usb: dwc3: Add dual-role support

If dr_mode is "otg" then support dual role mode of operation.
Currently this mode is only supported when an extcon handle is
present in the dwc3 device tree node. This is needed to
get the ID status events of the port.

We're using a workqueue to manage the dual-role state transitions
as the extcon notifier (dwc3_drd_notifier) is called in an atomic
context by extcon_sync() and this doesn't go well with
usb_del_gadget_udc() causing a lockdep and softirq warning.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
new file mode 100644
index 000000000000..2765c51c7ef5
--- /dev/null
+++ b/drivers/usb/dwc3/drd.c
@@ -0,0 +1,85 @@
+/**
+ * drd.c - DesignWare USB3 DRD Controller Dual-role support
+ *
+ * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Authors: Roger Quadros <rogerq@ti.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/extcon.h>
+
+#include "debug.h"
+#include "core.h"
+#include "gadget.h"
+
+static void dwc3_drd_update(struct dwc3 *dwc)
+{
+	int id;
+
+	id = extcon_get_state(dwc->edev, EXTCON_USB_HOST);
+	if (id < 0)
+		id = 0;
+
+	dwc3_set_mode(dwc, id ?
+		      DWC3_GCTL_PRTCAP_HOST :
+		      DWC3_GCTL_PRTCAP_DEVICE);
+}
+
+static int dwc3_drd_notifier(struct notifier_block *nb,
+			     unsigned long event, void *ptr)
+{
+	struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
+
+	dwc3_set_mode(dwc, event ?
+		      DWC3_GCTL_PRTCAP_HOST :
+		      DWC3_GCTL_PRTCAP_DEVICE);
+
+	return NOTIFY_DONE;
+}
+
+int dwc3_drd_init(struct dwc3 *dwc)
+{
+	int ret;
+
+	if (dwc->dev->of_node) {
+		if (of_property_read_bool(dwc->dev->of_node, "extcon"))
+			dwc->edev = extcon_get_edev_by_phandle(dwc->dev, 0);
+
+		if (IS_ERR(dwc->edev))
+			return PTR_ERR(dwc->edev);
+
+		dwc->edev_nb.notifier_call = dwc3_drd_notifier;
+		ret = extcon_register_notifier(dwc->edev, EXTCON_USB_HOST,
+					       &dwc->edev_nb);
+		if (ret < 0) {
+			dev_err(dwc->dev, "couldn't register cable notifier\n");
+			return ret;
+		}
+	}
+
+	dwc3_drd_update(dwc);
+
+	return 0;
+}
+
+void dwc3_drd_exit(struct dwc3 *dwc)
+{
+	extcon_unregister_notifier(dwc->edev, EXTCON_USB_HOST,
+				   &dwc->edev_nb);
+
+	dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
+	flush_work(&dwc->drd_work);
+	dwc3_gadget_exit(dwc);
+}