LXR linux/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
  36static 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
  68static 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. */
  78static void
  79out_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
  95static unsigned char
  96in_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
 120static void
 121start(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
 132static void
 133stop(void) 
 134{
 135        tempudelay(2);
 136        TK_RST_OUT(0);
 137}
 138
 139/* Enable writing. */
 140
 141static void
 142ds1302_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
 152static void
 153ds1302_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
 165unsigned char
 166ds1302_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
 180void
 181ds1302_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
 202void
 203get_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
 236static 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
 241static int
 242rtc_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
 357static void
 358print_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
 377static 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
 386static int __init
 387ds1302_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
 431int __init
 432ds1302_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
 492static 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
 504module_init(ds1302_register);
 505