[dpdk-dev] [PATCH v2] igb_uio: issue FLR during open and release of device file

[Shijith Thotton <shijith.thotton@caviumnetworks.com>]

Set UIO info device file operations open and release. Call pci reset
function inside open and release to clear device state at start and end.
Copied this behaviour from vfio_pci kernel module code. With this patch,
it is not mandatory to issue FLR by PMD's during init and close.

Bus master enable and disable are added in open and release respectively
to take care of device DMA.

Signed-off-by: Shijith Thotton <shijith.thotton@caviumnetworks.com>
---
v2 changes:
 - Replaced pci_try_reset_function with pci_reset_function as it is not
   available in older kernel versions.

v1 changes:
 - Added pci set master inside open and clear master inside release.
 - Remove obvious comments.

RFC: http://dpdk.org/ml/archives/dev/2017-May/066917.html

 lib/librte_eal/linuxapp/igb_uio/igb_uio.c | 33 +++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
index b9d427c..07a19a3 100644
--- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
+++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
@@ -170,6 +170,37 @@ struct rte_uio_pci_dev {
 	return IRQ_HANDLED;
 }
 
+/**
+ * This gets called while opening uio device file.
+ */
+static int
+igbuio_pci_open(struct uio_info *info, struct inode *inode)
+{
+	struct rte_uio_pci_dev *udev = info->priv;
+	struct pci_dev *dev = udev->pdev;
+
+	pci_reset_function(dev);
+
+	/* set bus master, which was cleared by the reset function */
+	pci_set_master(dev);
+
+	return 0;
+}
+
+static int
+igbuio_pci_release(struct uio_info *info, struct inode *inode)
+{
+	struct rte_uio_pci_dev *udev = info->priv;
+	struct pci_dev *dev = udev->pdev;
+
+	/* stop the device from further DMA */
+	pci_clear_master(dev);
+
+	pci_reset_function(dev);
+
+	return 0;
+}
+
 #ifdef CONFIG_XEN_DOM0
 static int
 igbuio_dom0_mmap_phys(struct uio_info *info, struct vm_area_struct *vma)
@@ -372,6 +403,8 @@ struct rte_uio_pci_dev {
 	udev->info.version = "0.1";
 	udev->info.handler = igbuio_pci_irqhandler;
 	udev->info.irqcontrol = igbuio_pci_irqcontrol;
+	udev->info.open = igbuio_pci_open;
+	udev->info.release = igbuio_pci_release;
 #ifdef CONFIG_XEN_DOM0
 	/* check if the driver run on Xen Dom0 */
 	if (xen_initial_domain())
-- 
1.8.3.1