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--- device_tree_standard_properties [2018/11/18 12:55]
rpjday [virtual-reg]
+++ device_tree_standard_properties [2018/11/18 13:54]
rpjday [ranges]
@@ Line 33: / Line 33: @@
 ==== ranges ====
+The format of the value of the ranges property is an arbitrary number of triplets of (child-bus-address, parent-bus-address, length)
+  * The child-bus-address is a physical address within the child bus’ address space. The number of cells to represent the address is bus dependent and can be determined from the #address-cells of this node (the node in which the ranges property appears).
+  * The parent-bus-address is a physical address within the parent bus’ address space. The number of cells to represent the parent address is bus dependent and can be determined from the #address-cells property of the node that defines the parent’s address space.
+  * The length specifies the size of the range in the child’s address space. The number of cells to represent the size can be determined from the #size-cells of this node (the node in which the ranges property appears).
+If the property is defined with an <empty> value, it specifies that the parent and child address space is identical, and no address translation is required.
+If the property is not present in a bus node, it is assumed that no mapping exists between children of the node and the parent address space.
 ==== dma-ranges ====

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