common: fdt_support: add support for setting usable memory

Add support for setting linux,usable-memory property in the memory
node of device tree for the kernel [1].

This property holds a base address and size, describing a
limited region in which memory may be considered available for use by
the kernel. Memory outside of this range is not available for use.

[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/chosen.txt

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 68343990395084f5fadea890a8d093682c49479f..02cf5c6241b2c2961b31c7aec8879025e36ffc50 100644 (file)
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -467,6 +467,41 @@ int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[], int banks)
        }
        return 0;
 }
+
+int fdt_set_usable_memory(void *blob, u64 start[], u64 size[], int areas)
+{
+       int err, nodeoffset;
+       int len;
+       u8 tmp[8 * 16]; /* Up to 64-bit address + 64-bit size */
+
+       if (areas > 8) {
+               printf("%s: num areas %d exceeds hardcoded limit %d\n",
+                      __func__, areas, 8);
+               return -1;
+       }
+
+       err = fdt_check_header(blob);
+       if (err < 0) {
+               printf("%s: %s\n", __func__, fdt_strerror(err));
+               return err;
+       }
+
+       /* find or create "/memory" node. */
+       nodeoffset = fdt_find_or_add_subnode(blob, 0, "memory");
+       if (nodeoffset < 0)
+               return nodeoffset;
+
+       len = fdt_pack_reg(blob, tmp, start, size, areas);
+
+       err = fdt_setprop(blob, nodeoffset, "linux,usable-memory", tmp, len);
+       if (err < 0) {
+               printf("WARNING: could not set %s %s.\n",
+                      "reg", fdt_strerror(err));
+               return err;
+       }
+
+       return 0;
+}
 #endif
 
 int fdt_fixup_memory(void *blob, u64 start, u64 size)

diff --git a/include/fdt_support.h b/include/fdt_support.h
index cefb2b2cce2396efa390a8e0f2c84b1a35b4e19e..2286ea7793924809bcbfe9f1e482889c44bda0d3 100644 (file)
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -94,6 +94,7 @@ int fdt_fixup_memory(void *blob, u64 start, u64 size);
  */
 #ifdef CONFIG_ARCH_FIXUP_FDT_MEMORY
 int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[], int banks);
+int fdt_set_usable_memory(void *blob, u64 start[], u64 size[], int banks);
 #else
 static inline int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[],
                                         int banks)