作業系統工程-Interrupt

Table Of Content

tags: 作業系統工程 Operating System Programming note, 110-1, 2021

• 作業系統工程-Interrupt
  • Table Of Content
• RT-Thread 中斷管理 function
• RT-Thread include .h file
  • Interrupt handler definition
  • Interrupt interfaces
• Interrupt .h file
• 稍微參考其中幾個 function 的寫法
  • void rt_hw_interrupt_init();
  • void rt_hw_interrupt_mask();
  • void rt_hw_interrupt_umask();
  • rt_isr_handler_t rt_hw_interrupt_install();

---

RT-Thread 中斷管理 function

RT-Thread include .h file

Interrupt handler definition

typedef void (*rt_isr_handler_t)(int vector, void *param);

struct rt_irq_desc
{
    rt_isr_handler_t handler;
    void            *param;

#ifdef RT_USING_INTERRUPT_INFO
    char             name[RT_NAME_MAX];
    rt_uint32_t      counter;
#endif
};

Interrupt interfaces

void rt_hw_interrupt_init(void);
void rt_hw_interrupt_mask(int vector);
void rt_hw_interrupt_umask(int vector);
rt_isr_handler_t rt_hw_interrupt_install(int vector, rt_isr_handler_t handler, void *param, const char *name);

• 以 ARM Cortex-a 介紹相關 function 內的 Coding

Interrupt .h file

#define __INTERRUPT_H__

#include <rthw.h>
#include <board.h>

#define INT_IRQ     0x00
#define INT_FIQ     0x01

void rt_hw_vector_init(void);

void rt_hw_interrupt_control(int vector, int priority, int route);

void rt_hw_interrupt_init(void);
void rt_hw_interrupt_mask(int vector);
void rt_hw_interrupt_umask(int vector);

int rt_hw_interrupt_get_irq(void);
void rt_hw_interrupt_ack(int vector);

rt_isr_handler_t rt_hw_interrupt_install(int vector, rt_isr_handler_t handler,
        void *param, const char *name);

#endif

稍微參考其中幾個 function 的寫法

void rt_hw_interrupt_init();

• 初始化

1. 中斷向量表

void rt_hw_vector_init(void)
{
    rt_cpu_vector_set_base((unsigned int)&system_vectors);
}

2. 例外處理表

struct rt_irq_desc isr_table[MAX_HANDLERS];

void rt_hw_interrupt_init(void)
{
    rt_uint32_t gic_cpu_base;
    rt_uint32_t gic_dist_base;
    rt_uint32_t gic_irq_start;

    rt_hw_vector_init();/* 1. initialize vector table */

    rt_memset(isr_table, 0x00, sizeof(isr_table));/* 2. initialize exceptions table */

    /* initialize ARM GIC */
    gic_dist_base = platform_get_gic_dist_base();
    gic_cpu_base = platform_get_gic_cpu_base();

    gic_irq_start = GIC_IRQ_START;

    arm_gic_dist_init(0, gic_dist_base, gic_irq_start);
    arm_gic_cpu_init(0, gic_cpu_base);
}

void rt_hw_interrupt_mask();

void rt_hw_interrupt_mask(int vector)
{
    arm_gic_mask(0, vector);
}

• Cortex-a 中 gic.c 的實作方式

#define GIC_DIST_ENABLE_CLEAR(hw_base, n)   __REG32((hw_base) + 0x180 + ((n)/32) * 4)

void arm_gic_mask(rt_uint32_t index, int irq)
{
    rt_uint32_t mask = 1 << (irq % 32);

    RT_ASSERT(index < ARM_GIC_MAX_NR);

    irq = irq - _gic_table[index].offset;
    RT_ASSERT(irq >= 0);

    GIC_DIST_ENABLE_CLEAR(_gic_table[index].dist_hw_base, irq) = mask;
    // 差別在這行！
}

void rt_hw_interrupt_umask();

void rt_hw_interrupt_umask(int vector)
{
    arm_gic_umask(0, vector);
}

• Cortex-a 中 gic.c 的實作方式

#define GIC_DIST_ENABLE_SET(hw_base, n)     __REG32((hw_base) + 0x100 + ((n)/32) * 4)

void arm_gic_umask(rt_uint32_t index, int irq)
{
    rt_uint32_t mask = 1 << (irq % 32);

    RT_ASSERT(index < ARM_GIC_MAX_NR);

    irq = irq - _gic_table[index].offset;
    RT_ASSERT(irq >= 0);

    GIC_DIST_ENABLE_SET(_gic_table[index].dist_hw_base, irq) = mask;
    // 差別在這行！
}

rt_isr_handler_t rt_hw_interrupt_install();

rt_isr_handler_t rt_hw_interrupt_install(int vector, rt_isr_handler_t handler,
        void *param, const char *name)
{
    rt_isr_handler_t old_handler = RT_NULL;

    if (vector < MAX_HANDLERS)
    {
        old_handler = isr_table[vector].handler;

        if (handler != RT_NULL)
        {
#ifdef RT_USING_INTERRUPT_INFO
            rt_strncpy(isr_table[vector].name, name, RT_NAME_MAX);
#endif /* RT_USING_INTERRUPT_INFO */
            isr_table[vector].handler = handler;
            isr_table[vector].param = param;
        }
    }

    return old_handler;
}