74 lines
2.4 KiB
C
74 lines
2.4 KiB
C
//
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// Created by rick on 9/22/19.
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//
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#include <cpu/timer.h>
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#include <drivers/ports.h>
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#include <cpu/isr.h>
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#include <libc/libc.h>
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#include <libk/libk.h>
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#include <libk/kprint.h>
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#include <tasks/task.h>
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// https://wiki.osdev.org/PIT
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#define PIT_MODE_BIN_BCD (1 << 0)
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#define PIT_MODE_BIN (0 << 0)
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#define PIT_MODE_BCD (1 << 0)
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#define PIT_GENERATOR_MODE (0b111 << 1)
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#define PIT_MODE_INTERRUPT_ON_TERMINAL_COUNT (0b000 << 1)
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#define PIT_MODE_HARDWARE_RETRIGGERABLE_ONE_SHOT (0b001 << 1)
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#define PIT_MODE_HARDWARE_RATE_GENERATOR (0b010 << 1)
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#define PIT_MODE_HARDWARE_SQUARE_WAVE_GENERATOR (0b011 << 1)
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#define PIT_MODE_SOFTWARE_TRIGGERED_STROBE (0b100 << 1)
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#define PIT_MODE_HARDWARE_TRIGGERED_STROBE (0b101 << 1)
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#define PIT_ACCESS_MODE (0b11 << 4)
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#define PIT_ACCESS_MODE_LATCH_COUNT (0b00 << 4)
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#define PIT_ACCESS_MODE_L (0b01 << 4)
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#define PIT_ACCESS_MODE_H (0b10 << 4)
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#define PIT_ACCESS_MODE_LH (0b11 << 4)
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#define PIT_CHANNEL (0b11 << 6)
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#define PIT_CHANNEL_0 (0b00 << 6)
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#define PIT_CHANNEL_1 (0b01 << 6)
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#define PIT_CHANNEL_2 (0b10 << 6)
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#define PIT_CHANNEL_READ_BACK (0b11 << 6)
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uint32_t tick = 0;
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static void timer_callback(isr_registers_t *regs) {
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tick++;
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task_switch_next();
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}
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uint32_t timer_get_tick() {
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return tick;
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}
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void sleep(uint32_t milliseconds) {
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uint32_t done = tick + milliseconds;
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while (tick != done) {
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k_wait_for_interrupt();
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}
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}
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void print_current_tick() {
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char msg[32];
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memset(msg, 0, 32);
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itoa(tick, msg, 10);
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kprint(msg);
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kprint("\n");
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}
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int init_timer(uint32_t freq) {
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register_interrupt_handler(IRQ0, timer_callback);
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uint32_t divisor = 1193180 / freq;
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uint8_t low = (uint8_t)(divisor & 0xFF);
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uint8_t high = (uint8_t)((divisor >> 8) & 0xFF);
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port_byte_out(PORT_PIT_COMMAND,
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PIT_MODE_BIN | PIT_MODE_HARDWARE_SQUARE_WAVE_GENERATOR | PIT_ACCESS_MODE_LH | PIT_CHANNEL_0);
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port_byte_out(PORT_PIT_DATA_0, low);
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port_byte_out(PORT_PIT_DATA_0, high);
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return 0;
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}
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