Robert Allan JamesandClaude Sonnet 5
5f4df673c1
Punch list §25 item 4.3.5b complete. sie.SEIE enabled, PLIC threshold/claim/complete wired into the trap handler. Verified with a UART-loopback synthetic interrupt (PLIC has no software set-pending register, unlike GICv2): claim_count=1, last_irq=10, IIR confirms genuine receive-data cause, byte matched exactly. Self-test code run once for evidence then fully reverted, per Captain Bob's ruling; only the permanent substrate remains, no source enabled by default. Three-arch acceptance boot clean, zero exceptions. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
54 lines
1.8 KiB
C
54 lines
1.8 KiB
C
/*
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StarForth — Steady-State Virtual Machine Runtime
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Copyright (c) 2023–2025 Robert A. James. All rights reserved.
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Licensed under the StarForth License, Version 1.0.
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*/
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/**
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* plic.h - Platform-Level Interrupt Controller interface (riscv64 only)
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*
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* Item 4.3.5a (FABRIC.md §27.5): Phase 0 (0.2/0.3) only ever enabled the
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* S-mode *timer* interrupt (sie.STIE). External interrupts (sie.SEIE) were
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* never touched, and the PLIC -- the only external-interrupt path on
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* RISC-V, there is no legacy PIC or I/O APIC equivalent -- had no driver
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* at all before this item. Pure substrate: this item wires the mechanism
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* (claim/dispatch/complete) with no permanent source enabled by default;
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* a real consumer (4.3.5b, virtio-keyboard) enables its own source later.
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*/
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#ifndef STARKERNEL_PLIC_H
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#define STARKERNEL_PLIC_H
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#include <stdint.h>
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/**
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* Map the PLIC and set the S-mode hart-0 context's priority threshold to 0
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* (maximally permissive -- safe because nothing is enabled at any source
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* by default; enabling a source is what actually lets it reach claim()).
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* Also sets sie.SEIE. Does not touch sstatus.SIE -- arch_enable_interrupts()
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* still owns that, same as the timer.
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*
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* @return 0 on success.
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*/
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int plic_init(void);
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/** Set a source's interrupt priority (1-7; 0 means "never interrupt"). */
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void plic_set_priority(uint32_t irq, uint32_t priority);
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/** Enable a source for the S-mode hart-0 context. */
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void plic_enable(uint32_t irq);
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/** Disable a source for the S-mode hart-0 context. */
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void plic_disable(uint32_t irq);
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/**
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* Claim the highest-priority pending interrupt for the S-mode hart-0
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* context. Returns the source ID, or 0 if none is pending.
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*/
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uint32_t plic_claim(void);
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/** Signal completion of the source previously returned by plic_claim(). */
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void plic_complete(uint32_t irq);
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#endif /* STARKERNEL_PLIC_H */
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