[OpenBIOS] Re: Openbios code for IRQ or interrupt handling?

[Jd Lyons]

> On Feb 17, 2025, at 7:58 PM, Jd Lyons  wrote:
>
> I think we need to assign the interrupt-parent to the /cpus node like we do for PCI/macio/ata and other devices, but I can’t figure out how to do it. The /cpus node is not finalized when the code runs in the pci.c from Openbios.
>
> Do we need a cpus.c and run it there?
>
> CPUs should have and interrupt-parent, no?
>
> Outside of that I’m at a loss why everything works in Openbios, but when I boot a kernel I lose USB, RTC, ATA, and just about everything assigned an IRQ or Interrupt?
> > On Feb 17, 2025, at 5:01 PM, Jd Lyons  wrote:
> >
> > Mark, anyone, is there code in Openbios that deals with IRQ’s or Interrupts?
> >
> > I’m tracking down an issue with IRQ’s casing the IDE,, RTC, USB…… not to work with SMP patches and I’m not sure if it’s an issue with QEMU or Openbios patches I have applied.

I don’t know why, I can’t seem to get Openbios to set and interrupt-parent in the init.c for any /cpus, this code should work, no?

void add_cpu_nodes(void) {
    int num_cpus = fw_cfg_read_i32(FW_CFG_NB_CPUS);
    printk("Detected %d CPUs\n", num_cpus);

/* Ensure /cpus node exists */
    phandle cpus_node = dt_find_by_path("/cpus");
    if (!cpus_node) {
        printk("ERROR: /cpus node not found! Delaying CPU setup.\n");
        return;
    }

/* Wait until the interrupt controller exists */
    phandle intc_node = NULL;
    int retries = 5;
    while (retries-- > 0) {
        intc_node = dt_find_by_path("/pci/mac-io/@40000");
        if (intc_node) {
            break;
        }
        printk("Waiting for /pci/mac-io/@40000...\n");
        msleep(100);  // Wait 100ms before retrying
    }

if (!intc_node) {
        printk("ERROR: Interrupt controller (/pci/mac-io/@40000) not found! SMP will not work.\n");
        return;
    }

for (int i = 0; i < num_cpus; i++) {
        phandle cpu_node = dt_new_node(cpus_node);
        if (!cpu_node) {
            printk("ERROR: Failed to create CPU node for CPU %d!\n", i);
            continue;
        }

dt_set_property_string(cpu_node, "device_type", "cpu");
        dt_set_property_string(cpu_node, "compatible", "PowerPC,G4");

/* Assign a unique CPU interrupt */
        int cpu_irq[2] = { 16 + i, 0 };
        dt_set_property_cells(cpu_node, "interrupts", cpu_irq, 2);
        printk("CPU %d assigned IRQ %d\n", i, cpu_irq[0]);

/* Ensure interrupt-parent is set */
        dt_set_property_phandle(cpu_node, "interrupt-parent", intc_node);
        printk("CPU %d linked to interrupt-parent /pci/mac-io/@40000\n", i);

/* Register CPU ID */
        PUSH(i);
        fword("encode-int");
        push_str("reg");
        fword("property");

fword("finish-device");
        printk("Initialized CPU %d\n", i);
    }
}