+/*
+ * PCI Frontend Operations - ensure only one PCI frontend runs at a time
+ *
+ * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/spinlock.h>
+#include "pcifront.h"
+
+DEFINE_SPINLOCK(pcifront_dev_lock);
+static struct pcifront_device *pcifront_dev = NULL;
+
+int pcifront_connect(struct pcifront_device *pdev)
+{
+ int err = 0;
+
+ spin_lock(&pcifront_dev_lock);
+
+ if (!pcifront_dev) {
+ dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
+ pcifront_dev = pdev;
+ }
+ else {
+ dev_err(&pdev->xdev->dev, "PCI frontend already installed!\n");
+ err = -EEXIST;
+ }
+
+ spin_unlock(&pcifront_dev_lock);
+
+ return err;
+}
+
+void pcifront_disconnect(struct pcifront_device *pdev)
+{
+ spin_lock(&pcifront_dev_lock);
+
+ if (pdev == pcifront_dev) {
+ dev_info(&pdev->xdev->dev,
+ "Disconnecting PCI Frontend Buses\n");
+ pcifront_dev = NULL;
+ }
+
+ spin_unlock(&pcifront_dev_lock);
+}