usb: dwc3: gadget: Implement setting of SSP rate

Implement gadget ops udc_set_ssp_rate(). This allows the gadget/core
driver to select SSP signaling rate and number of lanes to for DWC_usb32
controller.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/8998b65fddfa02cab57bfc6aa35e9f101b252068.1611106162.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/core.h

@@ -386,6 +386,8 @@
 #define DWC3_GUCTL3_SPLITDISABLE		BIT(14)
 
 /* Device Configuration Register */
+#define DWC3_DCFG_NUMLANES(n)	(((n) & 0x3) << 30) /* DWC_usb32 only */
+
 #define DWC3_DCFG_DEVADDR(addr)	((addr) << 3)
 #define DWC3_DCFG_DEVADDR_MASK	DWC3_DCFG_DEVADDR(0x7f)
 
@@ -966,6 +968,8 @@ struct dwc3_scratchpad_array {
  * @maximum_speed: maximum speed requested (mainly for testing purposes)
  * @max_ssp_rate: SuperSpeed Plus maximum signaling rate and lane count
  * @gadget_max_speed: maximum gadget speed requested
+ * @gadget_ssp_rate: Gadget driver's maximum supported SuperSpeed Plus signaling
+ *			rate and lane count.
  * @ip: controller's ID
  * @revision: controller's version of an IP
  * @version_type: VERSIONTYPE register contents, a sub release of a revision
@@ -1130,6 +1134,7 @@ struct dwc3 {
 	u32			maximum_speed;
 	u32			gadget_max_speed;
 	enum usb_ssp_rate	max_ssp_rate;
+	enum usb_ssp_rate	gadget_ssp_rate;
 
 	u32			ip;
 

drivers/usb/dwc3/gadget.c

@@ -2038,10 +2038,40 @@ static void dwc3_stop_active_transfers(struct dwc3 *dwc)
 	}
 }
 
+static void __dwc3_gadget_set_ssp_rate(struct dwc3 *dwc)
+{
+	enum usb_ssp_rate	ssp_rate = dwc->gadget_ssp_rate;
+	u32			reg;
+
+	if (ssp_rate == USB_SSP_GEN_UNKNOWN)
+		ssp_rate = dwc->max_ssp_rate;
+
+	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+	reg &= ~DWC3_DCFG_SPEED_MASK;
+	reg &= ~DWC3_DCFG_NUMLANES(~0);
+
+	if (ssp_rate == USB_SSP_GEN_1x2)
+		reg |= DWC3_DCFG_SUPERSPEED;
+	else if (dwc->max_ssp_rate != USB_SSP_GEN_1x2)
+		reg |= DWC3_DCFG_SUPERSPEED_PLUS;
+
+	if (ssp_rate != USB_SSP_GEN_2x1 &&
+	    dwc->max_ssp_rate != USB_SSP_GEN_2x1)
+		reg |= DWC3_DCFG_NUMLANES(1);
+
+	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+}
+
 static void __dwc3_gadget_set_speed(struct dwc3 *dwc)
 {
 	u32			reg;
 
+	if (dwc->gadget_max_speed == USB_SPEED_SUPER_PLUS &&
+	    DWC3_IP_IS(DWC32)) {
+		__dwc3_gadget_set_ssp_rate(dwc);
+		return;
+	}
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
 	reg &= ~(DWC3_DCFG_SPEED_MASK);
 
@@ -2475,6 +2505,17 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
 	spin_unlock_irqrestore(&dwc->lock, flags);
 }
 
+static void dwc3_gadget_set_ssp_rate(struct usb_gadget *g,
+				     enum usb_ssp_rate rate)
+{
+	struct dwc3		*dwc = gadget_to_dwc(g);
+	unsigned long		flags;
+
+	spin_lock_irqsave(&dwc->lock, flags);
+	dwc->gadget_ssp_rate = rate;
+	spin_unlock_irqrestore(&dwc->lock, flags);
+}
+
 static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
@@ -2493,6 +2534,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_start		= dwc3_gadget_start,
 	.udc_stop		= dwc3_gadget_stop,
 	.udc_set_speed		= dwc3_gadget_set_speed,
+	.udc_set_ssp_rate	= dwc3_gadget_set_ssp_rate,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
 };
@@ -3905,7 +3947,10 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 		goto err5;
 	}
 
-	dwc3_gadget_set_speed(dwc->gadget, dwc->maximum_speed);
+	if (DWC3_IP_IS(DWC32) && dwc->maximum_speed == USB_SPEED_SUPER_PLUS)
+		dwc3_gadget_set_ssp_rate(dwc->gadget, dwc->max_ssp_rate);
+	else
+		dwc3_gadget_set_speed(dwc->gadget, dwc->maximum_speed);
 
 	return 0;