shadow &
 596                                      ~IO_MASK(R_GEN_CONFIG, g0dir)) |
 597                                    (IO_STATE(R_GEN_CONFIG, g0dir, out)));
 598                 *R_GEN_CONFIG = genconfig_shadow;
 599 #endif
 600                 if (!ds1302_probe()) {
 601                         printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 602                         return -1;
 603                 }
 604 #else
 605                 printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 606                 return -1;
 607 #endif
 608         }
 609         /* Initialise trickle charger */
 610         ds1302_writereg(RTC_TRICKLECHARGER,
 611                         RTC_TCR_PATTERN |(CONFIG_ETRAX_DS1302_TRICKLE_CHARGE & 0x0F));
 612         /* Start clock by resetting CLOCK_HALT */
 613         ds1302_writereg(RTC_SECONDS, (ds1302_readreg(RTC_SECONDS) & 0x7F));
 614         return 0;
 615 }
 616
 617 static int __init ds1302_register(void)
 618 {
 619         ds1302_init();
 620         if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 621                 printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 622                        ds1302_name, RTC_MAJOR_NR);
 623                 return -1;
 624         }
 625         return 0;
 626
 627 }
 628
 629 module_init(ds1302_register);