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minix/drivers/cmos/cmos.c

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C
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/* This file contains a device driver that can access the CMOS chip to
* get or set the system time. It drives the special file:
*
* /dev/cmos - CMOS chip
*
* Changes:
* Aug 04, 2005 Created. Read CMOS time. (Jorrit N. Herder)
*
* 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
*/
#include "../drivers.h"
#include <sys/ioc_cmos.h>
#include <time.h>
#include <ibm/cmos.h>
#include <ibm/bios.h>
#include <minix/safecopies.h>
extern int errno; /* error number for PM calls */
FORWARD _PROTOTYPE( int gettime, (int who, int y2kflag, vir_bytes dst_time, int safe));
FORWARD _PROTOTYPE( void reply, (int reply, int replyee, int proc, cp_grant_id_t, int s));
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));
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC void main(void)
{
message m;
int y2kflag;
int result;
int suspended = NONE;
cp_grant_id_t susp_grant = GRANT_INVALID;
int s;
while(TRUE) {
int safe = 0;
/* Get work. */
if (OK != (s=receive(ANY, &m)))
panic("CMOS", "attempt to receive work failed", s);
/* Handle request. */
switch(m.m_type) {
case DEV_OPEN:
case DEV_CLOSE:
case CANCEL:
reply(TASK_REPLY, m.m_source, m.IO_ENDPT, GRANT_INVALID, OK);
break;
case DEV_PING:
notify(m.m_source);
break;
case DEV_IOCTL_S:
safe=1;
/* Fall through. */
case DEV_IOCTL:
/* Probably best to SUSPEND the caller, CMOS I/O has nasty timeouts.
* This way we don't block the rest of the system. First check if
* another process is already suspended. We cannot handle multiple
* requests at a time.
*/
if (suspended != NONE) {
reply(TASK_REPLY, m.m_source, m.IO_ENDPT, GRANT_INVALID, EBUSY);
break;
}
suspended = m.IO_ENDPT;
susp_grant = (cp_grant_id_t) m.IO_GRANT;
reply(TASK_REPLY, m.m_source, m.IO_ENDPT, susp_grant, SUSPEND);
switch(m.REQUEST) {
case CIOCGETTIME: /* get CMOS time */
case CIOCGETTIMEY2K:
y2kflag = (m.REQUEST == CIOCGETTIME) ? 0 : 1;
result = gettime(m.IO_ENDPT, y2kflag, (vir_bytes) m.ADDRESS, safe);
break;
case CIOCSETTIME:
case CIOCSETTIMEY2K:
default: /* unsupported ioctl */
result = ENOSYS;
}
/* Request completed. Tell the caller to check our status. */
notify(m.m_source);
break;
case DEV_STATUS:
/* The FS calls back to get our status. Revive the suspended
* processes and return the status of reading the CMOS.
*/
if (suspended == NONE)
reply(DEV_NO_STATUS, m.m_source, NONE, GRANT_INVALID, OK);
else
reply(DEV_REVIVE, m.m_source, suspended, susp_grant, result);
suspended = NONE;
break;
case SYN_ALARM: /* shouldn't happen */
case SYS_SIG: /* ignore system events */
continue;
default:
reply(TASK_REPLY, m.m_source, m.IO_ENDPT, GRANT_INVALID, EINVAL);
}
}
}
/*===========================================================================*
* reply *
*===========================================================================*/
PRIVATE void reply(int code, int replyee, int process, cp_grant_id_t grantid, int status)
{
message m;
int s;
m.m_type = code; /* TASK_REPLY or REVIVE */
m.REP_STATUS = status; /* result of device operation */
m.REP_ENDPT = process; /* which user made the request */
m.REP_IO_GRANT = grantid; /* I/O grant on which to unSUSPEND */
if (OK != (s=send(replyee, &m)))
panic("CMOS", "sending reply failed", s);
}
/*===========================================================================*
* gettime *
*===========================================================================*/
PRIVATE int gettime(int who, int y2kflag, vir_bytes dst_time, int safe)
{
unsigned char mach_id, cmos_state;
struct tm time1;
int i, s;
/* 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.
*/
sys_vircopy(SELF, BIOS_SEG, (vir_bytes) MACHINE_ID_ADDR,
SELF, D, (vir_bytes) &mach_id, MACHINE_ID_SIZE);
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);
/* Copy result back, safely or not. */
if(safe) {
sys_safecopyto(who, dst_time, 0, (vir_bytes) &time1,
sizeof(struct tm), D);
} else {
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;
clock_t t0,t1;
/* Start a timer to keep us from getting stuck on a dead clock. */
getuptime(&t0);
do {
osec = -1;
n = 0;
do {
getuptime(&t1);
if (t1-t0 > 5*HZ) {
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);
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. */
unsigned long r;
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);
}
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