mirror of
https://github.com/JannisHeydemann/BoredOS.git
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55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
// Copyright (c) 2023-2026 Chris (boreddevnl)
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// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
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// This header needs to maintain in any file it is present in, as per the GPL license terms.
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#include "lapic.h"
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#include "platform.h"
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extern void serial_write(const char *str);
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// LAPIC is at physical 0xFEE00000. Access via HHDM.
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static volatile uint32_t *lapic_base = 0;
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// LAPIC register offsets (byte offsets, divided by 4 for uint32_t* indexing)
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#define LAPIC_ID (0x020 / 4)
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#define LAPIC_EOI (0x0B0 / 4)
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#define LAPIC_SVR (0x0F0 / 4)
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#define LAPIC_ICR_LOW (0x300 / 4)
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#define LAPIC_ICR_HIGH (0x310 / 4)
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void lapic_enable(void) {
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if (!lapic_base) return;
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// Enable the LAPIC by setting the Spurious Interrupt Vector Register
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// Bit 8 = APIC Software Enable, vector = 0xFF (spurious)
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lapic_base[LAPIC_SVR] = 0x1FF;
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}
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void lapic_init(void) {
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extern uint64_t hhdm_offset;
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lapic_base = (volatile uint32_t *)(hhdm_offset + 0xFEE00000ULL);
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lapic_enable();
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serial_write("[LAPIC] Initialized at HHDM + 0xFEE00000\n");
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}
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void lapic_eoi(void) {
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if (lapic_base) {
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lapic_base[LAPIC_EOI] = 0;
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}
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}
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void lapic_send_ipi_all(void) {
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if (!lapic_base) return;
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// Send IPI to all excluding self
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// ICR format:
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// bits 7:0 = vector (IPI_SCHED_VECTOR = 0x41)
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// bits 10:8 = delivery mode (000 = Fixed)
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// bit 11 = destination mode (0 = Physical)
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// bit 14 = level (1 = Assert)
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// bits 19:18 = destination shorthand (11 = All Excluding Self)
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uint32_t icr_low = IPI_SCHED_VECTOR | (0b11 << 18) | (1 << 14);
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// Writing ICR_LOW triggers the IPI send
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lapic_base[LAPIC_ICR_LOW] = icr_low;
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}
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