diff --git a/lib/lmb.c b/lib/lmb.c
index cc2554dfa94..ccc8a8a139c 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -27,96 +27,11 @@ DECLARE_GLOBAL_DATA_PTR;
 #define MAP_OP_FREE		(u8)0x2
 #define MAP_OP_ADD		(u8)0x3
 
-static struct lmb lmb;
-
-static bool lmb_should_notify(enum lmb_flags flags)
-{
-	return !lmb.test && !(flags & LMB_NONOTIFY) &&
-		CONFIG_IS_ENABLED(EFI_LOADER);
-}
-
-static int lmb_map_update_notify(phys_addr_t addr, phys_size_t size, u8 op,
-				 enum lmb_flags flags)
-{
-	u64 efi_addr;
-	u64 pages;
-	efi_status_t status;
-
-	if (op != MAP_OP_RESERVE && op != MAP_OP_FREE && op != MAP_OP_ADD) {
-		log_err("Invalid map update op received (%d)\n", op);
-		return -1;
-	}
-
-	if (!lmb_should_notify(flags))
-		return 0;
-
-	efi_addr = (uintptr_t)map_sysmem(addr, 0);
-	pages = efi_size_in_pages(size + (efi_addr & EFI_PAGE_MASK));
-	efi_addr &= ~EFI_PAGE_MASK;
-
-	status = efi_add_memory_map_pg(efi_addr, pages,
-				       op == MAP_OP_RESERVE ?
-				       EFI_BOOT_SERVICES_DATA :
-				       EFI_CONVENTIONAL_MEMORY,
-				       false);
-	if (status != EFI_SUCCESS) {
-		log_err("%s: LMB Map notify failure %lu\n", __func__,
-			status & ~EFI_ERROR_MASK);
-		return -1;
-	}
-	unmap_sysmem((void *)(uintptr_t)efi_addr);
-
-	return 0;
-}
-
-static void lmb_print_region_flags(enum lmb_flags flags)
-{
-	u64 bitpos;
-	const char *flag_str[] = { "none", "no-map", "no-overwrite", "no-notify" };
-
-	do {
-		bitpos = flags ? fls(flags) - 1 : 0;
-		assert_noisy(bitpos < ARRAY_SIZE(flag_str));
-		printf("%s", flag_str[bitpos]);
-		flags &= ~(1ull << bitpos);
-		puts(flags ? ", " : "\n");
-	} while (flags);
-}
-
-static void lmb_dump_region(struct alist *lmb_rgn_lst, char *name)
-{
-	struct lmb_region *rgn = lmb_rgn_lst->data;
-	unsigned long long base, size, end;
-	enum lmb_flags flags;
-	int i;
-
-	printf(" %s.count = 0x%x\n", name, lmb_rgn_lst->count);
-
-	for (i = 0; i < lmb_rgn_lst->count; i++) {
-		base = rgn[i].base;
-		size = rgn[i].size;
-		end = base + size - 1;
-		flags = rgn[i].flags;
-
-		printf(" %s[%d]\t[0x%llx-0x%llx], 0x%08llx bytes flags: ",
-		       name, i, base, end, size);
-		lmb_print_region_flags(flags);
-	}
-}
-
-void lmb_dump_all_force(void)
-{
-	printf("lmb_dump_all:\n");
-	lmb_dump_region(&lmb.free_mem, "memory");
-	lmb_dump_region(&lmb.used_mem, "reserved");
-}
-
-void lmb_dump_all(void)
-{
-#ifdef DEBUG
-	lmb_dump_all_force();
-#endif
-}
+/*
+ * The following low level LMB functions must not access the global LMB memory
+ * map since they are also used to manage IOVA memory maps in iommu drivers like
+ * apple_dart.
+ */
 
 static long lmb_addrs_overlap(phys_addr_t base1, phys_size_t size1,
 			      phys_addr_t base2, phys_size_t size2)
@@ -205,115 +120,6 @@ static void lmb_fix_over_lap_regions(struct alist *lmb_rgn_lst,
 	lmb_remove_region(lmb_rgn_lst, r2);
 }
 
-static void lmb_reserve_uboot_region(void)
-{
-	int bank;
-	ulong end, bank_end;
-	phys_addr_t rsv_start;
-
-	rsv_start = gd->start_addr_sp - CONFIG_STACK_SIZE;
-	end = gd->ram_top;
-
-	/*
-	 * Reserve memory from aligned address below the bottom of U-Boot stack
-	 * until end of RAM area to prevent LMB from overwriting that memory.
-	 */
-	debug("## Current stack ends at 0x%08lx ", (ulong)rsv_start);
-
-	for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
-		if (!gd->bd->bi_dram[bank].size ||
-		    rsv_start < gd->bd->bi_dram[bank].start)
-			continue;
-		/* Watch out for RAM at end of address space! */
-		bank_end = gd->bd->bi_dram[bank].start +
-			gd->bd->bi_dram[bank].size - 1;
-		if (rsv_start > bank_end)
-			continue;
-		if (bank_end > end)
-			bank_end = end - 1;
-
-		lmb_reserve_flags(rsv_start, bank_end - rsv_start + 1,
-				  LMB_NOOVERWRITE);
-
-		if (gd->flags & GD_FLG_SKIP_RELOC)
-			lmb_reserve_flags((phys_addr_t)(uintptr_t)_start,
-					  gd->mon_len, LMB_NOOVERWRITE);
-
-		break;
-	}
-}
-
-static void lmb_reserve_common(void *fdt_blob)
-{
-	lmb_reserve_uboot_region();
-
-	if (CONFIG_IS_ENABLED(OF_LIBFDT) && fdt_blob)
-		boot_fdt_add_mem_rsv_regions(fdt_blob);
-}
-
-static __maybe_unused void lmb_reserve_common_spl(void)
-{
-	phys_addr_t rsv_start;
-	phys_size_t rsv_size;
-
-	/*
-	 * Assume a SPL stack of 16KB. This must be
-	 * more than enough for the SPL stage.
-	 */
-	if (IS_ENABLED(CONFIG_SPL_STACK_R_ADDR)) {
-		rsv_start = gd->start_addr_sp - 16384;
-		rsv_size = 16384;
-		lmb_reserve_flags(rsv_start, rsv_size, LMB_NOOVERWRITE);
-	}
-
-	if (IS_ENABLED(CONFIG_SPL_SEPARATE_BSS)) {
-		/* Reserve the bss region */
-		rsv_start = (phys_addr_t)(uintptr_t)__bss_start;
-		rsv_size = (phys_addr_t)(uintptr_t)__bss_end -
-			(phys_addr_t)(uintptr_t)__bss_start;
-		lmb_reserve_flags(rsv_start, rsv_size, LMB_NOOVERWRITE);
-	}
-}
-
-/**
- * lmb_add_memory() - Add memory range for LMB allocations
- *
- * Add the entire available memory range to the pool of memory that
- * can be used by the LMB module for allocations.
- *
- * Return: None
- */
-void lmb_add_memory(void)
-{
-	int i;
-	phys_size_t size;
-	u64 ram_top = gd->ram_top;
-	struct bd_info *bd = gd->bd;
-
-	if (CONFIG_IS_ENABLED(LMB_ARCH_MEM_MAP))
-		return lmb_arch_add_memory();
-
-	/* Assume a 4GB ram_top if not defined */
-	if (!ram_top)
-		ram_top = 0x100000000ULL;
-
-	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
-		size = bd->bi_dram[i].size;
-		if (size) {
-			lmb_add(bd->bi_dram[i].start, size);
-
-			/*
-			 * Reserve memory above ram_top as
-			 * no-overwrite so that it cannot be
-			 * allocated
-			 */
-			if (bd->bi_dram[i].start >= ram_top)
-				lmb_reserve_flags(bd->bi_dram[i].start, size,
-						  LMB_NOOVERWRITE);
-		}
-	}
-}
-
 static long lmb_resize_regions(struct alist *lmb_rgn_lst,
 			       unsigned long idx_start,
 			       phys_addr_t base, phys_size_t size)
@@ -473,25 +279,6 @@ static long lmb_add_region_flags(struct alist *lmb_rgn_lst, phys_addr_t base,
 	return 0;
 }
 
-static long lmb_add_region(struct alist *lmb_rgn_lst, phys_addr_t base,
-			   phys_size_t size)
-{
-	return lmb_add_region_flags(lmb_rgn_lst, base, size, LMB_NONE);
-}
-
-/* This routine may be called with relocation disabled. */
-long lmb_add(phys_addr_t base, phys_size_t size)
-{
-	long ret;
-	struct alist *lmb_rgn_lst = &lmb.free_mem;
-
-	ret = lmb_add_region(lmb_rgn_lst, base, size);
-	if (ret)
-		return ret;
-
-	return lmb_map_update_notify(base, size, MAP_OP_ADD, LMB_NONE);
-}
-
 static long _lmb_free(struct alist *lmb_rgn_lst, phys_addr_t base,
 		      phys_size_t size)
 {
@@ -543,6 +330,252 @@ static long _lmb_free(struct alist *lmb_rgn_lst, phys_addr_t base,
 				    rgn[i].flags);
 }
 
+static long lmb_overlaps_region(struct alist *lmb_rgn_lst, phys_addr_t base,
+				phys_size_t size)
+{
+	unsigned long i;
+	struct lmb_region *rgn = lmb_rgn_lst->data;
+
+	for (i = 0; i < lmb_rgn_lst->count; i++) {
+		phys_addr_t rgnbase = rgn[i].base;
+		phys_size_t rgnsize = rgn[i].size;
+		if (lmb_addrs_overlap(base, size, rgnbase, rgnsize))
+			break;
+	}
+
+	return (i < lmb_rgn_lst->count) ? i : -1;
+}
+
+static phys_addr_t lmb_align_down(phys_addr_t addr, phys_size_t size)
+{
+	return addr & ~(size - 1);
+}
+
+/*
+ * Low level LMB functions are used to manage IOVA memory maps for the Apple
+ * dart iommu. They must not access the global LMB memory map.
+ * So keep the global LMB variable declaration unreachable from them.
+ */
+
+static struct lmb lmb;
+
+static bool lmb_should_notify(enum lmb_flags flags)
+{
+	return !lmb.test && !(flags & LMB_NONOTIFY) &&
+		CONFIG_IS_ENABLED(EFI_LOADER);
+}
+
+static int lmb_map_update_notify(phys_addr_t addr, phys_size_t size, u8 op,
+				 enum lmb_flags flags)
+{
+	u64 efi_addr;
+	u64 pages;
+	efi_status_t status;
+
+	if (op != MAP_OP_RESERVE && op != MAP_OP_FREE && op != MAP_OP_ADD) {
+		log_err("Invalid map update op received (%d)\n", op);
+		return -1;
+	}
+
+	if (!lmb_should_notify(flags))
+		return 0;
+
+	efi_addr = (uintptr_t)map_sysmem(addr, 0);
+	pages = efi_size_in_pages(size + (efi_addr & EFI_PAGE_MASK));
+	efi_addr &= ~EFI_PAGE_MASK;
+
+	status = efi_add_memory_map_pg(efi_addr, pages,
+				       op == MAP_OP_RESERVE ?
+				       EFI_BOOT_SERVICES_DATA :
+				       EFI_CONVENTIONAL_MEMORY,
+				       false);
+	if (status != EFI_SUCCESS) {
+		log_err("%s: LMB Map notify failure %lu\n", __func__,
+			status & ~EFI_ERROR_MASK);
+		return -1;
+	}
+	unmap_sysmem((void *)(uintptr_t)efi_addr);
+
+	return 0;
+}
+
+static void lmb_print_region_flags(enum lmb_flags flags)
+{
+	u64 bitpos;
+	const char *flag_str[] = { "none", "no-map", "no-overwrite", "no-notify" };
+
+	do {
+		bitpos = flags ? fls(flags) - 1 : 0;
+		assert_noisy(bitpos < ARRAY_SIZE(flag_str));
+		printf("%s", flag_str[bitpos]);
+		flags &= ~(1ull << bitpos);
+		puts(flags ? ", " : "\n");
+	} while (flags);
+}
+
+static void lmb_dump_region(struct alist *lmb_rgn_lst, char *name)
+{
+	struct lmb_region *rgn = lmb_rgn_lst->data;
+	unsigned long long base, size, end;
+	enum lmb_flags flags;
+	int i;
+
+	printf(" %s.count = 0x%x\n", name, lmb_rgn_lst->count);
+
+	for (i = 0; i < lmb_rgn_lst->count; i++) {
+		base = rgn[i].base;
+		size = rgn[i].size;
+		end = base + size - 1;
+		flags = rgn[i].flags;
+
+		printf(" %s[%d]\t[0x%llx-0x%llx], 0x%08llx bytes flags: ",
+		       name, i, base, end, size);
+		lmb_print_region_flags(flags);
+	}
+}
+
+void lmb_dump_all_force(void)
+{
+	printf("lmb_dump_all:\n");
+	lmb_dump_region(&lmb.free_mem, "memory");
+	lmb_dump_region(&lmb.used_mem, "reserved");
+}
+
+void lmb_dump_all(void)
+{
+#ifdef DEBUG
+	lmb_dump_all_force();
+#endif
+}
+
+static void lmb_reserve_uboot_region(void)
+{
+	int bank;
+	ulong end, bank_end;
+	phys_addr_t rsv_start;
+
+	rsv_start = gd->start_addr_sp - CONFIG_STACK_SIZE;
+	end = gd->ram_top;
+
+	/*
+	 * Reserve memory from aligned address below the bottom of U-Boot stack
+	 * until end of RAM area to prevent LMB from overwriting that memory.
+	 */
+	debug("## Current stack ends at 0x%08lx ", (ulong)rsv_start);
+
+	for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
+		if (!gd->bd->bi_dram[bank].size ||
+		    rsv_start < gd->bd->bi_dram[bank].start)
+			continue;
+		/* Watch out for RAM at end of address space! */
+		bank_end = gd->bd->bi_dram[bank].start +
+			gd->bd->bi_dram[bank].size - 1;
+		if (rsv_start > bank_end)
+			continue;
+		if (bank_end > end)
+			bank_end = end - 1;
+
+		lmb_reserve_flags(rsv_start, bank_end - rsv_start + 1,
+				  LMB_NOOVERWRITE);
+
+		if (gd->flags & GD_FLG_SKIP_RELOC)
+			lmb_reserve_flags((phys_addr_t)(uintptr_t)_start,
+					  gd->mon_len, LMB_NOOVERWRITE);
+
+		break;
+	}
+}
+
+static void lmb_reserve_common(void *fdt_blob)
+{
+	lmb_reserve_uboot_region();
+
+	if (CONFIG_IS_ENABLED(OF_LIBFDT) && fdt_blob)
+		boot_fdt_add_mem_rsv_regions(fdt_blob);
+}
+
+static __maybe_unused void lmb_reserve_common_spl(void)
+{
+	phys_addr_t rsv_start;
+	phys_size_t rsv_size;
+
+	/*
+	 * Assume a SPL stack of 16KB. This must be
+	 * more than enough for the SPL stage.
+	 */
+	if (IS_ENABLED(CONFIG_SPL_STACK_R_ADDR)) {
+		rsv_start = gd->start_addr_sp - 16384;
+		rsv_size = 16384;
+		lmb_reserve_flags(rsv_start, rsv_size, LMB_NOOVERWRITE);
+	}
+
+	if (IS_ENABLED(CONFIG_SPL_SEPARATE_BSS)) {
+		/* Reserve the bss region */
+		rsv_start = (phys_addr_t)(uintptr_t)__bss_start;
+		rsv_size = (phys_addr_t)(uintptr_t)__bss_end -
+			(phys_addr_t)(uintptr_t)__bss_start;
+		lmb_reserve_flags(rsv_start, rsv_size, LMB_NOOVERWRITE);
+	}
+}
+
+/**
+ * lmb_add_memory() - Add memory range for LMB allocations
+ *
+ * Add the entire available memory range to the pool of memory that
+ * can be used by the LMB module for allocations.
+ *
+ * Return: None
+ */
+void lmb_add_memory(void)
+{
+	int i;
+	phys_size_t size;
+	u64 ram_top = gd->ram_top;
+	struct bd_info *bd = gd->bd;
+
+	if (CONFIG_IS_ENABLED(LMB_ARCH_MEM_MAP))
+		return lmb_arch_add_memory();
+
+	/* Assume a 4GB ram_top if not defined */
+	if (!ram_top)
+		ram_top = 0x100000000ULL;
+
+	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
+		size = bd->bi_dram[i].size;
+		if (size) {
+			lmb_add(bd->bi_dram[i].start, size);
+
+			/*
+			 * Reserve memory above ram_top as
+			 * no-overwrite so that it cannot be
+			 * allocated
+			 */
+			if (bd->bi_dram[i].start >= ram_top)
+				lmb_reserve_flags(bd->bi_dram[i].start, size,
+						  LMB_NOOVERWRITE);
+		}
+	}
+}
+
+static long lmb_add_region(struct alist *lmb_rgn_lst, phys_addr_t base,
+			   phys_size_t size)
+{
+	return lmb_add_region_flags(lmb_rgn_lst, base, size, LMB_NONE);
+}
+
+/* This routine may be called with relocation disabled. */
+long lmb_add(phys_addr_t base, phys_size_t size)
+{
+	long ret;
+	struct alist *lmb_rgn_lst = &lmb.free_mem;
+
+	ret = lmb_add_region(lmb_rgn_lst, base, size);
+	if (ret)
+		return ret;
+
+	return lmb_map_update_notify(base, size, MAP_OP_ADD, LMB_NONE);
+}
+
 /**
  * lmb_free_flags() - Free up a region of memory
  * @base: Base Address of region to be freed
@@ -587,27 +620,6 @@ long lmb_reserve(phys_addr_t base, phys_size_t size)
 	return lmb_reserve_flags(base, size, LMB_NONE);
 }
 
-static long lmb_overlaps_region(struct alist *lmb_rgn_lst, phys_addr_t base,
-				phys_size_t size)
-{
-	unsigned long i;
-	struct lmb_region *rgn = lmb_rgn_lst->data;
-
-	for (i = 0; i < lmb_rgn_lst->count; i++) {
-		phys_addr_t rgnbase = rgn[i].base;
-		phys_size_t rgnsize = rgn[i].size;
-		if (lmb_addrs_overlap(base, size, rgnbase, rgnsize))
-			break;
-	}
-
-	return (i < lmb_rgn_lst->count) ? i : -1;
-}
-
-static phys_addr_t lmb_align_down(phys_addr_t addr, phys_size_t size)
-{
-	return addr & ~(size - 1);
-}
-
 static phys_addr_t _lmb_alloc_base(phys_size_t size, ulong align,
 				    phys_addr_t max_addr, enum lmb_flags flags)
 {