文章系列
linux中斷子系統 - 中斷及執行流程
linux中斷子系統 - 申請中斷
linux中斷子系統 - irq_desc的建立
linux中斷子系統 - 中斷控制器的注冊
irq_desc的代碼主要在kernel/irq/irqdesc.c中linux4.6.3
1. irq_desc組織方式
1.1 組織方式
irq_desc在核心中有兩種組織方式,這是根據宏CONFIG_SPARSE_IRQ是否定義來決定的,這兩種方式分别是:
(1)radix-tree方式,這是以基數樹的方式來組織irq_desc
(2)數組的方式 ,前面的文章介紹irq結構時,就是用此方式舉例的,在系統初始化的時候會定義一個全局數組,詳細見下面代碼,NR_IRQS就代表總共的irq數量
struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[ ... NR_IRQS-] = {
.handle_irq = handle_bad_irq,
.depth = ,
.lock = __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
}
};
我們最終的目标是建立hwirq和virq的映射,上面兩種方式代表兩種不同的映射方式,數組簡單就是線性映射,而基數樹具體在這裡不說了。
irq_desc建立完後,要做的就是初始化,在核心中有兩方面會涉及到irq_desc的初始化,一個是在申請中斷的時候(主要是初始化irq_desc->action),另一個是在驅動初始化的時候,本文重點就在這裡
1.2 struct irq_desc
struct irq_desc {
struct irq_common_data irq_common_data;
struct irq_data irq_data;
unsigned int __percpu *kstat_irqs;
irq_flow_handler_t handle_irq;
#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
irq_preflow_handler_t preflow_handler;
#endif
struct irqaction *action; /* IRQ action list */
unsigned int status_use_accessors;
unsigned int core_internal_state__do_not_mess_with_it;
unsigned int depth; /* nested irq disables */
unsigned int wake_depth; /* nested wake enables */
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;
#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
int parent_irq;
struct module *owner;
const char *name;
} ____cacheline_internodealigned_in_smp;
2.irq_desc的配置設定
#define irq_alloc_descs(irq, from, cnt, node) \
__irq_alloc_descs(irq, from, cnt, node, THIS_MODULE)
#define irq_alloc_desc(node) \
irq_alloc_descs(-, , , node)
#define irq_alloc_desc_at(at, node) \
irq_alloc_descs(at, at, , node)
#define irq_alloc_desc_from(from, node) \
irq_alloc_descs(-, from, , node)
#define irq_alloc_descs_from(from, cnt, node) \
irq_alloc_descs(-, from, cnt, node)
從上面可以看出最終都是調用到函數__irq_alloc_descs,此函數最終會調用到函數alloc_descs,從第一節我們知道irq_desc組織方式有兩種,那麼alloc_descs會有兩個接口,下面分别介紹:
2.1線性數組方式
static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct module *owner)
{
u32 i;
for (i = ; i < cnt; i++) {
struct irq_desc *desc = irq_to_desc(start + i);
desc->owner = owner;
}
return start;
}
struct irq_desc *irq_to_desc(unsigned int irq)
{
return (irq < NR_IRQS) ? irq_desc + irq : NULL;----直接傳回irq_desc[irq]
}
2.2基數樹方式
static int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct module *owner)
{
struct irq_desc *desc;
int i;
for (i = ; i < cnt; i++) {
desc = alloc_desc(start + i, node, owner);------配置設定一個irq_desc
if (!desc)
goto err;
mutex_lock(&sparse_irq_lock);
irq_insert_desc(start + i, desc);---------------把irq_desc插入到radix tree
mutex_unlock(&sparse_irq_lock);
}
return start;
err:
for (i--; i >= ; i--)
free_desc(start + i);
mutex_lock(&sparse_irq_lock);
bitmap_clear(allocated_irqs, start, cnt);
mutex_unlock(&sparse_irq_lock);
return -ENOMEM;
}
static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
{
struct irq_desc *desc;
gfp_t gfp = GFP_KERNEL;
desc = kzalloc_node(sizeof(*desc), gfp, node);--------為irq_desc配置設定記憶體
if (!desc)
return NULL;
/* allocate based on nr_cpu_ids */
desc->kstat_irqs = alloc_percpu(unsigned int);
if (!desc->kstat_irqs)
goto err_desc;
if (alloc_masks(desc, gfp, node))
goto err_kstat;
raw_spin_lock_init(&desc->lock);
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
init_rcu_head(&desc->rcu);
desc_set_defaults(irq, desc, node, owner);
return desc;
err_kstat:
free_percpu(desc->kstat_irqs);
err_desc:
kfree(desc);
return NULL;
}
3.irq_desc的初始化
各個驅動中斷的配置在DT中(DT參考我的文章裝置樹的解釋),DT初始化中斷的一個簡易流程如下圖
走到of_irq_to_resource就脫離了DT過程,正式進入到本節的主題,函數調用流程圖如下:
這些沒什麼說的,隻是一個參數解析過程,重要的是下面這些函數
- A : 找到比對的irq_domain,irq_domain會在中斷控制器注冊的時候加入
- B : 判斷irq_domain是否是hierarchy,不同的類型需要不同的操作,從圖中可以看出雖然調用函數不一樣,但是具體要執行的步驟是一樣的:
()搜尋hwirq是否已經被映射到virq,如果是直接傳回
()如果沒有得到virq,那麼把hwirq映射到virq
(3)調用irq_domain的相關函數初始化irq_desc
上面的簡化分析不能說明問題,下面通過代碼來仔細分析,隻分析不是hierarchy的情況:
一、先分析函數irq_find_mapping
unsigned int irq_find_mapping(struct irq_domain *domain,
irq_hw_number_t hwirq)
{
struct irq_data *data;
/* Look for default domain if nececssary */
if (domain == NULL)
domain = irq_default_domain;
if (domain == NULL)
return ;
if (hwirq < domain->revmap_direct_max_irq) {
data = irq_domain_get_irq_data(domain, hwirq);
if (data && data->hwirq == hwirq)
return hwirq;
}
/* Check if the hwirq is in the linear revmap. */
if (hwirq < domain->revmap_size)
return domain->linear_revmap[hwirq];-----------------線性映射傳回
rcu_read_lock();
data = radix_tree_lookup(&domain->revmap_tree, hwirq);
rcu_read_unlock();
return data ? data->irq : 0;-----------------------------基數樹映射傳回
}
--------------linear_revmap或者revmap_tree的建立是在中斷控制器注冊的時候初始化的
二、再分析函數irq_domain_alloc_descs
int irq_domain_alloc_descs(int virq, unsigned int cnt, irq_hw_number_t hwirq,
int node)
{
unsigned int hint;
if (virq >= ) {--------------------從上面函數的分析可知道virq==
virq = irq_alloc_descs(virq, virq, cnt, node);-----真正的irq_desc配置設定函數
} else {
hint = hwirq % nr_irqs;
if (hint == )
hint++;
virq = irq_alloc_descs_from(hint, cnt, node);
if (virq <= && hint > )
virq = irq_alloc_descs_from(, cnt, node);
}
return virq;
}
三、最後分析函數irq_domain_associate
int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
irq_hw_number_t hwirq)
{
struct irq_data *irq_data = irq_get_irq_data(virq);
int ret;
if (WARN(hwirq >= domain->hwirq_max,
"error: hwirq 0x%x is too large for %s\n", (int)hwirq, domain->name))
return -EINVAL;
if (WARN(!irq_data, "error: virq%i is not allocated", virq))
return -EINVAL;
if (WARN(irq_data->domain, "error: virq%i is already associated", virq))
return -EINVAL;
mutex_lock(&irq_domain_mutex);
irq_data->hwirq = hwirq;
irq_data->domain = domain;
if (domain->ops->map) {
ret = domain->ops->map(domain, virq, hwirq);---------------調用irq_domain->irq_domain_ops->map函數初始化irq_desc,具體操作在中斷控制器注冊文章中介紹
if (ret != ) {
/*
* If map() returns -EPERM, this interrupt is protected
* by the firmware or some other service and shall not
* be mapped. Don't bother telling the user about it.
*/
if (ret != -EPERM) {
pr_info("%s didn't like hwirq-0x%lx to VIRQ%i mapping (rc=%d)\n",
domain->name, hwirq, virq, ret);
}
irq_data->domain = NULL;
irq_data->hwirq = ;
mutex_unlock(&irq_domain_mutex);
return ret;
}
/* If not already assigned, give the domain the chip's name */
if (!domain->name && irq_data->chip)
domain->name = irq_data->chip->name;
}
if (hwirq < domain->revmap_size) {
domain->linear_revmap[hwirq] = virq;-----------------------virq設定到domain
} else {
mutex_lock(&revmap_trees_mutex);
radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);--virq設定到domain
mutex_unlock(&revmap_trees_mutex);
}
mutex_unlock(&irq_domain_mutex);
irq_clear_status_flags(virq, IRQ_NOREQUEST);
return 0;
}
4. change log
日期 | 修改内容 | 核心版本 |
---|---|---|
2016.11.9 | 增加結構體irq_desc内容 | linux4.4 |