usb: dwc3: Calculate REFCLKPER based on reference clock

Instead of using a special property to determine the reference clock
period, use the rate of the reference clock. When we have a legacy
snps,ref-clock-period-ns property and no reference clock, use it
instead. Fractional clocks are not currently supported, and will be
dealt with in the next commit.

Tested-by: Robert Hancock <robert.hancock@calian.com>
Reviewed-by: Robert Hancock <robert.hancock@calian.com>
Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/20220127200636.1456175-4-sean.anderson@seco.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 699ab9abdc477e67f7783de454f9b885f9cd02b5..38fef5c743593c3fda972d63ce0222bd41a07531 100644 (file)
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -347,14 +347,24 @@ static void dwc3_frame_length_adjustment(struct dwc3 *dwc)
  */
 static void dwc3_ref_clk_period(struct dwc3 *dwc)
 {
+       unsigned long period;
+       unsigned long rate;
        u32 reg;
 
-       if (dwc->ref_clk_per == 0)
+       if (dwc->ref_clk) {
+               rate = clk_get_rate(dwc->ref_clk);
+               if (!rate)
+                       return;
+               period = NSEC_PER_SEC / rate;
+       } else if (dwc->ref_clk_per) {
+               period = dwc->ref_clk_per;
+       } else {
                return;
+       }
 
        reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
        reg &= ~DWC3_GUCTL_REFCLKPER_MASK;
-       reg |=  FIELD_PREP(DWC3_GUCTL_REFCLKPER_MASK, dwc->ref_clk_per);
+       reg |=  FIELD_PREP(DWC3_GUCTL_REFCLKPER_MASK, period);
        dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
 }