[PATCH 3/3] USB: dwc2: Don't turn off the usbphy in suspend if wakeup is enabled

[Douglas Anderson]

If the 'snps,need-phy-for-wake' is set in the device tree then:

- We know that we can wakeup, so call device_set_wakeup_capable().
  The USB core will use this knowledge to enable wakeup by default.
- We know that we should keep the PHY on during suspend if something
  on our root hub needs remote wakeup.  This requires the patch (USB:
  Export usb_wakeup_enabled_descendants()).  Note that we don't keep
  the PHY on at suspend time if it's not needed because it would be a
  power draw.

If we later find some users of dwc2 that can support wakeup without
keeping the PHY on we may want to add a way to call
device_set_wakeup_capable() without keeping the PHY on at suspend
time.

Signed-off-by: Chris Zhong <zyw at rock-chips.com>
Signed-off-by: Douglas Anderson <dianders at chromium.org>
---
 drivers/usb/dwc2/core.h     |  2 ++
 drivers/usb/dwc2/platform.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 53b8de0..b60a1e8 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -687,6 +687,8 @@ struct dwc2_hsotg {
 	enum usb_dr_mode dr_mode;
 	unsigned int hcd_enabled:1;
 	unsigned int gadget_enabled:1;
+	unsigned int need_phy_for_wake:1;
+	unsigned int phy_off_for_suspend:1;
 
 	struct phy *phy;
 	struct usb_phy *uphy;
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 9093530..38fce75 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -42,7 +42,9 @@
 #include <linux/of_device.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
+#include <linux/usb.h>
 
+#include <linux/usb/hcd.h>
 #include <linux/usb/of.h>
 
 #include "core.h"
@@ -222,6 +224,10 @@ static int dwc2_driver_probe(struct platform_device *dev)
 
 	hsotg->dr_mode = of_usb_get_dr_mode(dev->dev.of_node);
 
+	hsotg->need_phy_for_wake =
+		of_property_read_bool(dev->dev.of_node,
+				      "snps,need-phy-for-wake");
+
 	/*
 	 * Attempt to find a generic PHY, then look for an old style
 	 * USB PHY
@@ -265,6 +271,14 @@ static int dwc2_driver_probe(struct platform_device *dev)
 		hsotg->gadget_enabled = 1;
 	}
 
+	/*
+	 * If we need PHY for wakeup we must be wakeup capable.
+	 * When we have a device that can wake without the PHY we
+	 * can adjust this condition.
+	 */
+	if (hsotg->need_phy_for_wake)
+		device_set_wakeup_capable(&dev->dev, true);
+
 	if (hsotg->dr_mode != USB_DR_MODE_PERIPHERAL) {
 		retval = dwc2_hcd_init(hsotg, irq);
 		if (retval) {
@@ -282,6 +296,28 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	return retval;
 }
 
+static bool __maybe_unused dwc2_can_poweroff_phy(struct dwc2_hsotg *dwc2)
+{
+	struct usb_device *root_hub = dwc2_hsotg_to_hcd(dwc2)->self.root_hub;
+
+	if (dwc2->lx_state == DWC2_L0)
+		return false;
+
+	/* If the controller isn't allowed to wakeup then we can power off. */
+	if (!device_may_wakeup(dwc2->dev))
+		return true;
+
+	/*
+	 * We don't want to power off the PHY if something under the
+	 * root hub has wakeup enabled.
+	 */
+	if (usb_wakeup_enabled_descendants(root_hub))
+		return false;
+
+	/* No reason to keep the PHY powered, so allow poweroff */
+	return true;
+}
+
 static int __maybe_unused dwc2_suspend(struct device *dev)
 {
 	struct dwc2_hsotg *dwc2 = dev_get_drvdata(dev);
@@ -290,8 +326,10 @@ static int __maybe_unused dwc2_suspend(struct device *dev)
 	if (dwc2_is_device_mode(dwc2)) {
 		ret = s3c_hsotg_suspend(dwc2);
 	} else {
-		if (dwc2->lx_state == DWC2_L0)
+		if (!dwc2_can_poweroff_phy(dwc2))
 			return 0;
+
+		dwc2->phy_off_for_suspend = true;
 		phy_exit(dwc2->phy);
 		phy_power_off(dwc2->phy);
 
@@ -307,9 +345,12 @@ static int __maybe_unused dwc2_resume(struct device *dev)
 	if (dwc2_is_device_mode(dwc2)) {
 		ret = s3c_hsotg_resume(dwc2);
 	} else {
+		if (!dwc2->phy_off_for_suspend)
+			return ret;
+
 		phy_power_on(dwc2->phy);
 		phy_init(dwc2->phy);
-
+		dwc2->phy_off_for_suspend = false;
 	}
 	return ret;
 }
-- 
2.4.3.573.g4eafbef