[PATCH 2/3] usb: dwc3: Set reference clock period

[Thinh Nguyen]

Get the reference clock period from the device property and reprogram it
during core power-on initialization.

Signed-off-by: Thinh Nguyen <thi...@synopsys.com>
---
 drivers/usb/dwc3/core.c | 22 ++++++++++++++++++++++
 drivers/usb/dwc3/core.h | 10 ++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index becfbb87f791..4437db4a1e15 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1001,6 +1001,26 @@ static int dwc3_core_init(struct dwc3 *dwc)
                dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
        }
 
+       if (dwc->refclk_period_ns) {
+               switch (dwc->refclk_period_ns) {
+               case DWC3_GUCTL_REFCLKPER_25NS:
+               case DWC3_GUCTL_REFCLKPER_41NS:
+               case DWC3_GUCTL_REFCLKPER_50NS:
+               case DWC3_GUCTL_REFCLKPER_52NS:
+               case DWC3_GUCTL_REFCLKPER_58NS:
+               case DWC3_GUCTL_REFCLKPER_62NS:
+                       reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
+                       reg &= ~DWC3_GUCTL_REFCLKPER(~0);
+                       reg |= DWC3_GUCTL_REFCLKPER(dwc->refclk_period_ns);
+                       dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
+                       break;
+               default:
+                       dev_err(dwc->dev, "Invalid refclk period: %dns\n",
+                               dwc->refclk_period_ns);
+                       break;
+               }
+       }
+
        /*
         * Must config both number of packets and max burst settings to enable
         * RX and/or TX threshold.
@@ -1246,6 +1266,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
                                &hird_threshold);
        dwc->usb3_lpm_capable = device_property_read_bool(dev,
                                "snps,usb3_lpm_capable");
+       device_property_read_u8(dev, "snps,refclk-period-ns",
+                               &dwc->refclk_period_ns);
        device_property_read_u8(dev, "snps,rx-thr-num-pkt-prd",
                                &rx_thr_num_pkt_prd);
        device_property_read_u8(dev, "snps,rx-max-burst-prd",
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5bfb62533e0f..5ce985b2e6c7 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -240,6 +240,14 @@
 
 /* Global User Control Register */
 #define DWC3_GUCTL_HSTINAUTORETRY      BIT(14)
+#define DWC3_GUCTL_REFCLKPER(n)                (((n) & 0x3ff) << 22)
+
+#define DWC3_GUCTL_REFCLKPER_25NS      25
+#define DWC3_GUCTL_REFCLKPER_41NS      41
+#define DWC3_GUCTL_REFCLKPER_50NS      50
+#define DWC3_GUCTL_REFCLKPER_52NS      52
+#define DWC3_GUCTL_REFCLKPER_58NS      58
+#define DWC3_GUCTL_REFCLKPER_62NS      62
 
 /* Global User Control 1 Register */
 #define DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS     BIT(28)
@@ -991,6 +999,7 @@ struct dwc3_scratchpad_array {
  *                     change quirk.
  * @dis_tx_ipgap_linecheck_quirk: set if we disable u2mac linestate
  *                     check during HS transmit.
+ * @refclk_period_ns: reference clock period in nanoseconds.
  * @tx_de_emphasis_quirk: set if we enable Tx de-emphasis quirk
  * @tx_de_emphasis: Tx de-emphasis value
  *     0       - -6dB de-emphasis
@@ -1129,6 +1138,7 @@ struct dwc3 {
        u8                      rx_max_burst_prd;
        u8                      tx_thr_num_pkt_prd;
        u8                      tx_max_burst_prd;
+       u8                      refclk_period_ns;
 
        const char              *hsphy_interface;
 
-- 
2.11.0