[U-Boot] [PATCH 2/3] ARM: tegra: query_sdram_size() cleanup

[Stephen Warren]

From: Stephen Warren <swarren at nvidia.com>

The return value of query_sdram_size() is assigned directly to
gd->ram_size in dram_init(). Adjust the return type to match the field
it's assigned to. This has the beneficial effect that on 64-bit systems,
the return value can correctly represent large RAM sizes over 4GB.

For similar reasons, change the type of variable size_bytes in the same
way.

query_sdram_size() would previously clip the detected RAM size to at most
just under 4GB in all cases, since on 32-bit systems, larger values could
not be represented. Disable this feature on 64-bit systems since the
representation restriction does not exist.

On 64-bit systems, never call get_ram_size() to validate the detected/
calculated RAM size. On any system with a secure OS/... carve-out, RAM
may not have a single contiguous usable area, and this can confuse
get_ram_size(). Ideally, we'd make this call conditional upon some other
flag that indicates specifically that a carve-out is actually in use. At
present, building for a 64-bit system is the best indication we have of
this fact. In fact, the call to get_ram_size() is not useful by the time
U-Boot runs on any system, since U-Boot (and potentially much other early
boot software) always runs from RAM on Tegra, so any mistakes in memory
controller register programming will already have manifested themselves
and prevented U-Boot from running to this point. In the future, we may
simply delete the call to get_ram_size() in all cases.

Signed-off-by: Stephen Warren <swarren at nvidia.com>
---
 arch/arm/mach-tegra/board.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-tegra/board.c b/arch/arm/mach-tegra/board.c
index 40de72dc575f..b00e4b5c1e25 100644
--- a/arch/arm/mach-tegra/board.c
+++ b/arch/arm/mach-tegra/board.c
@@ -66,10 +66,11 @@ bool tegra_cpu_is_non_secure(void)
 #endif
 
 /* Read the RAM size directly from the memory controller */
-unsigned int query_sdram_size(void)
+static phys_size_t query_sdram_size(void)
 {
 	struct mc_ctlr *const mc = (struct mc_ctlr *)NV_PA_MC_BASE;
-	u32 emem_cfg, size_bytes;
+	u32 emem_cfg;
+	phys_size_t size_bytes;
 
 	emem_cfg = readl(&mc->mc_emem_cfg);
 #if defined(CONFIG_TEGRA20)
@@ -77,6 +78,7 @@ unsigned int query_sdram_size(void)
 	size_bytes = get_ram_size((void *)PHYS_SDRAM_1, emem_cfg * 1024);
 #else
 	debug("mc->mc_emem_cfg (MEM_SIZE_MB) = 0x%08x\n", emem_cfg);
+#ifndef CONFIG_PHYS_64BIT
 	/*
 	 * If >=4GB RAM is present, the byte RAM size won't fit into 32-bits
 	 * and will wrap. Clip the reported size to the maximum that a 32-bit
@@ -84,9 +86,12 @@ unsigned int query_sdram_size(void)
 	 */
 	if (emem_cfg >= 4096) {
 		size_bytes = U32_MAX & ~(0x1000 - 1);
-	} else {
+	} else
+#endif
+	{
 		/* RAM size EMC is programmed to. */
-		size_bytes = emem_cfg * 1024 * 1024;
+		size_bytes = (phys_size_t)emem_cfg * 1024 * 1024;
+#ifndef CONFIG_ARM64
 		/*
 		 * If all RAM fits within 32-bits, it can be accessed without
 		 * LPAE, so go test the RAM size. Otherwise, we can't access
@@ -97,6 +102,7 @@ unsigned int query_sdram_size(void)
 		if (emem_cfg <= (0 - PHYS_SDRAM_1) / (1024 * 1024))
 			size_bytes = get_ram_size((void *)PHYS_SDRAM_1,
 						  size_bytes);
+#endif
 	}
 #endif
 
-- 
1.9.1