85 lines
2.1 KiB
C
85 lines
2.1 KiB
C
#include "pit.h"
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#include "port.h"
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#include "../cpu/isr.h"
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enum {
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PIT_CRYSTAL_HZ = 1193182,
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CLOCK_PRECISION_HZ = 100,
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PIT_PROGRAM_REG = PIT_CRYSTAL_HZ / CLOCK_PRECISION_HZ,
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PIT_SELECT_CHANNEL0 = 0x0,
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PIT_SELECT_CHANNEL1 = 0x1,
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PIT_SELECT_CHANNEL2 = 0x2,
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PIT_SELECT_CHANNEL_RB = 0x3,
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PIT_ACCESS_MODE_LATCH_COUNT_VALUE_COMMAND = 0x0,
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PIT_ACCESS_MODE_LOBYTE_ONLY = 0x1,
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PIT_ACCESS_MODE_HIBYTE_ONLY = 0x2,
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PIT_ACCESS_MODE_LOHIBYTE = 0x3,
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PIT_MODE_INTERRUPT_ON_TERMINAL_COUNT = 0x0,
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PIT_MODE_HW_ONESHOT = 0x1,
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PIT_MODE_RATE_GENERATOR = 0x2,
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PIT_MODES_SQUARE_WAVE_GENERATOR = 0x3,
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PIT_MODES_SW_TRIGGERRED_STROBE = 0x4,
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PIT_MODES_HW_TRIGGERRED_STROBE = 0x5,
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};
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// Wtf is that O_o
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static timer_callback callbacks[100];
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static int registered_callbacks = 0;
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static volatile uint32_t uptime_ms = 0;
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void add_timer_callback(timer_callback tc) {
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callbacks[registered_callbacks++] = tc;
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}
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static void timer_interrupt_handler(registers_t *r) {
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for (int i = 0; i < registered_callbacks; ++i) {
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callbacks[i]();
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}
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}
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struct pit_command_t {
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unsigned char bcd : 1;
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unsigned char operating_mode : 3;
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unsigned char access_mode : 2;
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unsigned char select_channel : 2;
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} __attribute__((packed));
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static void timer_int_callback(void);
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void init_pit() {
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struct pit_command_t cmd = {
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.select_channel = PIT_SELECT_CHANNEL0,
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.access_mode = PIT_ACCESS_MODE_LOHIBYTE,
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.operating_mode = PIT_MODES_SQUARE_WAVE_GENERATOR,
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.bcd = 0,
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};
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port_byte_out(0x43, *(unsigned char *)(&cmd));
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port_byte_out(0x40, PIT_PROGRAM_REG & 0xff);
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port_byte_out(0x40, (PIT_PROGRAM_REG & 0xff00) >> 8);
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register_interrupt_handler(IRQ0, timer_interrupt_handler);
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add_timer_callback(timer_int_callback);
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}
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static volatile int sleep_counter = 0;
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static void timer_int_callback(void) {
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uptime_ms += 1000 / CLOCK_PRECISION_HZ;
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sleep_counter--;
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}
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uint32_t get_uptime_ms(void) {
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return uptime_ms;
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}
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void msleep(int ms) {
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sleep_counter = ms / 10;
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while (sleep_counter > 0) {
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asm volatile("hlt");
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}
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}
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