irq_create_mapping(domain, hwirq);
	irq_create_mapping_affinity();
		irq_domain_alloc_descs(); // 创建hw id和irq number的映射
		irq_domain_associate();
			domain->ops->map(); //调用到interrupt controller的map函数

irq_of_parse_and_map(struct device_node *dev, int index);
	of_irq_parse_one(dev, index, &oirq); // 解析设备树
	irq_create_of_mapping(&oirq);
		irq_create_fwspec_mapping();
			irq_create_mapping(domain, hwirq); // 最终还是调用到irq_create_mapping

platform_get_irq();
	platform_get_irq_optional();
		of_irq_get();
			of_irq_parse_one();
			irq_create_of_mapping(); // 到这里和上面一样了

if (irq_domain_is_hierarchy(domain)) {
    virq = irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, fwspec); // 往下追会调用到domain->ops->alloc
    if (virq <= 0)
        return 0;
} else {
    /* Create mapping */
    virq = irq_create_mapping(domain, hwirq); // 往下追会调用到domain->ops->map
    if (!virq)
        return virq;
}

struct irq_desc irq_desc[NR_IRQS] // 全局irq_desc数组，每个外设的中断对应一个irq_desc

// init/main.c
early_irq_init();
	desc_set_defaults(); // 对每个irq_desc都初始化赋值

struct irq_desc {
    struct irq_data        irq_data;
    irq_flow_handler_t    handle_irq;
    struct irqaction    *action;
	//...
}

struct irq_data {
    unsigned int        irq; // IRQ number
    unsigned long        hwirq; //HW interrupt ID
    struct irq_chip        *chip; //该中断描述符对应的irq chip数据结构
    struct irq_domain    *domain; //该中断描述符对应的irq domain数据结构
    void            *handler_data; //和外设specific handler相关的私有数据
    void            *chip_data; //和中断控制器相关的私有数据 e.g.irq_set_chip_data(gpioirq, rtspc);
};

struct irq_chip {
	const char	*name;
	unsigned int	(*irq_startup)(struct irq_data *data); // start up the interrupt (defaults to ->irq_enable if NULL)
	void		(*irq_shutdown)(struct irq_data *data);
	void		(*irq_enable)(struct irq_data *data); // enable the interrupt (defaults to ->irq_unmask if NULL)
	void		(*irq_disable)(struct irq_data *data);
	void		(*irq_mask)(struct irq_data *data);
	void		(*irq_unmask)(struct irq_data *data);
	int		(*irq_set_type)(struct irq_data *data, unsigned int flow_type); // 指定触发方式，电平触发还是边缘触发

irq_set_chip
irq_set_irq_type
irq_set_chip_data
__irq_set_handler
irq_set_chip_and_handler
irq_set_chip_and_handler_name
irq_domain_set_info

// init/main.c
init_IRQ();
//arch/riscv/kernel/irq.c
init_IRQ();
	irqchip_init();
// drivers/irqchip/irqchip.c
irqchip_init();
	of_irq_init();
		IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init); // 进入riscv_intc_init

riscv_intc_init();
intc_domain = irq_domain_add_linear(node, BITS_PER_LONG, &riscv_intc_domain_ops, NULL /// 注册irq_domain
set_handle_irq(&riscv_intc_irq); /// 设置中断handler

// 每个cpu int都会调用到cpu interrupt controller的map函数，会填充irq_desc。
irq_create_mapping();
domain->ops->map;
.map = riscv_intc_domain_map();
	irq_domain_set_info();
		irq_set_chip_and_handler_name(virq, chip, handler, handler_name);
			irq_set_chip();
				desc->irq_data.chip = chip;
			__irq_set_handler();
				desc->handle_irq = handle; // handle是handle_percpu_devid_irq
		irq_set_chip_data(virq, chip_data); // d->host_data irq_domain_add_linear最后一个参数
			desc->irq_data.chip_data = data; // irq chip的私有数据
		irq_set_handler_data(virq, handler_data);
			desc->irq_common_data.handler_data = data; // data=NULL

irq_domain_add_linear(node, nr_irqs + 1, &plic_irqdomain_ops, priv);
irq_of_parse_and_map(node, i);
irq_set_chained_handler(plic_parent_irq, plic_handle_irq); //发生9号外部中断(plic_parent_irq)，会进plic_handle_irq

rtspc->irq_domain = irq_domain_add_linear();
int gpioirq = irq_create_mapping();
irq_set_chip_and_handler();
// 中断来了会先进handle_simple_irq，再进rts_irq_handler
request_irq();

platform_get_irq();
...
irq_create_of_mapping
	irq_create_fwspec_mapping
		irq_domain_alloc_irqs
			__irq_domain_alloc_irqs
				irq_domain_alloc_irqs_hierarchy
					domain->ops->alloc
						irq_domain_translate_onecell
						plic_irqdomain_map
							irq_domain_set_info
								...
  								desc->handle_irq = handle; // handle: handle_fasteoi_irq

// head.S
setup_trap_vector:
	la a0, handle_exception
	csrw CSR_TVEC, a0     // handle_exception地址传入CSR_TVEC
	csrw CSR_SCRATCH, zero   // CSR_SCRATCH清零

// entry.S
ENTRY(handle_exception)
	handle_arch_irq();
		set_handle_irq();
			riscv_intc_irq();
				handle_domain_irq();
					__handle_domain_irq();
						generic_handle_irq();
							generic_handle_irq_desc();
								// 不同的中断控制器在一开始初始化会设置
								desc->handle_irq(desc);
	handle_syscall(); //处理系统调用
	excp_vect_table(); //处理异常

// 这里cpu int会进入handle_percpu_devid_irq, 在irq-riscv-intc.c irq_domain_set_info中设定
handle_percpu_devid_irq();
	action->handler(); // timer-riscv.c 中request_irq会把中断处理函数赋值给action->handler();

// external int 会进入plic_handle_irq, 在irq-realtek-plic.c irq_set_chained_handler中设定
plic_handle_irq();
	generic_handle_irq();
		generic_handle_irq_desc();
			desc->handle_irq(desc);
				handle_fasteoi_irq();
					...
                    // request_irq中会把自定义的handler function赋值给action->handler
                  	action->handler();