1 files changed, 58 insertions, 3 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index e633106b12f6..ca6a1536b205 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -623,7 +623,7 @@ resource_size_t resource_alignment(struct resource *res)
  */
 struct resource * __request_region(struct resource *parent,
                                    resource_size_t start, resource_size_t n,
-                                   const char *name)
+                                   const char *name, int flags)
 {
         struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);
 
@@ -634,6 +634,7 @@ struct resource * __request_region(struct resource *parent,
         res->start = start;
         res->end = start + n - 1;
         res->flags = IORESOURCE_BUSY;
+        res->flags |= flags;
 
         write_lock(&resource_lock);
 
@@ -679,7 +680,7 @@ int __check_region(struct resource *parent, resource_size_t start,
 {
         struct resource * res;
 
-        res = __request_region(parent, start, n, "check-region");
+        res = __request_region(parent, start, n, "check-region", 0);
         if (!res)
                 return -EBUSY;
 
@@ -776,7 +777,7 @@ struct resource * __devm_request_region(struct device *dev,
         dr->start = start;
         dr->n = n;
 
-        res = __request_region(parent, start, n, name);
+        res = __request_region(parent, start, n, name, 0);
         if (res)
                 devres_add(dev, dr);
         else
@@ -876,3 +877,57 @@ int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
 
         return err;
 }
+
+#ifdef CONFIG_STRICT_DEVMEM
+static int strict_iomem_checks = 1;
+#else
+static int strict_iomem_checks;
+#endif
+
+/*
+ * check if an address is reserved in the iomem resource tree
+ * returns 1 if reserved, 0 if not reserved.
+ */
+int iomem_is_exclusive(u64 addr)
+{
+        struct resource *p = &iomem_resource;
+        int err = 0;
+        loff_t l;
+        int size = PAGE_SIZE;
+
+        if (!strict_iomem_checks)
+                return 0;
+
+        addr = addr & PAGE_MASK;
+
+        read_lock(&resource_lock);
+        for (p = p->child; p ; p = r_next(NULL, p, &l)) {
+                /*
+                 * We can probably skip the resources without
+                 * IORESOURCE_IO attribute?
+                 */
+                if (p->start >= addr + size)
+                        break;
+                if (p->end < addr)
+                        continue;
+                if (p->flags & IORESOURCE_BUSY &&
+                     p->flags & IORESOURCE_EXCLUSIVE) {
+                        err = 1;
+                        break;
+                }
+        }
+        read_unlock(&resource_lock);
+
+        return err;
+}
+
+static int __init strict_iomem(char *str)
+{
+        if (strstr(str, "relaxed"))
+                strict_iomem_checks = 0;
+        if (strstr(str, "strict"))
+                strict_iomem_checks = 1;
+        return 1;
+}
+
+__setup("iomem=", strict_iomem);