[patch 28/37] genirq/msi: Provide interface to retrieve Linux interrupt number

[Thomas Gleixner <tglx@linutronix.de>]

This allows drivers to retrieve the Linux interrupt number instead of
fiddling with MSI descriptors.

msi_get_virq() returns the Linux interrupt number or 0, __msi_get_virq()
has more detailed return codes so pci_irq_vector() can use it as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/msi.h |   16 ++++++++++++++++
 kernel/irq/msi.c    |   38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -169,6 +169,22 @@ static inline bool msi_device_has_proper
 }
 #endif
 
+int __msi_get_virq(struct device *dev, unsigned int index);
+
+/**
+ * msi_get_virq - Return Linux interrupt number of a MSI interrupt
+ * @dev:	Device to operate on
+ * @index:	MSI interrupt index to look for (0-based)
+ *
+ * Return: The Linux interrupt number on success (> 0), 0 if not found
+ */
+static inline unsigned int msi_get_virq(struct device *dev, unsigned int index)
+{
+	int ret = __msi_get_virq(dev, index);
+
+	return ret < 0 ? 0 : ret;
+}
+
 /* Helpers to hide struct msi_desc implementation details */
 #define msi_desc_to_dev(desc)		((desc)->dev)
 #define dev_to_msi_list(dev)		(&(dev)->msi_list)
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -120,6 +120,44 @@ int msi_setup_device_data(struct device
 	return 0;
 }
 
+/**
+ * __msi_get_virq - Return Linux interrupt number of a MSI interrupt
+ * @dev:	Device to operate on
+ * @index:	MSI interrupt index to look for (0-based)
+ *
+ * Return: The Linux interrupt number on success (> 0)
+ *	   -ENODEV when the device is not using MSI
+ *	   -ENOENT if no such entry exists
+ */
+int __msi_get_virq(struct device *dev, unsigned int index)
+{
+	struct msi_desc *desc;
+	bool pcimsi;
+
+	if (!dev->msi.data)
+		return -ENODEV;
+
+	pcimsi = msi_device_has_property(dev, MSI_PROP_PCI_MSI);
+
+	for_each_msi_entry(desc, dev) {
+		/* PCI-MSI has only one descriptor for multiple interrupts. */
+		if (pcimsi) {
+			if (desc->irq && index < desc->nvec_used)
+				return desc->irq + index;
+			break;
+		}
+
+		/*
+		 * PCI-MSIX and platform MSI use a descriptor per
+		 * interrupt.
+		 */
+		if (desc->msi_index == index)
+			return desc->irq;
+	}
+	return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(__msi_get_virq);
+
 #ifdef CONFIG_SYSFS
 static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)