+/*
+ * Registers should always be accessed with double word or quad word accesses.
+ *
+ * Some xHCI implementations may support 64-bit address pointers. Registers
+ * with 64-bit address pointers should be written to with dword accesses by
+ * writing the low dword first (ptr[0]), then the high dword (ptr[1]) second.
+ * xHCI implementations that do not support 64-bit address pointers will ignore
+ * the high dword, and write order is irrelevant.
+ */
+static inline u64 xhci_read_64(const struct xhci_hcd *xhci,
+ __u64 __iomem *regs)
+{
+ __u32 __iomem *ptr = (__u32 __iomem *) regs;
+ u64 val_lo = readl(ptr);
+ u64 val_hi = readl(ptr + 1);
+ return val_lo + (val_hi << 32);
+}
+static inline void xhci_write_64(struct xhci_hcd *xhci,
+ const u64 val, __u64 __iomem *regs)
+{
+ __u32 __iomem *ptr = (__u32 __iomem *) regs;
+ u32 val_lo = lower_32_bits(val);
+ u32 val_hi = upper_32_bits(val);
+
+ xhci_dbg(xhci,
+ "`MEM_WRITE_DWORD(3'b000, 64'h%p, 64'h%0lx, 4'hf);\n",
+ regs, (long unsigned int) val);
+ writel(val_lo, ptr);
+ writel(val_hi, ptr + 1);
+}
+