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 *! ---------------------------------------------------------------------------
  10 *!
  11 *! (C) Copyright 1999-2007 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/capability.h>
  24
  25 #include <asm/uaccess.h>
  26 #include <asm/system.h>
  27 #include <arch/svinto.h>
  28 #include <asm/io.h>
  29 #include <asm/rtc.h>
  30 #include <arch/io_interface_mux.h>
  31
  32 #include "i2c.h"
  33
  34 #define RTC_MAJOR_NR 121 /* local major, change later */
  35
  36 static const char ds1302_name[] = "ds1302";
  37
  38 /* The DS1302 might be connected to different bits on different products.
  39  * It has three signals - SDA, SCL and RST. RST and SCL are always outputs,
  40  * but SDA can have a selected direction.
  41  * For now, only PORT_PB is hardcoded.
  42  */
  43
  44 /* The RST bit may be on either the Generic Port or Port PB. */
  45 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
  46 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_G_DATA,  port_g_data_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
  47 #define TK_RST_DIR(x)
  48 #else
  49 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
  50 #define TK_RST_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
  51 #endif
  52
  53
  54 #define TK_SDA_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SDABIT, x)
  55 #define TK_SCL_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SCLBIT, x)
  56
  57 #define TK_SDA_IN()   ((*R_PORT_PB_READ >> CONFIG_ETRAX_DS1302_SDABIT) & 1)
  58 /* 1 is out, 0 is in */
  59 #define TK_SDA_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SDABIT, x)
  60 #define TK_SCL_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SCLBIT, x)
  61
  62
  63 /*
  64  * The reason for tempudelay and not udelay is that loops_per_usec
  65  * (used in udelay) is not set when functions here are called from time.c
  66  */
  67
  68 static void tempudelay(int usecs)
  69 {
  70         volatile int loops;
  71
  72         for(loops = usecs * 12; loops > 0; loops--)
  73                 /* nothing */;
  74 }
  75
  76
  77 /* Send 8 bits. */
  78 static void
  79 out_byte(unsigned char x)
  80 {
  81         int i;
  82         TK_SDA_DIR(1);
  83         for (i = 8; i--;) {
  84                 /* The chip latches incoming bits on the rising edge of SCL. */
  85                 TK_SCL_OUT(0);
  86                 TK_SDA_OUT(x & 1);
  87                 tempudelay(1);
  88                 TK_SCL_OUT(1);
  89                 tempudelay(1);
  90                 x >>= 1;
  91         }
  92         TK_SDA_DIR(0);
  93 }
  94
  95 static unsigned char
  96 in_byte(void)
  97 {
  98         unsigned char x = 0;
  99         int i;
 100
 101         /* Read byte. Bits come LSB first, on the falling edge of SCL.
 102          * Assume SDA is in input direction already.
 103          */
 104         TK_SDA_DIR(0);
 105
 106         for (i = 8; i--;) {
 107                 TK_SCL_OUT(0);
 108                 tempudelay(1);
 109                 x >>= 1;
 110                 x |= (TK_SDA_IN() << 7);
 111                 TK_SCL_OUT(1);
 112                 tempudelay(1);
 113         }
 114
 115         return x;
 116 }
 117
 118 /* Prepares for a transaction by de-activating RST (active-low). */
 119
 120 static void
 121 start(void)
 122 {
 123         TK_SCL_OUT(0);
 124         tempudelay(1);
 125         TK_RST_OUT(0);
 126         tempudelay(5);
 127         TK_RST_OUT(1);
 128 }
 129
 130 /* Ends a transaction by taking RST active again. */
 131
 132 static void
 133 stop(void)
 134 {
 135         tempudelay(2);
 136         TK_RST_OUT(0);
 137 }
 138
 139 /* Enable writing. */
 140
 141 static void
 142 ds1302_wenable(void)
 143 {
 144         start();
 145         out_byte(0x8e); /* Write control register  */
 146         out_byte(0x00); /* Disable write protect bit 7 = 0 */
 147         stop();
 148 }
 149
 150 /* Disable writing. */
 151
 152 static void
 153 ds1302_wdisable(void)
 154 {
 155         start();
 156         out_byte(0x8e); /* Write control register  */
 157         out_byte(0x80); /* Disable write protect bit 7 = 0 */
 158         stop();
 159 }
 160
 161
 162
 163 /* Read a byte from the selected register in the DS1302. */
 164
 165 unsigned char
 166 ds1302_readreg(int reg)
 167 {
 168         unsigned char x;
 169
 170         start();
 171         out_byte(0x81 | (reg << 1)); /* read register */
 172         x = in_byte();
 173         stop();
 174
 175         return x;
 176 }
 177
 178 /* Write a byte to the selected register. */
 179
 180 void
 181 ds1302_writereg(int reg, unsigned char val)
 182 {
 183 #ifndef CONFIG_ETRAX_RTC_READONLY
 184         int do_writereg = 1;
 185 #else
 186         int do_writereg = 0;
 187
 188         if (reg == RTC_TRICKLECHARGER)
 189                 do_writereg = 1;
 190 #endif
 191
 192         if (do_writereg) {
 193                 ds1302_wenable();
 194                 start();
 195                 out_byte(0x80 | (reg << 1)); /* write register */
 196                 out_byte(val);
 197                 stop();
 198                 ds1302_wdisable();
 199         }
 200 }
 201
 202 void
 203 get_rtc_time(struct rtc_time *rtc_tm)
 204 {
 205         unsigned long flags;
 206
 207         local_irq_save(flags);
 208
 209         rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 210         rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 211         rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 212         rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 213         rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 214         rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
 215
 216         local_irq_restore(flags);
 217
 218         rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 219         rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 220         rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 221         rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 222         rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 223         rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 224
 225         /*
 226          * Account for differences between how the RTC uses the values
 227          * and how they are defined in a struct rtc_time;
 228          */
 229
 230         if (rtc_tm->tm_year <= 69)
 231                 rtc_tm->tm_year += 100;
 232
 233         rtc_tm->tm_mon--;
 234 }
 235
 236 static unsigned char days_in_mo[] =
 237     {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 238
 239 /* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
 240
 241 static int
 242 rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 243           unsigned long arg)
 244 {
 245         unsigned long flags;
 246
 247         switch(cmd) {
 248                 case RTC_RD_TIME:       /* read the time/date from RTC  */
 249                 {
 250                         struct rtc_time rtc_tm;
 251
 252                         memset(&rtc_tm, 0, sizeof (struct rtc_time));
 253                         get_rtc_time(&rtc_tm);
 254                         if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 255                                 return -EFAULT;
 256                         return 0;
 257                 }
 258
 259                 case RTC_SET_TIME:      /* set the RTC */
 260                 {
 261                         struct rtc_time rtc_tm;
 262                         unsigned char mon, day, hrs, min, sec, leap_yr;
 263                         unsigned int yrs;
 264
 265                         if (!capable(CAP_SYS_TIME))
 266                                 return -EPERM;
 267
 268                         if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 269                                 return -EFAULT;
 270
 271                         yrs = rtc_tm.tm_year + 1900;
 272                         mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 273                         day = rtc_tm.tm_mday;
 274                         hrs = rtc_tm.tm_hour;
 275                         min = rtc_tm.tm_min;
 276                         sec = rtc_tm.tm_sec;
 277
 278
 279                         if ((yrs < 1970) || (yrs > 2069))
 280                                 return -EINVAL;
 281
 282                         leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 283
 284                         if ((mon > 12) || (day == 0))
 285                                 return -EINVAL;
 286
 287                         if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 288                                 return -EINVAL;
 289
 290                         if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 291                                 return -EINVAL;
 292
 293                         if (yrs >= 2000)
 294                                 yrs -= 2000;    /* RTC (0, 1, ... 69) */
 295                         else
 296                                 yrs -= 1900;    /* RTC (70, 71, ... 99) */
 297
 298                         sec = bin2bcd(sec);
 299                         min = bin2bcd(min);
 300                         hrs = bin2bcd(hrs);
 301                         day = bin2bcd(day);
 302                         mon = bin2bcd(mon);
 303                         yrs = bin2bcd(yrs);
 304
 305                         local_irq_save(flags);
 306                         CMOS_WRITE(yrs, RTC_YEAR);
 307                         CMOS_WRITE(mon, RTC_MONTH);
 308                         CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 309                         CMOS_WRITE(hrs, RTC_HOURS);
 310                         CMOS_WRITE(min, RTC_MINUTES);
 311                         CMOS_WRITE(sec, RTC_SECONDS);
 312                         local_irq_restore(flags);
 313
 314                         /* Notice that at this point, the RTC is updated but
 315                          * the kernel is still running with the old time.
 316                          * You need to set that separately with settimeofday
 317                          * or adjtimex.
 318                          */
 319                         return 0;
 320                 }
 321
 322                 case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 323                 {
 324                         int tcs_val;
 325
 326                         if (!capable(CAP_SYS_TIME))
 327                                 return -EPERM;
 328
 329                         if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 330                                 return -EFAULT;
 331
 332                         tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 333                         ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 334                         return 0;
 335                 }
 336                 case RTC_VL_READ:
 337                 {
 338                         /* TODO:
 339                          * Implement voltage low detection support
 340                          */
 341                         printk(KERN_WARNING "DS1302: RTC Voltage Low detection"
 342                                " is not supported\n");
 343                         return 0;
 344                 }
 345                 case RTC_VL_CLR:
 346                 {
 347                         /* TODO:
 348                          * Nothing to do since Voltage Low detection is not supported
 349                          */
 350                         return 0;
 351                 }
 352                 default:
 353                         return -ENOIOCTLCMD;
 354         }
 355 }
 356
 357 static void
 358 print_rtc_status(void)
 359 {
 360         struct rtc_time tm;
 361
 362         get_rtc_time(&tm);
 363
 364         /*
 365          * There is no way to tell if the luser has the RTC set for local
 366          * time or for Universal Standard Time (GMT). Probably local though.
 367          */
 368
 369         printk(KERN_INFO "rtc_time\t: %02d:%02d:%02d\n",
 370                tm.tm_hour, tm.tm_min, tm.tm_sec);
 371         printk(KERN_INFO "rtc_date\t: %04d-%02d-%02d\n",
 372                tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 373 }
 374
 375 /* The various file operations we support. */
 376
 377 static const struct file_operations rtc_fops = {
 378         .owner =        THIS_MODULE,
 379         .ioctl =        rtc_ioctl,
 380 };
 381
 382 /* Probe for the chip by writing something to its RAM and try reading it back. */
 383
 384 #define MAGIC_PATTERN 0x42
 385
 386 static int __init
 387 ds1302_probe(void)
 388 {
 389         int retval, res;
 390
 391         TK_RST_DIR(1);
 392         TK_SCL_DIR(1);
 393         TK_SDA_DIR(0);
 394
 395         /* Try to talk to timekeeper. */
 396
 397         ds1302_wenable();
 398         start();
 399         out_byte(0xc0); /* write RAM byte 0 */
 400         out_byte(MAGIC_PATTERN); /* write something magic */
 401         start();
 402         out_byte(0xc1); /* read RAM byte 0 */
 403
 404         if((res = in_byte()) == MAGIC_PATTERN) {
 405                 stop();
 406                 ds1302_wdisable();
 407                 printk(KERN_INFO "%s: RTC found.\n", ds1302_name);
 408                 printk(KERN_INFO "%s: SDA, SCL, RST on PB%i, PB%i, %s%i\n",
 409                        ds1302_name,
 410                        CONFIG_ETRAX_DS1302_SDABIT,
 411                        CONFIG_ETRAX_DS1302_SCLBIT,
 412 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 413                        "GENIO",
 414 #else
 415                        "PB",
 416 #endif
 417                        CONFIG_ETRAX_DS1302_RSTBIT);
 418                        print_rtc_status();
 419                 retval = 1;
 420         } else {
 421                 stop();
 422                 retval = 0;
 423         }
 424
 425         return retval;
 426 }
 427
 428
 429 /* Just probe for the RTC and register the device to handle the ioctl needed. */
 430
 431 int __init
 432 ds1302_init(void)
 433 {
 434 #ifdef CONFIG_ETRAX_I2C
 435         i2c_init();
 436 #endif
 437
 438         if (!ds1302_probe()) {
 439 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 440 #if CONFIG_ETRAX_DS1302_RSTBIT == 27
 441                 /*
 442                  * The only way to set g27 to output is to enable ATA.
 443                  *
 444                  * Make sure that R_GEN_CONFIG is setup correct.
 445                  */
 446                 /* Allocating the ATA interface will grab almost all
 447                  * pins in I/O groups a, b, c and d.  A consequence of
 448                  * allocating the ATA interface is that the fixed
 449                  * interfaces shared RAM, parallel port 0, parallel
 450                  * port 1, parallel port W, SCSI-8 port 0, SCSI-8 port
 451                  * 1, SCSI-W, serial port 2, serial port 3,
 452                  * synchronous serial port 3 and USB port 2 and almost
 453                  * all GPIO pins on port g cannot be used.
 454                  */
 455                 if (cris_request_io_interface(if_ata, "ds1302/ATA")) {
 456                         printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 457                         return -1;
 458                 }
 459
 460 #elif CONFIG_ETRAX_DS1302_RSTBIT == 0
 461                 if (cris_io_interface_allocate_pins(if_gpio_grp_a,
 462                                                     'g',
 463                                                     CONFIG_ETRAX_DS1302_RSTBIT,
 464                                                     CONFIG_ETRAX_DS1302_RSTBIT)) {
 465                         printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 466                         return -1;
 467                 }
 468
 469                 /* Set the direction of this bit to out. */
 470                 genconfig_shadow = ((genconfig_shadow &
 471                                      ~IO_MASK(R_GEN_CONFIG, g0dir)) |
 472                                    (IO_STATE(R_GEN_CONFIG, g0dir, out)));
 473                 *R_GEN_CONFIG = genconfig_shadow;
 474 #endif
 475                 if (!ds1302_probe()) {
 476                         printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 477                         return -1;
 478                 }
 479 #else
 480                 printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 481                 return -1;
 482 #endif
 483         }
 484         /* Initialise trickle charger */
 485         ds1302_writereg(RTC_TRICKLECHARGER,
 486                         RTC_TCR_PATTERN |(CONFIG_ETRAX_DS1302_TRICKLE_CHARGE & 0x0F));
 487         /* Start clock by resetting CLOCK_HALT */
 488         ds1302_writereg(RTC_SECONDS, (ds1302_readreg(RTC_SECONDS) & 0x7F));
 489         return 0;
 490 }
 491
 492 static int __init ds1302_register(void)
 493 {
 494         ds1302_init();
 495         if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 496                 printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 497                        ds1302_name, RTC_MAJOR_NR);
 498                 return -1;
 499         }
 500         return 0;
 501
 502 }
 503
 504 module_init(ds1302_register);