[PATCH 4/4] usb: dwc3: core: Support the dwc3 host suspend/resume

[Baolin Wang <baolin.wang@linaro.org>]

For some mobile devices with strict power management, we also want to suspend
the host when the slave is detached for power saving.

Thus we add the host suspend/resume functions to support this requirement, and
we also should enable the 'XHCI_SLOW_SUSPEND' quirk for extraordinary delay when
suspending the xhci.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 drivers/usb/dwc3/Kconfig |    7 +++++++
 drivers/usb/dwc3/core.c  |   25 ++++++++++++++++++++++++-
 drivers/usb/dwc3/core.h  |   15 +++++++++++++++
 drivers/usb/dwc3/host.c  |   32 ++++++++++++++++++++++++++++++++
 4 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
index a64ce1c..725d2bd 100644
--- a/drivers/usb/dwc3/Kconfig
+++ b/drivers/usb/dwc3/Kconfig
@@ -45,6 +45,13 @@ config USB_DWC3_DUAL_ROLE
 	  This is the default mode of working of DWC3 controller where
 	  both host and gadget features are enabled.
 
+config USB_DWC3_HOST_SUSPEND
+	bool "Choose if the host (xhci) can be suspend/resume"
+	depends on USB_DWC3_HOST=y || USB_DWC3_DUAL_ROLE=y
+	help
+	  We can suspend the host when the slave is detached for power saving,
+	  and resume the host when one slave is attached.
+
 endchoice
 
 comment "Platform Glue Driver Support"
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 1485480..5140b4d 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1103,15 +1103,27 @@ static int dwc3_remove(struct platform_device *pdev)
 static int dwc3_suspend_common(struct dwc3 *dwc)
 {
 	unsigned long	flags;
+	int		ret;
 
 	switch (dwc->dr_mode) {
 	case USB_DR_MODE_PERIPHERAL:
+		spin_lock_irqsave(&dwc->lock, flags);
+		dwc3_gadget_suspend(dwc);
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		break;
 	case USB_DR_MODE_OTG:
+		ret = dwc3_host_suspend(dwc);
+		if (ret)
+			return ret;
+
 		spin_lock_irqsave(&dwc->lock, flags);
 		dwc3_gadget_suspend(dwc);
 		spin_unlock_irqrestore(&dwc->lock, flags);
 		break;
 	case USB_DR_MODE_HOST:
+		ret = dwc3_host_suspend(dwc);
+		if (ret)
+			return ret;
 	default:
 		/* do nothing */
 		break;
@@ -1133,12 +1145,23 @@ static int dwc3_resume_common(struct dwc3 *dwc)
 
 	switch (dwc->dr_mode) {
 	case USB_DR_MODE_PERIPHERAL:
+		spin_lock_irqsave(&dwc->lock, flags);
+		dwc3_gadget_resume(dwc);
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		break;
 	case USB_DR_MODE_OTG:
+		ret = dwc3_host_resume(dwc);
+		if (ret)
+			return ret;
+
 		spin_lock_irqsave(&dwc->lock, flags);
 		dwc3_gadget_resume(dwc);
 		spin_unlock_irqrestore(&dwc->lock, flags);
-		/* FALLTHROUGH */
+		break;
 	case USB_DR_MODE_HOST:
+		ret = dwc3_host_resume(dwc);
+		if (ret)
+			return ret;
 	default:
 		/* do nothing */
 		break;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 45d6de5..0ba203e 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1177,4 +1177,19 @@ static inline void dwc3_ulpi_exit(struct dwc3 *dwc)
 { }
 #endif
 
+#if IS_ENABLED(USB_DWC3_HOST_SUSPEND)
+int dwc3_host_suspend(struct dwc3 *dwc);
+int dwc3_host_resume(struct dwc3 *dwc);
+#else
+static inline int dwc3_host_suspend(struct dwc3 *dwc)
+{
+	return 0;
+}
+
+static inline int dwc3_host_resume(struct dwc3 *dwc)
+{
+	return 0;
+}
+#endif
+
 #endif /* __DRIVERS_USB_DWC3_CORE_H */
diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
index 2e960ed..2ec3eff 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -17,8 +17,11 @@
 
 #include <linux/platform_device.h>
 #include <linux/usb/xhci_pdriver.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
 
 #include "core.h"
+#include "../host/xhci.h"
 
 int dwc3_host_init(struct dwc3 *dwc)
 {
@@ -91,6 +94,8 @@ int dwc3_host_init(struct dwc3 *dwc)
 	memset(&pdata, 0, sizeof(pdata));
 
 	pdata.usb3_lpm_capable = dwc->usb3_lpm_capable;
+	/* dwc3 controller need an extraordinary delay when suspending xhci. */
+	pdata.usb3_slow_suspend = 1;
 
 	ret = platform_device_add_data(xhci, &pdata, sizeof(pdata));
 	if (ret) {
@@ -128,3 +133,30 @@ void dwc3_host_exit(struct dwc3 *dwc)
 			  dev_name(&dwc->xhci->dev));
 	platform_device_unregister(dwc->xhci);
 }
+
+int dwc3_host_suspend(struct dwc3 *dwc)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(&dwc->xhci->dev);
+	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+	int ret, cnt = 20;
+
+try_again:
+	 /* We should wait for xhci bus has been into suspend mode firstly. */
+	ret = xhci_suspend(xhci, device_may_wakeup(&dwc->xhci->dev));
+	if (ret && --cnt > 0) {
+		dev_warn(dwc->dev, "xhci suspend failed %d, try again...\n",
+			 ret);
+		msleep(200);
+		goto try_again;
+	}
+
+	return ret;
+}
+
+int dwc3_host_resume(struct dwc3 *dwc)
+{
+	struct usb_hcd *hcd = dev_get_drvdata(&dwc->xhci->dev);
+	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+
+	return xhci_resume(xhci, 0);
+}
-- 
1.7.9.5