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minix3/drivers/clock/readclock/arch/i386/arch_readclock.c

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/* readclock - read the real time clock Authors: T. Holm & E. Froese
*
* Changed to be user-space driver.
*/
/************************************************************************/
/* */
/* readclock.c */
/* */
/* Read the clock value from the 64 byte CMOS RAM */
/* area, then set system time. */
/* */
/* If the machine ID byte is 0xFC or 0xF8, the device */
/* /dev/mem exists and can be opened for reading, */
/* and no errors in the CMOS RAM are reported by the */
/* RTC, then the time is read from the clock RAM */
/* area maintained by the RTC. */
/* */
/* The clock RAM values are decoded and fed to mktime */
/* to make a time_t value, then stime(2) is called. */
/* */
/* This fails if: */
/* */
/* If the machine ID does not match 0xFC or 0xF8 (no */
/* error message.) */
/* */
/* If the machine ID is 0xFC or 0xF8 and /dev/mem */
/* is missing, or cannot be accessed. */
/* */
/* If the RTC reports errors in the CMOS RAM. */
/* */
/************************************************************************/
/* origination 1987-Dec-29 efth */
/* robustness 1990-Oct-06 C. Sylvain */
/* incorp. B. Evans ideas 1991-Jul-06 C. Sylvain */
/* set time & calibrate 1992-Dec-17 Kees J. Bot */
/* clock timezone 1993-Oct-10 Kees J. Bot */
/* set CMOS clock 1994-Jun-12 Kees J. Bot */
/************************************************************************/
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>
#include <minix/type.h>
#include <minix/const.h>
#include <minix/syslib.h>
#include <minix/sysutil.h>
#include <minix/com.h>
#include <minix/log.h>
#include <machine/cmos.h>
#include <sys/svrctl.h>
#include "readclock.h"
#define MACH_ID_ADDR 0xFFFFE /* BIOS Machine ID at FFFF:000E */
#define PC_AT 0xFC /* Machine ID byte for PC/AT,
* PC/XT286, and PS/2 Models 50, 60 */
#define PS_386 0xF8 /* Machine ID byte for PS/2 Model 80 */
/* 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
*/
/* used for logging */
static struct log log = {
.name = "cmos_clock",
.log_level = LEVEL_INFO,
.log_func = default_log
};
static int read_register(int reg_addr);
static int write_register(int reg_addr, int value);
static int arch_init(void);
static int arch_get_time(struct tm *t, int flags);
static int arch_set_time(struct tm *t, int flags);
static int arch_pwr_off(void);
static void arch_exit(void);
int
arch_setup(struct rtc *r)
{
r->init = arch_init;
r->get_time = arch_get_time;
r->set_time = arch_set_time;
r->pwr_off = arch_pwr_off;
r->exit = arch_exit;
return OK;
}
static int
arch_init(void)
{
int s;
unsigned char mach_id, cmos_state;
if ((s = sys_readbios(MACH_ID_ADDR, &mach_id, sizeof(mach_id))) != OK) {
log_warn(&log, "sys_readbios failed: %d.\n", s);
return -1;
}
if (mach_id != PS_386 && mach_id != PC_AT) {
log_warn(&log, "Machine ID unknown.");
log_warn(&log, "Machine ID byte = %02x\n", mach_id);
return -1;
}
cmos_state = read_register(CMOS_STATUS);
if (cmos_state & (CS_LOST_POWER | CS_BAD_CHKSUM | CS_BAD_TIME)) {
log_warn(&log, "CMOS RAM error(s) found...");
log_warn(&log, "CMOS state = 0x%02x\n", cmos_state);
if (cmos_state & CS_LOST_POWER)
log_warn(&log,
"RTC lost power. Reset CMOS RAM with SETUP.");
if (cmos_state & CS_BAD_CHKSUM)
log_warn(&log, "CMOS RAM checksum is bad. Run SETUP.");
if (cmos_state & CS_BAD_TIME)
log_warn(&log,
"Time invalid in CMOS RAM. Reset clock.");
return -1;
}
return OK;
}
/***********************************************************************/
/* */
/* arch_get_time( time ) */
/* */
/* 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. */
/* */
/***********************************************************************/
static int
arch_get_time(struct tm *t, int flags)
{
int osec, n;
do {
osec = -1;
n = 0;
do {
/* 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 ((flags & RTCDEV_Y2KBUG) == RTCDEV_Y2KBUG) {
/* Clock with Y2K bug, interpret 1980 as 2000, good until 2020. */
if (t->tm_year < 100)
t->tm_year += 20;
}
return OK;
}
static int
read_register(int reg_addr)
{
u32_t r;
if (sys_outb(RTC_INDEX, reg_addr) != OK) {
log_warn(&log, "outb failed of %x\n", RTC_INDEX);
return -1;
}
if (sys_inb(RTC_IO, &r) != OK) {
log_warn(&log, "inb failed of %x (index %x) failed\n", RTC_IO,
reg_addr);
return -1;
}
return r;
}
/***********************************************************************/
/* */
/* arch_set_time( time ) */
/* */
/* Set the CMOS RTC to the time found in the structure. */
/* */
/***********************************************************************/
static int
arch_set_time(struct tm *t, int flags)
{
int regA, regB;
if ((flags & RTCDEV_CMOSREG) == RTCDEV_CMOSREG) {
/* Set A and B registers to their proper values according to the AT
* reference manual. (For if it gets messed up, but the BIOS doesn't
* repair it.)
*/
write_register(RTC_REG_A, RTC_A_DV_OK | RTC_A_RS_DEF);
write_register(RTC_REG_B, RTC_B_24);
}
/* Inhibit updates. */
regB = read_register(RTC_REG_B);
write_register(RTC_REG_B, regB | RTC_B_SET);
t->tm_mon++; /* Counts from 1. */
if ((flags & RTCDEV_Y2KBUG) == RTCDEV_Y2KBUG) {
/* Set the clock back 20 years to avoid Y2K bug, good until 2020. */
if (t->tm_year >= 100)
t->tm_year -= 20;
}
if ((regB & 0x04) == 0) {
/* Convert binary to BCD (default RTC mode) */
t->tm_year = dec_to_bcd(t->tm_year % 100);
t->tm_mon = dec_to_bcd(t->tm_mon);
t->tm_mday = dec_to_bcd(t->tm_mday);
t->tm_hour = dec_to_bcd(t->tm_hour);
t->tm_min = dec_to_bcd(t->tm_min);
t->tm_sec = dec_to_bcd(t->tm_sec);
}
write_register(RTC_YEAR, t->tm_year);
write_register(RTC_MONTH, t->tm_mon);
write_register(RTC_MDAY, t->tm_mday);
write_register(RTC_HOUR, t->tm_hour);
write_register(RTC_MIN, t->tm_min);
write_register(RTC_SEC, t->tm_sec);
/* Stop the clock. */
regA = read_register(RTC_REG_A);
write_register(RTC_REG_A, regA | RTC_A_DV_STOP);
/* Allow updates and restart the clock. */
write_register(RTC_REG_B, regB);
write_register(RTC_REG_A, regA);
return OK;
}
static int
write_register(int reg_addr, int value)
{
if (sys_outb(RTC_INDEX, reg_addr) != OK) {
log_warn(&log, "outb failed of %x\n", RTC_INDEX);
return -1;
}
if (sys_outb(RTC_IO, value) != OK) {
log_warn(&log, "outb failed of %x (index %x)\n", RTC_IO,
reg_addr);
return -1;
}
return OK;
}
static int
arch_pwr_off(void)
{
/* Not Implemented */
return ENOSYS;
}
static void
arch_exit(void)
{
/* Nothing to clean up here */
log_debug(&log, "Exiting...");
}
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