board: samsung: add support for Samsung Exynos mobile device boards

Add support for a generic platform which intends to support multiple
boards powered by ARMv8 Samsung Exynos SoCs. Some important features
include:
 * Fastboot: This is present to provide an open alternative to Samsung's
   proprietary Odin protocol. The board file configures certain features
   for fastboot, such as a dynamically allocated fastboot buffer, and
   standardized (lowercase) partition aliases.
 * EFI: Kernel image can be loaded from an EFI partition. This
   adopts a standard booting process, which multiple OS distributions
   can rely on.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

arch/arm/mach-exynos/Kconfig

@@ -2,7 +2,7 @@ if ARCH_EXYNOS
 
 config BOARD_COMMON
 	def_bool y
-	depends on !TARGET_SMDKV310 && !TARGET_ARNDALE && !TARGET_E850_96
+	depends on !TARGET_SMDKV310 && !TARGET_ARNDALE && !TARGET_EXYNOS_MOBILE && !TARGET_E850_96
 
 config SPI_BOOTING
 	bool
@@ -252,6 +252,14 @@ config TARGET_E850_96
 endchoice
 endif
 
+config TARGET_EXYNOS_MOBILE
+	bool "Samsung Exynos Generic Boards (for mobile devices)"
+	select ARM64
+	select BOARD_EARLY_INIT_F
+	select CLK_EXYNOS
+	select LINUX_KERNEL_IMAGE_HEADER
+	select OF_CONTROL
+
 config SYS_SOC
 	default "exynos"
 
@@ -277,5 +285,6 @@ source "board/samsung/smdk5420/Kconfig"
 source "board/samsung/espresso7420/Kconfig"
 source "board/samsung/axy17lte/Kconfig"
 source "board/samsung/e850-96/Kconfig"
+source "board/samsung/exynos-mobile/Kconfig"
 
 endif

board/samsung/exynos-mobile/Kconfig

@@ -0,0 +1,18 @@
+if TARGET_EXYNOS_MOBILE
+
+config ENV_SOURCE_FILE
+	default "exynos-mobile"
+
+config LNX_KRNL_IMG_TEXT_OFFSET_BASE
+	default TEXT_BASE
+
+config SYS_BOARD
+	default "exynos-mobile"
+
+config SYS_CONFIG_NAME
+	default "exynos-mobile"
+
+config SYS_VENDOR
+	default "samsung"
+
+endif # TARGET_EXYNOS_MOBILE

board/samsung/exynos-mobile/MAINTAINERS

@@ -0,0 +1,6 @@
+Exynos Generic Boards (for mobile devices)
+M:	Kaustabh Chakraborty <kauschluss@disroot.org>
+S:	Maintained
+F:	board/samsung/exynos-mobile/
+F:	configs/exynos-mobile_defconfig
+F:	include/configs/exynos-mobile.h

board/samsung/exynos-mobile/Makefile

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2025 Kaustabh Chakraborty <kauschluss@disroot.org>
+
+obj-y := exynos-mobile.o

board/samsung/exynos-mobile/exynos-mobile.c

@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Samsung Exynos Generic Board Source (for mobile devices)
+ *
+ * Copyright (c) 2025 Kaustabh Chakraborty <kauschluss@disroot.org>
+ */
+
+#include <asm/armv8/mmu.h>
+#include <blk.h>
+#include <bootflow.h>
+#include <ctype.h>
+#include <dm/ofnode.h>
+#include <env.h>
+#include <errno.h>
+#include <init.h>
+#include <linux/sizes.h>
+#include <lmb.h>
+#include <part.h>
+#include <stdbool.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define lmb_alloc(size, addr) \
+	lmb_alloc_mem(LMB_MEM_ALLOC_ANY, SZ_2M, addr, size, LMB_NONE)
+
+struct exynos_board_info {
+	const char *name;
+	const char *chip;
+	const u64 *const dram_bank_bases;
+
+	char serial[64];
+
+	int (*const match)(struct exynos_board_info *);
+	const char *match_model;
+	const u8 match_max_rev;
+};
+
+/*
+ * The memory mapping includes all DRAM banks, along with the
+ * peripheral block, and a sentinel at the end. This is filled in
+ * dynamically.
+ */
+static struct mm_region exynos_mem_map[CONFIG_NR_DRAM_BANKS + 2] = {
+	{
+		/* Peripheral MMIO block */
+		.virt = 0x10000000UL,
+		.phys = 0x10000000UL,
+		.size = 0x10000000UL,
+		.attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |
+			 PTE_BLOCK_NON_SHARE | PTE_BLOCK_PXN | PTE_BLOCK_UXN,
+	},
+};
+
+struct mm_region *mem_map = exynos_mem_map;
+
+/*
+ * This array is used for matching the models and revisions with the
+ * devicetree used by U-Boot. This allows a single U-Boot to work on
+ * multiple devices.
+ *
+ * Entries are kept in lexicographical order of board SoCs, followed by
+ * board names.
+ */
+static struct exynos_board_info exynos_board_info_match[] = {
+};
+
+static void exynos_parse_dram_banks(const struct exynos_board_info *board_info,
+				    const void *fdt_base)
+{
+	u64 mem_addr, mem_size = 0;
+	u32 na, ns, i, j;
+	int offset;
+
+	if (fdt_check_header(fdt_base) < 0)
+		return;
+
+	/* #address-cells and #size-cells as defined in the fdt root. */
+	na = fdt_address_cells(fdt_base, 0);
+	ns = fdt_size_cells(fdt_base, 0);
+
+	fdt_for_each_subnode(offset, fdt_base, 0) {
+		if (strncmp(fdt_get_name(fdt_base, offset, NULL), "memory", 6))
+			continue;
+
+		for (i = 0; ; i++) {
+			mem_addr = fdtdec_get_addr_size_fixed(fdt_base, offset,
+							      "reg", i, na, ns,
+							      &mem_size, false);
+			if (mem_addr == FDT_ADDR_T_NONE)
+				break;
+
+			if (!mem_size)
+				continue;
+
+			for (j = 0; j < CONFIG_NR_DRAM_BANKS; j++) {
+				if (board_info->dram_bank_bases[j] != mem_addr)
+					continue;
+
+				mem_map[j + 1].phys = mem_addr;
+				mem_map[j + 1].virt = mem_addr;
+				mem_map[j + 1].size = mem_size;
+				mem_map[j + 1].attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |
+						       PTE_BLOCK_INNER_SHARE;
+				break;
+			}
+		}
+	}
+}
+
+static int exynos_fastboot_setup(void)
+{
+	struct blk_desc *blk_dev;
+	struct disk_partition info = {0};
+	char buf[128];
+	phys_addr_t addr;
+	int offset, i, j;
+
+	/* Allocate and define buffer address for fastboot interface. */
+	if (lmb_alloc(CONFIG_FASTBOOT_BUF_SIZE, &addr)) {
+		log_err("%s: failed to allocate fastboot buffer\n", __func__);
+		return -ENOMEM;
+	}
+	env_set_hex("fastboot_addr_r", addr);
+
+	blk_dev = blk_get_dev("mmc", CONFIG_FASTBOOT_FLASH_MMC_DEV);
+	if (!blk_dev) {
+		log_err("%s: required mmc device not available\n", __func__);
+		return -ENODEV;
+	}
+
+	strcpy(buf, "fastboot_partition_alias_");
+	offset = strlen(buf);
+
+	for (i = 1; i < CONFIG_EFI_PARTITION_ENTRIES_NUMBERS; i++) {
+		if (part_get_info(blk_dev, i, &info))
+			continue;
+
+		/*
+		 * The partition name must be lowercase (stored in buf[]),
+		 * as is expected in all fastboot partitions ...
+		 */
+		strlcpy(buf + offset, info.name, sizeof(buf) - offset);
+		for (j = offset; buf[j]; j++)
+			buf[j] = tolower(buf[j]);
+		if (!strcmp(buf + offset, info.name))
+			continue;
+		/*
+		 * ... However, if that isn't the case, a fastboot
+		 * partition alias must be defined to establish it.
+		 */
+		env_set(buf, info.name);
+	}
+
+	return 0;
+}
+
+int board_fit_config_name_match(const char *name)
+{
+	struct exynos_board_info *board_info;
+	char buf[128];
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Iterate over exynos_board_info_match[] to select the
+	 * appropriate board info struct. If not found, exit.
+	 */
+	for (i = 0; i < ARRAY_SIZE(exynos_board_info_match); i++) {
+		board_info = exynos_board_info_match + i;
+		snprintf(buf, sizeof(buf), "%s-%s", board_info->chip,
+			 board_info->name);
+
+		if (!strcmp(name, buf))
+			break;
+	}
+	if (i == ARRAY_SIZE(exynos_board_info_match))
+		return -1;
+
+	/*
+	 * Execute match logic for the target board. This is separated
+	 * as the process may be different for multiple boards.
+	 */
+	ret = board_info->match(board_info);
+	if (ret)
+		return ret;
+
+	/*
+	 * Store the correct board info struct in gd->board_type to
+	 * allow other functions to access it.
+	 */
+	gd->board_type = (ulong)board_info;
+	log_debug("%s: device detected: %s\n", __func__, name);
+
+	return 0;
+}
+
+int timer_init(void)
+{
+	ofnode timer_node;
+
+	/*
+	 * In a lot of Exynos devices, the previous bootloader does not
+	 * set CNTFRQ_EL0 properly. However, the timer node in
+	 * devicetree has the correct frequency, use that instead.
+	 */
+	timer_node = ofnode_by_compatible(ofnode_null(), "arm,armv8-timer");
+	gd->arch.timer_rate_hz = ofnode_read_u32_default(timer_node,
+							 "clock-frequency", 0);
+
+	return 0;
+}
+
+int board_early_init_f(void)
+{
+	const struct exynos_board_info *board_info;
+
+	if (!gd->board_type)
+		return -ENODATA;
+	board_info = (const struct exynos_board_info *)gd->board_type;
+
+	exynos_parse_dram_banks(board_info, gd->fdt_blob);
+	/*
+	 * Some devices have multiple variants based on the amount of
+	 * memory and internal storage. The lowest bank base has been
+	 * observed to have the same memory range in all board variants.
+	 * For variants with more memory, the previous bootloader should
+	 * overlay the devicetree with the required extra memory ranges.
+	 */
+	exynos_parse_dram_banks(board_info, (const void *)get_prev_bl_fdt_addr());
+
+	return 0;
+}
+
+int dram_init(void)
+{
+	unsigned int i;
+
+	/* Select the largest RAM bank for U-Boot. */
+	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
+		if (gd->ram_size < mem_map[i + 1].size) {
+			gd->ram_base = mem_map[i + 1].phys;
+			gd->ram_size = mem_map[i + 1].size;
+		}
+	}
+
+	return 0;
+}
+
+int dram_init_banksize(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
+		gd->bd->bi_dram[i].start = mem_map[i + 1].phys;
+		gd->bd->bi_dram[i].size = mem_map[i + 1].size;
+	}
+
+	return 0;
+}
+
+int board_init(void)
+{
+	return 0;
+}
+
+int misc_init_r(void)
+{
+	const struct exynos_board_info *board_info;
+	char buf[128];
+
+	if (!gd->board_type)
+		return -ENODATA;
+	board_info = (const struct exynos_board_info *)gd->board_type;
+
+	env_set("platform", board_info->chip);
+	env_set("board", board_info->name);
+
+	if (strlen(board_info->serial))
+		env_set("serial#", board_info->serial);
+
+	/* EFI booting requires the path to correct dtb, specify it here. */
+	snprintf(buf, sizeof(buf), "exynos/%s-%s.dtb", board_info->chip,
+		 board_info->name);
+	env_set("fdtfile", buf);
+
+	return exynos_fastboot_setup();
+}

board/samsung/exynos-mobile/exynos-mobile.env

@@ -0,0 +1,18 @@
+stdin=serial,button-kbd
+stdout=serial,vidconsole
+stderr=serial,vidconsole
+
+bootdelay=0
+bootcmd=bootefi bootmgr; pause; bootmenu
+
+fastbootcmd=echo "Fastboot Mode";
+	fastboot -l $fastboot_addr_r usb 0
+
+bootmenu_0=Continue Boot=boot
+bootmenu_1=Enter Fastboot Mode=run fastbootcmd
+bootmenu_2=UEFI Maintenance Menu=eficonfig
+bootmenu_3=Reboot=reset
+bootmenu_4=Power Off=poweroff
+
+button_cmd_0_name=Volume Down Key
+button_cmd_0=bootmenu

configs/exynos-mobile_defconfig

@@ -0,0 +1,68 @@
+CONFIG_ARM=y
+CONFIG_SKIP_LOWLEVEL_INIT=y
+CONFIG_COUNTER_FREQUENCY=26000000
+CONFIG_POSITION_INDEPENDENT=y
+CONFIG_ARCH_EXYNOS=y
+CONFIG_SYS_MALLOC_LEN=0x2000000
+CONFIG_SYS_MALLOC_F_LEN=0x16000
+CONFIG_TARGET_EXYNOS_MOBILE=y
+CONFIG_NR_DRAM_BANKS=3
+CONFIG_SYS_BOOTM_LEN=0x2000000
+CONFIG_SYS_LOAD_ADDR=0x80000000
+CONFIG_ARMV8_CNTFRQ_BROKEN=y
+# CONFIG_PSCI_RESET is not set
+CONFIG_BUTTON_CMD=y
+CONFIG_SAVE_PREV_BL_FDT_ADDR=y
+CONFIG_SAVE_PREV_BL_INITRAMFS_START_ADDR=y
+CONFIG_SYS_PBSIZE=1024
+CONFIG_BOARD_TYPES=y
+# CONFIG_DISPLAY_CPUINFO is not set
+CONFIG_MISC_INIT_R=y
+CONFIG_HUSH_PARSER=y
+CONFIG_CMD_BOOTMENU=y
+CONFIG_CMD_POWEROFF=y
+CONFIG_CMD_FS_GENERIC=y
+CONFIG_EFI_PARTITION=y
+CONFIG_OF_UPSTREAM=y
+CONFIG_MULTI_DTB_FIT=y
+CONFIG_BUTTON=y
+CONFIG_BUTTON_REMAP_PHONE_KEYS=y
+CONFIG_CLK=y
+CONFIG_CLK_CCF=y
+CONFIG_USB_FUNCTION_FASTBOOT=y
+CONFIG_FASTBOOT_BUF_ADDR=0xdead0000
+CONFIG_FASTBOOT_FLASH=y
+CONFIG_FASTBOOT_FLASH_MMC_DEV=0
+CONFIG_SYS_I2C_S3C24X0=y
+CONFIG_BUTTON_KEYBOARD=y
+CONFIG_MISC=y
+CONFIG_MMC_BROKEN_CD=y
+CONFIG_MMC_IO_VOLTAGE=y
+CONFIG_MMC_UHS_SUPPORT=y
+CONFIG_MMC_HS400_SUPPORT=y
+CONFIG_MMC_DW=y
+CONFIG_PHY=y
+CONFIG_PHY_EXYNOS_USBDRD=y
+CONFIG_PINCTRL=y
+CONFIG_DM_PMIC=y
+CONFIG_PMIC_S2MPS11=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_FIXED=y
+CONFIG_DM_REGULATOR_S2MPS11=y
+CONFIG_SOC_SAMSUNG=y
+CONFIG_EXYNOS_PMU=y
+CONFIG_SYSRESET=y
+CONFIG_SYSRESET_CMD_POWEROFF=y
+CONFIG_SYSRESET_SYSCON=y
+CONFIG_USB=y
+CONFIG_DM_USB_GADGET=y
+CONFIG_USB_DWC3=y
+CONFIG_USB_DWC3_GENERIC=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_GADGET_MANUFACTURER="Samsung"
+CONFIG_USB_GADGET_VENDOR_NUM=0x04e8
+CONFIG_USB_GADGET_PRODUCT_NUM=0x6602
+CONFIG_VIDEO=y
+CONFIG_VIDEO_SIMPLE=y
+CONFIG_FS_EXT4=y
+CONFIG_FS_FAT=y

doc/board/samsung/exynos-mobile.rst

@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. sectionauthor:: Kaustabh Chakraborty <kauschluss@disroot.org>
+
+Samsung Exynos Generic ARMv8 Boards (for mobile devices)
+=======================================================
+
+Overview
+--------
+This document describes how to build and run U-Boot for Samsung Exynos generic
+boards. Boards are expected to boot with a primary bootloader, such as S-BOOT or
+S-LK, which hands off control to U-Boot. Presently, only ARMv8 devices are
+supported.
+
+The U-Boot image is built with all device tree blobs packed in a single FIT
+image. During boot, it uses simple heuristics to detect the target board, and
+subsequently the appropriate FDT is selected.
+
+Installation
+------------
+Building
+^^^^^^^^
+If a cross-compiler is required, install it and set it up like so:
+
+.. prompt:: bash $
+
+	export CROSS_COMPILE=aarch64-linux-gnu-
+
+Then, run the following commands to build U-Boot:
+
+.. prompt:: bash $
+
+	make O=.output exynos-mobile_defconfig
+	make O=.output -j$(nproc)
+
+If successful, the U-Boot binary will be present in ``.output/u-boot.bin``.
+
+Preparation and Flashing
+^^^^^^^^^^^^^^^^^^^^^^^^
+Since U-Boot supports multiple boards, and devices have different requirements,
+this step will vary depending on your target.

doc/board/samsung/index.rst

@@ -8,4 +8,5 @@ Samsung
 
    axy17lte
    e850-96
+   exynos-mobile
    n1

include/configs/exynos-mobile.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Samsung Exynos Generic Board Configuration (for mobile devices)
+ *
+ * Copyright (C) 2025 Kaustabh Chakraborty <kauschluss@disroot.org>
+ */
+
+#ifndef __CONFIG_EXYNOS_MOBILE_H
+#define __CONFIG_EXYNOS_MOBILE_H
+
+#define CPU_RELEASE_ADDR	secondary_boot_addr
+#define CFG_SYS_BAUDRATE_TABLE	{9600, 115200}
+
+#endif /* __CONFIG_EXYNOS_MOBILE_H */