1/* 2 * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip 3 * 4 * Real Time Clock interface for Linux 5 * 6 * TODO: Implement periodic interrupts. 7 * 8 * Copyright (C) 2000 Silicon Graphics, Inc. 9 * Written by Ulf Carlsson (ulfc@engr.sgi.com) 10 * 11 * Based on code written by Paul Gortmaker. 12 * 13 * This driver allows use of the real time clock (built into 14 * nearly all computers) from user space. It exports the /dev/rtc 15 * interface supporting various ioctl() and also the /proc/rtc 16 * pseudo-file for status information. 17 * 18 * This program is free software; you can redistribute it and/or 19 * modify it under the terms of the GNU General Public License 20 * as published by the Free Software Foundation; either version 21 * 2 of the License, or (at your option) any later version. 22 * 23 */ 24 25#define RTC_VERSION "1.09b" 26 27#include <linux/bcd.h> 28#include <linux/module.h> 29#include <linux/kernel.h> 30#include <linux/types.h> 31#include <linux/miscdevice.h> 32#include <linux/ioport.h> 33#include <linux/fcntl.h> 34#include <linux/rtc.h> 35#include <linux/init.h> 36#include <linux/poll.h> 37#include <linux/proc_fs.h> 38 39#include <asm/m48t35.h> 40#include <asm/sn/ioc3.h> 41#include <asm/io.h> 42#include <asm/uaccess.h> 43#include <asm/system.h> 44#include <asm/sn/klconfig.h> 45#include <asm/sn/sn0/ip27.h> 46#include <asm/sn/sn0/hub.h> 47#include <asm/sn/sn_private.h> 48 49static int rtc_ioctl(struct inode *inode, struct file *file, 50 unsigned int cmd, unsigned long arg); 51 52static int rtc_read_proc(char *page, char **start, off_t off, 53 int count, int *eof, void *data); 54 55static void get_rtc_time(struct rtc_time *rtc_tm); 56 57/* 58 * Bits in rtc_status. (6 bits of room for future expansion) 59 */ 60 61#define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */ 62#define RTC_TIMER_ON 0x02 /* missed irq timer active */ 63 64static unsigned char rtc_status; /* bitmapped status byte. */ 65static unsigned long rtc_freq; /* Current periodic IRQ rate */ 66static struct m48t35_rtc *rtc; 67 68/* 69 * If this driver ever becomes modularised, it will be really nice 70 * to make the epoch retain its value across module reload... 71 */ 72 73static unsigned long epoch = 1970; /* year corresponding to 0x00 */ 74 75static const unsigned char days_in_mo[] = 76{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; 77 78static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 79 unsigned long arg) 80{ 81 82 struct rtc_time wtime; 83 84 switch (cmd) { 85 case RTC_RD_TIME: /* Read the time/date from RTC */ 86 { 87 get_rtc_time(&wtime); 88 break; 89 } 90 case RTC_SET_TIME: /* Set the RTC */ 91 { 92 struct rtc_time rtc_tm; 93 unsigned char mon, day, hrs, min, sec, leap_yr; 94 unsigned int yrs; 95 96 if (!capable(CAP_SYS_TIME)) 97 return -EACCES; 98 99 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, 100 sizeof(struct rtc_time))) 101 return -EFAULT; 102 103 yrs = rtc_tm.tm_year + 1900; 104 mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */ 105 day = rtc_tm.tm_mday; 106 hrs = rtc_tm.tm_hour; 107 min = rtc_tm.tm_min; 108 sec = rtc_tm.tm_sec; 109 110 if (yrs < 1970) 111 return -EINVAL; 112 113 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400)); 114 115 if ((mon > 12) || (day == 0)) 116 return -EINVAL; 117 118 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr))) 119 return -EINVAL; 120 121 if ((hrs >= 24) || (min >= 60) || (sec >= 60)) 122 return -EINVAL; 123 124 if ((yrs -= epoch) > 255) /* They are unsigned */ 125 return -EINVAL; 126 127 if (yrs > 169) 128 return -EINVAL; 129 130 if (yrs >= 100) 131 yrs -= 100; 132 133 sec = BIN2BCD(sec); 134 min = BIN2BCD(min); 135 hrs = BIN2BCD(hrs); 136 day = BIN2BCD(day); 137 mon = BIN2BCD(mon); 138 yrs = BIN2BCD(yrs); 139 140 spin_lock_irq(&rtc_lock); 141 rtc->control |= M48T35_RTC_SET; 142 rtc->year = yrs; 143 rtc->month = mon; 144 rtc->date = day; 145 rtc->hour = hrs; 146 rtc->min = min; 147 rtc->sec = sec; 148 rtc->control &= ~M48T35_RTC_SET; 149 spin_unlock_irq(&rtc_lock); 150 151 return 0; 152 } 153 default: 154 return -EINVAL; 155 } 156 return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0; 157} 158 159/* 160 * We enforce only one user at a time here with the open/close. 161 * Also clear the previous interrupt data on an open, and clean 162 * up things on a close. 163 */ 164 165static int rtc_open(struct inode *inode, struct file *file) 166{ 167 spin_lock_irq(&rtc_lock); 168 169 if (rtc_status & RTC_IS_OPEN) { 170 spin_unlock_irq(&rtc_lock); 171 return -EBUSY; 172 } 173 174 rtc_status |= RTC_IS_OPEN; 175 spin_unlock_irq(&rtc_lock); 176 177 return 0; 178} 179 180static int rtc_release(struct inode *inode, struct file *file) 181{ 182 /* 183 * Turn off all interrupts once the device is no longer 184 * in use, and clear the data. 185 */ 186 187 spin_lock_irq(&rtc_lock); 188 rtc_status &= ~RTC_IS_OPEN; 189 spin_unlock_irq(&rtc_lock); 190 191 return 0; 192} 193 194/* 195 * The various file operations we support. 196 */ 197 198static const struct file_operations rtc_fops = { 199 .owner = THIS_MODULE, 200 .ioctl = rtc_ioctl, 201 .open = rtc_open, 202 .release = rtc_release, 203}; 204 205static struct miscdevice rtc_dev= 206{ 207 RTC_MINOR, 208 "rtc", 209 &rtc_fops 210}; 211 212static int __init rtc_init(void) 213{ 214 rtc = (struct m48t35_rtc *) 215 (KL_CONFIG_CH_CONS_INFO(master_nasid)->memory_base + IOC3_BYTEBUS_DEV0); 216 217 printk(KERN_INFO "Real Time Clock Driver v%s\n", RTC_VERSION); 218 if (misc_register(&rtc_dev)) { 219 printk(KERN_ERR "rtc: cannot register misc device.\n"); 220 return -ENODEV; 221 } 222 if (!create_proc_read_entry("driver/rtc", 0, NULL, rtc_read_proc, NULL)) { 223 printk(KERN_ERR "rtc: cannot create /proc/rtc.\n"); 224 misc_deregister(&rtc_dev); 225 return -ENOENT; 226 } 227 228 rtc_freq = 1024; 229 230 return 0; 231} 232 233static void __exit rtc_exit (void) 234{ 235 /* interrupts and timer disabled at this point by rtc_release */ 236 237 remove_proc_entry ("rtc", NULL); 238 misc_deregister(&rtc_dev); 239} 240 241module_init(rtc_init); 242module_exit(rtc_exit); 243 244/* 245 * Info exported via "/proc/rtc". 246 */ 247 248static int rtc_get_status(char *buf) 249{ 250 char *p; 251 struct rtc_time tm; 252 253 /* 254 * Just emulate the standard /proc/rtc 255 */ 256 257 p = buf; 258 259 get_rtc_time(&tm); 260 261 /* 262 * There is no way to tell if the luser has the RTC set for local 263 * time or for Universal Standard Time (GMT). Probably local though. 264 */ 265 p += sprintf(p, 266 "rtc_time\t: %02d:%02d:%02d\n" 267 "rtc_date\t: %04d-%02d-%02d\n" 268 "rtc_epoch\t: %04lu\n" 269 "24hr\t\t: yes\n", 270 tm.tm_hour, tm.tm_min, tm.tm_sec, 271 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, epoch); 272 273 return p - buf; 274} 275 276static int rtc_read_proc(char *page, char **start, off_t off, 277 int count, int *eof, void *data) 278{ 279 int len = rtc_get_status(page); 280 if (len <= off+count) *eof = 1; 281 *start = page + off; 282 len -= off; 283 if (len>count) len = count; 284 if (len<0) len = 0; 285 return len; 286} 287 288static void get_rtc_time(struct rtc_time *rtc_tm) 289{ 290 /* 291 * Do we need to wait for the last update to finish? 292 */ 293 294 /* 295 * Only the values that we read from the RTC are set. We leave 296 * tm_wday, tm_yday and tm_isdst untouched. Even though the 297 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated 298 * by the RTC when initially set to a non-zero value. 299 */ 300 spin_lock_irq(&rtc_lock); 301 rtc->control |= M48T35_RTC_READ; 302 rtc_tm->tm_sec = rtc->sec; 303 rtc_tm->tm_min = rtc->min; 304 rtc_tm->tm_hour = rtc->hour; 305 rtc_tm->tm_mday = rtc->date; 306 rtc_tm->tm_mon = rtc->month; 307 rtc_tm->tm_year = rtc->year; 308 rtc->control &= ~M48T35_RTC_READ; 309 spin_unlock_irq(&rtc_lock); 310 311 rtc_tm->tm_sec = BCD2BIN(rtc_tm->tm_sec); 312 rtc_tm->tm_min = BCD2BIN(rtc_tm->tm_min); 313 rtc_tm->tm_hour = BCD2BIN(rtc_tm->tm_hour); 314 rtc_tm->tm_mday = BCD2BIN(rtc_tm->tm_mday); 315 rtc_tm->tm_mon = BCD2BIN(rtc_tm->tm_mon); 316 rtc_tm->tm_year = BCD2BIN(rtc_tm->tm_year); 317 318 /* 319 * Account for differences between how the RTC uses the values 320 * and how they are defined in a struct rtc_time; 321 */ 322 if ((rtc_tm->tm_year += (epoch - 1900)) <= 69) 323 rtc_tm->tm_year += 100; 324 325 rtc_tm->tm_mon--; 326} 327