Alternate driver for Avalon-MM DMA for PCIe

Hello @AlexGo

I started testing drivers.

I had problems to receive MSI interrupts by the driver. It basically hangs at xfer_rw() function if MSI interrupts are not received.

To make it work, I added init_arria_msi() function and called it in your init_interrupts() function as suggested by @OlegT here

static void init_arria_msi(struct pci_dev *pci_dev)
{
	u32 conf_reg;
	
	// set interrupt disable for legacy
	pci_read_config_dword(pci_dev, 0x04, &conf_reg);
	dev_info(&pci_dev->dev, "previous conf_reg = %08llx", (u64)conf_reg);
	conf_reg |= (1 << 10);	
	pci_write_config_dword(pci_dev, 0x04, conf_reg);

	//Set bit[1] (Memory space) and bit[2]
	conf_reg |= 0x06;
	pci_write_config_dword(pci_dev, 0x04, conf_reg);
	dev_info(&pci_dev->dev, "after conf_reg = %08llx", (u64)conf_reg);

	// set msi Ena
	pci_read_config_dword(pci_dev, 0x50, &conf_reg);
	dev_info(&pci_dev->dev, "previous msi Ena = %08llx", (u64)conf_reg);
	conf_reg |= (1 << 16);
	pci_write_config_dword(pci_dev, 0x50, conf_reg);	
	dev_info(&pci_dev->dev, "after msi Ena = %08llx", (u64)conf_reg);
}

static int init_interrupts(struct pci_dev *pci_dev)
{
	int ret;
	
	init_arria_msi(pci_dev);

	ret = pci_alloc_irq_vectors(pci_dev,
				    PCI_MSI_COUNT, PCI_MSI_COUNT,
				    PCI_IRQ_MSI);
	if (ret < 0) {
		goto msi_err;
	} else if (ret != PCI_MSI_COUNT) {
		ret = -ENOSPC;
		goto nr_msi_err;
	}

	ret = pci_irq_vector(pci_dev, PCI_MSI_VECTOR);
	if (ret < 0)
		goto vec_err;

	return ret;

vec_err:
nr_msi_err:
	pci_disable_msi(pci_dev);

msi_err:
	return ret;
}

After the modification, it seems I can complete dma transfers for writing and reading successfully. I will do couple of performance tests and let you know.

Thank you.