Linux aarch64 中断处理全流程分析

	tlmm: pinctrl@400000 {
		compatible = "qcom,pitti-pinctrl";                  // 与驱动匹配
		reg = <0x400000 0x1000000>;
		interrupts = <GIC_SPI 227 IRQ_TYPE_LEVEL_HIGH>;     // 表示其连接在GIC中断控制器的227号共享类型中断上
		gpio-controller;                                    // 标明是一个gpio控制器
		#gpio-cells = <2>;
		interrupt-controller;                               // 标明是一个中断控制器
		#interrupt-cells = <2>;
		wakeup-parent = <&mpm>;
		qcom,gpios-reserved = <36 37 38 39>;
	};

// 假设一个按钮设备使用TLMM的GPIO 5作为中断
button@0 {
    compatible = "gpio-keys";
    
    button0 {
        label = "Volume Up";
        gpios = <&tlmm 5 GPIO_ACTIVE_LOW>;
        // 中断描述：使用tlmm控制器的GPIO 5，下降沿触发
        interrupt-parent = <&tlmm>;
        interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
    };
};

  23 0x30002      0x3        19         0          0          0          0          0          0          0           qcom,smp2p-adsp                ipcc            v.v (struct irq_desc *)0xffffff8002331a00    
  24 0x60002      0x3        4          0          0          0          0          0          0          0           qcom,smp2p-cdsp                ipcc            v.v (struct irq_desc *)0xffffff8002333000   

0x00030002
    ├── 高16位 (0x0003): 可能表示中断控制器ID或bank编号
    └── 低16位 (0x0002): 该控制器上的具体中断线

IRQ  HWIRQ        affinity   CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7        Name                           Chip            IRQ Structure       
   1 0x0          0x3        9868       10031      8613       9408       8928       9616       25598      26045       IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045756a00    
   2 0x1          0x3        5330       2620       2012       1851       1709       1703       17407      13294       IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045755800    
   3 0x2          0x3        1          1          1          1          1          1          1          0           IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045757c00    
   4 0x3          0x3        0          0          0          0          0          0          0          0           IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045754e00    
   5 0x4          0x3        0          0          0          0          0          0          0          1           IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045757800    
   6 0x5          0x3        8902       4995       4536       4901       4530       4886       11392      12431       IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045756e00    
   7 0x6          0x3        0          0          0          0          0          0          0          0           IPI                            GICv3           v.v (struct irq_desc *)0xffffff8045756600    
  11 0x13         0x3        3487       3122       3065       2972       2950       2987       11748      12069       arch_timer                     GICv3           v.v (struct irq_desc *)0xffffff8045757600    
  13 0x26         0x1        26         6          0          0          7          3          13         10          arch_mem_timer                 GICv3           v.v (struct irq_desc *)0xffffff8045754200    
  15 0x15         0x3        11         10         10         9          9          9          49         50          arm-pmu                        GICv3           v.v (struct irq_desc *)0xffffff800b2e1800    
  16 0x16e        0x3        12345      0          0          0          0          0          0          0           ipcc_0                         GICv3           v.v (struct irq_desc *)0xffffff80020f8c00    
  17 0xe5         0x3        0          0          0          0          0          0          0          0           mpm                            GICv3           v.v (struct irq_desc *)0xffffff800b2e4c00    
  18 0x56         0x3        0          0          0          0          0          0          0          0           None                           mpm-gic         v.v (struct irq_desc *)0xffffff8002468a00    
  19 0x0          0x3        0          0          0          0          0          0          0          0           volume_up                      spmi-gpio       v.v (struct irq_desc *)0xffffff8002468c00    
  20 0x103        0x3        0          0          0          0          0          0          0          0           None                           GICv3           v.v (struct irq_desc *)0xffffff80457c2600    
  21 0x61         0x3        0          0          0          0          0          0          0          0           wifi_ant_check                 msmgpio         v.v (struct irq_desc *)0xffffff80023c6400    
  22 0x20         0x3        0          0          0          0          0          0          0          0           apps_wdog_bark                 GICv3           v.v (struct irq_desc *)0xffffff8002235800    
  23 0x30002      0x3        19         0          0          0          0          0          0          0           qcom,smp2p-adsp                ipcc            v.v (struct irq_desc *)0xffffff8002331a00  

/**
 * struct irq_desc - interrupt descriptor
 * @irq_common_data:	per irq and chip data passed down to chip functions
 * @kstat_irqs:		irq stats per cpu
 * @handle_irq:		highlevel irq-events handler
 * @action:		the irq action chain
 * @status_use_accessors: status information
 * @core_internal_state__do_not_mess_with_it: core internal status information
 * @depth:		disable-depth, for nested irq_disable() calls
 * @wake_depth:		enable depth, for multiple irq_set_irq_wake() callers
 * @tot_count:		stats field for non-percpu irqs
 * @irq_count:		stats field to detect stalled irqs
 * @last_unhandled:	aging timer for unhandled count
 * @irqs_unhandled:	stats field for spurious unhandled interrupts
 * @threads_handled:	stats field for deferred spurious detection of threaded handlers
 * @threads_handled_last: comparator field for deferred spurious detection of threaded handlers
 * @lock:		locking for SMP
 * @affinity_hint:	hint to user space for preferred irq affinity
 * @affinity_notify:	context for notification of affinity changes
 * @pending_mask:	pending rebalanced interrupts
 * @threads_oneshot:	bitfield to handle shared oneshot threads
 * @threads_active:	number of irqaction threads currently running
 * @wait_for_threads:	wait queue for sync_irq to wait for threaded handlers
 * @nr_actions:		number of installed actions on this descriptor
 * @no_suspend_depth:	number of irqactions on a irq descriptor with
 *			IRQF_NO_SUSPEND set
 * @force_resume_depth:	number of irqactions on a irq descriptor with
 *			IRQF_FORCE_RESUME set
 * @rcu:		rcu head for delayed free
 * @kobj:		kobject used to represent this struct in sysfs
 * @request_mutex:	mutex to protect request/free before locking desc->lock
 * @dir:		/proc/irq/ procfs entry
 * @debugfs_file:	dentry for the debugfs file
 * @name:		flow handler name for /proc/interrupts output
 */
struct irq_desc {
	struct irq_common_data	irq_common_data;
	struct irq_data		irq_data;
	unsigned int __percpu	*kstat_irqs;        // 中断统计
	irq_flow_handler_t	handle_irq;             // 流处理函数
	struct irqaction	*action;	/* IRQ action list */   // IRQ动作链表
	unsigned int		status_use_accessors;
	unsigned int		core_internal_state__do_not_mess_with_it;
	unsigned int		depth;		/* nested irq disables */   // 禁止嵌套计数
	unsigned int		wake_depth;	/* nested wake enables */
	unsigned int		tot_count;
	unsigned int		irq_count;	/* For detecting broken IRQs */
	unsigned long		last_unhandled;	/* Aging timer for unhandled count */
	unsigned int		irqs_unhandled;
	atomic_t		threads_handled;
	int			threads_handled_last;
	raw_spinlock_t		lock;
	struct cpumask		*percpu_enabled;
	const struct cpumask	*percpu_affinity;
#ifdef CONFIG_SMP
	const struct cpumask	*affinity_hint;
	struct irq_affinity_notify *affinity_notify;
#ifdef CONFIG_GENERIC_PENDING_IRQ
	cpumask_var_t		pending_mask;
#endif
#endif
	unsigned long		threads_oneshot;
	atomic_t		threads_active;
	wait_queue_head_t       wait_for_threads;
#ifdef CONFIG_PM_SLEEP
	unsigned int		nr_actions;
	unsigned int		no_suspend_depth;
	unsigned int		cond_suspend_depth;
	unsigned int		force_resume_depth;
#endif
#ifdef CONFIG_PROC_FS
	struct proc_dir_entry	*dir;
#endif
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
	struct dentry		*debugfs_file;
	const char		*dev_name;
#endif
#ifdef CONFIG_SPARSE_IRQ
	struct rcu_head		rcu;
	struct kobject		kobj;
#endif
	struct mutex		request_mutex;
	int			parent_irq;
	struct module		*owner;
	const char		*name;
} ____cacheline_internodealigned_in_smp;

struct irq_domain {
	struct list_head link;
	const char *name;
	const struct irq_domain_ops *ops;
	void *host_data;
	unsigned int flags;
	unsigned int mapcount;

	/* Optional data */
	struct fwnode_handle *fwnode;
	enum irq_domain_bus_token bus_token;
	struct irq_domain_chip_generic *gc;
	struct device *dev;
#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
	struct irq_domain *parent;
#endif

	ANDROID_KABI_RESERVE(1);
	ANDROID_KABI_RESERVE(2);
	ANDROID_KABI_RESERVE(3);
	ANDROID_KABI_RESERVE(4);

	/* reverse map data. The linear map gets appended to the irq_domain */
	irq_hw_number_t hwirq_max;
	unsigned int revmap_size;
	struct radix_tree_root revmap_tree;
	struct mutex revmap_mutex;
	struct irq_data __rcu *revmap[];
};

struct irq_domain_ops {
	int (*match)(struct irq_domain *d, struct device_node *node,
		     enum irq_domain_bus_token bus_token);
	int (*select)(struct irq_domain *d, struct irq_fwspec *fwspec,
		      enum irq_domain_bus_token bus_token);
	int (*map)(struct irq_domain *d, unsigned int virq, irq_hw_number_t hw);
	void (*unmap)(struct irq_domain *d, unsigned int virq);
	int (*xlate)(struct irq_domain *d, struct device_node *node,
		     const u32 *intspec, unsigned int intsize,
		     unsigned long *out_hwirq, unsigned int *out_type);
#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
	/* extended V2 interfaces to support hierarchy irq_domains */
	int (*alloc)(struct irq_domain *d, unsigned int virq,
		     unsigned int nr_irqs, void *arg);
	void (*free)(struct irq_domain *d, unsigned int virq,
		     unsigned int nr_irqs);
	int (*activate)(struct irq_domain *d, struct irq_data *irqd, bool reserve);
	void (*deactivate)(struct irq_domain *d, struct irq_data *irq_data);
	int (*translate)(struct irq_domain *d, struct irq_fwspec *fwspec,
			 unsigned long *out_hwirq, unsigned int *out_type);
#endif
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
	void (*debug_show)(struct seq_file *m, struct irq_domain *d,
			   struct irq_data *irqd, int ind);
#endif
};

struct irq_data {
	u32			mask;
	unsigned int		irq;
	unsigned long		hwirq;
	struct irq_common_data	*common;
	struct irq_chip		*chip;
	struct irq_domain	*domain;
#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
	struct irq_data		*parent_data;
#endif
	void			*chip_data;
};

struct irq_chip {
	const char	*name;
	unsigned int	(*irq_startup)(struct irq_data *data);
	void		(*irq_shutdown)(struct irq_data *data);
	void		(*irq_enable)(struct irq_data *data);
	void		(*irq_disable)(struct irq_data *data);

	void		(*irq_ack)(struct irq_data *data);
	void		(*irq_mask)(struct irq_data *data);
	void		(*irq_mask_ack)(struct irq_data *data);
	void		(*irq_unmask)(struct irq_data *data);
	void		(*irq_eoi)(struct irq_data *data);

	int		(*irq_set_affinity)(struct irq_data *data, const struct cpumask *dest, bool force);
	int		(*irq_retrigger)(struct irq_data *data);
	int		(*irq_set_type)(struct irq_data *data, unsigned int flow_type);
	int		(*irq_set_wake)(struct irq_data *data, unsigned int on);

	void		(*irq_bus_lock)(struct irq_data *data);
	void		(*irq_bus_sync_unlock)(struct irq_data *data);

#ifdef CONFIG_DEPRECATED_IRQ_CPU_ONOFFLINE
	void		(*irq_cpu_online)(struct irq_data *data);
	void		(*irq_cpu_offline)(struct irq_data *data);
#endif
	void		(*irq_suspend)(struct irq_data *data);
	void		(*irq_resume)(struct irq_data *data);
	void		(*irq_pm_shutdown)(struct irq_data *data);

	void		(*irq_calc_mask)(struct irq_data *data);

	void		(*irq_print_chip)(struct irq_data *data, struct seq_file *p);
	int		(*irq_request_resources)(struct irq_data *data);
	void		(*irq_release_resources)(struct irq_data *data);

	void		(*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg);
	void		(*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg);

	int		(*irq_get_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool *state);
	int		(*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state);

	int		(*irq_set_vcpu_affinity)(struct irq_data *data, void *vcpu_info);

	void		(*ipi_send_single)(struct irq_data *data, unsigned int cpu);
	void		(*ipi_send_mask)(struct irq_data *data, const struct cpumask *dest);

	int		(*irq_nmi_setup)(struct irq_data *data);
	void		(*irq_nmi_teardown)(struct irq_data *data);

	unsigned long	flags;
};

platform_get_irq()
→ of_irq_get() / irq_of_parse_and_map()（drivers/of/irq.c）
→ irq_create_fwspec_mapping()（kernel/irq/irqdomain.c）
→ irq_domain_alloc_irqs() / irq_domain_alloc_irqs_hierarchy()
→ __irq_alloc_descs()（kernel/irq/irqdesc.c）
→ alloc_descs() 创建并初始化 irq_desc
→ domain->ops->alloc() 完成 chip/handler/hwirq 绑定、建立 revmap

unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
{
	struct irq_domain *domain;
	struct irq_data *irq_data;
	irq_hw_number_t hwirq;
	unsigned int type = IRQ_TYPE_NONE;
	int virq;
    
    // 目的找到fwspec对应的irq_domain
	if (fwspec->fwnode) {
		domain = irq_find_matching_fwspec(fwspec, DOMAIN_BUS_WIRED);
		if (!domain)
			domain = irq_find_matching_fwspec(fwspec, DOMAIN_BUS_ANY);
	} else {
		domain = irq_default_domain;
	}

	if (!domain) {
		pr_warn("no irq domain found for %s !\n",
			of_node_full_name(to_of_node(fwspec->fwnode)));
		return 0;
	}
    // 调用irq_domain_ops中的translate函数翻译，获取hwirq
	if (irq_domain_translate(domain, fwspec, &hwirq, &type))
		return 0;
    // 从相应irq_domain维护的revmap或者revmap_tree中查找hwirq，获取其virq
    virq = irq_find_mapping(domain, hwirq);
    //...
	if (irq_domain_is_hierarchy(domain)) {
		virq = irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, fwspec);
		if (virq <= 0)
			return 0;
	} else {
		/* Create mapping */
		virq = irq_create_mapping(domain, hwirq);
		if (!virq)
			return virq;
	}
}

unsigned int irq_create_mapping_affinity(struct irq_domain *domain,
				       irq_hw_number_t hwirq,
				       const struct irq_affinity_desc *affinity)
{
	struct device_node *of_node;
	int virq;

	pr_debug("irq_create_mapping(0x%p, 0x%lx)\n", domain, hwirq);

	/* Look for default domain if necessary */
	if (domain == NULL)
		domain = irq_default_domain;
	if (domain == NULL) {
		WARN(1, "%s(, %lx) called with NULL domain\n", __func__, hwirq);
		return 0;
	}
	pr_debug("-> using domain @%p\n", domain);

	of_node = irq_domain_get_of_node(domain);

	/* Check if mapping already exists */
	virq = irq_find_mapping(domain, hwirq);
	if (virq) {
		pr_debug("-> existing mapping on virq %d\n", virq);
		return virq;
	}

	/* Allocate a virtual interrupt number */
	virq = irq_domain_alloc_descs(-1, 1, hwirq, of_node_to_nid(of_node),
				      affinity);
	if (virq <= 0) {
		pr_debug("-> virq allocation failed\n");
		return 0;
	}

	if (irq_domain_associate(domain, virq, hwirq)) {
		irq_free_desc(virq);
		return 0;
	}

	pr_debug("irq %lu on domain %s mapped to virtual irq %u\n",
		hwirq, of_node_full_name(of_node), virq);

	return virq;
}

	start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
					   from, cnt, 0);

	tlmm: pinctrl@400000 {
		compatible = "qcom,pitti-pinctrl";                  // 与驱动匹配
		reg = <0x400000 0x1000000>;
		interrupts = <GIC_SPI 227 IRQ_TYPE_LEVEL_HIGH>;     // 表示其连接在GIC中断控制器的227号共享类型中断上
		gpio-controller;                                    // 标明是一个gpio控制器
		#gpio-cells = <2>;
		interrupt-controller;                               // 标明是一个中断控制器
		#interrupt-cells = <2>;
		wakeup-parent = <&mpm>;
		qcom,gpios-reserved = <36 37 38 39>;
	};

static const struct irq_chip msm_gpio_irq_chip = {
	.name			= "msmgpio",
	.irq_enable		= msm_gpio_irq_enable,
	.irq_disable		= msm_gpio_irq_disable,
	.irq_mask		= msm_gpio_irq_mask,
	.irq_unmask		= msm_gpio_irq_unmask,
	.irq_ack		= msm_gpio_irq_ack,
	.irq_eoi		= msm_gpio_irq_eoi,
	.irq_set_type		= msm_gpio_irq_set_type,
	.irq_set_wake		= msm_gpio_irq_set_wake,
	.irq_request_resources	= msm_gpio_irq_reqres,
	.irq_release_resources	= msm_gpio_irq_relres,
	.irq_set_affinity	= msm_gpio_irq_set_affinity,
	.irq_set_irqchip_state = msm_gpio_irq_set_irqchip_state,
	.irq_get_irqchip_state = msm_gpio_irq_get_irqchip_state,
	.irq_set_vcpu_affinity	= msm_gpio_irq_set_vcpu_affinity,
	.flags			= (IRQCHIP_MASK_ON_SUSPEND |
				   IRQCHIP_SET_TYPE_MASKED |
				   IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND |
				   IRQCHIP_IMMUTABLE),
};

static int msm_gpio_init(struct msm_pinctrl *pctrl)
{
	struct gpio_chip *chip;
	struct gpio_irq_chip *girq;
//...
	chip = &pctrl->chip;      //msm_pinctrl的chip成员
	chip->base = -1;
	chip->ngpio = ngpio;
	chip->label = dev_name(pctrl->dev);
	chip->parent = pctrl->dev;
	chip->owner = THIS_MODULE;
    //...
	girq = &chip->irq;         // 填充msm_pinctrl的chip结构中的irq成员
	gpio_irq_chip_set_chip(girq, &msm_gpio_irq_chip);
	girq->parent_handler = msm_gpio_irq_handler;
	girq->fwnode = pctrl->dev->fwnode;
	girq->num_parents = 1;
	girq->parents = devm_kcalloc(pctrl->dev, 1, sizeof(*girq->parents),
				     GFP_KERNEL);
	if (!girq->parents)
		return -ENOMEM;
	girq->default_type = IRQ_TYPE_NONE;
	girq->handler = handle_bad_irq;
	girq->parents[0] = pctrl->irq;

	ret = gpiochip_add_data(&pctrl->chip, pctrl);  //注册irq_domain
    //...
}

/**
 * struct gpio_irq_chip - GPIO interrupt controller
 */
struct gpio_irq_chip {
	/**
	 * @chip:
	 *
	 * GPIO IRQ chip implementation, provided by GPIO driver.
	 */
	struct irq_chip *chip;

	/**
	 * @domain:
	 *
	 * Interrupt translation domain; responsible for mapping between GPIO
	 * hwirq number and Linux IRQ number.
	 */
	struct irq_domain *domain;

	/**
	 * @domain_ops:
	 *
	 * Table of interrupt domain operations for this IRQ chip.
	 */
	const struct irq_domain_ops *domain_ops;

#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
	/**
	 * @fwnode:
	 *
	 * Firmware node corresponding to this gpiochip/irqchip, necessary
	 * for hierarchical irqdomain support.
	 */
	struct fwnode_handle *fwnode;

	/**
	 * @parent_domain:
	 *
	 * If non-NULL, will be set as the parent of this GPIO interrupt
	 * controller's IRQ domain to establish a hierarchical interrupt
	 * domain. The presence of this will activate the hierarchical
	 * interrupt support.
	 */
	struct irq_domain *parent_domain;

///......
}

struct msm_pinctrl {
	struct device *dev;
	struct pinctrl_dev *pctrl;
	struct gpio_chip chip;
	struct pinctrl_desc desc;
	struct notifier_block restart_nb;

	int irq;
	int n_dir_conns;

	bool intr_target_use_scm;

	raw_spinlock_t lock;

	DECLARE_BITMAP(dual_edge_irqs, MAX_NR_GPIO);
	DECLARE_BITMAP(enabled_irqs, MAX_NR_GPIO);
	DECLARE_BITMAP(skip_wake_irqs, MAX_NR_GPIO);
	DECLARE_BITMAP(disabled_for_mux, MAX_NR_GPIO);
	DECLARE_BITMAP(ever_gpio, MAX_NR_GPIO);

	const struct msm_pinctrl_soc_data *soc;
	void __iomem *regs[MAX_NR_TILES];
	u32 phys_base[MAX_NR_TILES];

	struct msm_gpio_regs *gpio_regs;
	struct msm_tile *msm_tile_regs;
	bool hibernation;
};

static struct msm_pinctrl *msm_pinctrl_data;

#define gpiochip_add_data(gc, data) ({		\
		static struct lock_class_key lock_key;	\
		static struct lock_class_key request_key;	  \
		gpiochip_add_data_with_key(gc, data, &lock_key, \
					   &request_key);	  \
	})

static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
{
	ops->activate = gpiochip_irq_domain_activate;
	ops->deactivate = gpiochip_irq_domain_deactivate;
	ops->alloc = gpiochip_hierarchy_irq_domain_alloc;

	/*
	 * We only allow overriding the translate() and free() functions for
	 * hierarchical chips, and this should only be done if the user
	 * really need something other than 1:1 translation for translate()
	 * callback and free if user wants to free up any resources which
	 * were allocated during callbacks, for example populate_parent_alloc_arg.
	 */
	if (!ops->translate)
		ops->translate = gpiochip_hierarchy_irq_domain_translate;
	if (!ops->free)
		ops->free = irq_domain_free_irqs_common;
}

static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d,
					       unsigned int irq,
					       unsigned int nr_irqs,
					       void *data)
{
	struct gpio_chip *gc = d->host_data;
	irq_hw_number_t hwirq;
	unsigned int type = IRQ_TYPE_NONE;
	struct irq_fwspec *fwspec = data;
	union gpio_irq_fwspec gpio_parent_fwspec = {};
	unsigned int parent_hwirq;
	unsigned int parent_type;
	struct gpio_irq_chip *girq = &gc->irq;
	int ret;

	/*
	 * The nr_irqs parameter is always one except for PCI multi-MSI
	 * so this should not happen.
	 */
	WARN_ON(nr_irqs != 1);

	ret = gc->irq.child_irq_domain_ops.translate(d, fwspec, &hwirq, &type);   //从trace32可以直接得到为gpiochip_hierarchy_irq_domain_translate函数
	if (ret)
		return ret;

	chip_dbg(gc, "allocate IRQ %d, hwirq %lu\n", irq,  hwirq);

	ret = girq->child_to_parent_hwirq(gc, hwirq, type,
					  &parent_hwirq, &parent_type);
	if (ret) {
		chip_err(gc, "can't look up hwirq %lu\n", hwirq);
		return ret;
	}
	chip_dbg(gc, "found parent hwirq %u\n", parent_hwirq);

	/*
	 * We set handle_bad_irq because the .set_type() should
	 * always be invoked and set the right type of handler.
	 */
	irq_domain_set_info(d,
			    irq,
			    hwirq,
			    gc->irq.chip,
			    gc,
			    girq->handler,
			    NULL, NULL);
	irq_set_probe(irq);

	/* This parent only handles asserted level IRQs */
	ret = girq->populate_parent_alloc_arg(gc, &gpio_parent_fwspec,
					      parent_hwirq, parent_type);
	if (ret)
		return ret;

	chip_dbg(gc, "alloc_irqs_parent for %d parent hwirq %d\n",
		  irq, parent_hwirq);
	irq_set_lockdep_class(irq, gc->irq.lock_key, gc->irq.request_key);
	ret = irq_domain_alloc_irqs_parent(d, irq, 1, &gpio_parent_fwspec);
	/*
	 * If the parent irqdomain is msi, the interrupts have already
	 * been allocated, so the EEXIST is good.
	 */
	if (irq_domain_is_msi(d->parent) && (ret == -EEXIST))
		ret = 0;
	if (ret)
		chip_err(gc,
			 "failed to allocate parent hwirq %d for hwirq %lu\n",
			 parent_hwirq, hwirq);

	return ret;
}

d->ops->alloc == gpiochip_hierarchy_irq_domain_alloc

ret = gc->irq.child_irq_domain_ops.translate(d, fwspec, &hwirq, &type); //从trace32可以直接得到为gpiochip_hierarchy_irq_domain_translate函数

ret = girq->child_to_parent_hwirq(gc, hwirq, type,
                                 &parent_hwirq, &parent_type);

irq_domain_set_info(d, irq, hwirq,
                    gc->irq.chip, gc,
                    girq->handler,
                    NULL, NULL);
irq_set_probe(irq);

int request_threaded_irq(unsigned int irq, irq_handler_t handler,
			 irq_handler_t thread_fn, unsigned long irqflags,
			 const char *devname, void *dev_id)
{
	struct irqaction *action;
	struct irq_desc *desc;
	int retval;

	if (irq == IRQ_NOTCONNECTED)
		return -ENOTCONN;

	/*
	 * Sanity-check: shared interrupts must pass in a real dev-ID,
	 * otherwise we'll have trouble later trying to figure out
	 * which interrupt is which (messes up the interrupt freeing
	 * logic etc).
	 *
	 * Also shared interrupts do not go well with disabling auto enable.
	 * The sharing interrupt might request it while it's still disabled
	 * and then wait for interrupts forever.
	 *
	 * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
	 * it cannot be set along with IRQF_NO_SUSPEND.
	 */
	if (((irqflags & IRQF_SHARED) && !dev_id) ||			//如果设置了共享中断，dev_id不能为空
	    ((irqflags & IRQF_SHARED) && (irqflags & IRQF_NO_AUTOEN)) ||
	    (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
	    ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
		return -EINVAL;

	desc = irq_to_desc(irq);	//从中断号获取中断描述符
	if (!desc)
		return -EINVAL;

	if (!irq_settings_can_request(desc) ||	//判断中断描述符是否可以被请求
	    WARN_ON(irq_settings_is_per_cpu_devid(desc)))
		return -EINVAL;

	if (!handler) {	//判断中断处理函数是否为空
		if (!thread_fn)	//如果中断处理函数为空，判断中断线程化处理函数是否为空
			return -EINVAL;
		//如果中断线程化，且中断处理函数为空，走默认的中断处理函数
		handler = irq_default_primary_handler;
	}

	// 分配一个struct irqaction空间
	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
	if (!action)
		return -ENOMEM;

	action->handler = handler;
	action->thread_fn = thread_fn;
	action->flags = irqflags;
	action->name = devname;
	action->dev_id = dev_id;

	retval = irq_chip_pm_get(&desc->irq_data);
	if (retval < 0) {
		kfree(action);
		return retval;
	}

	// 设置中断的函数
	retval = __setup_irq(irq, desc, action);

	if (retval) {
		irq_chip_pm_put(&desc->irq_data);
		kfree(action->secondary);
		kfree(action);
	}

#ifdef CONFIG_DEBUG_SHIRQ_FIXME
	if (!retval && (irqflags & IRQF_SHARED)) {
		/*
		 * It's a shared IRQ -- the driver ought to be prepared for it
		 * to happen immediately, so let's make sure....
		 * We disable the irq to make sure that a 'real' IRQ doesn't
		 * run in parallel with our fake.
		 */
		unsigned long flags;

		disable_irq(irq);
		local_irq_save(flags);

		handler(irq, dev_id);

		local_irq_restore(flags);
		enable_irq(irq);
	}
#endif
	return retval;
}

if (((irqflags & IRQF_SHARED) && !dev_id) ||			// 如果设置了共享中断，dev_id不能为空
    ((irqflags & IRQF_SHARED) && (irqflags & IRQF_NO_AUTOEN)) ||
    (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
    ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
    return -EINVAL;

if (!handler) { // 判断中断处理函数是否为空
    if (!thread_fn) // 如果中断处理函数为空，判断中断线程化处理函数是否为空
        return -EINVAL;
    handler = irq_default_primary_handler; // 如果线程化，且中断处理函数为空，走默认的处理函数
}

action->handler = handler;
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;

retval = irq_chip_pm_get(&desc->irq_data);
if (retval < 0) {
    kfree(action);
    return retval;
}

retval = __setup_irq(irq, desc, action);

static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
	struct irqaction *old, **old_ptr;
	unsigned long flags, thread_mask = 0;
	int ret, nested, shared = 0;

	if (!desc)
		return -EINVAL;

	if (desc->irq_data.chip == &no_irq_chip)
		return -ENOSYS;
	if (!try_module_get(desc->owner))
		return -ENODEV;

	new->irq = irq;

	/*
	 * If the trigger type is not specified by the caller,
	 * then use the default for this interrupt.
	 */
	if (!(new->flags & IRQF_TRIGGER_MASK))
		new->flags |= irqd_get_trigger_type(&desc->irq_data);

	/*
	 * Check whether the interrupt nests into another interrupt
	 * thread.
	 */
	//判断是否是嵌套线程
	nested = irq_settings_is_nested_thread(desc);
	if (nested) {
		if (!new->thread_fn) {
			ret = -EINVAL;
			goto out_mput;
		}
		/*
		 * Replace the primary handler which was provided from
		 * the driver for non nested interrupt handling by the
		 * dummy function which warns when called.
		 */
		new->handler = irq_nested_primary_handler;
	} else {
		// 判断中断设置是否线程化
		if (irq_settings_can_thread(desc)) {
			ret = irq_setup_forced_threading(new);
			if (ret)
				goto out_mput;
		}
	}

	/*
	 * Create a handler thread when a thread function is supplied
	 * and the interrupt does not nest into another interrupt
	 * thread.
	 */
	//如果线程化没有嵌套，则走这里
	if (new->thread_fn && !nested) {
		// 设置中断线程
		ret = setup_irq_thread(new, irq, false);
		if (ret)
			goto out_mput;
		if (new->secondary) {
			ret = setup_irq_thread(new->secondary, irq, true);
			if (ret)
				goto out_thread;
		}
	}

	/*
	 * Drivers are often written to work w/o knowledge about the
	 * underlying irq chip implementation, so a request for a
	 * threaded irq without a primary hard irq context handler
	 * requires the ONESHOT flag to be set. Some irq chips like
	 * MSI based interrupts are per se one shot safe. Check the
	 * chip flags, so we can avoid the unmask dance at the end of
	 * the threaded handler for those.
	 */
	//中断描述符如果支持IRQCHIP_ONESHOT_SAFE，则需要清楚IRQF_ONESHOT,
	// IRQCHIP_ONESHOT_SAFE是一个中断控制器的特定标志，用于指定该控制器
	// 是否支持硬件级别的oneshot中断
	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
		new->flags &= ~IRQF_ONESHOT;

	/*
	 * Protects against a concurrent __free_irq() call which might wait
	 * for synchronize_hardirq() to complete without holding the optional
	 * chip bus lock and desc->lock. Also protects against handing out
	 * a recycled oneshot thread_mask bit while it's still in use by
	 * its previous owner.
	 */
	mutex_lock(&desc->request_mutex);

	/*
	 * Acquire bus lock as the irq_request_resources() callback below
	 * might rely on the serialization or the magic power management
	 * functions which are abusing the irq_bus_lock() callback,
	 */
	chip_bus_lock(desc);

	/* First installed action requests resources. */
	// 判断中断描述符的struct irqaction成员是否为空
	if (!desc->action) {
		ret = irq_request_resources(desc); // 用于分配和配置中断相关的资源
		if (ret) {
			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
			       new->name, irq, desc->irq_data.chip->name);
			goto out_bus_unlock;
		}
	}

	/*
	 * The following block of code has to be executed atomically
	 * protected against a concurrent interrupt and any of the other
	 * management calls which are not serialized via
	 * desc->request_mutex or the optional bus lock.
	 */
	raw_spin_lock_irqsave(&desc->lock, flags);
	old_ptr = &desc->action;
	old = *old_ptr;
	if (old) {
		/*
		 * Can't share interrupts unless both agree to and are
		 * the same type (level, edge, polarity). So both flag
		 * fields must have IRQF_SHARED set and the bits which
		 * set the trigger type must match. Also all must
		 * agree on ONESHOT.
		 * Interrupt lines used for NMIs cannot be shared.
		 */
		unsigned int oldtype;

		if (desc->istate & IRQS_NMI) {
			pr_err("Invalid attempt to share NMI for %s (irq %d) on irqchip %s.\n",
				new->name, irq, desc->irq_data.chip->name);
			ret = -EINVAL;
			goto out_unlock;
		}

		/*
		 * If nobody did set the configuration before, inherit
		 * the one provided by the requester.
		 */
		// 中断触发类型如果被设置了
		if (irqd_trigger_type_was_set(&desc->irq_data)) {
			oldtype = irqd_get_trigger_type(&desc->irq_data);
		} else {
			// 中断触发类型如果没有被设置
			oldtype = new->flags & IRQF_TRIGGER_MASK;
			irqd_set_trigger_type(&desc->irq_data, oldtype); //设置中断触发类型
		}

		if (!((old->flags & new->flags) & IRQF_SHARED) ||
		    (oldtype != (new->flags & IRQF_TRIGGER_MASK)) ||
		    ((old->flags ^ new->flags) & IRQF_ONESHOT))
			goto mismatch;

		/* All handlers must agree on per-cpuness */
		if ((old->flags & IRQF_PERCPU) !=
		    (new->flags & IRQF_PERCPU))	//IRQF_PERCPU用于指定中断是否与每个CPU关联
			goto mismatch;

		/* add new interrupt at end of irq queue */
		do {
			/*
			 * Or all existing action->thread_mask bits,
			 * so we can find the next zero bit for this
			 * new action.
			 */
			thread_mask |= old->thread_mask;
			old_ptr = &old->next;
			old = *old_ptr;
		} while (old);
		shared = 1;
	}

	/*
	 * Setup the thread mask for this irqaction for ONESHOT. For
	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
	 * conditional in irq_wake_thread().
	 */
	// 是否设置了中断处理程序只被触发一次后立即禁用
	if (new->flags & IRQF_ONESHOT) {
		/*
		 * Unlikely to have 32 resp 64 irqs sharing one line,
		 * but who knows.
		 */
		if (thread_mask == ~0UL) {
			ret = -EBUSY;
			goto out_unlock;
		}
		/*
		 * The thread_mask for the action is or'ed to
		 * desc->thread_active to indicate that the
		 * IRQF_ONESHOT thread handler has been woken, but not
		 * yet finished. The bit is cleared when a thread
		 * completes. When all threads of a shared interrupt
		 * line have completed desc->threads_active becomes
		 * zero and the interrupt line is unmasked. See
		 * handle.c:irq_wake_thread() for further information.
		 *
		 * If no thread is woken by primary (hard irq context)
		 * interrupt handlers, then desc->threads_active is
		 * also checked for zero to unmask the irq line in the
		 * affected hard irq flow handlers
		 * (handle_[fasteoi|level]_irq).
		 *
		 * The new action gets the first zero bit of
		 * thread_mask assigned. See the loop above which or's
		 * all existing action->thread_mask bits.
		 */
		new->thread_mask = 1UL << ffz(thread_mask);

	} else if (new->handler == irq_default_primary_handler &&
		   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
		/*
		 * The interrupt was requested with handler = NULL, so
		 * we use the default primary handler for it. But it
		 * does not have the oneshot flag set. In combination
		 * with level interrupts this is deadly, because the
		 * default primary handler just wakes the thread, then
		 * the irq lines is reenabled, but the device still
		 * has the level irq asserted. Rinse and repeat....
		 *
		 * While this works for edge type interrupts, we play
		 * it safe and reject unconditionally because we can't
		 * say for sure which type this interrupt really
		 * has. The type flags are unreliable as the
		 * underlying chip implementation can override them.
		 */
		pr_err("Threaded irq requested with handler=NULL and !ONESHOT for %s (irq %d)\n",
		       new->name, irq);
		ret = -EINVAL;
		goto out_unlock;
	}

	if (!shared) { // 如果没有设置共享中断
		init_waitqueue_head(&desc->wait_for_threads); // 初始化等待队列

		/* Setup the type (level, edge polarity) if configured: */
		if (new->flags & IRQF_TRIGGER_MASK) {
			ret = __irq_set_trigger(desc,
						new->flags & IRQF_TRIGGER_MASK);	// 设置中断触发类型

			if (ret)
				goto out_unlock;
		}

		/*
		 * Activate the interrupt. That activation must happen
		 * independently of IRQ_NOAUTOEN. request_irq() can fail
		 * and the callers are supposed to handle
		 * that. enable_irq() of an interrupt requested with
		 * IRQ_NOAUTOEN is not supposed to fail. The activation
		 * keeps it in shutdown mode, it merily associates
		 * resources if necessary and if that's not possible it
		 * fails. Interrupts which are in managed shutdown mode
		 * will simply ignore that activation request.
		 */
		ret = irq_activate(desc);
		if (ret)
			goto out_unlock;

		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
				  IRQS_ONESHOT | IRQS_WAITING);
		irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);

		if (new->flags & IRQF_PERCPU) {
			irqd_set(&desc->irq_data, IRQD_PER_CPU);
			irq_settings_set_per_cpu(desc);
			if (new->flags & IRQF_NO_DEBUG)
				irq_settings_set_no_debug(desc);
		}

		if (noirqdebug)
			irq_settings_set_no_debug(desc);

		if (new->flags & IRQF_ONESHOT)
			desc->istate |= IRQS_ONESHOT;

		/* Exclude IRQ from balancing if requested */
		if (new->flags & IRQF_NOBALANCING) {
			irq_settings_set_no_balancing(desc);
			irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
		}

		if (!(new->flags & IRQF_NO_AUTOEN) &&
		    irq_settings_can_autoenable(desc)) {
			irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
		} else {
			/*
			 * Shared interrupts do not go well with disabling
			 * auto enable. The sharing interrupt might request
			 * it while it's still disabled and then wait for
			 * interrupts forever.
			 */
			WARN_ON_ONCE(new->flags & IRQF_SHARED);
			/* Undo nested disables: */
			desc->depth = 1;
		}

	} else if (new->flags & IRQF_TRIGGER_MASK) {
		unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
		unsigned int omsk = irqd_get_trigger_type(&desc->irq_data);

		if (nmsk != omsk)
			/* hope the handler works with current  trigger mode */
			pr_warn("irq %d uses trigger mode %u; requested %u\n",
				irq, omsk, nmsk);
	}

	*old_ptr = new;	// 将新的action给中断描述符

	irq_pm_install_action(desc, new);

	/* Reset broken irq detection when installing new handler */
	desc->irq_count = 0;
	desc->irqs_unhandled = 0;

	/*
	 * Check whether we disabled the irq via the spurious handler
	 * before. Reenable it and give it another chance.
	 */
	if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
		desc->istate &= ~IRQS_SPURIOUS_DISABLED;
		__enable_irq(desc);	//使能中断
	}

	raw_spin_unlock_irqrestore(&desc->lock, flags);
	chip_bus_sync_unlock(desc);
	mutex_unlock(&desc->request_mutex);

	irq_setup_timings(desc, new);	//设置中断控制器的时序参数

	/*
	 * Strictly no need to wake it up, but hung_task complains
	 * when no hard interrupt wakes the thread up.
	 */
	if (new->thread)
		wake_up_process(new->thread);
	if (new->secondary)
		wake_up_process(new->secondary->thread);

	register_irq_proc(irq, desc);	// 注册procfs文件系统
	new->dir = NULL;
	register_handler_proc(irq, new);	// 注册irq文件系统
	return 0;

mismatch:
	if (!(new->flags & IRQF_PROBE_SHARED)) {
		pr_err("Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
		       irq, new->flags, new->name, old->flags, old->name);
#ifdef CONFIG_DEBUG_SHIRQ
		dump_stack();
#endif
	}
	ret = -EBUSY;

out_unlock:
	raw_spin_unlock_irqrestore(&desc->lock, flags);

	if (!desc->action)
		irq_release_resources(desc);
out_bus_unlock:
	chip_bus_sync_unlock(desc);
	mutex_unlock(&desc->request_mutex);

out_thread:
	if (new->thread) {
		struct task_struct *t = new->thread;

		new->thread = NULL;
		kthread_stop(t);
		put_task_struct(t);
	}
	if (new->secondary && new->secondary->thread) {
		struct task_struct *t = new->secondary->thread;

		new->secondary->thread = NULL;
		kthread_stop(t);
		put_task_struct(t);
	}
out_mput:
	module_put(desc->owner);
	return ret;
}

if (!(new->flags & IRQF_TRIGGER_MASK))
    new->flags |= irqd_get_trigger_type(&desc->irq_data);

nested = irq_settings_is_nested_thread(desc);
if (nested) {
    if (!new->thread_fn) {
        ret = -EINVAL;
        goto out_mput;
    }
    new->handler = irq_nested_primary_handler;
}

if (new->thread_fn && !nested) {
    ret = setup_irq_thread(new, irq, false);
    if (ret)
        goto out_mput;
    if (new->secondary) {
        ret = setup_irq_thread(new->secondary, irq, true);
        if (ret)
            goto out_thread;
    }
}

if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
    new->flags &= ~IRQF_ONESHOT;

mutex_lock(&desc->request_mutex);
chip_bus_lock(desc);
if (!desc->action) {
    ret = irq_request_resources(desc);
    if (ret) {
        pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
               new->name, irq, desc->irq_data.chip->name);
        goto out_bus_unlock;
    }
}

raw_spin_lock_irqsave(&desc->lock, flags);
old_ptr = &desc->action;
old = *old_ptr;
if (old) {
    // 共享中断的处理逻辑
}

if (new->flags & IRQF_ONESHOT) {
    if (thread_mask == ~0UL) {
        ret = -EBUSY;
        goto out_unlock;
    }
    new->thread_mask = 1UL << ffz(thread_mask);
}

if (!shared) {
    init_waitqueue_head(&desc->wait_for_threads);
    if (new->flags & IRQF_TRIGGER_MASK) {
        ret = __irq_set_trigger(desc, new->flags & IRQF_TRIGGER_MASK);
        if (ret)
            goto out_unlock;
    }
    ret = irq_activate(desc);
    if (ret)
        goto out_unlock;
}

register_irq_proc(irq, desc);
register_handler_proc(irq, new);

static int
setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
{
	struct task_struct *t;

	if (!secondary) {
		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
				   new->name);
	} else {
		t = kthread_create(irq_thread, new, "irq/%d-s-%s", irq,
				   new->name);
	}

	if (IS_ERR(t))
		return PTR_ERR(t);

	sched_set_fifo(t);

	/*
	 * We keep the reference to the task struct even if
	 * the thread dies to avoid that the interrupt code
	 * references an already freed task_struct.
	 */
	new->thread = get_task_struct(t);
	/*
	 * Tell the thread to set its affinity. This is
	 * important for shared interrupt handlers as we do
	 * not invoke setup_affinity() for the secondary
	 * handlers as everything is already set up. Even for
	 * interrupts marked with IRQF_NO_BALANCE this is
	 * correct as we want the thread to move to the cpu(s)
	 * on which the requesting code placed the interrupt.
	 */
	set_bit(IRQTF_AFFINITY, &new->thread_flags);
	return 0;
}

static int irq_thread(void *data)
{
	struct callback_head on_exit_work;
	struct irqaction *action = data;
	struct irq_desc *desc = irq_to_desc(action->irq);
	irqreturn_t (*handler_fn)(struct irq_desc *desc,
			struct irqaction *action);

	if (force_irqthreads() && test_bit(IRQTF_FORCED_THREAD,
					   &action->thread_flags))
		handler_fn = irq_forced_thread_fn;
	else
		handler_fn = irq_thread_fn;

	init_task_work(&on_exit_work, irq_thread_dtor);
	task_work_add(current, &on_exit_work, TWA_NONE);

	irq_thread_check_affinity(desc, action);

	while (!irq_wait_for_interrupt(action)) {
		irqreturn_t action_ret;

		irq_thread_check_affinity(desc, action);

		action_ret = handler_fn(desc, action);
		if (action_ret == IRQ_WAKE_THREAD)
			irq_wake_secondary(desc, action);

		wake_threads_waitq(desc);
	}

	/*
	 * This is the regular exit path. __free_irq() is stopping the
	 * thread via kthread_stop() after calling
	 * synchronize_hardirq(). So neither IRQTF_RUNTHREAD nor the
	 * oneshot mask bit can be set.
	 */
	task_work_cancel(current, irq_thread_dtor);
	return 0;
}

static int irq_wait_for_interrupt(struct irqaction *action)
{
	for (;;) {
        // 设置线程状态为可中断睡眠：线程可以接收信号和中断唤醒
		set_current_state(TASK_INTERRUPTIBLE);

		if (kthread_should_stop()) {
            // 如果还有中断标志，处理最后一次
			/* may need to run one last time */
			if (test_and_clear_bit(IRQTF_RUNTHREAD,
					       &action->thread_flags)) {
                // 设置线程状态为running，从睡眠状态转为运行状态
				__set_current_state(TASK_RUNNING);
				return 0;
			}
			__set_current_state(TASK_RUNNING);
			return -1;
		}

		if (test_and_clear_bit(IRQTF_RUNTHREAD,
				       &action->thread_flags)) {
			__set_current_state(TASK_RUNNING);
			return 0;
		}
        // 主动让出CPU：进入睡眠状态等待唤醒
		schedule();
	}
}