doc: add README doc for bcmns3 platform
Add README doc for bcmns3 platform.
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/README.bcmns3 b/doc/README.bcmns3
new file mode 100644
index 0000000..c51f914
--- /dev/null
+++ b/doc/README.bcmns3
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+BCMNS3 QSPI memory layout
+=========================
+
+BCMNS3 has total 8MB non-volatile SPI flash memory. It is used to store
+different images like fip.bin, nitro firmware, DDR shmo value and other backup
+images.
+
+Following is the QSPI flash memory layout.
+
+/* QSPI layout
+ * |---------------------------|->0x000000
+ * | |
+ * | |
+ * | fip.bin |
+ * | 2MB |
+ * | |
+ * ~ ~
+ * ~ ~
+ * | |
+ * | |
+ * | |
+ * |---------------------------|->0x200000
+ * | |
+ * | |
+ * | |
+ * | fip.bin (Mirror) |
+ * | 2MB |
+ * ~ ~
+ * ~ ~
+ * | |
+ * | |
+ * | |
+ * |---------------------------|->0x400000
+ * | |
+ * | Nitro NS3 Config |
+ * | 1.5M |
+ * | |
+ * ~ ~
+ * ~ ~
+ * | |
+ * |---------------------------|->0x580000
+ * | Nitro NS3 Config |
+ * | 1.5M |
+ * | (Mirror) |
+ * ~ ~
+ * ~ ~
+ * | |
+ * |---------------------------|->0x700000
+ * | Nitro NS3 bspd Config |
+ * | 64KB |
+ * ~ ~
+ * ~ ~
+ * | |
+ * |---------------------------|->0x710000
+ * | Nitro NS3 bspd Config |
+ * | 64KB |
+ * ~ (Mirror) ~
+ * ~ ~
+ * | |
+ * |---------------------------|->0x720000
+ * | SHMOO |
+ * | 64KB |
+ * | |
+ * ~ ~
+ * ~ ~
+ * |---------------------------|->0x730000
+ * | Meta Data |
+ * | 832KB |
+ * | |
+ * ~ ~
+ * ~ ~
+ * | |
+ * |---------------------------|
+ */