2 files changed, 86 insertions, 0 deletions

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 1e75f48b61f8..d420ae2d3413 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -47,6 +47,13 @@ config EFI_RUNTIME_MAP
 
 	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
 
+config EFI_PARAMS_FROM_FDT
+	bool
+	help
+	  Select this config option from the architecture Kconfig if
+	  the EFI runtime support gets system table address, memory
+          map address, and other parameters from the device tree.
+
 endmenu
 
 config UEFI_CPER
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index af20f1712337..cd36deb619fa 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -20,6 +20,8 @@
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/efi.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
 #include <linux/io.h>
 
 struct efi __read_mostly efi = {
@@ -318,3 +320,80 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables)
 
 	return 0;
 }
+
+#ifdef CONFIG_EFI_PARAMS_FROM_FDT
+
+#define UEFI_PARAM(name, prop, field)			   \
+	{						   \
+		{ name },				   \
+		{ prop },				   \
+		offsetof(struct efi_fdt_params, field),    \
+		FIELD_SIZEOF(struct efi_fdt_params, field) \
+	}
+
+static __initdata struct {
+	const char name[32];
+	const char propname[32];
+	int offset;
+	int size;
+} dt_params[] = {
+	UEFI_PARAM("System Table", "linux,uefi-system-table", system_table),
+	UEFI_PARAM("MemMap Address", "linux,uefi-mmap-start", mmap),
+	UEFI_PARAM("MemMap Size", "linux,uefi-mmap-size", mmap_size),
+	UEFI_PARAM("MemMap Desc. Size", "linux,uefi-mmap-desc-size", desc_size),
+	UEFI_PARAM("MemMap Desc. Version", "linux,uefi-mmap-desc-ver", desc_ver)
+};
+
+struct param_info {
+	int verbose;
+	void *params;
+};
+
+static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
+				       int depth, void *data)
+{
+	struct param_info *info = data;
+	void *prop, *dest;
+	unsigned long len;
+	u64 val;
+	int i;
+
+	if (depth != 1 ||
+	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
+		return 0;
+
+	pr_info("Getting parameters from FDT:\n");
+
+	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
+		prop = of_get_flat_dt_prop(node, dt_params[i].propname, &len);
+		if (!prop) {
+			pr_err("Can't find %s in device tree!\n",
+			       dt_params[i].name);
+			return 0;
+		}
+		dest = info->params + dt_params[i].offset;
+
+		val = of_read_number(prop, len / sizeof(u32));
+
+		if (dt_params[i].size == sizeof(u32))
+			*(u32 *)dest = val;
+		else
+			*(u64 *)dest = val;
+
+		if (info->verbose)
+			pr_info("  %s: 0x%0*llx\n", dt_params[i].name,
+				dt_params[i].size * 2, val);
+	}
+	return 1;
+}
+
+int __init efi_get_fdt_params(struct efi_fdt_params *params, int verbose)
+{
+	struct param_info info;
+
+	info.verbose = verbose;
+	info.params = params;
+
+	return of_scan_flat_dt(fdt_find_uefi_params, &info);
+}
+#endif /* CONFIG_EFI_PARAMS_FROM_FDT */