usb: dwc3: gadget: re-factor Link state change to a function

Most link changes will, of course, happen with
the help of a matching host HW, but in some cases
we might want to debug very low level details about
the link and exposing this to debugfs sounds like
a good plan.

This is a preparation for such setup.

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

2 files changed, 42 insertions, 11 deletions

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1dee17e7b778..80003952547e 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -89,6 +89,42 @@ int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode)
         return 0;
 }
 
+/**
+ * dwc3_gadget_set_link_state - Sets USB Link to a particular State
+ * @dwc: pointer to our context structure
+ * @state: the state to put link into
+ *
+ * Caller should take care of locking. This function will
+ * return 0 on success or -EINVAL.
+ */
+int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
+{
+        int             retries = 100;
+        u32             reg;
+
+        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
+        reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
+
+        /* set requested state */
+        reg |= DWC3_DCTL_ULSTCHNGREQ(state);
+        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
+
+        /* wait for a change in DSTS */
+        while (--retries) {
+                reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+
+                /* in HS, means ON */
+                if (DWC3_DSTS_USBLNKST(reg) == state)
+                        return 0;
+
+                usleep_range(500, 1500);
+        }
+
+        dev_vdbg(dwc->dev, "link state change request timed out\n");
+
+        return -ETIMEDOUT;
+}
+
 void dwc3_map_buffer_to_dma(struct dwc3_request *req)
 {
         struct dwc3                     *dwc = req->dep->dwc;
@@ -1155,17 +1191,11 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
                 goto out;
         }
 
-        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
-
-        /*
-         * Switch link state to Recovery. In HS/FS/LS this means
-         * RemoteWakeup Request
-         */
-        reg |= DWC3_DCTL_ULSTCHNG_RECOVERY;
-        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
-
-        /* wait for at least 2000us */
-        usleep_range(2000, 2500);
+        ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
+        if (ret < 0) {
+                dev_err(dwc->dev, "failed to put link in Recovery\n");
+                goto out;
+        }
 
         /* write zeroes to Link Change Request */
         reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h
index 2cf6f2989f73..152b6de0649d 100644
--- a/drivers/usb/dwc3/gadget.h
+++ b/drivers/usb/dwc3/gadget.h
@@ -101,6 +101,7 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
                 int status);
 
 int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode);
+int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state);
 
 void dwc3_ep0_interrupt(struct dwc3 *dwc,
                 const struct dwc3_event_depevt *event);