usb: dwc3: add dual role support using OTG block

This is useful on platforms (e.g. TI AM437x) that don't
have ID available on a GPIO but do have the OTG block.

We can obtain the ID state via the OTG block and use it
for dual-role switching.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.c

@@ -89,10 +89,7 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
 	return 0;
 }
 
-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)
+void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
 {
 	u32 reg;
 
@@ -110,16 +107,19 @@ static void __dwc3_set_mode(struct work_struct *work)
 	unsigned long flags;
 	int ret;
 
-	if (!dwc->desired_dr_role)
+	if (dwc->dr_mode != USB_DR_MODE_OTG)
 		return;
 
-	if (dwc->desired_dr_role == dwc->current_dr_role)
+	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG)
+		dwc3_otg_update(dwc, 0);
+
+	if (!dwc->desired_dr_role)
 		return;
 
-	if (dwc->dr_mode != USB_DR_MODE_OTG)
+	if (dwc->desired_dr_role == dwc->current_dr_role)
 		return;
 
-	if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG)
+	if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev)
 		return;
 
 	switch (dwc->current_dr_role) {
@@ -130,6 +130,13 @@ static void __dwc3_set_mode(struct work_struct *work)
 		dwc3_gadget_exit(dwc);
 		dwc3_event_buffers_cleanup(dwc);
 		break;
+	case DWC3_GCTL_PRTCAP_OTG:
+		dwc3_otg_exit(dwc);
+		spin_lock_irqsave(&dwc->lock, flags);
+		dwc->desired_otg_role = DWC3_OTG_ROLE_IDLE;
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		dwc3_otg_update(dwc, 1);
+		break;
 	default:
 		break;
 	}
@@ -165,9 +172,14 @@ static void __dwc3_set_mode(struct work_struct *work)
 		if (ret)
 			dev_err(dwc->dev, "failed to initialize peripheral\n");
 		break;
+	case DWC3_GCTL_PRTCAP_OTG:
+		dwc3_otg_init(dwc);
+		dwc3_otg_update(dwc, 0);
+		break;
 	default:
 		break;
 	}
+
 }
 
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
@@ -351,7 +363,7 @@ static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned length)
  *
  * Returns 0 on success otherwise negative errno.
  */
-static int dwc3_event_buffers_setup(struct dwc3 *dwc)
+int dwc3_event_buffers_setup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
 
@@ -368,7 +380,7 @@ static int dwc3_event_buffers_setup(struct dwc3 *dwc)
 	return 0;
 }
 
-static void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
+void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
 
@@ -1329,6 +1341,20 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 		if (!PMSG_IS_AUTO(msg))
 			dwc3_core_exit(dwc);
 		break;
+	case DWC3_GCTL_PRTCAP_OTG:
+		/* do nothing during runtime_suspend */
+		if (PMSG_IS_AUTO(msg))
+			break;
+
+		if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
+			spin_lock_irqsave(&dwc->lock, flags);
+			dwc3_gadget_suspend(dwc);
+			spin_unlock_irqrestore(&dwc->lock, flags);
+		}
+
+		dwc3_otg_exit(dwc);
+		dwc3_core_exit(dwc);
+		break;
 	default:
 		/* do nothing */
 		break;
@@ -1359,6 +1385,27 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
 			if (ret)
 				return ret;
 		}
+		break;
+	case DWC3_GCTL_PRTCAP_OTG:
+		/* nothing to do on runtime_resume */
+		if (PMSG_IS_AUTO(msg))
+			break;
+
+		ret = dwc3_core_init(dwc);
+		if (ret)
+			return ret;
+
+		dwc3_set_prtcap(dwc, dwc->current_dr_role);
+
+		dwc3_otg_init(dwc);
+		if (dwc->current_otg_role == DWC3_OTG_ROLE_HOST) {
+			dwc3_otg_host_init(dwc);
+		} else if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
+			spin_lock_irqsave(&dwc->lock, flags);
+			dwc3_gadget_resume(dwc);
+			spin_unlock_irqrestore(&dwc->lock, flags);
+		}
+
 		break;
 	default:
 		/* do nothing */

drivers/usb/dwc3/core.h

@@ -58,6 +58,11 @@
 #define DWC3_DEVICE_EVENT_CMD_CMPL		10
 #define DWC3_DEVICE_EVENT_OVERFLOW		11
 
+/* Controller's role while using the OTG block */
+#define DWC3_OTG_ROLE_IDLE	0
+#define DWC3_OTG_ROLE_HOST	1
+#define DWC3_OTG_ROLE_DEVICE	2
+
 #define DWC3_GEVNTCOUNT_MASK	0xfffc
 #define DWC3_GEVNTCOUNT_EHB	BIT(31)
 #define DWC3_GSNPSID_MASK	0xffff0000
@@ -863,6 +868,10 @@ struct dwc3_scratchpad_array {
  * @regs_size: address space size
  * @fladj: frame length adjustment
  * @irq_gadget: peripheral controller's IRQ number
+ * @otg_irq: IRQ number for OTG IRQs
+ * @current_otg_role: current role of operation while using the OTG block
+ * @desired_otg_role: desired role of operation while using the OTG block
+ * @otg_restart_host: flag that OTG controller needs to restart host
  * @nr_scratch: number of scratch buffers
  * @u1u2: only used on revisions <1.83a for workaround
  * @maximum_speed: maximum speed requested (mainly for testing purposes)
@@ -996,6 +1005,10 @@ struct dwc3 {
 
 	u32			fladj;
 	u32			irq_gadget;
+	u32			otg_irq;
+	u32			current_otg_role;
+	u32			desired_otg_role;
+	bool			otg_restart_host;
 	u32			nr_scratch;
 	u32			u1u2;
 	u32			maximum_speed;
@@ -1257,6 +1270,7 @@ struct dwc3_gadget_ep_cmd_params {
 #define DWC3_HAS_OTG			BIT(3)
 
 /* prototypes */
+void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode);
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode);
 u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type);
 
@@ -1274,6 +1288,9 @@ static inline bool dwc3_is_usb31(struct dwc3 *dwc)
 
 bool dwc3_has_imod(struct dwc3 *dwc);
 
+int dwc3_event_buffers_setup(struct dwc3 *dwc);
+void dwc3_event_buffers_cleanup(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);
@@ -1317,11 +1334,23 @@ static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_drd_init(struct dwc3 *dwc);
 void dwc3_drd_exit(struct dwc3 *dwc);
+void dwc3_otg_init(struct dwc3 *dwc);
+void dwc3_otg_exit(struct dwc3 *dwc);
+void dwc3_otg_update(struct dwc3 *dwc, bool ignore_idstatus);
+void dwc3_otg_host_init(struct dwc3 *dwc);
 #else
 static inline int dwc3_drd_init(struct dwc3 *dwc)
 { return 0; }
 static inline void dwc3_drd_exit(struct dwc3 *dwc)
 { }
+static inline void dwc3_otg_init(struct dwc3 *dwc)
+{ }
+static inline void dwc3_otg_exit(struct dwc3 *dwc)
+{ }
+static inline void dwc3_otg_update(struct dwc3 *dwc, bool ignore_idstatus)
+{ }
+static inline void dwc3_otg_host_init(struct dwc3 *dwc)
+{ }
 #endif
 
 /* power management interface */