Re: [PATCH 2/4] esp-pci.c: generate PCI interrupt from separate ESP and PCI sources

[Guenter Roeck]

On Fri, Jan 12, 2024 at 01:15:27PM +0000, Mark Cave-Ayland wrote:
> The am53c974/dc390 PCI interrupt has two separate sources: the first is from 
> the
> internal ESP device, and the second is from the PCI DMA transfer logic.
> 
> Update the ESP interrupt handler so that it sets DMA_STAT_SCSIINT rather than
> driving the PCI IRQ directly, and introduce a new esp_pci_update_irq() 
> function
> to generate the correct PCI IRQ level. In particular this fixes spurious 
> interrupts
> being generated by setting DMA_STAT_DONE at the end of a transfer if 
> DMA_CMD_INTE_D
> isn't set in the DMA_CMD register.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  hw/scsi/esp-pci.c | 32 +++++++++++++++++++++++++++-----
>  1 file changed, 27 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/scsi/esp-pci.c b/hw/scsi/esp-pci.c
> index 7117725371..15dc3c004d 100644
> --- a/hw/scsi/esp-pci.c
> +++ b/hw/scsi/esp-pci.c
> @@ -77,6 +77,29 @@ struct PCIESPState {
>      ESPState esp;
>  };
>  
> +static void esp_pci_update_irq(PCIESPState *pci)
> +{
> +    int scsi_level = !!(pci->dma_regs[DMA_STAT] & DMA_STAT_SCSIINT);
> +    int dma_level = (pci->dma_regs[DMA_CMD] & DMA_CMD_INTE_D) ?
> +                    !!(pci->dma_regs[DMA_STAT] & DMA_STAT_DONE) : 0;
> +    int level = scsi_level || dma_level;
> +
> +    pci_set_irq(PCI_DEVICE(pci), level);
> +}
> +
> +static void esp_irq_handler(void *opaque, int irq_num, int level)
> +{
> +    PCIESPState *pci = PCI_ESP(opaque);
> +
> +    if (level) {
> +        pci->dma_regs[DMA_STAT] |= DMA_STAT_SCSIINT;
> +    } else {
> +        pci->dma_regs[DMA_STAT] &= ~DMA_STAT_SCSIINT;
> +    }
> +
> +    esp_pci_update_irq(pci);
> +}
> +
>  static void esp_pci_handle_idle(PCIESPState *pci, uint32_t val)
>  {
>      ESPState *s = &pci->esp;
> @@ -151,6 +174,7 @@ static void esp_pci_dma_write(PCIESPState *pci, uint32_t 
> saddr, uint32_t val)
>              /* clear some bits on write */
>              uint32_t mask = DMA_STAT_ERROR | DMA_STAT_ABORT | DMA_STAT_DONE;
>              pci->dma_regs[DMA_STAT] &= ~(val & mask);
> +            esp_pci_update_irq(pci);
>          }
>          break;
>      default:
> @@ -161,17 +185,14 @@ static void esp_pci_dma_write(PCIESPState *pci, 
> uint32_t saddr, uint32_t val)
>  
>  static uint32_t esp_pci_dma_read(PCIESPState *pci, uint32_t saddr)
>  {
> -    ESPState *s = &pci->esp;
>      uint32_t val;
>  
>      val = pci->dma_regs[saddr];
>      if (saddr == DMA_STAT) {
> -        if (s->rregs[ESP_RSTAT] & STAT_INT) {
> -            val |= DMA_STAT_SCSIINT;
> -        }
>          if (!(pci->sbac & SBAC_STATUS)) {
>              pci->dma_regs[DMA_STAT] &= ~(DMA_STAT_ERROR | DMA_STAT_ABORT |
>                                           DMA_STAT_DONE);
> +            esp_pci_update_irq(pci);
>          }
>      }
>  
> @@ -350,6 +371,7 @@ static void esp_pci_command_complete(SCSIRequest *req, 
> size_t resid)
>      esp_command_complete(req, resid);
>      pci->dma_regs[DMA_WBC] = 0;
>      pci->dma_regs[DMA_STAT] |= DMA_STAT_DONE;
> +    esp_pci_update_irq(pci);
>  }
>  
>  static const struct SCSIBusInfo esp_pci_scsi_info = {
> @@ -386,7 +408,7 @@ static void esp_pci_scsi_realize(PCIDevice *dev, Error 
> **errp)
>                            "esp-io", 0x80);
>  
>      pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &pci->io);
> -    s->irq = pci_allocate_irq(dev);
> +    s->irq = qemu_allocate_irq(esp_irq_handler, pci, 0);
>  
>      scsi_bus_init(&s->bus, sizeof(s->bus), d, &esp_pci_scsi_info);
>  }
> -- 
> 2.39.2
>