#include "platform.h"
#include "plic.h"
#include "plic_driver.h"
#include "encoding.h"
#include <string.h>
//把区间内的值初始化为0，volatile表示变量不需要进行优化，随时可变
void volatile_memzero(u8_t * base, unsigned int size)
{
volatile u8_t * ptr;
for (ptr = base; ptr < (base + size); ptr++){
*ptr = 0;
}
}
//初始化
void PLIC_init (
plic_instance_t * this_plic,
uintptr_t base_addr,
u32_t num_sources,
u32_t num_priorities
)
{
//访问this_plic_struct内的变量
this_plic->base_addr = base_addr;
this_plic->num_sources = num_sources;
this_plic->num_priorities = num_priorities;
// 禁用所有中断
unsigned long hart_id = read_csr(mhartid); //可适用于多核系统
volatile_memzero((u8_t*) (this_plic->base_addr +
PLIC_ENABLE_OFFSET +
(hart_id << PLIC_ENABLE_SHIFT_PER_TARGET)),
//地址区间单位为1byte/8 bit，+8是因为整数的除法上舍入(round up)， 这里num_sources = 64
(num_sources + 8) / 8);
// 将所有中断的优先级设为0
volatile_memzero ((u8_t *)(this_plic->base_addr + PLIC_PRIORITY_OFFSET),
(num_sources + 1) << PLIC_PRIORITY_SHIFT_PER_SOURCE);
// 将优先级阈值初始化为0， volatile表示变量不需要进行优化，随时可变
volatile plic_threshold* threshold = (plic_threshold*)
(this_plic->base_addr +
PLIC_THRESHOLD_OFFSET +
(hart_id << PLIC_THRESHOLD_SHIFT_PER_TARGET));
*threshold = 0; //指针所指向的阈值设为0
}
//设置优先级阈值
void PLIC_set_threshold (plic_instance_t * this_plic,
plic_threshold threshold){
unsigned long hart_id = read_csr(mhartid); //可适用于多核系统
//pointer value
volatile plic_threshold* threshold_ptr = (plic_threshold*) (this_plic->base_addr +
PLIC_THRESHOLD_OFFSET +
(hart_id << PLIC_THRESHOLD_SHIFT_PER_TARGET));
*threshold_ptr = threshold;//address
}
//设置优先级
void PLIC_set_priority (plic_instance_t * this_plic, plic_source source, plic_priority priority){
if (this_plic->num_priorities > 0) {
volatile plic_priority * priority_ptr = (volatile plic_priority *)
(this_plic->base_addr +
PLIC_PRIORITY_OFFSET +
(source << PLIC_PRIORITY_SHIFT_PER_SOURCE)); //地址区间单位为1byte
*priority_ptr = priority;
}
}
//读取中断声明寄存器
plic_source PLIC_claim_interrupt(plic_instance_t * this_plic){
unsigned long hart_id = read_csr(mhartid); //可适用于多核系统
volatile plic_source * claim_addr = (volatile plic_source * )
(this_plic->base_addr +
PLIC_CLAIM_OFFSET +
(hart_id << PLIC_CLAIM_SHIFT_PER_TARGET));
return *claim_addr;
}
//中断完成
void PLIC_complete_interrupt(plic_instance_t * this_plic, plic_source source){
unsigned long hart_id = read_csr(mhartid); //可适用于多核系统
volatile plic_source * claim_addr = (volatile plic_source *) (this_plic->base_addr +
PLIC_CLAIM_OFFSET +
(hart_id << PLIC_CLAIM_SHIFT_PER_TARGET));
*claim_addr = source;
}
这里只列出了主函数中和PLIC相关的函数，主函数中其他的详细部分将在PLIC有关的工程中进行介绍。
//PLIC使能
static void enable_plic_int(u8_t int_src)
{
u8_t reg_off = 0;
u8_t reg_val = 0;
reg_off = (int_src / 32) * 4; //根据定义
reg_val = int_src & 0x1f; //只保留31位，1F（16）=31（10）
PLIC_REG(PLIC_ENABLE_OFFSET + reg_off) |= 1 << reg_val; //立起相应的位
return;
}
//PLIC禁止
static void disable_plic_int(u8_t int_src)
{
u8_t reg_off = 0;
u8_t reg_val = 0;
reg_off = (int_src / 32) * 4; //根据定义
reg_val = int_src & 0x1f; //只保留31位，1F（16）=31（10）
PLIC_REG(PLIC_ENABLE_OFFSET + reg_off) &= ~(1 << reg_val); //清除相应的位
return;
}
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