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@xxxxxxxxxx>
---
Changes in v2:
-Use pcim_iomap instead of parsing resources ourselves
-Add a comment about the msleep(100) call
---
drivers/usb/dwc3/dwc3-pci.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
index c58f87b01ac7..046f7f55789f 100644
--- a/drivers/usb/dwc3/dwc3-pci.c
+++ b/drivers/usb/dwc3/dwc3-pci.c
@@ -41,6 +41,10 @@
#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
@@ -76,6 +80,28 @@ 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;
@@ -131,6 +157,11 @@ 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)
--
2.17.1
--
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