[U-Boot] [PATCH 1/9] dm: allow 4GB of DRAM on 32bit systems

[Philipp Tomsich]

Even on 32bit systems a full 4GB of DRAM may be installed and reported
by the DRAM controller.  Whether these 4GB are larger available
depends on the size/configuration of address decoding windows and
architectural features (e.g. consider a hypothetical architecture that
uses dedicated instructions to access the 'memory-mapped' peripheral
IO ranges).  In U-Boot, the available DRAM, as reported by the
device-model is independent of the accessible DRAM (i.e. adjusted top
and effective size).

This was first reported against the RK3288, which may have 4GB DRAM
attached, but will have a small (e.g. 128MB) window not accessible due
to address decoding limitations.

The solution is to increase the types used for storing the ram_size to
have at least 33 bits even on 32bit systems... i.e. we need to use a
u64 for these always (this was previously only the case for
PHYS_64BIT, which will have unwanted side-effects for 32bit systems
and would require more intrusive changes).

This commit changes the size-field in 'struct ram' and the ram_size in
'gd' to be a u64.

Reported-by: Marty E. Plummer <hanetzer at startmail.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
---

 include/asm-generic/global_data.h | 2 +-
 include/ram.h                     | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index 0fd4900..f3d687c 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -55,7 +55,7 @@ typedef struct global_data {
 	unsigned long ram_base;		/* Base address of RAM used by U-Boot */
 	unsigned long ram_top;		/* Top address of RAM used by U-Boot */
 	unsigned long relocaddr;	/* Start address of U-Boot in RAM */
-	phys_size_t ram_size;		/* RAM size */
+	u64 ram_size;			/* RAM size */
 	unsigned long mon_len;		/* monitor len */
 	unsigned long irq_sp;		/* irq stack pointer */
 	unsigned long start_addr_sp;	/* start_addr_stackpointer */
diff --git a/include/ram.h b/include/ram.h
index 67e22d7..1fe024f 100644
--- a/include/ram.h
+++ b/include/ram.h
@@ -9,7 +9,14 @@
 
 struct ram_info {
 	phys_addr_t base;
-	size_t size;
+	/*
+	 * We use a 64bit type for the size to correctly handle 32bit
+	 * systems with 4GB of DRAM (which would overflow a 32bit type
+	 * and read back as 0).  For 64bit systems, we assume (for now)
+	 * that they will always have less than 2^65 byte of DRAM
+	 * installed. -- prt
+	 */
+	u64 size;
 };
 
 struct ram_ops {
-- 
2.1.4