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/***************************************************************************
* Copyright (c) 2026 Eclipse ThreadX contributors
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* AI Disclosure: This file was largely AI-generated by Claude Code (Opus 5.5).
* The AI-generated portions may be considered public domain (CC0-1.0)
* and not subject to the project's licence. The human contributor has
* reviewed and verified that the code is correct.
*
* SPDX-License-Identifier: MIT and CC0-1.0
**************************************************************************/
/* PLIC driver for Erbium, machine-mode context of the current hart. */
#include "plic.h"
#include <stddef.h>
static irq_callback callbacks[MAX_CALLBACK_NUM];
/* Source 0 is reserved and the six sources fit in the first enable word. */
static int plic_source_valid(int irqno)
{
return (irqno > 0) && (irqno < MAX_CALLBACK_NUM);
}
void plic_irq_enable(int irqno)
{
volatile uint32_t *reg = (volatile uint32_t *)PLIC_MENABLE(riscv_get_core());
int intr_enable;
if (!plic_source_valid(irqno))
return;
intr_enable = riscv_mintr_save();
*reg = *reg | (1u << (unsigned int)irqno);
riscv_mintr_restore(intr_enable);
}
void plic_irq_disable(int irqno)
{
volatile uint32_t *reg = (volatile uint32_t *)PLIC_MENABLE(riscv_get_core());
int intr_enable;
if (!plic_source_valid(irqno))
return;
intr_enable = riscv_mintr_save();
*reg = *reg & ~(1u << (unsigned int)irqno);
riscv_mintr_restore(intr_enable);
}
int plic_register_callback(int irqno, irq_callback callback)
{
if (!plic_source_valid(irqno))
return -1;
callbacks[irqno] = callback;
return 0;
}
int plic_unregister_callback(int irqno)
{
return plic_register_callback(irqno, NULL);
}
int plic_init(void)
{
uintptr_t hart = riscv_get_core();
for (int i = 0; i < MAX_CALLBACK_NUM; i++)
callbacks[i] = NULL;
/* Do not depend on the reset state or on a prior boot stage: start
with every source disabled for this context. Drivers enable their
own sources. */
*(volatile uint32_t *)PLIC_MENABLE(hart) = 0;
/* The values the silicon hardwires; see plic.h. */
*(volatile uint32_t *)PLIC_MTHRESHOLD(hart) = 0;
for (int i = 1; i <= PLIC_NUM_SOURCES; i++)
*(volatile uint32_t *)PLIC_PRIORITY(i) = 1;
return 0;
}
int plic_claim(void)
{
return (int)(*(volatile uint32_t *)PLIC_MCLAIM(riscv_get_core()));
}
void plic_complete(int irqno)
{
*(volatile uint32_t *)PLIC_MCOMPLETE(riscv_get_core()) = (uint32_t)irqno;
}
int plic_irq_intr(void)
{
int ret = -1;
int irqno = plic_claim();
/* Nothing pending: another context claimed it first. */
if (irqno == 0)
return 0;
if (!plic_source_valid(irqno))
{
plic_complete(irqno);
return -1;
}
if (callbacks[irqno] != NULL)
ret = (callbacks[irqno])(irqno);
plic_complete(irqno);
return ret;
}
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