request_irq+ work queue Intel架构中的键盘(rhel5 2.6.18测试通过)-优快云博客

本文介绍了一个Linux内核模块的实现方式，该模块通过键盘中断来读取扫描码，并使用工作队列将非时间关键任务推迟到安全时刻执行。

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/*
* intrpt.c - An interrupt handler.
*
* Copyright (C) 2001 by Peter Jay Salzman
*/

/*
* The necessary header files
*/

/*
* Standard in kernel modules
*/
#include <linux/kernel.h>      /* We're doing kernel work */
#include <linux/module.h>      /* Specifically, a module */
#include <linux/sched.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>   /* We want an interrupt */
#include <asm/io.h>

#define MY_WORK_QUEUE_NAME "WQsched.c"

static struct workqueue_struct *my_workqueue;

/*
* This will get called by the kernel as soon as it's safe
* to do everything normally allowed by kernel modules.
*/
static void got_char(void *scancode)
{
        printk("Scan Code %x %s./n",
               (int)*((char *)scancode) & 0x7F,
               *((char *)scancode) & 0x80 ? "Released" : "Pressed");
}

/*
* This function services keyboard interrupts. It reads the relevant
* information from the keyboard and then puts the non time critical
* part into the work queue. This will be run when the kernel considers it safe.
*/
irqreturn_t irq_handler(int irq, void *dev_id, struct pt_regs *regs)
{
        /*
        * This variables are static because they need to be
        * accessible (through pointers) to the bottom half routine.
        */
        static int initialised = 0;
        static unsigned char scancode;
        static struct work_struct task;
        unsigned char status;

        /*
        * Read keyboard status
        */
        status = inb(0x64);
        scancode = inb(0x60);

        if (initialised == 0) {
               INIT_WORK(&task, got_char, &scancode);
               initialised = 1;
        } else {
               PREPARE_WORK(&task, got_char, &scancode);
        }

        queue_work(my_workqueue, &task);

        return IRQ_HANDLED;
}

/*
* Initialize the module - register the IRQ handler
*/
int init_module()
{
        my_workqueue = create_workqueue(MY_WORK_QUEUE_NAME);

        /*
        * Since the keyboard handler won't co-exist with another handler,
        * such as us, we have to disable it (free its IRQ) before we do
        * anything. Since we don't know where it is, there's no way to
        * reinstate it later - so the computer will have to be rebooted
        * when we're done.
        */
        free_irq(1, NULL);

        /*
        * Request IRQ 1, the keyboard IRQ, to go to our irq_handler.
        * SA_SHIRQ means we're willing to have othe handlers on this IRQ.
        * SA_INTERRUPT can be used to make the handler into a fast interrupt.
        */
        return request_irq(1, /* The number of the keyboard IRQ on PCs */
                          irq_handler, /* our handler */
                          SA_SHIRQ, "test_keyboard_irq_handler",
                          (void *)(irq_handler));
}

/*
* Cleanup
*/
void cleanup_module()
{
        /*
        * This is only here for completeness. It's totally irrelevant, since
        * we don't have a way to restore the normal keyboard interrupt so the
        * computer is completely useless and has to be rebooted.
        */
        free_irq(1, NULL);
}

/*
* some work_queue related functions are just available to GPL licensed Modules
*/
MODULE_LICENSE("GPL");