On 25/08/15 10:35, Ley Foon Tan wrote:

I still wonder under which circumstances you can obtain a valid virq and
yet not find the bit in the bitmap. Unless you have a scenario when that
can happen, I suggest you remove that test.

+				generic_handle_irq(virq);
+			else
+				dev_err(&msi->pdev->dev, "unexpected MSI\n");
+
+			/* Clear the bit from status and repeat without reading
+			 * again status register. */
+			__clear_bit(bit, &status);
+		} while (status);
+	} while (1);

I think this could be rewritten as:

while ((status = msi_readl(msi, MSI_STATUS)) != 0) {
	for_each_set_bit(bit, &status, msi->num_of_vectors) {
		/* Dummy read from vector to clear the interrupt */
		readl_relaxed(msi->vector_base + (bit * sizeof(u32)));

		virq = irq_find_mapping(msi->inner_domain, bit);
		if (virq)
			generic_handle_irq(virq);
		else
			dev_err(&msi->pdev->dev, "unexpected MSI\n");
	}
}

which saves the __clear_bit call and the double test of status which I
find a bit awkward.

+
+	chained_irq_exit(chip, desc);
+}
+
+static struct irq_chip altera_msi_irq_chip = {
+	.name = "Altera PCIe MSI",
+	.irq_enable = pci_msi_unmask_irq,
+	.irq_disable = pci_msi_mask_irq,
+	.irq_mask = pci_msi_mask_irq,
+	.irq_unmask = pci_msi_unmask_irq,

Why do you have both enable/disable and unmask/mask? Specially pointing
to the same function? This is completely useless. Just stick with
unmask/mask and remove the enable/disable.

+};
+
+static struct msi_domain_info altera_msi_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		     MSI_FLAG_PCI_MSIX),
+	.chip	= &altera_msi_irq_chip,
+};
+
+static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
+{
+	struct altera_msi *msi = irq_data_get_irq_chip_data(data);
+	phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
+
+	msg->address_lo = lower_32_bits(addr);
+	msg->address_hi = upper_32_bits(addr);
+	msg->data = data->hwirq;
+
+	dev_dbg(&msi->pdev->dev, "msi#%d address_lo 0x%x address_hi 0x%x\n",
+		(int)data->hwirq, msg->address_hi, msg->address_lo);
+}
+
+static int altera_msi_set_affinity(struct irq_data *irq_data,
+				   const struct cpumask *mask, bool force)
+{
+	 return -EINVAL;
+}
+
+static struct irq_chip altera_msi_bottom_irq_chip = {
+	.name			= "Altera MSI",
+	.irq_compose_msi_msg	= altera_compose_msi_msg,
+	.irq_set_affinity	= altera_msi_set_affinity,
+};
+
+static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				   unsigned int nr_irqs, void *args)
+{
+	struct altera_msi *msi = domain->host_data;
+	unsigned long bit;
+	u32 mask;
+
+	WARN_ON(nr_irqs != 1);
+	mutex_lock(&msi->lock);
+
+	bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
+	if (bit >= msi->num_of_vectors)
+		return -ENOSPC;
+
+	set_bit(bit, msi->used);
+
+	mutex_unlock(&msi->lock);
+
+	irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
+			    domain->host_data, handle_simple_irq,
+			    NULL, NULL);
+	set_irq_flags(virq, IRQF_VALID);
+
+	mask = msi_readl(msi, MSI_INTMASK);
+	mask |= 1 << bit;
+	msi_writel(msi, mask, MSI_INTMASK);
+
+	return 0;
+}
+
+static void altera_irq_domain_free(struct irq_domain *domain,
+				   unsigned int virq, unsigned int nr_irqs)
+{
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+	struct altera_msi *msi = irq_data_get_irq_chip_data(d);
+	u32 mask;
+
+	mutex_lock(&msi->lock);
+
+	if (!test_bit(d->hwirq, msi->used)) {
+		dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
+			d->hwirq);
+	} else {
+		__clear_bit(d->hwirq, msi->used);
+		mask = msi_readl(msi, MSI_INTMASK);
+		mask &= ~(1 << d->hwirq);
+		msi_writel(msi, mask, MSI_INTMASK);
+	}
+
+	mutex_unlock(&msi->lock);
+}
+
+static const struct irq_domain_ops msi_domain_ops = {
+	.alloc	= altera_irq_domain_alloc,
+	.free	= altera_irq_domain_free,
+};
+
+static int altera_allocate_domains(struct altera_msi *msi)
+{
+	msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
+					     &msi_domain_ops, msi);
+	if (!msi->inner_domain) {
+		dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	msi->msi_domain = pci_msi_create_irq_domain(msi->pdev->dev.of_node,
+				&altera_msi_domain_info, msi->inner_domain);
+	if (!msi->msi_domain) {
+		dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
+		irq_domain_remove(msi->inner_domain);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void altera_free_domains(struct altera_msi *msi)
+{
+	irq_domain_remove(msi->msi_domain);
+	irq_domain_remove(msi->inner_domain);
+}
+
+static int altera_msi_remove(struct platform_device *pdev)
+{
+	struct altera_msi *msi = platform_get_drvdata(pdev);
+
+	msi_writel(msi, 0, MSI_INTMASK);
+	irq_set_chained_handler(msi->irq, NULL);
+	irq_set_handler_data(msi->irq, NULL);
+
+	altera_free_domains(msi);
+
+	platform_set_drvdata(pdev, NULL);
+	return 0;
+}
+
+static int altera_msi_probe(struct platform_device *pdev)
+{
+	struct altera_msi *msi;
+	struct device_node *np = pdev->dev.of_node;
+	struct resource *res;
+	int ret;
+
+	msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
+			   GFP_KERNEL);
+	if (!msi)
+		return -ENOMEM;
+
+	mutex_init(&msi->lock);
+	msi->pdev = pdev;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "csr");
+	if (!res) {
+		dev_err(&pdev->dev,
+			"no csr memory resource defined\n");
+		return -ENODEV;
+	}
+
+	msi->csr_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(msi->csr_base)) {
+		dev_err(&pdev->dev, "failed to map csr memory\n");
+		return PTR_ERR(msi->csr_base);
+	}
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "vector_slave");
+	if (!res) {
+		dev_err(&pdev->dev,
+			"no vector_slave memory resource defined\n");
+		return -ENODEV;
+	}
+
+	msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(msi->vector_base)) {
+		dev_err(&pdev->dev, "failed to map vector_slave memory\n");
+		return PTR_ERR(msi->vector_base);
+	}
+
+	msi->vector_phy = res->start;
+
+	if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
+		dev_err(&pdev->dev, "failed to parse the number of vectors\n");
+		return -EINVAL;
+	}
+
+	ret = altera_allocate_domains(msi);
+	if (ret)
+		return ret;
+
+	msi->irq = platform_get_irq(pdev, 0);
+	if (msi->irq <= 0) {
+		dev_err(&pdev->dev, "failed to map IRQ: %d\n", msi->irq);
+		ret = -ENODEV;
+		goto err;
+	}
+
+	irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
+	platform_set_drvdata(pdev, msi);
+
+	return 0;
+
+err:
+	altera_msi_remove(pdev);
+	return ret;
+}
+
+static const struct of_device_id altera_msi_of_match[] = {
+	{ .compatible = "altr,msi-1.0", NULL },
+	{ },
+};
+
+static struct platform_driver altera_msi_driver = {
+	.driver = {
+		.name = "altera-msi",
+		.of_match_table = altera_msi_of_match,
+	},
+	.probe = altera_msi_probe,
+	.remove = altera_msi_remove,
+};
+
+static int __init altera_msi_init(void)
+{
+	return platform_driver_register(&altera_msi_driver);
+}
+
+subsys_initcall(altera_msi_init);
+
+MODULE_AUTHOR("Ley Foon Tan [off-list ref]");
+MODULE_DESCRIPTION("Altera PCIe MSI support");
+MODULE_LICENSE("GPL v2");

Once you've fixed the above issues, you can add my:

Reviewed-by: Marc Zyngier <redacted>

	M.
-- 
Jazz is not dead. It just smells funny...