minix/servers/fs/cmostime.c

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#include "fs.h"
#include <minix/com.h>
#include <minix/callnr.h>
#include <time.h>
#include <ibm/cmos.h>
#include <ibm/bios.h>
/* Manufacturers usually use the ID value of the IBM model they emulate.
* However some manufacturers, notably HP and COMPAQ, have had different
* ideas in the past.
*
* Machine ID byte information source:
* _The Programmer's PC Sourcebook_ by Thom Hogan,
* published by Microsoft Press
*/
FORWARD _PROTOTYPE( int read_register, (int register_address));
FORWARD _PROTOTYPE( int get_cmostime, (struct tm *tmp, int y2kflag));
FORWARD _PROTOTYPE( int dec_to_bcd, (int dec));
FORWARD _PROTOTYPE( int bcd_to_dec, (int bcd));
PUBLIC int do_cmostime(void)
{
unsigned char mach_id, cmos_state;
struct tm time1;
int i, s;
int y2kflag = m_in.REQUEST;
vir_bytes dst_time = (vir_bytes) m_in.ADDRESS;
/* First obtain the machine ID to see if we can read the CMOS clock. Only
* for PS_386 and PC_AT this is possible. Otherwise, return an error.
*/
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sys_vircopy(SELF, BIOS_SEG, (vir_bytes) MACHINE_ID_ADDR,
SELF, D, (vir_bytes) &mach_id, MACHINE_ID_SIZE);
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if (mach_id != PS_386_MACHINE && mach_id != PC_AT_MACHINE) {
printf("IS: Machine ID unknown. ID byte = %02x.\n", mach_id);
return(EFAULT);
}
/* Now check the CMOS' state to see if we can read a proper time from it.
* If the state is crappy, return an error.
*/
cmos_state = read_register(CMOS_STATUS);
if (cmos_state & (CS_LOST_POWER | CS_BAD_CHKSUM | CS_BAD_TIME)) {
printf( "IS: CMOS RAM error(s) found. State = 0x%02x\n", cmos_state );
if (cmos_state & CS_LOST_POWER)
printf("IS: RTC lost power. Reset CMOS RAM with SETUP." );
if (cmos_state & CS_BAD_CHKSUM)
printf("IS: CMOS RAM checksum is bad. Run SETUP." );
if (cmos_state & CS_BAD_TIME)
printf("IS: Time invalid in CMOS RAM. Reset clock." );
return(EFAULT);
}
/* Everything seems to be OK. Read the CMOS real time clock and copy the
* result back to the caller.
*/
if (get_cmostime(&time1, y2kflag) != 0)
return(EFAULT);
sys_datacopy(SELF, (vir_bytes) &time1,
who, dst_time, sizeof(struct tm));
return(OK);
}
PRIVATE int get_cmostime(struct tm *t, int y2kflag)
{
/* Update the structure pointed to by time with the current time as read
* from CMOS RAM of the RTC. If necessary, the time is converted into a
* binary format before being stored in the structure.
*/
int osec, n;
unsigned long i;
static int timeout_flag;
/* Start a timer to keep us from getting stuck on a dead clock. */
timeout_flag = 0;
sys_flagalrm(5*HZ, &timeout_flag);
do {
osec = -1;
n = 0;
do {
if (timeout_flag) {
printf("readclock: CMOS clock appears dead\n");
return(1);
}
/* Clock update in progress? */
if (read_register(RTC_REG_A) & RTC_A_UIP) continue;
t->tm_sec = read_register(RTC_SEC);
if (t->tm_sec != osec) {
/* Seconds changed. First from -1, then because the
* clock ticked, which is what we're waiting for to
* get a precise reading.
*/
osec = t->tm_sec;
n++;
}
} while (n < 2);
/* Read the other registers. */
t->tm_min = read_register(RTC_MIN);
t->tm_hour = read_register(RTC_HOUR);
t->tm_mday = read_register(RTC_MDAY);
t->tm_mon = read_register(RTC_MONTH);
t->tm_year = read_register(RTC_YEAR);
/* Time stable? */
} while (read_register(RTC_SEC) != t->tm_sec
|| read_register(RTC_MIN) != t->tm_min
|| read_register(RTC_HOUR) != t->tm_hour
|| read_register(RTC_MDAY) != t->tm_mday
|| read_register(RTC_MONTH) != t->tm_mon
|| read_register(RTC_YEAR) != t->tm_year);
sys_flagalrm(0, &timeout_flag); /* not strictly necessarily; flag is static */
if ((read_register(RTC_REG_B) & RTC_B_DM_BCD) == 0) {
/* Convert BCD to binary (default RTC mode). */
t->tm_year = bcd_to_dec(t->tm_year);
t->tm_mon = bcd_to_dec(t->tm_mon);
t->tm_mday = bcd_to_dec(t->tm_mday);
t->tm_hour = bcd_to_dec(t->tm_hour);
t->tm_min = bcd_to_dec(t->tm_min);
t->tm_sec = bcd_to_dec(t->tm_sec);
}
t->tm_mon--; /* Counts from 0. */
/* Correct the year, good until 2080. */
if (t->tm_year < 80) t->tm_year += 100;
if (y2kflag) {
/* Clock with Y2K bug, interpret 1980 as 2000, good until 2020. */
if (t->tm_year < 100) t->tm_year += 20;
}
return 0;
}
PRIVATE int read_register(int reg_addr)
{
/* Read a single CMOS register value. */
int r = 0;
sys_outb(RTC_INDEX, reg_addr);
sys_inb(RTC_IO, &r);
return r;
}
PRIVATE int bcd_to_dec(int n)
{
return ((n >> 4) & 0x0F) * 10 + (n & 0x0F);
}
PRIVATE int dec_to_bcd(int n)
{
return ((n / 10) << 4) | (n % 10);
}