[Patch V1 6/6] PCI, MSI: Provide mechanism to alloc/free MSI/MSIX interrupt from irqdomain

[Jiang Liu <jiang.liu@linux.intel.com>]

Provide mechanism to directly alloc/free MSI/MSIX interrupt from
irqdomain, which will be used to replace arch_setup_msi_irq()/
arch_setup_msi_irqs()/arch_teardown_msi_irq()/arch_teardown_msi_irqs().

To kill weak functions, this patch introduce a new weak function
arch_get_pci_msi_domain(), which is to retrieve the MSI irqdomain
for a PCI device. This weak function could be killed once we get
a common way to associate MSI domain with PCI device.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
 drivers/pci/msi.c   |   60 +++++++++++++++++++++++++++++++++++++++++++++++----
 include/linux/msi.h |    3 +++
 2 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0319c21dd208..6f8a2f93187a 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -27,8 +27,41 @@ static int pci_msi_enable = 1;
 
 #define msix_table_size(flags)	((flags & PCI_MSIX_FLAGS_QSIZE) + 1)
 
-/* Arch hooks */
+#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
+static struct irq_domain *pci_msi_default_domain;
+
+struct irq_domain * __weak arch_get_pci_msi_domain(struct pci_dev *dev)
+{
+	return pci_msi_default_domain;
+}
+
+static int pci_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
+{
+	struct irq_domain *domain;
 
+	domain = arch_get_pci_msi_domain(dev);
+	if (domain)
+		return pci_msi_domain_alloc_irqs(domain, type, dev);
+
+	return arch_setup_msi_irqs(dev, nvec, type);
+}
+
+static void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
+{
+	struct irq_domain *domain;
+
+	domain = arch_get_pci_msi_domain(dev);
+	if (domain)
+		pci_msi_domain_free_irqs(domain, dev);
+	else
+		arch_teardown_msi_irqs(dev);
+}
+#else
+#define pci_msi_setup_msi_irqs		arch_setup_msi_irqs
+#define pci_msi_teardown_msi_irqs	arch_teardown_msi_irqs
+#endif
+
+/* Arch hooks */
 int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 {
 	struct msi_chip *chip = dev->bus->msi;
@@ -329,7 +362,7 @@ static void free_msi_irqs(struct pci_dev *dev)
 			for (i = 0; i < entry->nvec_used; i++)
 				BUG_ON(irq_has_action(entry->irq + i));
 
-	arch_teardown_msi_irqs(dev);
+	pci_msi_teardown_msi_irqs(dev);
 
 	list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
 		if (entry->msi_attrib.is_msix) {
@@ -581,7 +614,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
 	list_add_tail(&entry->list, &dev->msi_list);
 
 	/* Configure MSI capability structure */
-	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
+	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
 	if (ret) {
 		msi_mask_irq(entry, mask, ~mask);
 		free_msi_irqs(dev);
@@ -696,7 +729,7 @@ static int msix_capability_init(struct pci_dev *dev,
 	if (ret)
 		return ret;
 
-	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
+	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
 	if (ret)
 		goto out_avail;
 
@@ -1183,4 +1216,23 @@ void pci_msi_domain_free_irqs(struct irq_domain *domain, struct pci_dev *dev)
 {
 	msi_domain_free_irqs(domain, &dev->dev);
 }
+
+struct irq_domain *pci_msi_create_default_irq_domain(struct device_node *node,
+		 struct msi_domain_info *info, struct irq_domain *parent)
+{
+	struct irq_domain *domain;
+	static DEFINE_MUTEX(pci_msi_domain_lock);
+
+	mutex_lock(&pci_msi_domain_lock);
+	if (pci_msi_default_domain) {
+		pr_err("PCI: default irq domain for PCI MSI has already been created.\n");
+		domain = NULL;
+	} else {
+		domain = msi_create_irq_domain(node, info, parent);
+		pci_msi_default_domain = domain;
+	}
+	mutex_unlock(&pci_msi_domain_lock);
+
+	return domain;
+}
 #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 9031791e9b4c..e3ec97349535 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -185,6 +185,9 @@ struct irq_domain *pci_msi_create_irq_domain(struct device_node *node,
 int pci_msi_domain_alloc_irqs(struct irq_domain *domain, int type,
 			      struct pci_dev *dev);
 void pci_msi_domain_free_irqs(struct irq_domain *domain, struct pci_dev *dev);
+struct irq_domain *pci_msi_create_default_irq_domain(struct device_node *node,
+		 struct msi_domain_info *info, struct irq_domain *parent);
+
 irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
 					  struct msi_desc *desc);
 int pci_msi_domain_check_cap(struct irq_domain *domain,
-- 
1.7.10.4