USB EHCI/Xen: propagate controller reset information to hypervisor

Just like for the in-tree early console debug port driver, the
hypervisor - when using a debug port based console - also needs to be
told about controller resets, so it can suppress using and then
re-initialize the debug port accordingly.

Other than the in-tree driver, the hypervisor driver actually cares
about doing this only for the device where the debug is port actually
in use, i.e. it needs to be told the coordinates of the device being
reset (quite obviously, leveraging the addition done for that would
likely benefit the in-tree driver too).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/drivers/xen/dbgp.c b/drivers/xen/dbgp.c
new file mode 100644
index 000000000000..42569c77ccc8
--- /dev/null
+++ b/drivers/xen/dbgp.c
@@ -0,0 +1,48 @@
+#include <linux/pci.h>
+#include <linux/usb.h>
+#include <linux/usb/ehci_def.h>
+#include <linux/usb/hcd.h>
+#include <asm/xen/hypercall.h>
+#include <xen/interface/physdev.h>
+#include <xen/xen.h>
+
+static int xen_dbgp_op(struct usb_hcd *hcd, int op)
+{
+        const struct device *ctrlr = hcd_to_bus(hcd)->controller;
+        struct physdev_dbgp_op dbgp;
+
+        if (!xen_initial_domain())
+                return 0;
+
+        dbgp.op = op;
+
+#ifdef CONFIG_PCI
+        if (ctrlr->bus == &pci_bus_type) {
+                const struct pci_dev *pdev = to_pci_dev(ctrlr);
+
+                dbgp.u.pci.seg = pci_domain_nr(pdev->bus);
+                dbgp.u.pci.bus = pdev->bus->number;
+                dbgp.u.pci.devfn = pdev->devfn;
+                dbgp.bus = PHYSDEVOP_DBGP_BUS_PCI;
+        } else
+#endif
+                dbgp.bus = PHYSDEVOP_DBGP_BUS_UNKNOWN;
+
+        return HYPERVISOR_physdev_op(PHYSDEVOP_dbgp_op, &dbgp);
+}
+
+int xen_dbgp_reset_prep(struct usb_hcd *hcd)
+{
+        return xen_dbgp_op(hcd, PHYSDEVOP_DBGP_RESET_PREPARE);
+}
+
+int xen_dbgp_external_startup(struct usb_hcd *hcd)
+{
+        return xen_dbgp_op(hcd, PHYSDEVOP_DBGP_RESET_DONE);
+}
+
+#ifndef CONFIG_EARLY_PRINTK_DBGP
+#include <linux/export.h>
+EXPORT_SYMBOL_GPL(xen_dbgp_reset_prep);
+EXPORT_SYMBOL_GPL(xen_dbgp_external_startup);
+#endif