linux/drivers/char/ds1302.c
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   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#include <linux/mutex.h>
  24#include <linux/uaccess.h>
  25#include <linux/io.h>
  26
  27#include <asm/system.h>
  28#include <asm/rtc.h>
  29#if defined(CONFIG_M32R)
  30#include <asm/m32r.h>
  31#endif
  32
  33#define RTC_MAJOR_NR 121 /* local major, change later */
  34
  35static DEFINE_MUTEX(rtc_mutex);
  36static const char ds1302_name[] = "ds1302";
  37
  38/* Send 8 bits. */
  39static void
  40out_byte_rtc(unsigned int reg_addr, unsigned char x)
  41{
  42        //RST H
  43        outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  44        //write data
  45        outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
  46        //WE
  47        outw(0x0002,(unsigned long)PLD_RTCCR);
  48        //wait
  49        while(inw((unsigned long)PLD_RTCCR));
  50
  51        //RST L
  52        outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  53
  54}
  55
  56static unsigned char
  57in_byte_rtc(unsigned int reg_addr)
  58{
  59        unsigned char retval;
  60
  61        //RST H
  62        outw(0x0001,(unsigned long)PLD_RTCRSTODT);
  63        //write data
  64        outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
  65        //RE
  66        outw(0x0001,(unsigned long)PLD_RTCCR);
  67        //wait
  68        while(inw((unsigned long)PLD_RTCCR));
  69
  70        //read data
  71        retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;
  72
  73        //RST L
  74        outw(0x0000,(unsigned long)PLD_RTCRSTODT);
  75
  76        return retval;
  77}
  78
  79/* Enable writing. */
  80
  81static void
  82ds1302_wenable(void)
  83{
  84        out_byte_rtc(0x8e,0x00);
  85}
  86
  87/* Disable writing. */
  88
  89static void
  90ds1302_wdisable(void)
  91{
  92        out_byte_rtc(0x8e,0x80);
  93}
  94
  95
  96
  97/* Read a byte from the selected register in the DS1302. */
  98
  99unsigned char
 100ds1302_readreg(int reg)
 101{
 102        unsigned char x;
 103
 104        x=in_byte_rtc((0x81 | (reg << 1))); /* read register */
 105
 106        return x;
 107}
 108
 109/* Write a byte to the selected register. */
 110
 111void
 112ds1302_writereg(int reg, unsigned char val)
 113{
 114        ds1302_wenable();
 115        out_byte_rtc((0x80 | (reg << 1)),val);
 116        ds1302_wdisable();
 117}
 118
 119void
 120get_rtc_time(struct rtc_time *rtc_tm)
 121{
 122        unsigned long flags;
 123
 124        local_irq_save(flags);
 125
 126        rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 127        rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 128        rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 129        rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 130        rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 131        rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
 132
 133        local_irq_restore(flags);
 134
 135        rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 136        rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 137        rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 138        rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 139        rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 140        rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 141
 142        /*
 143         * Account for differences between how the RTC uses the values
 144         * and how they are defined in a struct rtc_time;
 145         */
 146
 147        if (rtc_tm->tm_year <= 69)
 148                rtc_tm->tm_year += 100;
 149
 150        rtc_tm->tm_mon--;
 151}
 152
 153static unsigned char days_in_mo[] =
 154    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 155
 156/* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
 157
 158static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 159{
 160        unsigned long flags;
 161
 162        switch(cmd) {
 163                case RTC_RD_TIME:       /* read the time/date from RTC  */
 164                {
 165                        struct rtc_time rtc_tm;
 166
 167                        memset(&rtc_tm, 0, sizeof (struct rtc_time));
 168                        mutex_lock(&rtc_mutex);
 169                        get_rtc_time(&rtc_tm);
 170                        mutex_unlock(&rtc_mutex);
 171                        if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 172                                return -EFAULT;
 173                        return 0;
 174                }
 175
 176                case RTC_SET_TIME:      /* set the RTC */
 177                {
 178                        struct rtc_time rtc_tm;
 179                        unsigned char mon, day, hrs, min, sec, leap_yr;
 180                        unsigned int yrs;
 181
 182                        if (!capable(CAP_SYS_TIME))
 183                                return -EPERM;
 184
 185                        if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 186                                return -EFAULT;
 187
 188                        yrs = rtc_tm.tm_year + 1900;
 189                        mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 190                        day = rtc_tm.tm_mday;
 191                        hrs = rtc_tm.tm_hour;
 192                        min = rtc_tm.tm_min;
 193                        sec = rtc_tm.tm_sec;
 194
 195
 196                        if ((yrs < 1970) || (yrs > 2069))
 197                                return -EINVAL;
 198
 199                        leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
 200
 201                        if ((mon > 12) || (day == 0))
 202                                return -EINVAL;
 203
 204                        if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 205                                return -EINVAL;
 206
 207                        if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 208                                return -EINVAL;
 209
 210                        if (yrs >= 2000)
 211                                yrs -= 2000;    /* RTC (0, 1, ... 69) */
 212                        else
 213                                yrs -= 1900;    /* RTC (70, 71, ... 99) */
 214
 215                        sec = bin2bcd(sec);
 216                        min = bin2bcd(min);
 217                        hrs = bin2bcd(hrs);
 218                        day = bin2bcd(day);
 219                        mon = bin2bcd(mon);
 220                        yrs = bin2bcd(yrs);
 221
 222                        mutex_lock(&rtc_mutex);
 223                        local_irq_save(flags);
 224                        CMOS_WRITE(yrs, RTC_YEAR);
 225                        CMOS_WRITE(mon, RTC_MONTH);
 226                        CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 227                        CMOS_WRITE(hrs, RTC_HOURS);
 228                        CMOS_WRITE(min, RTC_MINUTES);
 229                        CMOS_WRITE(sec, RTC_SECONDS);
 230                        local_irq_restore(flags);
 231                        mutex_unlock(&rtc_mutex);
 232
 233                        /* Notice that at this point, the RTC is updated but
 234                         * the kernel is still running with the old time.
 235                         * You need to set that separately with settimeofday
 236                         * or adjtimex.
 237                         */
 238                        return 0;
 239                }
 240
 241                case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 242                {
 243                        int tcs_val;
 244
 245                        if (!capable(CAP_SYS_TIME))
 246                                return -EPERM;
 247
 248                        if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 249                                return -EFAULT;
 250
 251                        mutex_lock(&rtc_mutex);
 252                        tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 253                        ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 254                        mutex_unlock(&rtc_mutex);
 255                        return 0;
 256                }
 257                default:
 258                        return -EINVAL;
 259        }
 260}
 261
 262int
 263get_rtc_status(char *buf)
 264{
 265        char *p;
 266        struct rtc_time tm;
 267
 268        p = buf;
 269
 270        get_rtc_time(&tm);
 271
 272        /*
 273         * There is no way to tell if the luser has the RTC set for local
 274         * time or for Universal Standard Time (GMT). Probably local though.
 275         */
 276
 277        p += sprintf(p,
 278                "rtc_time\t: %02d:%02d:%02d\n"
 279                "rtc_date\t: %04d-%02d-%02d\n",
 280                tm.tm_hour, tm.tm_min, tm.tm_sec,
 281                tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 282
 283        return  p - buf;
 284}
 285
 286
 287/* The various file operations we support. */
 288
 289static const struct file_operations rtc_fops = {
 290        .owner          = THIS_MODULE,
 291        .unlocked_ioctl = rtc_ioctl,
 292        .llseek         = noop_llseek,
 293};
 294
 295/* Probe for the chip by writing something to its RAM and try reading it back. */
 296
 297#define MAGIC_PATTERN 0x42
 298
 299static int __init
 300ds1302_probe(void)
 301{
 302        int retval, res, baur;
 303
 304        baur=(boot_cpu_data.bus_clock/(2*1000*1000));
 305
 306        printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);
 307
 308        outw(0x0000,(unsigned long)PLD_RTCCR);
 309        outw(0x0000,(unsigned long)PLD_RTCRSTODT);
 310        outw(baur,(unsigned long)PLD_RTCBAUR);
 311
 312        /* Try to talk to timekeeper. */
 313
 314        ds1302_wenable();
 315        /* write RAM byte 0 */
 316        /* write something magic */
 317        out_byte_rtc(0xc0,MAGIC_PATTERN);
 318
 319        /* read RAM byte 0 */
 320        if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
 321                char buf[100];
 322                ds1302_wdisable();
 323                printk("%s: RTC found.\n", ds1302_name);
 324                get_rtc_status(buf);
 325                printk(buf);
 326                retval = 1;
 327        } else {
 328                printk("%s: RTC not found.\n", ds1302_name);
 329                retval = 0;
 330        }
 331
 332        return retval;
 333}
 334
 335
 336/* Just probe for the RTC and register the device to handle the ioctl needed. */
 337
 338int __init
 339ds1302_init(void)
 340{
 341        if (!ds1302_probe()) {
 342                return -1;
 343        }
 344        return 0;
 345}
 346
 347static int __init ds1302_register(void)
 348{
 349        ds1302_init();
 350        if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 351                printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 352                       ds1302_name, RTC_MAJOR_NR);
 353                return -1;
 354        }
 355        return 0;
 356}
 357
 358module_init(ds1302_register);
 359
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