1 files changed, 65 insertions, 1 deletions

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index b777d8f46bd5..9aa012e6ea0a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -26,6 +26,54 @@
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #include <asm/page.h>
 
+/*
+ * of_fdt_limit_memory - limit the number of regions in the /memory node
+ * @limit: maximum entries
+ *
+ * Adjust the flattened device tree to have at most 'limit' number of
+ * memory entries in the /memory node. This function may be called
+ * any time after initial_boot_param is set.
+ */
+void of_fdt_limit_memory(int limit)
+{
+	int memory;
+	int len;
+	const void *val;
+	int nr_address_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
+	int nr_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
+	const uint32_t *addr_prop;
+	const uint32_t *size_prop;
+	int root_offset;
+	int cell_size;
+
+	root_offset = fdt_path_offset(initial_boot_params, "/");
+	if (root_offset < 0)
+		return;
+
+	addr_prop = fdt_getprop(initial_boot_params, root_offset,
+				"#address-cells", NULL);
+	if (addr_prop)
+		nr_address_cells = fdt32_to_cpu(*addr_prop);
+
+	size_prop = fdt_getprop(initial_boot_params, root_offset,
+				"#size-cells", NULL);
+	if (size_prop)
+		nr_size_cells = fdt32_to_cpu(*size_prop);
+
+	cell_size = sizeof(uint32_t)*(nr_address_cells + nr_size_cells);
+
+	memory = fdt_path_offset(initial_boot_params, "/memory");
+	if (memory > 0) {
+		val = fdt_getprop(initial_boot_params, memory, "reg", &len);
+		if (len > limit*cell_size) {
+			len = limit*cell_size;
+			pr_debug("Limiting number of entries to %d\n", limit);
+			fdt_setprop(initial_boot_params, memory, "reg", val,
+					len);
+		}
+	}
+}
+
 /**
  * of_fdt_is_compatible - Return true if given node from the given blob has
  * compat in its compatible list
@@ -937,7 +985,7 @@ int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
 }
 #endif
 
-bool __init early_init_dt_scan(void *params)
+bool __init early_init_dt_verify(void *params)
 {
 	if (!params)
 		return false;
@@ -951,6 +999,12 @@ bool __init early_init_dt_scan(void *params)
 		return false;
 	}
 
+	return true;
+}
+
+
+void __init early_init_dt_scan_nodes(void)
+{
 	/* Retrieve various information from the /chosen node */
 	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
 
@@ -959,7 +1013,17 @@ bool __init early_init_dt_scan(void *params)
 
 	/* Setup memory, calling early_init_dt_add_memory_arch */
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+}
+
+bool __init early_init_dt_scan(void *params)
+{
+	bool status;
+
+	status = early_init_dt_verify(params);
+	if (!status)
+		return false;
 
+	early_init_dt_scan_nodes();
 	return true;
 }