[PATCH] efi/libstub/arm*: Set default address and size cells values for an empty dtb

[jhugo@codeaurora.org (Jeffrey Hugo)]

From: Sameer Goel <sgoel@codeaurora.org>

In cases where a device tree is not provided (ie ACPI based system), an
empty fdt is generated by efistub.  Sets the address and size cell values
in a generated fdt to support 64 bit addressing.

This enables kexec/kdump on Qualcomm Technologies QDF24XX platforms as those
utilities will read the address/size values from the fdt, and such values
may exceed the range provided by the 32 bit default.

Change-Id: Ie7f3637e375bd6631c6bda1f7b3c9003765ff4a5
Signed-off-by: Sameer Goel <sgoel@codeaurora.org>
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
---
 drivers/firmware/efi/libstub/fdt.c | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 921dfa0..def5c9c 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -16,6 +16,34 @@
 
 #include "efistub.h"
 
+#define EFI_DT_ADDR_CELLS_DEFAULT 2
+#define EFI_DT_SIZE_CELLS_DEFAULT 2
+
+static void fdt_update_cell_size(efi_system_table_t *sys_table, void *fdt)
+{
+	int offset;
+	int status;
+
+	offset = fdt_path_offset(fdt, "/");
+	/* Set the #address-cells and #size-cells values for an empty tree */
+
+	status = fdt_setprop_u32(fdt, offset, "#address-cells",
+				 EFI_DT_ADDR_CELLS_DEFAULT);
+	if (status) {
+		pr_efi(sys_table,
+		       "Failed to set #address-cells for empty dtb\n");
+		return;
+	}
+
+	status = fdt_setprop_u32(fdt, offset, "#size-cells",
+				 EFI_DT_SIZE_CELLS_DEFAULT);
+	if (status) {
+		pr_efi(sys_table,
+		       "Failed to set #size-cells for empty dtb\n");
+		return;
+	}
+}
+
 static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 			       unsigned long orig_fdt_size,
 			       void *fdt, int new_fdt_size, char *cmdline_ptr,
@@ -44,8 +72,16 @@ static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 
 	if (orig_fdt)
 		status = fdt_open_into(orig_fdt, fdt, new_fdt_size);
-	else
+	else {
 		status = fdt_create_empty_tree(fdt, new_fdt_size);
+		if (status == 0) {
+			/*
+			 * Any failure from the following function is non
+			 * critical
+			 */
+			fdt_update_cell_size(sys_table, fdt);
+		}
+	}
 
 	if (status != 0)
 		goto fdt_set_fail;
-- 
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