short.c

LINUX设备驱动程序第二版配套源码 LINUX设备驱动程序第二版配套源码 Alessandro rubini&Jonathan corbet著 中国电力出版社 魏永明 骆刚 姜君译 69元

    /*
     * Then, write the time values. Write exactly 16 bytes at a time,
     * so it aligns with PAGE_SIZE
     */

    do {
        short_head += sprintf((char *)short_head,"%08u.%06u\n",
                              (int)(tv_tail->tv_sec % 100000000),
                              (int)(tv_tail->tv_usec));
        if (short_head == short_buffer + PAGE_SIZE)
            short_head = short_buffer; /* wrap */
        
        tv_tail++;
        if (tv_tail == (tv_data + NR_TIMEVAL) ) 
            tv_tail = tv_data; /* wrap */
        
    } while (tv_tail != tv_head);

    wake_up_interruptible(&short_queue); /* awake any reading process */
}


/*
 * use two implementations: before version 1.3.70 you couldn't
 * re-enqueue tasks, and "dev_id" was missing. I like re-enqueueing,
 * so I'd better keep the modern version clean
 */

#if LINUX_VERSION_CODE < VERSION_CODE(1,3,70) /* old */
void short_bh_interrupt(int irq, struct pt_regs *regs)
{
    do_gettimeofday(tv_head);
    tv_head++;

    if (tv_head == (tv_data + NR_TIMEVAL) ) 
        tv_head = tv_data; /* wrap */

    /* Queue the bh. Don't re-enqueue */
    if (!short_bh_count)
        queue_task_irq_off(&short_task, &tq_immediate);
    mark_bh(IMMEDIATE_BH);

    short_bh_count++; /* record that an interrupt arrived */
}
#else /* recent */
void short_bh_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
    do_gettimeofday(tv_head);
    tv_head++;

    if (tv_head == (tv_data + NR_TIMEVAL) ) 
        tv_head = tv_data; /* wrap */

    /* Queue the bh. Don't care for multiple enqueueing */
    queue_task_irq_off(&short_task, &tq_immediate);
    mark_bh(IMMEDIATE_BH);

    short_bh_count++; /* record that an interrupt arrived */
}
#endif


#if LINUX_VERSION_CODE < VERSION_CODE(1,3,70)
void short_sh_interrupt(int irq, struct pt_regs *regs)
{
    void *dev_id = NULL;
#else
void short_sh_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
#endif
    int value;
    struct timeval tv;

    /* If it wasn't short, return immediately */
    value = inb(short_base);
    if (!(value & 0x80)) return;
        
    /* clear the interrupting bit */
    outb(value & 0x7F, short_base);

    /* the rest is unchanged */

    do_gettimeofday(&tv);
    short_head += sprintf((char *)short_head,"%08u.%06u\n",
                          (int)(tv.tv_sec % 100000000), (int)(tv.tv_usec));
    if (short_head == short_buffer + PAGE_SIZE)
        short_head = short_buffer; /* wrap */

    wake_up_interruptible(&short_queue); /* awake any reading process */
}

#if LINUX_VERSION_CODE >= VERSION_CODE(1,3,30)
void short_kernelprobe(void)
{
    int count = 0;
    do {
        unsigned long mask;

        mask = probe_irq_on();
        outb_p(0x10,short_base+2); /* enable reporting */
        outb_p(0x00,short_base);   /* clear the bit */
        outb_p(0xFF,short_base);   /* set the bit: interrupt! */
        outb_p(0x00,short_base+2); /* disable reporting */
        short_irq = probe_irq_off(mask);

        if (short_irq == 0) { /* none of them? */
            printk(KERN_INFO "short: no irq reported by probe\n");
            short_irq = -1;
        }
        /*
         * if more than one line has been activated, the result is
         * negative. We should service the interrupt (no need for lpt port)
         * and loop over again. Loop at most five times, then give up
         */
    } while (short_irq < 0 && count++ < 5);
    if (short_irq < 0)
        printk("short: probe failed %i times, giving up\n", count);
}
#else
void short_kernelprobe(void)
{
    printk(KERN_WARNING "short: kernel probing not available before 1.3.30\n");
}
#endif /* 1.3.30 */

#if LINUX_VERSION_CODE < VERSION_CODE(1,3,70)
void short_probing(int irq, struct pt_regs *regs)
#else
void short_probing(int irq, void *dev_id, struct pt_regs *regs)
#endif
{
    if (short_irq == 0) short_irq = irq;    /* found */
    if (short_irq != irq) short_irq = -irq; /* ambiguous */
}

void short_selfprobe(void)
{
    int trials[] = {3, 5, 7, 9, 0};
    int tried[]  = {0, 0, 0, 0, 0};
    int i, count = 0;

     /*
      * install the probing handler for all possible lines. Remember
      * the result (0 for success, or -EBUSY) in order to only free
      * what has been acquired
      */
    for (i=0; trials[i]; i++)
        tried[i] = request_irq(trials[i], short_probing,
                               SA_INTERRUPT, "short probe", NULL);

    do {
        short_irq = 0; /* none got, yet */
        outb_p(0x10,short_base+2); /* enable */
        outb_p(0x00,short_base);
        outb_p(0xFF,short_base); /* toggle the bit */
        outb_p(0x10,short_base+2); /* disable */

        /* the value has been set by the handler */
        if (short_irq == 0) { /* none of them? */
            printk(KERN_INFO "short: no irq reported by probe\n");
        }
        /*
         * If more than one line has been activated, the result is
         * negative. We should service the interrupt (but the lpt port
         * doesn't need it) and loop over again. Do it at most 5 times
         */
    } while (short_irq <=0 && count++ < 5);

    /* end of loop, uninstall the handler */
    for (i=0; trials[i]; i++)
        if (tried[i] == 0)
            free_irq(trials[i], NULL);

    if (short_irq < 0)
        printk("short: probe failed %i times, giving up\n", count);
}
int init_module(void)
{
    int result = check_region(short_base,4);

    if (result) {
        printk(KERN_INFO "short: can't get I/O address 0x%x\n",short_base);
        return result;
    }
    request_region(short_base,4,"short");

    result = register_chrdev(short_major, "short", &short_fops);
    if (result < 0) {
        printk(KERN_INFO "short: can't get major number\n");
        release_region(short_base,4);
        return result;
    }
    if (short_major == 0) short_major = result; /* dynamic */

    short_buffer = __get_free_page(GFP_KERNEL); /* never fails */
    short_head = short_tail = short_buffer;

    /*
     * Fill the short_task structure, used for the bottom half handler
     */
    short_task.routine = short_bottom_half;
    short_task.data = NULL; /* unused */

    /*
     * Now we deal with the interrupt: either kernel-based
     * autodetection, DIY detection or default number
     */

    if (short_irq < 0 && probe == 1)
        short_kernelprobe();

    if (short_irq < 0 && probe == 2)
        short_selfprobe();

    if (short_irq < 0) /* not yet specified: force the default on */
        switch(short_base) {
          case 0x378: short_irq = 7; break;
          case 0x278: short_irq = 2; break;
          case 0x3bc: short_irq = 5; break;
        }

    /*
     * If shared has been specified, installed the shared handler
     * instead of the normal one. Do it first, before a -EBUSY will
     * force short_irq to -1.
     */
    if (short_irq >= 0 && share > 0) {
        free_irq(short_irq,NULL);
        result = request_irq(short_irq, short_sh_interrupt,
                             SA_SHIRQ | SA_INTERRUPT,"short",
                             short_sh_interrupt);
        if (result) {
            printk(KERN_INFO "short: can't get assigned irq %i\n", short_irq);
            short_irq = -1;
        }
        else { /* actually enable it -- assume this *is* a parallel port */
            outb(0x10,short_base+2);
        }
        return 0; /* the rest of the function only installs handlers */
    }

    if (short_irq >= 0) {
        result = request_irq(short_irq, short_interrupt,
                             SA_INTERRUPT, "short", NULL);
        if (result) {
            printk(KERN_INFO "short: can't get assigned irq %i\n",
                   short_irq);
            short_irq = -1;
        }
        else { /* actually enable it -- assume this *is* a parallel port */
            outb(0x10,short_base+2);
        }
    }

    /*
     * Ok, now change the interrupt handler if using top/bottom halves
     * has been requested
     */
    if (short_irq >= 0 && bh > 0) {
        free_irq(short_irq,NULL);
        result = request_irq(short_irq, short_bh_interrupt,
                             SA_INTERRUPT,"short-bh", NULL);
        if (result) {
            printk(KERN_INFO "short-bh: can't get assigned irq %i\n",
                   short_irq);
            short_irq = -1;
        }
    }

    return 0;
}

void cleanup_module(void)
{
    if (short_irq >= 0) {
        if (!share) free_irq(short_irq, NULL);
        else free_irq(short_irq, short_sh_interrupt);
    }
        
    unregister_chrdev(short_major, "short");
    release_region(short_base,4);
    if (short_buffer) free_page(short_buffer);
}


#endif /* __sparc__ */