linux-kernel - [patch V3 26/35] genirq/msi: Provide interface to retrieve Linux interrupt number

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Message-ID: <20211210221814.780824745@linutronix.de>
Date:   Fri, 10 Dec 2021 23:19:23 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
        Cedric Le Goater <clg@...d.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Juergen Gross <jgross@...e.com>,
        xen-devel@...ts.xenproject.org, Arnd Bergmann <arnd@...db.de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linuxppc-dev@...ts.ozlabs.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org,
        Jassi Brar <jassisinghbrar@...il.com>,
        Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Sinan Kaya <okaya@...nel.org>
Subject: [patch V3 26/35] genirq/msi: Provide interface to retrieve Linux
 interrupt number

From: Thomas Gleixner <tglx@...utronix.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 in case that there
is no entry for the given MSI index.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
V2: Simplify the implementation and let PCI deal with the PCI specialities - Marc
---
 include/linux/msi.h |    2 ++
 kernel/irq/msi.c    |   36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -153,6 +153,8 @@ struct msi_device_data {
 
 int msi_setup_device_data(struct device *dev);
 
+unsigned int msi_get_virq(struct device *dev, unsigned int index);
+
 /* 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
@@ -105,6 +105,42 @@ 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), 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)