LXR linux/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
  34static DEFINE_MUTEX(rtc_mutex);
  35static const char ds1302_name[] = "ds1302";
  36
  37/* Send 8 bits. */
  38static void
  39out_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
  55static unsigned char
  56in_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
  80static void
  81ds1302_wenable(void)
  82{
  83        out_byte_rtc(0x8e,0x00);
  84}
  85
  86/* Disable writing. */
  87
  88static void
  89ds1302_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
  98unsigned char
  99ds1302_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
 110void
 111ds1302_writereg(int reg, unsigned char val)
 112{
 113        ds1302_wenable();
 114        out_byte_rtc((0x80 | (reg << 1)),val);
 115        ds1302_wdisable();
 116}
 117
 118void
 119get_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
 152static 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
 157static 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
 261int
 262get_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
 288static 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
 298static int __init
 299ds1302_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
 337int __init
 338ds1302_init(void)
 339{
 340        if (!ds1302_probe()) {
 341                return -1;
 342        }
 343        return 0;
 344}
 345
 346static 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
 357module_init(ds1302_register);
 358