[PATCH v4 2/2] 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.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes since v3:
 - No updates.

Changes since v2:
 - Remove pm_children_suspended() and other unused macros.

 Changes since v1:
   - Add pm_runtime.h head file to avoid kbuild error.
---
 drivers/usb/dwc3/Kconfig |    7 +++++++
 drivers/usb/dwc3/core.c  |   26 +++++++++++++++++++++++++-
 drivers/usb/dwc3/core.h  |   15 +++++++++++++++
 drivers/usb/dwc3/host.c  |   37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
index a45b4f1..47bb2f3 100644
--- a/drivers/usb/dwc3/Kconfig
+++ b/drivers/usb/dwc3/Kconfig
@@ -47,6 +47,13 @@ config USB_DWC3_DUAL_ROLE
 
 endchoice
 
+config USB_DWC3_HOST_SUSPEND
+	bool "Choose if the DWC3 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.
+
 comment "Platform Glue Driver Support"
 
 config USB_DWC3_OMAP
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9a4a5e4..7ad4bc3 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1091,6 +1091,7 @@ 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;
@@ -1215,15 +1216,27 @@ 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;
@@ -1245,12 +1258,23 @@ 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 b585a30..db41908 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1226,4 +1226,19 @@ static inline void dwc3_ulpi_exit(struct dwc3 *dwc)
 { }
 #endif
 
+#if IS_ENABLED(CONFIG_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 ed82464..8e5309d6 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"
 
@@ -130,3 +131,39 @@ void dwc3_host_exit(struct dwc3 *dwc)
 			  dev_name(&dwc->xhci->dev));
 	platform_device_unregister(dwc->xhci);
 }
+
+#ifdef CONFIG_USB_DWC3_HOST_SUSPEND
+int dwc3_host_suspend(struct dwc3 *dwc)
+{
+	struct device *xhci = &dwc->xhci->dev;
+	int ret;
+
+	/*
+	 * Note: if we get the -EBUSY, which means the xHCI children devices are
+	 * not in suspend state yet, the glue layer need to wait for a while and
+	 * try to suspend xHCI device again.
+	 */
+	ret = pm_runtime_put_sync(xhci);
+	if (ret) {
+		dev_err(xhci, "failed to suspend xHCI device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+int dwc3_host_resume(struct dwc3 *dwc)
+{
+	struct device *xhci = &dwc->xhci->dev;
+	int ret;
+
+	/* Resume the xHCI device synchronously. */
+	ret = pm_runtime_get_sync(xhci);
+	if (ret) {
+		dev_err(xhci, "failed to resume xHCI device\n");
+		return ret;
+	}
+
+	return 0;
+}
+#endif
-- 
1.7.9.5