99 lines
3.0 KiB
C
99 lines
3.0 KiB
C
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/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2021-05-20 bigmagic first version
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*/
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#include "rtthread.h"
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#include "plic.h"
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#include <riscv_io.h>
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#include "encoding.h"
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/*
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* Each PLIC interrupt source can be assigned a priority by writing
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* to its 32-bit memory-mapped priority register.
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* The QEMU-virt (the same as FU540-C000) supports 7 levels of priority.
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* A priority value of 0 is reserved to mean "never interrupt" and
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* effectively disables the interrupt.
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* Priority 1 is the lowest active priority, and priority 7 is the highest.
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* Ties between global interrupts of the same priority are broken by
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* the Interrupt ID; interrupts with the lowest ID have the highest
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* effective priority.
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*/
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void plic_set_priority(int irq, int priority)
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{
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*(uint32_t*)PLIC_PRIORITY(irq) = priority;
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}
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/*
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* Each global interrupt can be enabled by setting the corresponding
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* bit in the enables registers.
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*/
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void plic_irq_enable(int irq)
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{
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int hart = r_mhartid();
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*(uint32_t*)PLIC_ENABLE(hart) = ((*(uint32_t*)PLIC_ENABLE(hart)) | (1 << irq));
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#ifdef RISCV_S_MODE
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set_csr(sie, read_csr(sie) | MIP_SEIP);
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#else
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set_csr(mie, read_csr(mie) | MIP_MEIP);
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#endif
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}
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void plic_irq_disable(int irq)
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{
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int hart = r_mhartid();
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*(uint32_t*)PLIC_ENABLE(hart) = (((*(uint32_t*)PLIC_ENABLE(hart)) & (~(1 << irq))));
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}
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/*
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* PLIC will mask all interrupts of a priority less than or equal to threshold.
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* Maximum threshold is 7.
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* For example, a threshold value of zero permits all interrupts with
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* non-zero priority, whereas a value of 7 masks all interrupts.
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* Notice, the threshold is global for PLIC, not for each interrupt source.
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*/
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void plic_set_threshold(int threshold)
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{
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int hart = r_mhartid();
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*(uint32_t*)PLIC_THRESHOLD(hart) = threshold;
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}
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/*
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* DESCRIPTION:
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* Query the PLIC what interrupt we should serve.
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* Perform an interrupt claim by reading the claim register, which
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* returns the ID of the highest-priority pending interrupt or zero if there
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* is no pending interrupt.
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* A successful claim also atomically clears the corresponding pending bit
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* on the interrupt source.
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* RETURN VALUE:
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* the ID of the highest-priority pending interrupt or zero if there
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* is no pending interrupt.
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*/
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int plic_claim(void)
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{
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int hart = r_mhartid();
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int irq = *(uint32_t*)PLIC_CLAIM(hart);
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return irq;
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}
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/*
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* DESCRIPTION:
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* Writing the interrupt ID it received from the claim (irq) to the
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* complete register would signal the PLIC we've served this IRQ.
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* The PLIC does not check whether the completion ID is the same as the
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* last claim ID for that target. If the completion ID does not match an
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* interrupt source that is currently enabled for the target, the completion
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* is silently ignored.
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* RETURN VALUE: none
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*/
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void plic_complete(int irq)
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{
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int hart = r_mhartid();
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*(uint32_t*)PLIC_COMPLETE(hart) = irq;
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}
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