sandbox: Add un/map_sysmen() to deal with sandbox's ram_buf

Sandbox doesn't actually provide U-Boot access to the machine's physical
memory. Instead it provides a RAM buffer of configurable size, and all
memory accesses are within that buffer. Sandbox memory starts at 0 and
is CONFIG_DRAM_SIZE bytes in size. Allowing access outside this buffer
might produce unpredictable results in the event of an error, and would
expose the host machine's memory architecture to the sandbox U-Boot.

Most U-Boot functions assume that they can just access memory at given
address. For sandbox this is not true.

Add a map_sysmem() call which converts a U-Boot address to a system
address. In most cases this is a NOP, but for sandbox it returns a
pointer to that memory inside the RAM buffer.

To get a U-Boot feature to work correctly within sandbox, you should call
map_sysmem() to get a pointer to the address, and then use that address for
any U-Boot memory accesses.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/sandbox/include/asm/io.h b/arch/sandbox/include/asm/io.h
index 0392d21..d8c0236 100644
--- a/arch/sandbox/include/asm/io.h
+++ b/arch/sandbox/include/asm/io.h
@@ -39,3 +39,13 @@ static inline void unmap_physmem(void *vaddr, unsigned long flags)
 {
 
 }
+
+/* For sandbox, we want addresses to point into our RAM buffer */
+static inline void *map_sysmem(phys_addr_t paddr, unsigned long len)
+{
+	return map_physmem(paddr, len, MAP_WRBACK);
+}
+
+static inline void unmap_sysmem(const void *vaddr)
+{
+}