usb: dwc3: allow forcing a maximum speed

this is mainly for testing. In order to be able
to test if we're enumerating correctly on all
speeds, let that be controlled by a module
parameter.

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.c

@@ -59,6 +59,10 @@
 
 #include "debug.h"
 
+static char *maximum_speed = "super";
+module_param(maximum_speed, charp, 0);
+MODULE_PARM_DESC(maximum_speed, "Maximum supported speed.");
+
 /**
  * dwc3_core_soft_reset - Issues core soft reset and PHY reset
  * @dwc: pointer to our context structure
@@ -370,6 +374,17 @@ static int __devinit dwc3_probe(struct platform_device *pdev)
 	dwc->dev	= &pdev->dev;
 	dwc->irq	= irq;
 
+	if (!strncmp("super", maximum_speed, 5))
+		dwc->maximum_speed = DWC3_DCFG_SUPERSPEED;
+	else if (!strncmp("high", maximum_speed, 4))
+		dwc->maximum_speed = DWC3_DCFG_HIGHSPEED;
+	else if (!strncmp("full", maximum_speed, 4))
+		dwc->maximum_speed = DWC3_DCFG_FULLSPEED1;
+	else if (!strncmp("low", maximum_speed, 3))
+		dwc->maximum_speed = DWC3_DCFG_LOWSPEED;
+	else
+		dwc->maximum_speed = DWC3_DCFG_SUPERSPEED;
+
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 	pm_runtime_forbid(&pdev->dev);

drivers/usb/dwc3/core.h

@@ -555,6 +555,7 @@ struct dwc3_hwparams {
  * @regs: base address for our registers
  * @regs_size: address space size
  * @irq: IRQ number
+ * @maximum_speed: maximum speed requested (mainly for testing purposes)
  * @revision: revision register contents
  * @is_selfpowered: true when we are selfpowered
  * @three_stage_setup: set if we perform a three phase setup
@@ -595,6 +596,7 @@ struct dwc3 {
 
 	int			irq;
 
+	u32			maximum_speed;
 	u32			revision;
 
 #define DWC3_REVISION_173A	0x5533173a

drivers/usb/dwc3/gadget.c

@@ -1183,7 +1183,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 
 	reg = dwc3_readl(dwc->regs, DWC3_DCFG);
 	reg &= ~(DWC3_DCFG_SPEED_MASK);
-	reg |= DWC3_DCFG_SUPERSPEED;
+	reg |= dwc->maximum_speed;
 	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
 
 	dwc->start_config_issued = false;