genirq/msi: Provide interface to retrieve Linux interrupt number
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 in case that there
is no entry for the given MSI index.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211210221814.780824745@linutronix.de
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 8e433f1..ab5e83f 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -105,6 +105,42 @@ int msi_setup_device_data(struct device *dev)
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), 0 if not found
+ */
+unsigned int msi_get_virq(struct device *dev, unsigned int index)
+{
+ struct msi_desc *desc;
+ bool pcimsi;
+
+ if (!dev->msi.data)
+ return 0;
+
+ pcimsi = dev_is_pci(dev) ? to_pci_dev(dev)->msi_enabled : false;
+
+ 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 0;
+}
+EXPORT_SYMBOL_GPL(msi_get_virq);
+
#ifdef CONFIG_SYSFS
static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,
char *buf)