On Thu, 6 Nov 2014, Thomas Gleixner wrote:

On Tue, 4 Nov 2014, Jiang Liu wrote:

quoted

+#ifdef	CONFIG_PCI_MSI_IRQ_DOMAIN
+static inline irq_hw_number_t
+msi_get_hwirq(struct pci_dev *pdev, struct msi_desc *msidesc)
+{
+	return (irq_hw_number_t)msidesc->msi_attrib.entry_nr |
+		PCI_DEVID(pdev->bus->number, pdev->devfn) << 11 |
+		(pci_domain_nr(pdev->bus) & 0xFFFFFFFF) << 27;
+}
+
+static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
+			    unsigned int nr_irqs, void *arg)
+{
+	int i, ret;
+	irq_hw_number_t hwirq = arch_msi_irq_domain_get_hwirq(arg);
+
+	if (irq_find_mapping(domain, hwirq) > 0)
+		return -EEXIST;
+
+	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
+	if (ret >= 0)
+		for (i = 0; i < nr_irqs; i++) {
+			irq_domain_set_hwirq_and_chip(domain, virq + i,
+					hwirq + i, &msi_chip, (void *)(long)i);

I think msi_chip being a global unique thing is problematic. It does
not allow multi platform kernels to select a chip at boot time and it
does not allow per domain chip implementations when you have multiple
msi domains. Aside of that msi_chip is a pretty bad name for a global.

The solution is rather simple and msi is wide spread enough to justify
that.

struct irqdomain_msi_data {
       struct irq_chip       *irq_chip;
};

We make that a struct so we can accomodate for other special things
which might be domain rather than architecture specific. One
obvious use case would be to hold the arch_msi_irq_domain_get/set_hwirq
callbacks.

That needs to hand in the domain as an argument as well.

Thanks,

	tglx