x86: Add helper code for running from EFI

When U-Boot is running from EFI some of the x86 init is replaced with
EFI-specific init. For example, since DRAM has already been set up, we only
need to find it, not init it. Add these functions so that boards can easily
allow booting from EFI if required.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/lib/Makefile

@@ -11,6 +11,7 @@ obj-y += bios_interrupts.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
 obj-y	+= cmd_boot.o
 obj-$(CONFIG_HAVE_FSP) += cmd_hob.o
+obj-$(CONFIG_EFI) += efi/
 obj-y	+= gcc.o
 obj-y	+= init_helpers.o
 obj-y	+= interrupts.o

arch/x86/lib/efi/Makefile

@@ -5,6 +5,9 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+obj-$(CONFIG_EFI_STUB) += car.o
+obj-$(CONFIG_EFI_STUB) += efi.o
+
 obj-$(CONFIG_EFI_APP) += crt0-efi-ia32.o reloc_ia32.o
 
 ifneq ($(CONFIG_EFI_STUB),)

arch/x86/lib/efi/car.S

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+.globl car_init
+car_init:
+	jmp	car_init_ret

arch/x86/lib/efi/efi.c

@@ -0,0 +1,151 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <debug_uart.h>
+#include <efi.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/types.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * This function looks for the highest region of memory lower than 4GB which
+ * has enough space for U-Boot where U-Boot is aligned on a page boundary.
+ * It overrides the default implementation found elsewhere which simply
+ * picks the end of ram, wherever that may be. The location of the stack,
+ * the relocation address, and how far U-Boot is moved by relocation are
+ * set in the global data structure.
+ */
+ulong board_get_usable_ram_top(ulong total_size)
+{
+	struct efi_mem_desc *desc, *end;
+	struct efi_entry_memmap *map;
+	int ret, size;
+	uintptr_t dest_addr = 0;
+	struct efi_mem_desc *largest = NULL;
+
+	/*
+	 * Find largest area of memory below 4GB. We could
+	 * call efi_build_mem_table() for a more accurate picture since it
+	 * merges areas together where possible. But that function uses more
+	 * pre-relocation memory, and it's not critical that we find the
+	 * absolute largest region.
+	 */
+	ret = efi_info_get(EFIET_MEMORY_MAP, (void **)&map, &size);
+	if (ret) {
+		/* We should have stopped in dram_init(), something is wrong */
+		debug("%s: Missing memory map\n", __func__);
+		goto err;
+	}
+
+	end = (struct efi_mem_desc *)((ulong)map + size);
+	desc = map->desc;
+	for (; desc < end; desc = efi_get_next_mem_desc(map, desc)) {
+		if (desc->type != EFI_CONVENTIONAL_MEMORY ||
+		    desc->physical_start >= 1ULL << 32)
+			continue;
+		if (!largest || desc->num_pages > largest->num_pages)
+			largest = desc;
+	}
+
+	/* If no suitable area was found, return an error. */
+	assert(largest);
+	if (!largest || (largest->num_pages << EFI_PAGE_SHIFT) < (2 << 20))
+		goto err;
+
+	dest_addr = largest->physical_start + (largest->num_pages <<
+			EFI_PAGE_SHIFT);
+
+	return (ulong)dest_addr;
+err:
+	panic("No available memory found for relocation");
+	return 0;
+}
+
+int dram_init(void)
+{
+	struct efi_mem_desc *desc, *end;
+	struct efi_entry_memmap *map;
+	int size, ret;
+
+	ret = efi_info_get(EFIET_MEMORY_MAP, (void **)&map, &size);
+	if (ret) {
+		printf("Cannot find EFI memory map tables, ret=%d\n", ret);
+
+		return -ENODEV;
+	}
+
+	end = (struct efi_mem_desc *)((ulong)map + size);
+	gd->ram_size = 0;
+	desc = map->desc;
+	for (; desc < end; desc = efi_get_next_mem_desc(map, desc)) {
+		if (desc->type < EFI_MMAP_IO)
+			gd->ram_size += desc->num_pages << EFI_PAGE_SHIFT;
+	}
+
+	return 0;
+}
+
+void dram_init_banksize(void)
+{
+	struct efi_mem_desc *desc, *end;
+	struct efi_entry_memmap *map;
+	int ret, size;
+	int num_banks;
+
+	ret = efi_info_get(EFIET_MEMORY_MAP, (void **)&map, &size);
+	if (ret) {
+		/* We should have stopped in dram_init(), something is wrong */
+		debug("%s: Missing memory map\n", __func__);
+		return;
+	}
+	end = (struct efi_mem_desc *)((ulong)map + size);
+	desc = map->desc;
+	for (num_banks = 0;
+	     desc < end && num_banks < CONFIG_NR_DRAM_BANKS;
+	     desc = efi_get_next_mem_desc(map, desc)) {
+		/*
+		 * We only use conventional memory below 4GB, and ignore
+		 * anything less than 1MB.
+		 */
+		if (desc->type != EFI_CONVENTIONAL_MEMORY ||
+		    desc->physical_start >= 1ULL << 32 ||
+		    (desc->num_pages << EFI_PAGE_SHIFT) < 1 << 20)
+			continue;
+		gd->bd->bi_dram[num_banks].start = desc->physical_start;
+		gd->bd->bi_dram[num_banks].size = desc->num_pages <<
+			EFI_PAGE_SHIFT;
+		num_banks++;
+	}
+}
+
+int print_cpuinfo(void)
+{
+	return default_print_cpuinfo();
+}
+
+/* Find any available tables and copy them to a safe place */
+int reserve_arch(void)
+{
+	struct efi_info_hdr *hdr;
+
+	debug("table=%lx\n", gd->arch.table);
+	if (!gd->arch.table)
+		return 0;
+
+	hdr = (struct efi_info_hdr *)gd->arch.table;
+
+	gd->start_addr_sp -= hdr->total_size;
+	memcpy((void *)gd->start_addr_sp, hdr, hdr->total_size);
+	debug("Stashing EFI table at %lx to %lx, size %x\n",
+	      gd->arch.table, gd->start_addr_sp, hdr->total_size);
+	gd->arch.table = gd->start_addr_sp;
+
+	return 0;
+}