[PATCH v2 1/3] board: samsung: add support for Samsung Exynos mobile device boards
Kaustabh Chakraborty
kauschluss at disroot.org
Fri Oct 24 19:28:27 CEST 2025
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 at disroot.org>
---
arch/arm/mach-exynos/Kconfig | 11 +-
board/samsung/exynos-mobile/Kconfig | 18 ++
board/samsung/exynos-mobile/MAINTAINERS | 6 +
board/samsung/exynos-mobile/Makefile | 5 +
board/samsung/exynos-mobile/exynos-mobile.c | 287 ++++++++++++++++++++++++++
board/samsung/exynos-mobile/exynos-mobile.env | 18 ++
configs/exynos-mobile_defconfig | 68 ++++++
doc/board/samsung/exynos-mobile.rst | 40 ++++
doc/board/samsung/index.rst | 1 +
include/configs/exynos-mobile.h | 14 ++
10 files changed, 467 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig
index 2cd67d023867de29bf85fe6d68b3485dbb67853c..b084b7284aa08eafbc740e47fbc8385f8eb2d7db 100644
--- a/arch/arm/mach-exynos/Kconfig
+++ b/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
diff --git a/board/samsung/exynos-mobile/Kconfig b/board/samsung/exynos-mobile/Kconfig
new file mode 100644
index 0000000000000000000000000000000000000000..ed7d16b8c6b718e1a0c2bcb24113b62135ec397c
--- /dev/null
+++ b/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
diff --git a/board/samsung/exynos-mobile/MAINTAINERS b/board/samsung/exynos-mobile/MAINTAINERS
new file mode 100644
index 0000000000000000000000000000000000000000..11fea212fb15bb5714ad1de46aace231f0600b69
--- /dev/null
+++ b/board/samsung/exynos-mobile/MAINTAINERS
@@ -0,0 +1,6 @@
+Exynos Generic Boards (for mobile devices)
+M: Kaustabh Chakraborty <kauschluss at disroot.org>
+S: Maintained
+F: board/samsung/exynos-mobile/
+F: configs/exynos-mobile_defconfig
+F: include/configs/exynos-mobile.h
diff --git a/board/samsung/exynos-mobile/Makefile b/board/samsung/exynos-mobile/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..e049ed217c18c7e2c173249608a8abc433299687
--- /dev/null
+++ b/board/samsung/exynos-mobile/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2025 Kaustabh Chakraborty <kauschluss at disroot.org>
+
+obj-y := exynos-mobile.o
diff --git a/board/samsung/exynos-mobile/exynos-mobile.c b/board/samsung/exynos-mobile/exynos-mobile.c
new file mode 100644
index 0000000000000000000000000000000000000000..c16281dbc36fb07cf5e9f64604632bb98393cd86
--- /dev/null
+++ b/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 at 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();
+}
diff --git a/board/samsung/exynos-mobile/exynos-mobile.env b/board/samsung/exynos-mobile/exynos-mobile.env
new file mode 100644
index 0000000000000000000000000000000000000000..aa2e89afbacadcc86d0f1f5539f06bdb28bdc3b3
--- /dev/null
+++ b/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
diff --git a/configs/exynos-mobile_defconfig b/configs/exynos-mobile_defconfig
new file mode 100644
index 0000000000000000000000000000000000000000..2dbf90010bac8182ea202a484252a5b527eb6ad9
--- /dev/null
+++ b/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
diff --git a/doc/board/samsung/exynos-mobile.rst b/doc/board/samsung/exynos-mobile.rst
new file mode 100644
index 0000000000000000000000000000000000000000..d5c1c83a4e84ac0fc9401b02de0ec786c9397892
--- /dev/null
+++ b/doc/board/samsung/exynos-mobile.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. sectionauthor:: Kaustabh Chakraborty <kauschluss at 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.
diff --git a/doc/board/samsung/index.rst b/doc/board/samsung/index.rst
index 1b92c9518a57df102c2b64ff934b460548ce3d53..1fbe88130c049e1a33d22ae9230fb60ddccea131 100644
--- a/doc/board/samsung/index.rst
+++ b/doc/board/samsung/index.rst
@@ -8,4 +8,5 @@ Samsung
axy17lte
e850-96
+ exynos-mobile
n1
diff --git a/include/configs/exynos-mobile.h b/include/configs/exynos-mobile.h
new file mode 100644
index 0000000000000000000000000000000000000000..862db5779ef4c9ff7f53bef78d7cee5107b7226e
--- /dev/null
+++ b/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 at 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 */
--
2.51.0
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