Re: [PATCH v3 4/8] hw/isa/vt82c686: Implement PCI IRQ routing

[Bernhard Beschow]

Am 26. Februar 2023 22:27:50 UTC schrieb "Philippe Mathieu-Daudé" 
<philmd@linaro.org>:
>On 25/2/23 19:11, BALATON Zoltan wrote:
>> From: Bernhard Beschow <shentey@gmail.com>
>> 
>> The real VIA south bridges implement a PCI IRQ router which is configured
>> by the BIOS or the OS. In order to respect these configurations, QEMU
>> needs to implement it as well.
>> 
>> Note: The implementation was taken from piix4_set_irq() in hw/isa/piix4.
>> 
>> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
>> [balaton: declare gpio inputs instead of changing pci bus irqs so it can
>>   be connected in board code; remove some empty lines]
>> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
>> Tested-by: Rene Engel <ReneEngel80@emailn.de>
>> ---
>>   hw/isa/vt82c686.c | 39 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 39 insertions(+)
>
>> +static int via_isa_get_pci_irq(const ViaISAState *s, int irq_num)
>> +{
>> +    switch (irq_num) {
>> +    case 0:
>> +        return s->dev.config[0x55] >> 4;
>> +    case 1:
>> +        return s->dev.config[0x56] & 0xf;
>> +    case 2:
>> +        return s->dev.config[0x56] >> 4;
>> +    case 3:
>> +        return s->dev.config[0x57] >> 4;
>> +    }
>> +    return 0;
>> +}
>> +
>> +static void via_isa_set_pci_irq(void *opaque, int irq_num, int level)
>> +{
>> +    ViaISAState *s = opaque;
>> +    PCIBus *bus = pci_get_bus(&s->dev);
>> +    int pic_irq;
>> +
>> +    /* now we change the pic irq level according to the via irq mappings */
>> +    /* XXX: optimize */
>> +    pic_irq = via_isa_get_pci_irq(s, irq_num);
>> +    if (pic_irq < ISA_NUM_IRQS) {
>
>the ISA IRQ is stored in 4-bit so will always be in range.

Indeed. I'd turn this into an assert to keep this assum visible. I'll do 
another iteration of the PCI IRQ router series.

Best regards,
Bernhard
>
>> +        int i, pic_level;
>> +
>> +        /* The pic level is the logical OR of all the PCI irqs mapped to 
>> it. */
>> +        pic_level = 0;
>> +        for (i = 0; i < PCI_NUM_PINS; i++) {
>> +            if (pic_irq == via_isa_get_pci_irq(s, i)) {
>> +                pic_level |= pci_bus_get_irq_level(bus, i);
>> +            }
>> +        }
>> +        qemu_set_irq(s->isa_irqs[pic_irq], pic_level);
>> +    }
>> +}
>
>