[RFC PATCH 1/1] usb: dwc3: drd: Register a USB role switch

[Heikki Krogerus]

The Type-C drivers use USB role switch API to inform the
system about the negotiated data role, so registering a role
switch in the DRD code in order to support platforms with
USB Type-C connectors.

Signed-off-by: Heikki Krogerus <heikki.kroge...@linux.intel.com>
---
Hi Chen Yu,

This is related to your Hikey960 USB patches series [1]. I can't test
this patch, but I don't think this part should require anything else.

And about the device graph you'll need for this and the other
components, I noticed that

        Documentation/devicetree/bindings/connector/usb-connector.txt

has some nice examples. I believe your port controller device will be
one remote-endpoint for dwc3, and that hub/mux device another.

cheers,

[1] https://lkml.org/lkml/2018/10/27/178

---
 drivers/usb/dwc3/core.h |  2 ++
 drivers/usb/dwc3/drd.c  | 45 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5bfb62533e0f..9d2a236354f9 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -25,6 +25,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/usb/otg.h>
+#include <linux/usb/role.h>
 #include <linux/ulpi/interface.h>
 
 #include <linux/phy/phy.h>
@@ -1053,6 +1054,7 @@ struct dwc3 {
        struct extcon_dev       *edev;
        struct notifier_block   edev_nb;
        enum usb_phy_interface  hsphy_mode;
+       struct usb_role_switch  *role_sw;
 
        u32                     fladj;
        u32                     irq_gadget;
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index 218371f985ca..1795ea2a4570 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -463,6 +463,44 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
        return edev;
 }
 
+static int dwc3_usb_role_switch_set(struct device *dev, enum usb_role role)
+{
+       u32 mode;
+
+       switch (role) {
+       case USB_ROLE_HOST:
+               mode = DWC3_GCTL_PRTCAP_HOST;
+               break;
+       case USB_ROLE_DEVICE:
+               mode = DWC3_GCTL_PRTCAP_DEVICE;
+               break;
+       default:
+               mode = DWC3_GCTL_PRTCAP_OTG;
+               break;
+       };
+
+       dwc3_set_mode(dev_get_drvdata(dev), mode);
+       return 0;
+}
+
+static enum usb_role dwc3_usb_role_switch_get(struct device *dev)
+{
+       struct dwc3 *dwc = dev_get_drvdata(dev);
+       unsigned long flags;
+       enum usb_role role;
+
+       spin_lock_irqsave(&dwc->lock, flags);
+       role = dwc->current_otg_role;
+       spin_unlock_irqrestore(&dwc->lock, flags);
+
+       return role;
+}
+
+static const struct usb_role_switch_desc dwc3_role_switch = {
+       .set = dwc3_usb_role_switch_set,
+       .get = dwc3_usb_role_switch_get,
+};
+
 int dwc3_drd_init(struct dwc3 *dwc)
 {
        int ret, irq;
@@ -511,6 +549,11 @@ int dwc3_drd_init(struct dwc3 *dwc)
                dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
        }
 
+       dwc->role_sw = usb_role_switch_register(dwc->dev, &dwc3_role_switch);
+       if (ret) {
+               dwc3_drd_exit(dwc);
+               return PTR_ERR(dwc->role_sw);
+       }
        return 0;
 }
 
@@ -546,4 +589,6 @@ void dwc3_drd_exit(struct dwc3 *dwc)
 
        if (!dwc->edev)
                free_irq(dwc->otg_irq, dwc);
+
+       usb_role_switch_unregister(dwc->role_sw);
 }
-- 
2.19.1