LXR linux/arch/cris/arch-v10/drivers/pcf8563.c

   1/*
   2 * PCF8563 RTC
   3 *
   4 * From Phillips' datasheet:
   5 *
   6 * The PCF8563 is a CMOS real-time clock/calendar optimized for low power
   7 * consumption. A programmable clock output, interrupt output and voltage
   8 * low detector are also provided. All address and data are transferred
   9 * serially via two-line bidirectional I2C-bus. Maximum bus speed is
  10 * 400 kbits/s. The built-in word address register is incremented
  11 * automatically after each written or read byte.
  12 *
  13 * Copyright (c) 2002-2007, Axis Communications AB
  14 * All rights reserved.
  15 *
  16 * Author: Tobias Anderberg <tobiasa@axis.com>.
  17 *
  18 */
  19
  20#include <linux/module.h>
  21#include <linux/kernel.h>
  22#include <linux/types.h>
  23#include <linux/sched.h>
  24#include <linux/init.h>
  25#include <linux/fs.h>
  26#include <linux/ioctl.h>
  27#include <linux/delay.h>
  28#include <linux/bcd.h>
  29#include <linux/mutex.h>
  30
  31#include <asm/uaccess.h>
  32#include <asm/system.h>
  33#include <asm/io.h>
  34#include <asm/rtc.h>
  35
  36#include "i2c.h"
  37
  38#define PCF8563_MAJOR 121       /* Local major number. */
  39#define DEVICE_NAME "rtc"       /* Name which is registered in /proc/devices. */
  40#define PCF8563_NAME "PCF8563"
  41#define DRIVER_VERSION "$Revision: 1.24 $"
  42
  43/* I2C bus slave registers. */
  44#define RTC_I2C_READ            0xa3
  45#define RTC_I2C_WRITE           0xa2
  46
  47/* Two simple wrapper macros, saves a few keystrokes. */
  48#define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
  49#define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
  50
  51static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
  52
  53static const unsigned char days_in_month[] =
  54        { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  55
  56int pcf8563_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
  57
  58/* Cache VL bit value read at driver init since writing the RTC_SECOND
  59 * register clears the VL status.
  60 */
  61static int voltage_low;
  62
  63static const struct file_operations pcf8563_fops = {
  64        .owner = THIS_MODULE,
  65        .ioctl = pcf8563_ioctl,
  66};
  67
  68unsigned char
  69pcf8563_readreg(int reg)
  70{
  71        unsigned char res = rtc_read(reg);
  72
  73        /* The PCF8563 does not return 0 for unimplemented bits. */
  74        switch (reg) {
  75        case RTC_SECONDS:
  76        case RTC_MINUTES:
  77                res &= 0x7F;
  78                break;
  79        case RTC_HOURS:
  80        case RTC_DAY_OF_MONTH:
  81                res &= 0x3F;
  82                break;
  83        case RTC_WEEKDAY:
  84                res &= 0x07;
  85                break;
  86        case RTC_MONTH:
  87                res &= 0x1F;
  88                break;
  89        case RTC_CONTROL1:
  90                res &= 0xA8;
  91                break;
  92        case RTC_CONTROL2:
  93                res &= 0x1F;
  94                break;
  95        case RTC_CLOCKOUT_FREQ:
  96        case RTC_TIMER_CONTROL:
  97                res &= 0x83;
  98                break;
  99        }
 100        return res;
 101}
 102
 103void
 104pcf8563_writereg(int reg, unsigned char val)
 105{
 106        rtc_write(reg, val);
 107}
 108
 109void
 110get_rtc_time(struct rtc_time *tm)
 111{
 112        tm->tm_sec  = rtc_read(RTC_SECONDS);
 113        tm->tm_min  = rtc_read(RTC_MINUTES);
 114        tm->tm_hour = rtc_read(RTC_HOURS);
 115        tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
 116        tm->tm_wday = rtc_read(RTC_WEEKDAY);
 117        tm->tm_mon  = rtc_read(RTC_MONTH);
 118        tm->tm_year = rtc_read(RTC_YEAR);
 119
 120        if (tm->tm_sec & 0x80) {
 121                printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
 122                       "information is no longer guaranteed!\n", PCF8563_NAME);
 123        }
 124
 125        tm->tm_year  = bcd2bin(tm->tm_year) +
 126                       ((tm->tm_mon & 0x80) ? 100 : 0);
 127        tm->tm_sec  &= 0x7F;
 128        tm->tm_min  &= 0x7F;
 129        tm->tm_hour &= 0x3F;
 130        tm->tm_mday &= 0x3F;
 131        tm->tm_wday &= 0x07; /* Not coded in BCD. */
 132        tm->tm_mon  &= 0x1F;
 133
 134        tm->tm_sec = bcd2bin(tm->tm_sec);
 135        tm->tm_min = bcd2bin(tm->tm_min);
 136        tm->tm_hour = bcd2bin(tm->tm_hour);
 137        tm->tm_mday = bcd2bin(tm->tm_mday);
 138        tm->tm_mon = bcd2bin(tm->tm_mon);
 139        tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
 140}
 141
 142int __init
 143pcf8563_init(void)
 144{
 145        static int res;
 146        static int first = 1;
 147
 148        if (!first)
 149                return res;
 150        first = 0;
 151
 152        /* Initiate the i2c protocol. */
 153        res = i2c_init();
 154        if (res < 0) {
 155                printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
 156                return res;
 157        }
 158
 159        /*
 160         * First of all we need to reset the chip. This is done by
 161         * clearing control1, control2 and clk freq and resetting
 162         * all alarms.
 163         */
 164        if (rtc_write(RTC_CONTROL1, 0x00) < 0)
 165                goto err;
 166
 167        if (rtc_write(RTC_CONTROL2, 0x00) < 0)
 168                goto err;
 169
 170        if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
 171                goto err;
 172
 173        if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
 174                goto err;
 175
 176        /* Reset the alarms. */
 177        if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
 178                goto err;
 179
 180        if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
 181                goto err;
 182
 183        if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
 184                goto err;
 185
 186        if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
 187                goto err;
 188
 189        /* Check for low voltage, and warn about it. */
 190        if (rtc_read(RTC_SECONDS) & 0x80) {
 191                voltage_low = 1;
 192                printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
 193                       "date/time information is no longer guaranteed!\n",
 194                       PCF8563_NAME);
 195        }
 196
 197        return res;
 198
 199err:
 200        printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
 201        res = -1;
 202        return res;
 203}
 204
 205void __exit
 206pcf8563_exit(void)
 207{
 208        unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
 209}
 210
 211/*
 212 * ioctl calls for this driver. Why return -ENOTTY upon error? Because
 213 * POSIX says so!
 214 */
 215int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
 216        unsigned long arg)
 217{
 218        /* Some sanity checks. */
 219        if (_IOC_TYPE(cmd) != RTC_MAGIC)
 220                return -ENOTTY;
 221
 222        if (_IOC_NR(cmd) > RTC_MAX_IOCTL)
 223                return -ENOTTY;
 224
 225        switch (cmd) {
 226        case RTC_RD_TIME:
 227        {
 228                struct rtc_time tm;
 229
 230                mutex_lock(&rtc_lock);
 231                memset(&tm, 0, sizeof tm);
 232                get_rtc_time(&tm);
 233
 234                if (copy_to_user((struct rtc_time *) arg, &tm,
 235                                 sizeof tm)) {
 236                        mutex_unlock(&rtc_lock);
 237                        return -EFAULT;
 238                }
 239
 240                mutex_unlock(&rtc_lock);
 241
 242                return 0;
 243        }
 244        case RTC_SET_TIME:
 245        {
 246                int leap;
 247                int year;
 248                int century;
 249                struct rtc_time tm;
 250
 251                memset(&tm, 0, sizeof tm);
 252                if (!capable(CAP_SYS_TIME))
 253                        return -EPERM;
 254
 255                if (copy_from_user(&tm, (struct rtc_time *) arg, sizeof tm))
 256                        return -EFAULT;
 257
 258                /* Convert from struct tm to struct rtc_time. */
 259                tm.tm_year += 1900;
 260                tm.tm_mon += 1;
 261
 262                /*
 263                 * Check if tm.tm_year is a leap year. A year is a leap
 264                 * year if it is divisible by 4 but not 100, except
 265                 * that years divisible by 400 _are_ leap years.
 266                 */
 267                year = tm.tm_year;
 268                leap = (tm.tm_mon == 2) &&
 269                        ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
 270
 271                /* Perform some sanity checks. */
 272                if ((tm.tm_year < 1970) ||
 273                    (tm.tm_mon > 12) ||
 274                    (tm.tm_mday == 0) ||
 275                    (tm.tm_mday > days_in_month[tm.tm_mon] + leap) ||
 276                    (tm.tm_wday >= 7) ||
 277                    (tm.tm_hour >= 24) ||
 278                    (tm.tm_min >= 60) ||
 279                    (tm.tm_sec >= 60))
 280                        return -EINVAL;
 281
 282                century = (tm.tm_year >= 2000) ? 0x80 : 0;
 283                tm.tm_year = tm.tm_year % 100;
 284
 285                tm.tm_year = bin2bcd(tm.tm_year);
 286                tm.tm_mon = bin2bcd(tm.tm_mon);
 287                tm.tm_mday = bin2bcd(tm.tm_mday);
 288                tm.tm_hour = bin2bcd(tm.tm_hour);
 289                tm.tm_min = bin2bcd(tm.tm_min);
 290                tm.tm_sec = bin2bcd(tm.tm_sec);
 291                tm.tm_mon |= century;
 292
 293                mutex_lock(&rtc_lock);
 294
 295                rtc_write(RTC_YEAR, tm.tm_year);
 296                rtc_write(RTC_MONTH, tm.tm_mon);
 297                rtc_write(RTC_WEEKDAY, tm.tm_wday); /* Not coded in BCD. */
 298                rtc_write(RTC_DAY_OF_MONTH, tm.tm_mday);
 299                rtc_write(RTC_HOURS, tm.tm_hour);
 300                rtc_write(RTC_MINUTES, tm.tm_min);
 301                rtc_write(RTC_SECONDS, tm.tm_sec);
 302
 303                mutex_unlock(&rtc_lock);
 304
 305                return 0;
 306        }
 307        case RTC_VL_READ:
 308                if (voltage_low) {
 309                        printk(KERN_ERR "%s: RTC Voltage Low - "
 310                               "reliable date/time information is no "
 311                               "longer guaranteed!\n", PCF8563_NAME);
 312                }
 313
 314                if (copy_to_user((int *) arg, &voltage_low, sizeof(int)))
 315                        return -EFAULT;
 316                return 0;
 317
 318        case RTC_VL_CLR:
 319        {
 320                /* Clear the VL bit in the seconds register in case
 321                 * the time has not been set already (which would
 322                 * have cleared it). This does not really matter
 323                 * because of the cached voltage_low value but do it
 324                 * anyway for consistency. */
 325
 326                int ret = rtc_read(RTC_SECONDS);
 327
 328                rtc_write(RTC_SECONDS, (ret & 0x7F));
 329
 330                /* Clear the cached value. */
 331                voltage_low = 0;
 332
 333                return 0;
 334        }
 335        default:
 336                return -ENOTTY;
 337        }
 338
 339        return 0;
 340}
 341
 342static int __init pcf8563_register(void)
 343{
 344        if (pcf8563_init() < 0) {
 345                printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
 346                       "Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
 347                return -1;
 348        }
 349
 350        if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
 351                printk(KERN_INFO "%s: Unable to get major number %d for RTC device.\n",
 352                       PCF8563_NAME, PCF8563_MAJOR);
 353                return -1;
 354        }
 355
 356        printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
 357               DRIVER_VERSION);
 358
 359        /* Check for low voltage, and warn about it. */
 360        if (voltage_low) {
 361                printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
 362                       "information is no longer guaranteed!\n", PCF8563_NAME);
 363        }
 364
 365        return 0;
 366}
 367
 368module_init(pcf8563_register);
 369module_exit(pcf8563_exit);
 370