usb: dwc3: core: make dwc3_set_mode() work properly

We can't have both Host and Peripheral roles active at the same time
because of one detail on DWC3: it shares the same memory area for both
Host and Peripheral registers.

When swapping roles we must reinitialize the new role every
time. Let's make sure this works for our debugfs interface.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

1 files changed, 72 insertions, 31 deletions

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 68e6a7b6fd81..458e7c6cc002 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -100,7 +100,10 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
 	return 0;
 }
 
-void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
+static void dwc3_event_buffers_cleanup(struct dwc3 *dwc);
+static int dwc3_event_buffers_setup(struct dwc3 *dwc);
+
+static void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
 {
 	u32 reg;
 
@@ -108,8 +111,69 @@ void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
 	reg &= ~(DWC3_GCTL_PRTCAPDIR(DWC3_GCTL_PRTCAP_OTG));
 	reg |= DWC3_GCTL_PRTCAPDIR(mode);
 	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+}
+
+static void __dwc3_set_mode(struct work_struct *work)
+{
+	struct dwc3 *dwc = work_to_dwc(work);
+	unsigned long flags;
+	int ret;
+
+	if (!dwc->desired_dr_role)
+		return;
+
+	if (dwc->desired_dr_role == dwc->current_dr_role)
+		return;
+
+	if (dwc->dr_mode != USB_DR_MODE_OTG)
+		return;
+
+	switch (dwc->current_dr_role) {
+	case DWC3_GCTL_PRTCAP_HOST:
+		dwc3_host_exit(dwc);
+		break;
+	case DWC3_GCTL_PRTCAP_DEVICE:
+		dwc3_gadget_exit(dwc);
+		dwc3_event_buffers_cleanup(dwc);
+		break;
+	default:
+		break;
+	}
+
+	spin_lock_irqsave(&dwc->lock, flags);
+
+	dwc3_set_prtcap(dwc, dwc->desired_dr_role);
 
-	dwc->current_dr_role = mode;
+	dwc->current_dr_role = dwc->desired_dr_role;
+
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	switch (dwc->desired_dr_role) {
+	case DWC3_GCTL_PRTCAP_HOST:
+		ret = dwc3_host_init(dwc);
+		if (ret)
+			dev_err(dwc->dev, "failed to initialize host\n");
+		break;
+	case DWC3_GCTL_PRTCAP_DEVICE:
+		dwc3_event_buffers_setup(dwc);
+		ret = dwc3_gadget_init(dwc);
+		if (ret)
+			dev_err(dwc->dev, "failed to initialize peripheral\n");
+		break;
+	default:
+		break;
+	}
+}
+
+void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	dwc->desired_dr_role = mode;
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	queue_work(system_power_efficient_wq, &dwc->drd_work);
 }
 
 u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type)
@@ -721,21 +785,6 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		goto err4;
 	}
 
-	switch (dwc->dr_mode) {
-	case USB_DR_MODE_PERIPHERAL:
-		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
-		break;
-	case USB_DR_MODE_HOST:
-		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_HOST);
-		break;
-	case USB_DR_MODE_OTG:
-		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_OTG);
-		break;
-	default:
-		dev_warn(dwc->dev, "Unsupported mode %d\n", dwc->dr_mode);
-		break;
-	}
-
 	/*
 	 * ENDXFER polling is available on version 3.10a and later of
 	 * the DWC_usb3 controller. It is NOT available in the
@@ -853,6 +902,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
 
 	switch (dwc->dr_mode) {
 	case USB_DR_MODE_PERIPHERAL:
+		dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
 		ret = dwc3_gadget_init(dwc);
 		if (ret) {
 			if (ret != -EPROBE_DEFER)
@@ -861,6 +911,7 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
 		}
 		break;
 	case USB_DR_MODE_HOST:
+		dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);
 		ret = dwc3_host_init(dwc);
 		if (ret) {
 			if (ret != -EPROBE_DEFER)
@@ -869,19 +920,8 @@ static int dwc3_core_init_mode(struct dwc3 *dwc)
 		}
 		break;
 	case USB_DR_MODE_OTG:
-		ret = dwc3_host_init(dwc);
-		if (ret) {
-			if (ret != -EPROBE_DEFER)
-				dev_err(dev, "failed to initialize host\n");
-			return ret;
-		}
-
-		ret = dwc3_gadget_init(dwc);
-		if (ret) {
-			if (ret != -EPROBE_DEFER)
-				dev_err(dev, "failed to initialize gadget\n");
-			return ret;
-		}
+		INIT_WORK(&dwc->drd_work, __dwc3_set_mode);
+		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
 		break;
 	default:
 		dev_err(dev, "Unsupported mode of operation %d\n", dwc->dr_mode);
@@ -901,8 +941,9 @@ static void dwc3_core_exit_mode(struct dwc3 *dwc)
 		dwc3_host_exit(dwc);
 		break;
 	case USB_DR_MODE_OTG:
-		dwc3_host_exit(dwc);
+		dwc3_set_mode(dwc, DWC3_GCTL_PRTCAP_DEVICE);
 		dwc3_gadget_exit(dwc);
+		flush_work(&dwc->drd_work);
 		break;
 	default:
 		/* do nothing */