linux-kernel - [PATCH 2/2] uio: Prefer MSI(X) interrupts in PCI drivers

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Date:   Fri, 6 Oct 2017 13:33:32 +0000
From:   "Stahl, Manuel" <manuel.stahl@...-extern.fraunhofer.de>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "hjk@...utronix.de" <hjk@...utronix.de>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "sojkam1@....cvut.cz" <sojkam1@....cvut.cz>
Subject: [PATCH 2/2] uio: Prefer MSI(X) interrupts in PCI drivers


Signed-off-by: Manuel Stahl <manuel.stahl@....fraunhofer.de>
---
 drivers/uio/uio_pci_dmem_genirq.c | 27 ++++++++++++++++++++-------
 drivers/uio/uio_pci_generic.c     | 24 ++++++++++++++++++------
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/drivers/uio/uio_pci_dmem_genirq.c b/drivers/uio/uio_pci_dmem_genirq.c
index d1dfd8002c6d..ebb3f9012cd8 100644
--- a/drivers/uio/uio_pci_dmem_genirq.c
+++ b/drivers/uio/uio_pci_dmem_genirq.c
@@ -173,11 +173,13 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
 {
 	struct uio_pci_dmem_dev *gdev = to_uio_pci_dmem_dev(info);
 
-	if (!pci_check_and_mask_intx(gdev->pdev))
-		return IRQ_NONE;
+	if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+		return IRQ_HANDLED;
 
-	/* UIO core will signal the user process. */
-	return IRQ_HANDLED;
+	if (pci_check_and_mask_intx(gdev->pdev))
+		return IRQ_HANDLED;
+
+	return IRQ_NONE;
 }
 
 static unsigned int uio_dmem_dma_bits = 32;
@@ -269,11 +271,19 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	}
 	pci_set_master(pdev);
 
-	dev_info(&pdev->dev, "Legacy IRQ: %i", pdev->irq);
-	if (pdev->irq && !pci_intx_mask_supported(pdev)) {
-		err = -ENODEV;
+	/* Try to use MSI interrupts */
+	err = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
+	if (err) {
+		dev_err(&pdev->dev, "%s: pci_alloc_irq_vectors failed: %d\n",
+			__func__, err);
 		goto err_disable_pci;
 	}
+	if (!pdev->msi_enabled && !pdev->msix_enabled &&
+	    !pci_intx_mask_supported(pdev)) {
+		err = -ENODEV;
+		goto err_free_irq_vectors;
+	}
+	dev_info(&pdev->dev, "IRQ: %i", pdev->irq);
 
 	gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
 	if (!gdev) {
@@ -316,6 +326,8 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	return 0;
 err_free_gdev:
 	kfree(gdev);
+err_free_irq_vectors:
+	pci_free_irq_vectors(pdev);
 err_disable_pci:
 	pci_clear_master(pdev);
 	pci_disable_device(pdev);
@@ -327,6 +339,7 @@ static void remove(struct pci_dev *pdev)
 	struct uio_pci_dmem_dev *gdev = pci_get_drvdata(pdev);
 
 	uio_unregister_device(&gdev->info);
+	pci_free_irq_vectors(pdev);
 	pci_clear_master(pdev);
 	pci_disable_device(pdev);
 	kfree(gdev);
diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c
index a56fdf972dbe..23a800e76303 100644
--- a/drivers/uio/uio_pci_generic.c
+++ b/drivers/uio/uio_pci_generic.c
@@ -46,11 +46,13 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
 {
 	struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
 
-	if (!pci_check_and_mask_intx(gdev->pdev))
-		return IRQ_NONE;
+	if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+		return IRQ_HANDLED;
 
-	/* UIO core will signal the user process. */
-	return IRQ_HANDLED;
+	if (pci_check_and_mask_intx(gdev->pdev))
+		return IRQ_HANDLED;
+
+	return IRQ_NONE;
 }
 
 static int probe(struct pci_dev *pdev,
@@ -66,10 +68,18 @@ static int probe(struct pci_dev *pdev,
 		return err;
 	}
 
-	if (pdev->irq && !pci_intx_mask_supported(pdev)) {
-		err = -ENODEV;
+	/* Try to use MSI interrupts */
+	err = pci_alloc_irq_vectors(pdev, 0, 1, PCI_IRQ_ALL_TYPES);
+	if (err) {
+		dev_err(&pdev->dev, "%s: pci_alloc_irq_vectors failed: %d\n",
+			__func__, err);
 		goto err_verify;
 	}
+	if (pdev->irq && !pdev->msi_enabled && !pdev->msix_enabled &&
+	    !pci_intx_mask_supported(pdev)) {
+		err = -ENODEV;
+		goto err_alloc;
+	}
 
 	gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
 	if (!gdev) {
@@ -98,6 +108,7 @@ static int probe(struct pci_dev *pdev,
 err_register:
 	kfree(gdev);
 err_alloc:
+	pci_free_irq_vectors(pdev);
 err_verify:
 	pci_disable_device(pdev);
 	return err;
@@ -108,6 +119,7 @@ static void remove(struct pci_dev *pdev)
 	struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
 
 	uio_unregister_device(&gdev->info);
+	pci_free_irq_vectors(pdev);
 	pci_disable_device(pdev);
 	kfree(gdev);
 }
-- 
2.11.0