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.

[ marek: Ported from Linux kernel commit
         5114c3ee24875 ("usb: dwc3: Calculate REFCLKPER based on reference clock") ]

Reviewed-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Marek Vasut <marex@denx.de> # Port from Linux

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 300450100c90c6bd55faf58361322e5d41cfd22d..ed5d0d16f78541aad5fda17b26efae13fe55ece2 100644 (file)
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -14,6 +14,7 @@
  */
 
 #include <common.h>
+#include <clk.h>
 #include <cpu_func.h>
 #include <malloc.h>
 #include <dwc3-uboot.h>
@@ -126,14 +127,24 @@ static void dwc3_frame_length_adjustment(struct dwc3 *dwc, u32 fladj)
  */
 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);
 }