irqchip: GICv3: ITS: MSI support

Now, the bit of code that allow us to use the ITS as a MSI controller.
Both MSI and MSI-X are supported.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-10-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-gic-v3-its.c

@@ -587,12 +587,47 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 	return IRQ_SET_MASK_OK_DONE;
 }
 
+static void its_irq_compose_msi_msg(struct irq_data *d, struct msi_msg *msg)
+{
+	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
+	struct its_node *its;
+	u64 addr;
+
+	its = its_dev->its;
+	addr = its->phys_base + GITS_TRANSLATER;
+
+	msg->address_lo		= addr & ((1UL << 32) - 1);
+	msg->address_hi		= addr >> 32;
+	msg->data		= its_get_event_id(d);
+}
+
 static struct irq_chip its_irq_chip = {
 	.name			= "ITS",
 	.irq_mask		= its_mask_irq,
 	.irq_unmask		= its_unmask_irq,
 	.irq_eoi		= its_eoi_irq,
 	.irq_set_affinity	= its_set_affinity,
+	.irq_compose_msi_msg	= its_irq_compose_msi_msg,
+};
+
+static void its_mask_msi_irq(struct irq_data *d)
+{
+	pci_msi_mask_irq(d);
+	irq_chip_mask_parent(d);
+}
+
+static void its_unmask_msi_irq(struct irq_data *d)
+{
+	pci_msi_unmask_irq(d);
+	irq_chip_unmask_parent(d);
+}
+
+static struct irq_chip its_msi_irq_chip = {
+	.name			= "ITS-MSI",
+	.irq_unmask		= its_unmask_msi_irq,
+	.irq_mask		= its_mask_msi_irq,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_write_msi_msg	= pci_msi_domain_write_msg,
 };
 
 /*
@@ -1055,3 +1090,144 @@ static void its_free_device(struct its_device *its_dev)
 	kfree(its_dev->itt);
 	kfree(its_dev);
 }
+
+static int its_alloc_device_irq(struct its_device *dev, irq_hw_number_t *hwirq)
+{
+	int idx;
+
+	idx = find_first_zero_bit(dev->lpi_map, dev->nr_lpis);
+	if (idx == dev->nr_lpis)
+		return -ENOSPC;
+
+	*hwirq = dev->lpi_base + idx;
+	set_bit(idx, dev->lpi_map);
+
+	/* Map the GIC irq ID to the device */
+	its_send_mapvi(dev, *hwirq, idx);
+
+	return 0;
+}
+
+static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
+			   int nvec, msi_alloc_info_t *info)
+{
+	struct pci_dev *pdev;
+	struct its_node *its;
+	u32 dev_id;
+	struct its_device *its_dev;
+
+	if (!dev_is_pci(dev))
+		return -EINVAL;
+
+	pdev = to_pci_dev(dev);
+	dev_id = PCI_DEVID(pdev->bus->number, pdev->devfn);
+	its = domain->parent->host_data;
+
+	its_dev = its_find_device(its, dev_id);
+	if (WARN_ON(its_dev))
+		return -EINVAL;
+
+	its_dev = its_create_device(its, dev_id, nvec);
+	if (!its_dev)
+		return -ENOMEM;
+
+	dev_dbg(&pdev->dev, "ITT %d entries, %d bits\n", nvec, ilog2(nvec));
+
+	info->scratchpad[0].ptr = its_dev;
+	info->scratchpad[1].ptr = dev;
+	return 0;
+}
+
+static struct msi_domain_ops its_pci_msi_ops = {
+	.msi_prepare	= its_msi_prepare,
+};
+
+static struct msi_domain_info its_pci_msi_domain_info = {
+	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+		   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
+	.ops	= &its_pci_msi_ops,
+	.chip	= &its_msi_irq_chip,
+};
+
+static int its_irq_gic_domain_alloc(struct irq_domain *domain,
+				    unsigned int virq,
+				    irq_hw_number_t hwirq)
+{
+	struct of_phandle_args args;
+
+	args.np = domain->parent->of_node;
+	args.args_count = 3;
+	args.args[0] = GIC_IRQ_TYPE_LPI;
+	args.args[1] = hwirq;
+	args.args[2] = IRQ_TYPE_EDGE_RISING;
+
+	return irq_domain_alloc_irqs_parent(domain, virq, 1, &args);
+}
+
+static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				unsigned int nr_irqs, void *args)
+{
+	msi_alloc_info_t *info = args;
+	struct its_device *its_dev = info->scratchpad[0].ptr;
+	irq_hw_number_t hwirq;
+	int err;
+	int i;
+
+	for (i = 0; i < nr_irqs; i++) {
+		err = its_alloc_device_irq(its_dev, &hwirq);
+		if (err)
+			return err;
+
+		err = its_irq_gic_domain_alloc(domain, virq + i, hwirq);
+		if (err)
+			return err;
+
+		irq_domain_set_hwirq_and_chip(domain, virq + i,
+					      hwirq, &its_irq_chip, its_dev);
+		dev_dbg(info->scratchpad[1].ptr, "ID:%d pID:%d vID:%d\n",
+			(int)(hwirq - its_dev->lpi_base), (int)hwirq, virq + i);
+	}
+
+	return 0;
+}
+
+static void its_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 its_device *its_dev = irq_data_get_irq_chip_data(d);
+	int i;
+
+	for (i = 0; i < nr_irqs; i++) {
+		struct irq_data *data = irq_domain_get_irq_data(domain,
+								virq + i);
+		int event = its_get_event_id(data);
+
+		/* Stop the delivery of interrupts */
+		its_send_discard(its_dev, event);
+
+		/* Mark interrupt index as unused */
+		clear_bit(event, its_dev->lpi_map);
+
+		/* Nuke the entry in the domain */
+		irq_domain_reset_irq_data(d);
+	}
+
+	/* If all interrupts have been freed, start mopping the floor */
+	if (bitmap_empty(its_dev->lpi_map, its_dev->nr_lpis)) {
+		its_lpi_free(its_dev->lpi_map,
+			     its_dev->lpi_base,
+			     its_dev->nr_lpis);
+
+		/* Unmap device/itt */
+		its_send_mapd(its_dev, 0);
+		its_free_device(its_dev);
+	}
+
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+}
+
+static const struct irq_domain_ops its_domain_ops = {
+	.alloc			= its_irq_domain_alloc,
+	.free			= its_irq_domain_free,
+};

include/linux/irqchip/arm-gic-v3.h

@@ -295,6 +295,12 @@
 
 #include <linux/stringify.h>
 
+/*
+ * We need a value to serve as a irq-type for LPIs. Choose one that will
+ * hopefully pique the interest of the reviewer.
+ */
+#define GIC_IRQ_TYPE_LPI		0xa110c8ed
+
 struct rdists {
 	struct {
 		void __iomem	*rd_base;