intel_th: pci: Use MSI interrupt signalling

Since Intel TH is capable of MSI interrupt signalling, make use of it.
The way it works is, each of the 7 interrupt triggering events has its
own vector in this mode, as opposed to interrupt line delivery, where
all events are signalled via the same line. Failing to enable MSI, the
driver falls back to using an interrupt line.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/intel_th/intel_th.h

@@ -238,6 +238,9 @@ enum th_mmio_idx {
 #define TH_CONFIGURABLE_MASTERS 256
 #define TH_MSC_MAX		2
 
+/* Maximum IRQ vectors */
+#define TH_NVEC_MAX		8
+
 /**
  * struct intel_th - Intel TH controller
  * @dev:	driver core's device

drivers/hwtracing/intel_th/pci.c

@@ -72,11 +72,11 @@ static int intel_th_pci_probe(struct pci_dev *pdev,
 			      const struct pci_device_id *id)
 {
 	struct intel_th_drvdata *drvdata = (void *)id->driver_data;
-	struct resource resource[TH_MMIO_END + 1] = {
+	struct resource resource[TH_MMIO_END + TH_NVEC_MAX] = {
 		[TH_MMIO_CONFIG]	= pdev->resource[TH_PCI_CONFIG_BAR],
 		[TH_MMIO_SW]		= pdev->resource[TH_PCI_STH_SW_BAR],
 	};
-	int err, r = TH_MMIO_SW + 1;
+	int err, r = TH_MMIO_SW + 1, i;
 	struct intel_th *th;
 
 	err = pcim_enable_device(pdev);
@@ -92,10 +92,12 @@ static int intel_th_pci_probe(struct pci_dev *pdev,
 		r++;
 	}
 
-	if (pdev->irq > 0) {
-		resource[r].flags   = IORESOURCE_IRQ;
-		resource[r++].start = pdev->irq;
-	}
+	err = pci_alloc_irq_vectors(pdev, 1, 8, PCI_IRQ_ALL_TYPES);
+	if (err > 0)
+		for (i = 0; i < err; i++, r++) {
+			resource[r].flags = IORESOURCE_IRQ;
+			resource[r].start = pci_irq_vector(pdev, i);
+		}
 
 	th = intel_th_alloc(&pdev->dev, drvdata, resource, r);
 	if (IS_ERR(th))
@@ -114,6 +116,8 @@ static void intel_th_pci_remove(struct pci_dev *pdev)
 	struct intel_th *th = pci_get_drvdata(pdev);
 
 	intel_th_free(th);
+
+	pci_free_irq_vectors(pdev);
 }
 
 static const struct intel_th_drvdata intel_th_2x = {