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

["Chan Kim" <ckim@etri.re.kr>]

Hello all

I think I'm asking too many question recently but sometimes I get very big
help from here so please forgive me.
(and I think someone else can get help from this email thread)
I'm doing experiment for interrupt of a device called axpu on an arm64
virtual machine.
In QEMU virtual machine, the interrupts are assigned as below.
(These numbers are SPI(shared peripheral interrupt) numbers, 
and there are 16 SGI and 16 PPI before SPI, so we have to add 32 to get the
INTID value(hwirq number))

static const int a15irqmap[] = {
    [AB21Q_UART] = 1,
    [AB21Q_RTC] = 2,
    [AB21Q_PCIE] = 3, /* ... to 6 */
    [AB21Q_GPIO] = 7,
    [AB21Q_SECURE_UART] = 8,
    [AB21Q_ACPI_GED] = 9,
    [AB21Q_MMIO] = 16, /* ...to 16 + NUM_VIRTIO_TRANSPORTS - 1 */
    [AB21Q_GIC_V2M] = 48, /* ...to 48 + NUM_GICV2M_SPIS - 1 */
    [AB21Q_SMMU] = 74,    /* ...to 74 + NUM_SMMU_IRQS - 1 */
    [AB21Q_PLATFORM_BUS] = 112, /* ...to 112 + PLATFORM_BUS_NUM_IRQS -1 */
    [AB21Q_AXPU] = 15,
};

In the driver, when I do request_irq(32+15, axpu_irq_handler, IRQF_SHARED,
"axpu_irq", &axpu_cdev) for my device axpu,
the /proc/interrupts' looks like this. See the 10th item(axpu_irq).

	           CPU0       
	  1:          0     GICv3  25 Level     vgic
	  3:          0     GICv3  30 Level     kvm guest ptimer
	  4:          0     GICv3  27 Level     kvm guest vtimer
	  5:      20432     GICv3  26 Level     arch_timer
	 40:          0     GICv3 106 Edge      arm-smmu-v3-evtq
	 43:          0     GICv3 109 Edge      arm-smmu-v3-gerror
	 44:          0     GICv3  34 Level     rtc-pl031
	 45:        164     GICv3  33 Level     uart-pl011
	 46:          0     GICv3  23 Level     arm-pmu
	 47:       7789     GICv3  36 Level     virtio0, axpu_irq
	 48:          0  9030000.pl061   3 Edge      GPIO Key Poweroff
	IPI0:         0       Rescheduling interrupts
	IPI1:         0       Function call interrupts
	IPI2:         0       CPU stop interrupts
	IPI3:         0       CPU stop (for crash dump) interrupts
	IPI4:         0       Timer broadcast interrupts
	IPI5:         0       IRQ work interrupts
	IPI6:         0       CPU wake-up interrupts
        Err:          0

There are two numbers. One in the first column and the other in the 4th
column.
After observing uart-pl011 driver's action(who's irq in 8th row), I found
the number in the first column is the one I should pass to the request_irq
funcion, and the second number in the 4th column is the input to the GICv3.
(uart was assigned SPI 1, so 32+1 = 33).
In my axpu driver case, I requested request_irq(47, ...) so hwirq is 47 but
I don't know why it was assigned to GICv3 input 36.
Shouldn't it be 47 too? (32+15=47).

Without fixing QEMU code(still using SPI 15), I tried doing request_irq(15,
axpu_irq_handler, ..) for test and this time it looks like this.(see the 5th
row)

           CPU0       
  1:          0     GICv3  25 Level     vgic
  3:          0     GICv3  30 Level     kvm guest ptimer
  4:          0     GICv3  27 Level     kvm guest vtimer
  5:       8174     GICv3  26 Level     arch_timer
 15:          0     GICv3  56 Edge      axpu_irq
 40:          0     GICv3 106 Edge      arm-smmu-v3-evtq
 43:          0     GICv3 109 Edge      arm-smmu-v3-gerror
 44:          0     GICv3  34 Level     rtc-pl031
 45:        175     GICv3  33 Level     uart-pl011
 46:          0     GICv3  23 Level     arm-pmu
 47:       7790     GICv3  36 Level     virtio0
 48:          0  9030000.pl061   3 Edge      GPIO Key Poweroff
IPI0:         0       Rescheduling interrupts
IPI1:         0       Function call interrupts
IPI2:         0       CPU stop interrupts
IPI3:         0       CPU stop (for crash dump) interrupts
IPI4:         0       Timer broadcast interrupts
IPI5:         0       IRQ work interrupts
IPI6:         0       CPU wake-up interrupts
Err:          0

Now axpu_irq has moved to INTID 15 (as expected), but it changed to "GICv3
56 Edge".
How is this GICv3 number is assigned? (and I guess edge trigger is the
default for INTID < 16. Because it's SGI..?)

I thought I connected my device (axpu) to SPI 15 in qemu code but this GICv3
input number changes according to with what number I called reqeust_irq.
Could anyone tell me what is going on here?

Thank you.
Chan Kim






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