MIPS: generic/yamon-dt: Support > 256MB of RAM

YAMON can expose more than 256MB of RAM to Linux on Malta by passing an
ememsize environment variable with the full size, but the kernel then
needs to be careful to choose the corresponding physical memory regions,
avoiding the IO memory window. This is platform dependent, and on Malta
it also depends on the memory layout which varies between system
controllers.

Extend yamon_dt_amend_memory() to generically handle this by taking
[e]memsize bytes of memory from an array of memory regions passed in as
a new parameter. Board code provides this array as appropriate depending
on its own memory map.

[paul.burton@imgtec.com: SEAD-3 supports 384MB DDR from 0]

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16182/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 19 insertions, 3 deletions

diff --git a/arch/mips/include/asm/yamon-dt.h b/arch/mips/include/asm/yamon-dt.h
index 3f3367de4836..485cfe3e45e1 100644
--- a/arch/mips/include/asm/yamon-dt.h
+++ b/arch/mips/include/asm/yamon-dt.h
@@ -11,6 +11,20 @@
 #ifndef __MIPS_ASM_YAMON_DT_H__
 #define __MIPS_ASM_YAMON_DT_H__
 
+#include <linux/types.h>
+
+/**
+ * struct yamon_mem_region - Represents a contiguous range of physical RAM.
+ * @start:	Start physical address.
+ * @size:	Maximum size of region.
+ * @discard:	Length of additional memory to discard after the region.
+ */
+struct yamon_mem_region {
+	phys_addr_t	start;
+	phys_addr_t	size;
+	phys_addr_t	discard;
+};
+
 /**
  * yamon_dt_append_cmdline() - Append YAMON-provided command line to /chosen
  * @fdt: the FDT blob
@@ -24,14 +38,16 @@ extern __init int yamon_dt_append_cmdline(void *fdt);
 
 /**
  * yamon_dt_append_memory() - Append YAMON-provided memory info to /memory
- * @fdt: the FDT blob
+ * @fdt:	the FDT blob
+ * @regions:	zero size terminated array of physical memory regions
  *
  * Generate a /memory node in @fdt based upon memory size information provided
- * by YAMON in its environment.
+ * by YAMON in its environment and the @regions array.
  *
  * Return: 0 on success, else -errno
  */
-extern __init int yamon_dt_append_memory(void *fdt);
+extern __init int yamon_dt_append_memory(void *fdt,
+					const struct yamon_mem_region *regions);
 
 /**
  * yamon_dt_serial_config() - Append YAMON-provided serial config to /chosen