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seabios/src/clock.c

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// 16bit code to handle system clocks.
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002 MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "biosvar.h" // SET_BDA
#include "util.h" // debug_enter
#include "disk.h" // floppy_tick
#include "cmos.h" // inb_cmos
#include "pic.h" // eoi_pic1
#include "bregs.h" // struct bregs
#include "biosvar.h" // GET_GLOBAL
// RTC register flags
#define RTC_A_UIP 0x80
#define RTC_B_SET 0x80
#define RTC_B_PIE 0x40
#define RTC_B_AIE 0x20
#define RTC_B_UIE 0x10
// Bits for PORT_PS2_CTRLB
#define PPCB_T2GATE (1<<0)
#define PPCB_SPKR (1<<1)
#define PPCB_T2OUT (1<<5)
// Bits for PORT_PIT_MODE
#define PM_SEL_TIMER0 (0<<6)
#define PM_SEL_TIMER1 (1<<6)
#define PM_SEL_TIMER2 (2<<6)
#define PM_SEL_READBACK (3<<6)
#define PM_ACCESS_LATCH (0<<4)
#define PM_ACCESS_LOBYTE (1<<4)
#define PM_ACCESS_HIBYTE (2<<4)
#define PM_ACCESS_WORD (3<<4)
#define PM_MODE0 (0<<1)
#define PM_MODE1 (1<<1)
#define PM_MODE2 (2<<1)
#define PM_MODE3 (3<<1)
#define PM_MODE4 (4<<1)
#define PM_MODE5 (5<<1)
#define PM_CNT_BINARY (0<<0)
#define PM_CNT_BCD (1<<0)
/****************************************************************
* TSC timer
****************************************************************/
#define PIT_TICK_RATE 1193182 // Underlying HZ of PIT
#define CALIBRATE_COUNT 0x800 // Approx 1.7ms
u32 cpu_khz VAR16_32;
static void
calibrate_tsc()
{
// Setup "timer2"
u8 orig = inb(PORT_PS2_CTRLB);
outb((orig & ~PPCB_SPKR) | PPCB_T2GATE, PORT_PS2_CTRLB);
/* binary, mode 0, LSB/MSB, Ch 2 */
outb(PM_SEL_TIMER2|PM_ACCESS_WORD|PM_MODE0|PM_CNT_BINARY, PORT_PIT_MODE);
/* LSB of ticks */
outb(CALIBRATE_COUNT & 0xFF, PORT_PIT_COUNTER2);
/* MSB of ticks */
outb(CALIBRATE_COUNT >> 8, PORT_PIT_COUNTER2);
u64 start = rdtscll();
while ((inb(PORT_PS2_CTRLB) & PPCB_T2OUT) == 0)
;
u64 end = rdtscll();
// Restore PORT_PS2_CTRLB
outb(orig, PORT_PS2_CTRLB);
// Store calibrated cpu khz.
u64 diff = end - start;
dprintf(6, "tsc calibrate start=%u end=%u diff=%u\n"
, (u32)start, (u32)end, (u32)diff);
u32 hz = diff * PIT_TICK_RATE / CALIBRATE_COUNT;
SET_GLOBAL(cpu_khz, hz / 1000);
dprintf(1, "CPU Mhz=%u\n", hz / 1000000);
}
static void
tscsleep(u64 diff)
{
u64 start = rdtscll();
u64 end = start + diff;
while (rdtscll() < end)
cpu_relax();
}
void
ndelay(u32 count)
{
u32 khz = GET_GLOBAL(cpu_khz);
tscsleep(count * khz / 1000000);
}
void
udelay(u32 count)
{
u32 khz = GET_GLOBAL(cpu_khz);
tscsleep(count * khz / 1000);
}
void
mdelay(u32 count)
{
u32 khz = GET_GLOBAL(cpu_khz);
tscsleep(count * khz);
}
// Return the TSC value that is 'msecs' time in the future.
u64
calc_future_tsc(u32 msecs)
{
u32 khz = GET_GLOBAL(cpu_khz);
return rdtscll() + ((u64)khz * msecs);
}
/****************************************************************
* Init
****************************************************************/
static int
rtc_updating()
{
// This function checks to see if the update-in-progress bit
// is set in CMOS Status Register A. If not, it returns 0.
// If it is set, it tries to wait until there is a transition
// to 0, and will return 0 if such a transition occurs. A -1
// is returned only after timing out. The maximum period
// that this bit should be set is constrained to 244useconds, so
// we wait for 1 msec max.
if ((inb_cmos(CMOS_STATUS_A) & 0x80) == 0)
return 0;
u64 end = calc_future_tsc(1);
do {
if ((inb_cmos(CMOS_STATUS_A) & 0x80) == 0)
return 0;
} while (rdtscll() <= end);
// update-in-progress never transitioned to 0
return -1;
}
static void
pit_setup()
{
// timer0: binary count, 16bit count, mode 2
outb(PM_SEL_TIMER0|PM_ACCESS_WORD|PM_MODE2|PM_CNT_BINARY, PORT_PIT_MODE);
// maximum count of 0000H = 18.2Hz
outb(0x0, PORT_PIT_COUNTER0);
outb(0x0, PORT_PIT_COUNTER0);
}
static u32
bcd2bin(u8 val)
{
return (val & 0xf) + ((val >> 4) * 10);
}
void
timer_setup()
{
dprintf(3, "init timer\n");
calibrate_tsc();
pit_setup();
rtc_updating();
u32 seconds = bcd2bin(inb_cmos(CMOS_RTC_SECONDS));
u32 ticks = (seconds * 18206507) / 1000000;
u32 minutes = bcd2bin(inb_cmos(CMOS_RTC_MINUTES));
ticks += (minutes * 10923904) / 10000;
u32 hours = bcd2bin(inb_cmos(CMOS_RTC_HOURS));
ticks += (hours * 65543427) / 1000;
SET_BDA(timer_counter, ticks);
SET_BDA(timer_rollover, 0);
enable_hwirq(0, entry_08);
enable_hwirq(8, entry_70);
}
static void
init_rtc()
{
outb_cmos(0x26, CMOS_STATUS_A);
outb_cmos(0x02, CMOS_STATUS_B);
inb_cmos(CMOS_STATUS_C);
inb_cmos(CMOS_STATUS_D);
}
/****************************************************************
* Standard clock functions
****************************************************************/
// get current clock count
static void
handle_1a00(struct bregs *regs)
{
u32 ticks = GET_BDA(timer_counter);
regs->cx = ticks >> 16;
regs->dx = ticks;
regs->al = GET_BDA(timer_rollover);
SET_BDA(timer_rollover, 0); // reset flag
set_success(regs);
}
// Set Current Clock Count
static void
handle_1a01(struct bregs *regs)
{
u32 ticks = (regs->cx << 16) | regs->dx;
SET_BDA(timer_counter, ticks);
SET_BDA(timer_rollover, 0); // reset flag
// XXX - should use set_code_success()?
regs->ah = 0;
set_success(regs);
}
// Read CMOS Time
static void
handle_1a02(struct bregs *regs)
{
if (rtc_updating()) {
set_fail(regs);
return;
}
regs->dh = inb_cmos(CMOS_RTC_SECONDS);
regs->cl = inb_cmos(CMOS_RTC_MINUTES);
regs->ch = inb_cmos(CMOS_RTC_HOURS);
regs->dl = inb_cmos(CMOS_STATUS_B) & 0x01;
regs->ah = 0;
regs->al = regs->ch;
set_success(regs);
}
// Set CMOS Time
static void
handle_1a03(struct bregs *regs)
{
// Using a debugger, I notice the following masking/setting
// of bits in Status Register B, by setting Reg B to
// a few values and getting its value after INT 1A was called.
//
// try#1 try#2 try#3
// before 1111 1101 0111 1101 0000 0000
// after 0110 0010 0110 0010 0000 0010
//
// Bit4 in try#1 flipped in hardware (forced low) due to bit7=1
// My assumption: RegB = ((RegB & 01100000b) | 00000010b)
if (rtc_updating()) {
init_rtc();
// fall through as if an update were not in progress
}
outb_cmos(regs->dh, CMOS_RTC_SECONDS);
outb_cmos(regs->cl, CMOS_RTC_MINUTES);
outb_cmos(regs->ch, CMOS_RTC_HOURS);
// Set Daylight Savings time enabled bit to requested value
u8 val8 = (inb_cmos(CMOS_STATUS_B) & 0x60) | 0x02 | (regs->dl & 0x01);
outb_cmos(val8, CMOS_STATUS_B);
regs->ah = 0;
regs->al = val8; // val last written to Reg B
set_success(regs);
}
// Read CMOS Date
static void
handle_1a04(struct bregs *regs)
{
regs->ah = 0;
if (rtc_updating()) {
set_fail(regs);
return;
}
regs->cl = inb_cmos(CMOS_RTC_YEAR);
regs->dh = inb_cmos(CMOS_RTC_MONTH);
regs->dl = inb_cmos(CMOS_RTC_DAY_MONTH);
regs->ch = inb_cmos(CMOS_CENTURY);
regs->al = regs->ch;
set_success(regs);
}
// Set CMOS Date
static void
handle_1a05(struct bregs *regs)
{
// Using a debugger, I notice the following masking/setting
// of bits in Status Register B, by setting Reg B to
// a few values and getting its value after INT 1A was called.
//
// try#1 try#2 try#3 try#4
// before 1111 1101 0111 1101 0000 0010 0000 0000
// after 0110 1101 0111 1101 0000 0010 0000 0000
//
// Bit4 in try#1 flipped in hardware (forced low) due to bit7=1
// My assumption: RegB = (RegB & 01111111b)
if (rtc_updating()) {
init_rtc();
set_fail(regs);
return;
}
outb_cmos(regs->cl, CMOS_RTC_YEAR);
outb_cmos(regs->dh, CMOS_RTC_MONTH);
outb_cmos(regs->dl, CMOS_RTC_DAY_MONTH);
outb_cmos(regs->ch, CMOS_CENTURY);
// clear halt-clock bit
u8 val8 = inb_cmos(CMOS_STATUS_B) & ~RTC_B_SET;
outb_cmos(val8, CMOS_STATUS_B);
regs->ah = 0;
regs->al = val8; // AL = val last written to Reg B
set_success(regs);
}
// Set Alarm Time in CMOS
static void
handle_1a06(struct bregs *regs)
{
// Using a debugger, I notice the following masking/setting
// of bits in Status Register B, by setting Reg B to
// a few values and getting its value after INT 1A was called.
//
// try#1 try#2 try#3
// before 1101 1111 0101 1111 0000 0000
// after 0110 1111 0111 1111 0010 0000
//
// Bit4 in try#1 flipped in hardware (forced low) due to bit7=1
// My assumption: RegB = ((RegB & 01111111b) | 00100000b)
u8 val8 = inb_cmos(CMOS_STATUS_B); // Get Status Reg B
regs->ax = 0;
if (val8 & 0x20) {
// Alarm interrupt enabled already
set_fail(regs);
return;
}
if (rtc_updating()) {
init_rtc();
// fall through as if an update were not in progress
}
outb_cmos(regs->dh, CMOS_RTC_SECONDS_ALARM);
outb_cmos(regs->cl, CMOS_RTC_MINUTES_ALARM);
outb_cmos(regs->ch, CMOS_RTC_HOURS_ALARM);
// enable Status Reg B alarm bit, clear halt clock bit
outb_cmos((val8 & ~RTC_B_SET) | RTC_B_AIE, CMOS_STATUS_B);
set_success(regs);
}
// Turn off Alarm
static void
handle_1a07(struct bregs *regs)
{
// Using a debugger, I notice the following masking/setting
// of bits in Status Register B, by setting Reg B to
// a few values and getting its value after INT 1A was called.
//
// try#1 try#2 try#3 try#4
// before 1111 1101 0111 1101 0010 0000 0010 0010
// after 0100 0101 0101 0101 0000 0000 0000 0010
//
// Bit4 in try#1 flipped in hardware (forced low) due to bit7=1
// My assumption: RegB = (RegB & 01010111b)
u8 val8 = inb_cmos(CMOS_STATUS_B); // Get Status Reg B
// clear clock-halt bit, disable alarm bit
outb_cmos(val8 & ~(RTC_B_SET|RTC_B_AIE), CMOS_STATUS_B);
regs->ah = 0;
regs->al = val8; // val last written to Reg B
set_success(regs);
}
// Unsupported
static void
handle_1aXX(struct bregs *regs)
{
set_fail(regs);
}
// INT 1Ah Time-of-day Service Entry Point
void VISIBLE16
handle_1a(struct bregs *regs)
{
debug_enter(regs, DEBUG_HDL_1a);
switch (regs->ah) {
case 0x00: handle_1a00(regs); break;
case 0x01: handle_1a01(regs); break;
case 0x02: handle_1a02(regs); break;
case 0x03: handle_1a03(regs); break;
case 0x04: handle_1a04(regs); break;
case 0x05: handle_1a05(regs); break;
case 0x06: handle_1a06(regs); break;
case 0x07: handle_1a07(regs); break;
case 0xb1: handle_1ab1(regs); break;
default: handle_1aXX(regs); break;
}
}
// User Timer Tick
void VISIBLE16
handle_1c()
{
debug_isr(DEBUG_ISR_1c);
}
// INT 08h System Timer ISR Entry Point
void VISIBLE16
handle_08()
{
debug_isr(DEBUG_ISR_08);
floppy_tick();
u32 counter = GET_BDA(timer_counter);
counter++;
// compare to one days worth of timer ticks at 18.2 hz
if (counter >= 0x001800B0) {
// there has been a midnight rollover at this point
counter = 0;
SET_BDA(timer_rollover, GET_BDA(timer_rollover) + 1);
}
SET_BDA(timer_counter, counter);
// chain to user timer tick INT #0x1c
u32 eax=0, flags;
call16_simpint(0x1c, &eax, &flags);
eoi_pic1();
}
/****************************************************************
* Periodic timer
****************************************************************/
static int
set_usertimer(u32 usecs, u16 seg, u16 offset)
{
if (GET_BDA(rtc_wait_flag) & RWS_WAIT_PENDING)
return -1;
// Interval not already set.
SET_BDA(rtc_wait_flag, RWS_WAIT_PENDING); // Set status byte.
SET_BDA(ptr_user_wait_complete_flag, (seg << 16) | offset);
SET_BDA(user_wait_timeout, usecs);
// Turn on the Periodic Interrupt timer
u8 bRegister = inb_cmos(CMOS_STATUS_B);
outb_cmos(bRegister | RTC_B_PIE, CMOS_STATUS_B);
return 0;
}
static void
clear_usertimer()
{
// Turn off status byte.
SET_BDA(rtc_wait_flag, 0);
// Clear the Periodic Interrupt.
u8 bRegister = inb_cmos(CMOS_STATUS_B);
outb_cmos(bRegister & ~RTC_B_PIE, CMOS_STATUS_B);
}
#define RET_ECLOCKINUSE 0x83
// Wait for CX:DX microseconds
void
handle_1586(struct bregs *regs)
{
// Use the rtc to wait for the specified time.
u8 statusflag = 0;
u32 count = (regs->cx << 16) | regs->dx;
int ret = set_usertimer(count, GET_SEG(SS), (u32)&statusflag);
if (ret) {
set_code_fail(regs, RET_ECLOCKINUSE);
return;
}
irq_enable();
while (!statusflag)
cpu_relax();
irq_disable();
set_success(regs);
}
// Set Interval requested.
static void
handle_158300(struct bregs *regs)
{
int ret = set_usertimer((regs->cx << 16) | regs->dx, regs->es, regs->bx);
if (ret)
// Interval already set.
set_code_fail(regs, RET_EUNSUPPORTED);
else
set_success(regs);
}
// Clear interval requested
static void
handle_158301(struct bregs *regs)
{
clear_usertimer();
set_success(regs);
}
static void
handle_1583XX(struct bregs *regs)
{
set_code_fail(regs, RET_EUNSUPPORTED);
regs->al--;
}
void
handle_1583(struct bregs *regs)
{
switch (regs->al) {
case 0x00: handle_158300(regs); break;
case 0x01: handle_158301(regs); break;
default: handle_1583XX(regs); break;
}
}
// int70h: IRQ8 - CMOS RTC
void VISIBLE16
handle_70()
{
debug_isr(DEBUG_ISR_70);
// Check which modes are enabled and have occurred.
u8 registerB = inb_cmos(CMOS_STATUS_B);
u8 registerC = inb_cmos(CMOS_STATUS_C);
if (!(registerB & (RTC_B_PIE|RTC_B_AIE)))
goto done;
if (registerC & 0x20) {
// Handle Alarm Interrupt.
u32 eax=0, flags;
call16_simpint(0x4a, &eax, &flags);
}
if (!(registerC & 0x40))
goto done;
// Handle Periodic Interrupt.
if (!GET_BDA(rtc_wait_flag))
goto done;
// Wait Interval (Int 15, AH=83) active.
u32 time = GET_BDA(user_wait_timeout); // Time left in microseconds.
if (time < 0x3D1) {
// Done waiting - write to specified flag byte.
u32 segoff = GET_BDA(ptr_user_wait_complete_flag);
u16 segment = segoff >> 16;
u16 offset = segoff & 0xffff;
u8 oldval = GET_FARVAR(segment, *(u8*)(offset+0));
SET_FARVAR(segment, *(u8*)(offset+0), oldval | 0x80);
clear_usertimer();
} else {
// Continue waiting.
time -= 0x3D1;
SET_BDA(user_wait_timeout, time);
}
done:
eoi_pic2();
}
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