ANDROID: GKI: drivers: of: Add API to find ddr device type

Add API to find the ddr device type from memory node.

Test: build
Bug: 150980314
Change-Id: I1cfc38d46f1ea0abc6fbe8cbb6e37cde72b9fc2e
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>
(cherry picked from commit 368f22bc0d)
[hridya: added an EXPORT_SYMBOL_GPL statement to make the new
symbol avaialable to kernel modules].
Signed-off-by: Hridya Valsaraju <hridya@google.com>

drivers/of/fdt.c

@@ -80,6 +80,33 @@ void of_fdt_limit_memory(int limit)
 	}
 }
 
+/**
+ * of_fdt_get_ddrtype - Return the type of ddr (4/5) on the current device
+ *
+ * On match, returns a non-zero positive value which matches the ddr type.
+ * Otherwise returns -ENOENT.
+ */
+int of_fdt_get_ddrtype(void)
+{
+	int memory;
+	int len;
+	int ret;
+	fdt32_t *prop = NULL;
+
+	memory = fdt_path_offset(initial_boot_params, "/memory");
+	if (memory > 0)
+		prop = fdt_getprop_w(initial_boot_params, memory,
+				  "ddr_device_type", &len);
+
+	if (!prop || len != sizeof(u32))
+		return -ENOENT;
+
+	ret = fdt32_to_cpu(*prop);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_fdt_get_ddrtype);
+
 /**
  * of_fdt_is_compatible - Return true if given node from the given blob has
  * compat in its compatible list

include/linux/of_fdt.h

@@ -47,6 +47,7 @@ extern char __dtb_end[];
 /* Other Prototypes */
 extern u64 of_flat_dt_translate_address(unsigned long node);
 extern void of_fdt_limit_memory(int limit);
+extern int of_fdt_get_ddrtype(void);
 #endif /* CONFIG_OF_FLATTREE */
 
 #ifdef CONFIG_OF_EARLY_FLATTREE