Can't understand /proc/interrupts output for GICv3 case

[Ozgur Karatas]

Re-hi,

On Mon, Apr 11, 2022 at 6:16 PM Chan Kim <ckim at etri.re.kr> wrote:

>
> > > > What bus type is your driver written for?
> > > >
> > > That sounds very logical. In my case I added it to system bus.
> >
> > What exactly do you mean by "system bus"?
> >
> I meant 'sysbus' in qemu code that I showed in the qemu code.
> And I think it's the CPU bus.
>
> >
> > Where is your kernel code?
> >
> This is the init function of my char driver. I thought if the struct cdev
> contains struct device, maybe I could use the struct device's of_node to
> call of_irq_get but it doesn't.
> And I remember I've seen the cdev in usually contained in the driver data
> of
> platform driver(?). Can I implement platform driver in kernel module form?
> Below is the char driver init code. Currently it's request_irq(6, ... ) but
> I want to know out the number 6 using program. If you have any advice,
> please tell me.
>
> static int __init chr_driver_init(void)
> {
>         int ret;
>         /* Allocating Major number */
>         if ((alloc_chrdev_region(&dev, 0, 1, "axpu_Dev")) < 0) {
>                 printk(KERN_INFO"Cannot allocate the major number..\n");
>                 return -1;
>         }
>
>         printk(KERN_INFO"Major = %d Minor = %d..\n",MAJOR(dev),MINOR(dev));
>
>         /* creating cdev structure */
>         cdev_init(&axpu_cdev, &fops);
>         axpu_cdev.owner = THIS_MODULE;
>
>         /* Adding character device to the system */
>         if ((cdev_add(&axpu_cdev,dev,1)) < 0) {
>                 printk(KERN_INFO "Cannot add the device to the
> system...\n");
>                 goto r_class;
>         }
>

I guess you got address 0x80000 randomly also may have this code from
stackoverflow but it wont work for you.
as written stackoverflow, device_create must be a character device and an
address under /sys/dev/char before getting NULL.
So did you create a char device with use mknod command?

Actually register_chrdev will do this for you but you can do it with mknod
if you wish.

        /* creating struct class */
>         if ((dev_class = class_create(THIS_MODULE, "axpu_class")) == NULL)
> {
>                 printk(KERN_INFO "cannot create the struct class...\n");
>                 goto r_class;
>         }
>
>         /* for interrupt test !! */
>         /*  for vanilla work-around.. already made by mkdev */
>         if ((device_create(dev_class, NULL, dev, NULL, "axpu_device")) ==
> NULL) {
>                 printk(KERN_INFO "cannot create the device ..\n");
>                 goto r_device;
>         }
>         else { printk(KERN_INFO "axpu_device created..\n"); }
>         /**/
>
>         vaddr = ioremap(AXPU_BASE, 0x80000);   \
>

Please first read Documentation/devices.txt because kernel can do dynamic
allocation I think.
*
https://www.oreilly.com/library/view/linux-device-drivers/0596000081/ch03s02.html
*
https://www.oreilly.com/library/view/linux-device-drivers/0596005903/ch03.html



>         if(!vaddr)
>         {
>                 printk(KERN_INFO"Failed to map the address.\n");
>                 release_mem_region(AXPU_BASE,AXPU_SIZE);
>                 return 1;
>         }
>         printk("----- AXPU_BASE mapped at vaddr = %px\n", vaddr);
>
>         ret = request_irq(6, axpu_irq_handler, IRQF_SHARED, "axpu_irq",
> &axpu_cdev);
>         printk("request_irq returned %d\n", ret); // -EINVAL
>         printk(KERN_INFO "Device driver inserted ..done properly..\n");
>         return 0;
>
>
You dont need to call manual, because it is defined in cdev.h.
*
https://embeddedguruji.blogspot.com/2019/01/automatically-creating-device-nodes.html

in example for example device_destroy already destroys class.


> r_device :
>         class_destroy(dev_class);
>
> r_class :
>         unregister_chrdev_region(dev,1);
>         return -1;
> }
>
>
it will be great that i will recommend three books to you again.

* Understanding the Linux Kernel
* Linux Device Drivers
* Linux Kernel Development


> Thank you.
> Chan Kim
>
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