+ * Additionaly, the register page maps in the CPG register base relative
+ * to the nearest page-aligned boundary, which requires that userspace do
+ * the appropriate CPU subtype math for calculating the page offset for
+ * the counter value.
+ */
+static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int ret = -ENOSYS;
+
+#ifdef CONFIG_SH_WDT_MMAP
+ unsigned long addr;
+
+ /* Only support the simple cases where we map in a register page. */
+ if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
+ return -EINVAL;
+
+ /*
+ * Pick WTCNT as the start, it's usually the first register after the
+ * FRQCR, and neither one are generally page-aligned out of the box.
+ */
+ addr = WTCNT & ~(PAGE_SIZE - 1);
+
+ vma->vm_flags |= VM_IO;
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+ if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
+ PAGE_SIZE, vma->vm_page_prot)) {
+ printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
+ __FUNCTION__);
+ return -EAGAIN;
+ }
+
+ ret = 0;
+#endif
+
+ return ret;
+}
+
+/**
+ * sh_wdt_ioctl - Query Device