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

[Baolin Wang]

For some mobile devices with strict power management, we also want to
suspend the host when the slave was detached for power saving. Thus
adding the host suspend/resume functions to support this requirement.

We will issue the pm_suspend_ignore_children() for the dwc3 device,
since we will resume the child device (xHCI device) in runtime resume
callback (dwc3_host_resume()) of dwc3 device, now the dwc3 device's
runtime state is not RPM_ACTIVE, which will block to resume its
child device (xHCI device). Add ignore children flag can avoid this
situation.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
 drivers/usb/dwc3/core.c |   26 +++++++++++++++++++++++++-
 drivers/usb/dwc3/core.h |    7 +++++++
 drivers/usb/dwc3/host.c |   15 +++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 326b302..2be7ddc 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1193,6 +1193,7 @@ static int dwc3_probe(struct platform_device *pdev)
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_set_autosuspend_delay(dev, DWC3_DEFAULT_AUTOSUSPEND_DELAY);
 	pm_runtime_enable(dev);
+	pm_suspend_ignore_children(dev, true);
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
 		goto err1;
@@ -1292,15 +1293,27 @@ 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;
@@ -1322,12 +1335,23 @@ 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 ea910ac..9b5a4eb 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1193,11 +1193,18 @@ static inline bool dwc3_is_usb31(struct dwc3 *dwc)
 #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);
+int dwc3_host_suspend(struct dwc3 *dwc);
+int dwc3_host_resume(struct dwc3 *dwc);
 #else
 static inline int dwc3_host_init(struct dwc3 *dwc)
 { return 0; }
 static inline void dwc3_host_exit(struct dwc3 *dwc)
 { }
+
+static inline int dwc3_host_suspend(struct dwc3 *dwc)
+{ return 0; }
+static inline int dwc3_host_resume(struct dwc3 *dwc)
+{ return 0; }
 #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 76f0b0d..3fa4414 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -16,6 +16,7 @@
  */
 
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 
 #include "core.h"
 
@@ -151,3 +152,17 @@ void dwc3_host_exit(struct dwc3 *dwc)
 			  dev_name(dwc->dev));
 	platform_device_unregister(dwc->xhci);
 }
+
+int dwc3_host_suspend(struct dwc3 *dwc)
+{
+	struct device *xhci = &dwc->xhci->dev;
+
+	return pm_runtime_suspend(xhci);
+}
+
+int dwc3_host_resume(struct dwc3 *dwc)
+{
+	struct device *xhci = &dwc->xhci->dev;
+
+	return pm_runtime_resume(xhci);
+}
-- 
1.7.9.5