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| uclinux-2008r1-rc8(bf561)的中断处理（8）：中断描述 | |||||
作者：快乐虾 文章来源：http://blog.csdn.net/lights_joy 点击数： 更新时间：2008-5-26  |
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uclinux内核为每一个中断设置了一个称为irq_desc的结构体进行描述：
/**
* struct irq_desc - interrupt descriptor
*
* @handle_irq: highlevel irq-events handler [if NULL, __do_IRQ()]
* @chip: low level interrupt hardware access
* @msi_desc: MSI descriptor
* @handler_data: per-IRQ data for the irq_chip methods
* @chip_data: platform-specific per-chip private data for the chip
* methods, to allow shared chip implementations
* @action: the irq action chain
* @status: status information
* @depth: disable-depth, for nested irq_disable() calls
* @wake_depth: enable depth, for multiple set_irq_wake() callers
* @irq_count: stats field to detect stalled irqs
* @irqs_unhandled: stats field for spurious unhandled interrupts
* @lock: locking for SMP
* @affinity: IRQ affinity on SMP
* @cpu: cpu index useful for balancing
* @pending_mask: pending rebalanced interrupts
* @dir: /proc/irq/ procfs entry
* @affinity_entry: /proc/irq/smp_affinity procfs entry on SMP
* @name: flow handler name for /proc/interrupts output
*/
struct irq_desc {
irq_flow_handler_t handle_irq;
struct irq_chip *chip;
struct msi_desc *msi_desc;
void *handler_data;
void *chip_data;
struct irqaction *action; /* IRQ action list */
unsigned int status; /* IRQ status */
unsigned int depth; /* nested irq disables */
unsigned int wake_depth; /* nested wake enables */
unsigned int irq_count; /* For detecting broken IRQs */
unsigned int irqs_unhandled;
spinlock_t lock;
#ifdef CONFIG_SMP
cpumask_t affinity;
unsigned int cpu;
#endif
#if defined(CONFIG_GENERIC_PENDING_IRQ) || defined(CONFIG_IRQBALANCE)
cpumask_t pending_mask;
#endif
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *dir;
#endif
const char *name;
} ____cacheline_internodealigned_in_smp;
extern struct irq_desc irq_desc[NR_IRQS];
对它的各个成员的描述其注释已经比较清楚了，这里需要注意的是NR_IRQS的定义。在bf561中，提供了64个外部中断和6个内部中断，其中60-63这4个外部中断保留。但是NR_IRQS的定义高达121，这主要是因为在BF561中对PF0 – PF47这48个PF口仅仅用了8个中断源，但是在内核中则为这48个PF口每个都留了中断描述。
irq_desc这个数组的定义在kernel/irq/handle.c中：
/*
* Linux has a controller-independent interrupt architecture.
* Every controller has a 'controller-template', that is used
* by the main code to do the right thing. Each driver-visible
* interrupt source is transparently wired to the appropriate
* controller. Thus drivers need not be aware of the
* interrupt-controller.
*
* The code is designed to be easily extended with new/different
* interrupt controllers, without having to do assembly magic or
* having to touch the generic code.
*
* Controller mappings for all interrupt sources:
*/
struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS-1] = {
.status = IRQ_DISABLED,
.chip = &no_irq_chip,
.handle_irq = handle_bad_irq,
.depth = 1,
.lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
#ifdef CONFIG_SMP
.affinity = CPU_MASK_ALL
#endif
}
};
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