[PATCH v3 2/3] PCI/sysfs: Don't depend on pci_dev.irq for IRQ entry

[Barry Song]

From: Barry Song <song.bao.hua@xxxxxxxxxxxxx>

Explicitly use IRQ number from MSI list for IRQ sysfs entry. Then sysfs
will decouple with the odd implementation depending on pci_dev.irq.

Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
---
 drivers/pci/pci-sysfs.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 7bbf2673..f5a06b9 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -26,6 +26,7 @@
 #include <linux/slab.h>
 #include <linux/vgaarb.h>
 #include <linux/pm_runtime.h>
+#include <linux/msi.h>
 #include <linux/of.h>
 #include "pci.h"
 
@@ -49,7 +50,27 @@ static DEVICE_ATTR_RO(field)
 pci_config_attr(subsystem_device, "0x%04x\n");
 pci_config_attr(revision, "0x%02x\n");
 pci_config_attr(class, "0x%06x\n");
-pci_config_attr(irq, "%u\n");
+
+static ssize_t irq_show(struct device *dev,
+			struct device_attribute *attr,
+			char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+#ifdef CONFIG_PCI_MSI
+	/*
+	 * For MSI, return the 1st IRQ in IRQ vector; for all other cases
+	 * including MSI-X, return legacy INTx
+	 */
+	if (pdev->msi_enabled) {
+		struct msi_desc *desc = first_pci_msi_entry(pdev);
+
+		return sysfs_emit(buf, "%u\n", desc->irq);
+	}
+#endif
+
+	return sysfs_emit(buf, "%u\n", pdev->irq);
+}
+static DEVICE_ATTR_RO(irq);
 
 static ssize_t broken_parity_status_show(struct device *dev,
 					 struct device_attribute *attr,
-- 
1.8.3.1