usb: dwc3: pci: Enable ULPI Refclk on platforms where the firmware does not

On some Bay Trail (BYT) systems the firmware does not enable the
ULPI Refclk.

This commit adds a helper which checks and if necessary enabled the Refclk
and calls this helper for BYT machines.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
index 5c175f839efd185ca0c66f0a1479bad7cc94d550..26829b299482c561cc8ded6d0e5d25438c6b19a3 100644 (file)
--- a/drivers/usb/dwc3/dwc3-pci.c
+++ b/drivers/usb/dwc3/dwc3-pci.c
@@ -39,6 +39,10 @@
 #define PCI_INTEL_BXT_STATE_D0         0
 #define PCI_INTEL_BXT_STATE_D3         3
 
+#define GP_RWBAR                       1
+#define GP_RWREG1                      0xa0
+#define GP_RWREG1_ULPI_REFCLK_DISABLE  (1 << 17)
+
 /**
  * struct dwc3_pci - Driver private structure
  * @dwc3: child dwc3 platform_device
@@ -74,6 +78,28 @@ static struct gpiod_lookup_table platform_bytcr_gpios = {
        },
 };
 
+static int dwc3_byt_enable_ulpi_refclock(struct pci_dev *pci)
+{
+       void __iomem    *reg;
+       u32             value;
+
+       reg = pcim_iomap(pci, GP_RWBAR, 0);
+       if (IS_ERR(reg))
+               return PTR_ERR(reg);
+
+       value = readl(reg + GP_RWREG1);
+       if (!(value & GP_RWREG1_ULPI_REFCLK_DISABLE))
+               goto unmap; /* ULPI refclk already enabled */
+
+       value &= ~GP_RWREG1_ULPI_REFCLK_DISABLE;
+       writel(value, reg + GP_RWREG1);
+       /* This comes from the Intel Android x86 tree w/o any explanation */
+       msleep(100);
+unmap:
+       pcim_iounmap(pci, reg);
+       return 0;
+}
+
 static int dwc3_pci_quirks(struct dwc3_pci *dwc)
 {
        struct platform_device          *dwc3 = dwc->dwc3;
@@ -129,6 +155,11 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
                if (pdev->device == PCI_DEVICE_ID_INTEL_BYT) {
                        struct gpio_desc *gpio;
 
+                       /* On BYT the FW does not always enable the refclock */
+                       ret = dwc3_byt_enable_ulpi_refclock(pdev);
+                       if (ret)
+                               return ret;
+
                        ret = devm_acpi_dev_add_driver_gpios(&pdev->dev,
                                        acpi_dwc3_byt_gpios);
                        if (ret)