sbosse/basekernel
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Mon 14 Oct 23:06:38 CEST 2024

Browse Source
This commit is contained in:
sbosse 2024-10-14 23:07:30 +02:00
parent eb18aae083
commit c9375c1ea8
1 changed files with 196 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

196
kernel/rtc.c Normal file
View File

@ -0,0 +1,196 @@
/*
Copyright (C) 2015-2019 The University of Notre Dame
This software is distributed under the GNU General Public License.
See the file LICENSE for details.
*/
/*
Driver for the Motorola MC 146818A Real Time Clock
Recommended reading: page 11-15 of the RTC data sheet
*/
#include "kernel/types.h"
#include "ioports.h"
#include "rtc.h"
#include "console.h"
#include "string.h"
#include "interrupt.h"
#define RTC_BASE 0x80
#define RTC_SECONDS (RTC_BASE+0)
#define RTC_SECONDS_ALARM (RTC_BASE+1)
#define RTC_MINUTES (RTC_BASE+2)
#define RTC_MINUTES_ALARM (RTC_BASE+3)
#define RTC_HOURS (RTC_BASE+4)
#define RTC_HOURS_ALARM (RTC_BASE+5)
#define RTC_DAY_OF_WEEK (RTC_BASE+6)
#define RTC_DAY_OF_MONTH (RTC_BASE+7)
#define RTC_MONTH (RTC_BASE+8)
#define RTC_YEAR (RTC_BASE+9)
#define RTC_REGISTER_A (RTC_BASE+10)
#define RTC_REGISTER_B (RTC_BASE+11)
#define RTC_REGISTER_C (RTC_BASE+12)
#define RTC_REGISTER_D (RTC_BASE+13)
#define RTC_ADDRESS_PORT 0x70
#define RTC_DATA_PORT 0x71
/* Register A bits */
#define RTC_A_UIP (1<<7)
#define RTC_A_DV2 (1<<6)
#define RTC_A_DV1 (1<<5)
#define RTC_A_DV0 (1<<4)
#define RTC_A_RS3 (1<<3)
#define RTC_A_RS2 (1<<2)
#define RTC_A_RS1 (1<<1)
#define RTC_A_RS0 (1<<0)
/* Register B bits */
#define RTC_B_SET (1<<7) /* if set, may write new time */
#define RTC_B_PIE (1<<6) /* periodic interrupt enabled */
#define RTC_B_AIE (1<<5) /* alarm interrupt enabled */
#define RTC_B_UIE (1<<4) /* update interrupt enabled */
#define RTC_B_SQWE (1<<3) /* square wave enabled */
#define RTC_B_DM (1<<2) /* data mode: 1=binary 0=decimal */
#define RTC_B_2412 (1<<1) /* 1=24 hour mode 0=12 hour mode */
#define RTC_B_DSE (1<<0) /* daylight savings enable */
/* Register C bits */
/* Note that reading C is necessary to acknowledge an interrupt */
#define RTC_C_IRQF (1<<7) /* 1=any interrupt pending */
#define RTC_C_PF (1<<6) /* periodic interrupt pending */
#define RTC_C_AF (1<<5) /* alarm interrupt pending */
#define RTC_C_UF (1<<4) /* update interrupt pending */
#define SECS_PER_MIN 60
#define SECS_PER_HOUR 3600
#define SECS_PER_DAY SECS_PER_HOUR * 24
#define DAYS_PER_WEEK 7
#define SECS_PER_WEEK SECS_PER_DAY * DAYS_PER_WEEK
#define SECS_PER_YEAR SECS_PER_WEEK * 52
#define LEAP_YEAR(Y) ( (Y>0) && !(Y%4) && ( (Y%100) || !(Y%400) ) )
uint32_t boottime;
static const uint8_t monthDays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
static uint8_t rtc_bcd_to_binary(uint8_t bcd)
{
return (bcd & 0x0f) + (bcd >> 4) * 10;
}
static uint8_t rtc_read_port(uint16_t address)
{
outb_slow(address, RTC_ADDRESS_PORT);
return inb_slow(RTC_DATA_PORT);
}
static void rtc_write_port(uint8_t value, uint16_t address)
{
outb_slow(address, RTC_ADDRESS_PORT);
outb_slow(value, RTC_DATA_PORT);
}
static struct rtc_time cached_time;
static void rtc_fetch_time()
{
struct rtc_time t;
int addpm = 0;
do {
t.second = rtc_read_port(RTC_SECONDS);
t.minute = rtc_read_port(RTC_MINUTES);
t.hour = rtc_read_port(RTC_HOURS);
t.day = rtc_read_port(RTC_DAY_OF_MONTH);
t.month = rtc_read_port(RTC_MONTH);
t.year = rtc_read_port(RTC_YEAR);
} while(t.second != rtc_read_port(RTC_SECONDS));
if(t.hour & 0x80) {
addpm = 1;
t.hour &= 0x7f;
} else {
addpm = 0;
}
t.second = rtc_bcd_to_binary(t.second);
t.minute = rtc_bcd_to_binary(t.minute);
t.hour = rtc_bcd_to_binary(t.hour);
if(addpm)
t.hour += 12;
t.day = rtc_bcd_to_binary(t.day);
t.month = rtc_bcd_to_binary(t.month);
t.year = rtc_bcd_to_binary(t.year);
if(t.year >= 70) {
t.year += 1900;
} else {
t.year += 2000;
}
cached_time = t;
}
static void rtc_interrupt_handler(int intr, int code)
{
rtc_fetch_time();
rtc_read_port(RTC_REGISTER_C);
}
void rtc_init()
{
uint8_t status;
status = rtc_read_port(RTC_REGISTER_B);
status |= RTC_B_UIE;
rtc_write_port(status, RTC_REGISTER_B);
interrupt_register(40, rtc_interrupt_handler);
interrupt_enable(40);
rtc_fetch_time();
struct rtc_time t = {0};
rtc_read(&t);
boottime = rtc_time_to_timestamp(&t);
printf("rtc: ready\n");
}
void rtc_read(struct rtc_time *tout)
{
memcpy(tout, &cached_time, sizeof(cached_time));
}
uint32_t rtc_time_to_timestamp(struct rtc_time *t)
{
int i;
uint32_t seconds;
seconds = (t->year - 1970) * (SECS_PER_DAY * 365);
for(i = 1970; i < t->year; i++) {
if(LEAP_YEAR(i)) {
seconds += SECS_PER_DAY;
}
}
for(i = 1; i < t->month; i++) {
if((i == 2) && LEAP_YEAR(t->year)) {
seconds += SECS_PER_DAY * 29;
} else {
seconds += SECS_PER_DAY * monthDays[i - 1];
}
}
seconds += (t->day - 1) * SECS_PER_DAY;
seconds += t->hour * SECS_PER_HOUR;
seconds += t->minute * SECS_PER_MIN;
seconds += t->second;
return seconds;
}