[PATCH v3 4/4] usb: dwc3: Notify XHCI core of tunneled status

[Konrad Dybcio <konradybcio@kernel.org>]

From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

The Thunderbolt framework relies on the USB core to create device links
for tunneled ports, so that the USB3 controller is only kept
runtime-resumed for the duration of the tunneling. This depends on
first knowing whether a connection is tunneled or native.

Add the logic to handle that for DWC3 controllers.

Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
---
 drivers/usb/dwc3/core.c | 16 ++++++++++++++++
 drivers/usb/dwc3/core.h | 18 ++++++++++++++++++
 drivers/usb/dwc3/host.c | 12 ++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index fd5c2cd36c59..6af8937525ff 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -162,6 +162,22 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode, bool ignore_susphy)
 }
 EXPORT_SYMBOL_GPL(dwc3_set_prtcap);
 
+enum usb_link_tunnel_mode dwc3_link_tunnel_mode(struct dwc3 *dwc, u8 port)
+{
+	/* Prior versions had no CIO support */
+	if (!DWC3_VER_IS_WITHIN(DWC31, 191A, ANY))
+		return USB_LINK_UNKNOWN;
+
+	/* Not all DWC3 instances have CIO HW, trust the platform firmware */
+	if (!device_property_present(dwc->dev, "usb4-host-interface"))
+		return USB_LINK_UNKNOWN;
+
+	if (dwc3_readl(dwc, DWC3_CIOCTRL(port)) & DWC3_CIOCTRL_CIO_EN)
+		return USB_LINK_TUNNELED;
+
+	return USB_LINK_NATIVE;
+}
+
 static void __dwc3_set_mode(struct work_struct *work)
 {
 	struct dwc3 *dwc = work_to_dwc(work);
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 608daeb7ef10..decc51cd6505 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -179,6 +179,11 @@
 #define DWC3_OEVTEN		0xcc0C
 #define DWC3_OSTS		0xcc10
 
+/* CIO regs */
+#define DWC3_CIO_BASE(n)	(0xcd20 + ((n) * 0x30))
+#define DWC3_CIOCTRL(n)		(DWC3_CIO_BASE(n) + 0x00)
+#define DWC3_CIOCTRL_CIO_EN	BIT(0)
+
 #define DWC3_LLUCTL(n)		(0xd024 + ((n) * 0x80))
 
 /* Bit fields */
@@ -1314,6 +1319,7 @@ struct dwc3 {
 #define DWC31_REVISION_170A	0x3137302a
 #define DWC31_REVISION_180A	0x3138302a
 #define DWC31_REVISION_190A	0x3139302a
+#define DWC31_REVISION_191A	0x3139312a
 #define DWC31_REVISION_200A	0x3230302a
 
 #define DWC32_REVISION_ANY	0x0
@@ -1658,11 +1664,23 @@ static inline void dwc3_pre_run_stop(struct dwc3 *dwc, bool is_on)
 #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_host_init(struct dwc3 *dwc);
 void dwc3_host_exit(struct dwc3 *dwc);
+
+/**
+ * dwc3_link_tunnel_mode - Check whether the link is tunneled over TBT/USB4
+ * @dwc: Pointer to DWC3 controller context
+ * @port: 0-based port index
+ *
+ * Returns: USB_LINK_TUNNELED if tunneled, USB_LINK_NATIVE if not, or
+ *          when the controller does not have USB4 capabilities.
+ */
+enum usb_link_tunnel_mode dwc3_link_tunnel_mode(struct dwc3 *dwc, u8 port);
 #else
 static inline int dwc3_host_init(struct dwc3 *dwc)
 { return 0; }
 static inline void dwc3_host_exit(struct dwc3 *dwc)
 { }
+static inline enum usb_link_tunnel_mode dwc3_link_tunnel_mode(struct dwc3 *dwc, u8 port)
+{ return USB_LINK_UNKNOWN; }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_GADGET) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
index c5674161b2b0..1b9c4f94c2fd 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -78,8 +78,20 @@ static void dwc3_xhci_plat_start(struct usb_hcd *hcd)
 	dwc3_enable_susphy(dwc, true);
 }
 
+static enum usb_link_tunnel_mode dwc3_xhci_tunnel_mode(struct usb_hcd *hcd, int portnum)
+{
+	struct platform_device *pdev;
+	struct dwc3 *dwc;
+
+	pdev = to_platform_device(hcd->self.controller);
+	dwc = dev_get_drvdata(pdev->dev.parent);
+
+	return dwc3_link_tunnel_mode(dwc, portnum);
+}
+
 static const struct xhci_plat_priv dwc3_xhci_plat_quirk = {
 	.plat_start = dwc3_xhci_plat_start,
+	.tunnel_mode = dwc3_xhci_tunnel_mode,
 };
 
 static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,

-- 
2.55.0