linux - request_irq- irq 标志设置为 0 ；这是有效的吗？

Question

在浏览 2.6.35 时，在某些驱动程序中，观察到 request_irq 被传递给 irq 标志的值 0。当在 interrupt.h 中看到时 - 0 对应于 IRQ_TRIGGER_NONE;

这是否等同于以前内核中的 IRQ_NONE 的情况？

谢谢。

Answer 1

传递到 request_irq() 中的实际标志在注释中定义:

/*
 * These flags used only by the kernel as part of the
 * irq handling routines.
 *
 * IRQF_DISABLED - keep irqs disabled when calling the action handler.
 *                 DEPRECATED. This flag is a NOOP and scheduled to be removed
 * IRQF_SAMPLE_RANDOM - irq is used to feed the random generator
 * IRQF_SHARED - allow sharing the irq among several devices
 * IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
 * IRQF_TIMER - Flag to mark this interrupt as timer interrupt
 * IRQF_PERCPU - Interrupt is per cpu
 * IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
 * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
 *                registered first in an shared interrupt is considered for
 *                performance reasons)
 * IRQF_ONESHOT - Interrupt is not reenabled after the hardirq handler finished.
 *                Used by threaded interrupts which need to keep the
 *                irq line disabled until the threaded handler has been run.
 * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend
 * IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND is set
 * IRQF_NO_THREAD - Interrupt cannot be threaded
 * IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
 *                resume time.
 */

这些是位，因此可以传入其中一个子集的逻辑或(即|)；如果没有应用，则空集完全没问题——即 flags 参数的值为 0。

由于 IRQF_TRIGGER_NONE 为 0，将 0 传递给 request_irq() 只是表示单独保留 IRQ 的触发配置——即不管硬件/固件如何配置它。

IRQ_NONE 在不同的命名空间中；它是中断处理程序(传递给 request_irq() 的函数)可能的返回值之一，这意味着中断处理程序没有处理中断。