[PATCH v4 02/14] spacemit: k1: enable SPL with debug UART

[Guodong Xu]

From: Raymond Mao <raymond.mao at riscstar.com>

Add SPL support featuring debug UART output for early boot
diagnostics on K1 SoC.

Signed-off-by: Raymond Mao <raymond.mao at riscstar.com>
Signed-off-by: Guodong Xu <guodong at riscstar.com>
---
v4:
- Reuse upstream BPI-F3 DT in both SPL and U-Boot proper phases
  via OF_UPSTREAM;
- Add SPL bootph-* markers in k1-bananapi-f3-u-boot.dtsi.
---
 arch/riscv/cpu/k1/Kconfig                 |  2 ++
 arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi |  4 ++++
 board/spacemit/k1/Makefile                |  2 ++
 board/spacemit/k1/spl.c                   | 24 ++++++++++++++++++++++++
 configs/spacemit_k1_defconfig             | 16 ++++++++++++++++
 include/configs/k1.h                      |  6 ++++--
 6 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/cpu/k1/Kconfig b/arch/riscv/cpu/k1/Kconfig
index 3701bf2b5da..b155535658d 100644
--- a/arch/riscv/cpu/k1/Kconfig
+++ b/arch/riscv/cpu/k1/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 #
 # Copyright (C) 2024, Kongyang Liu <seashell11234455 at gmail.com>
+# Copyright (C) 2025-2026, RISCstar Ltd.
 
 if TARGET_SPACEMIT_K1
 
@@ -9,6 +10,7 @@ config SPACEMIT_K1
 	select BINMAN
 	select ARCH_EARLY_INIT_R
 	select SYS_CACHE_SHIFT_6
+	select SUPPORT_SPL
 	imply CPU
 	imply CPU_RISCV
 	imply RISCV_TIMER if (RISCV_SMODE || SPL_RISCV_SMODE)
diff --git a/arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi b/arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi
index 9e1925eb68e..4e4d0e0c49e 100644
--- a/arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi
+++ b/arch/riscv/dts/k1-bananapi-f3-u-boot.dtsi
@@ -28,3 +28,7 @@
 	clock-names = "osc", "vctcxo_1m", "vctcxo_3m", "vctcxo_24m",
 		      "pll1_d4", "pll1_d78_31p5", "pmua_aclk";
 };
+
+&uart0 {
+	bootph-pre-ram;
+};
diff --git a/board/spacemit/k1/Makefile b/board/spacemit/k1/Makefile
index 2168698402b..f9cbf4b0e06 100644
--- a/board/spacemit/k1/Makefile
+++ b/board/spacemit/k1/Makefile
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 #
 # Copyright (c) 2024, Kongyang Liu <seashell11234455 at gmail.com>
+# Copyright (c) 2025-2026, RISCstar Ltd.
 
 obj-y := board.o
+obj-$(CONFIG_SPL_BUILD) += spl.o
diff --git a/board/spacemit/k1/spl.c b/board/spacemit/k1/spl.c
new file mode 100644
index 00000000000..e15cf5f1abf
--- /dev/null
+++ b/board/spacemit/k1/spl.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2025-2026, RISCstar Ltd.
+ */
+
+#include <spl.h>
+
+void board_init_f(ulong dummy)
+{
+	int ret;
+
+	ret = spl_early_init();
+	if (ret)
+		panic("spl_early_init() failed:%d\n", ret);
+
+	riscv_cpu_setup();
+
+	preloader_console_init();
+}
+
+u32 spl_boot_device(void)
+{
+	return BOOT_DEVICE_NONE;
+}
diff --git a/configs/spacemit_k1_defconfig b/configs/spacemit_k1_defconfig
index fae561bbf8a..29050ece278 100644
--- a/configs/spacemit_k1_defconfig
+++ b/configs/spacemit_k1_defconfig
@@ -4,17 +4,30 @@ CONFIG_NR_DRAM_BANKS=2
 CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
 CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x1000000
 CONFIG_DEFAULT_DEVICE_TREE="spacemit/k1-bananapi-f3"
+CONFIG_SPL_STACK=0xc083fb00
+CONFIG_SPL_TEXT_BASE=0xc0801000
+CONFIG_SPL_BSS_START_ADDR=0xc083fc00
+CONFIG_SPL_BSS_MAX_SIZE=0x400
 CONFIG_SYS_BOOTM_LEN=0xa000000
 CONFIG_SYS_LOAD_ADDR=0x200000
+CONFIG_SPL_SIZE_LIMIT=0x31000
+CONFIG_SPL=y
+CONFIG_DEBUG_UART_BASE=0xd4017000
+CONFIG_DEBUG_UART_CLOCK=14700000
 CONFIG_TARGET_SPACEMIT_K1=y
 CONFIG_ARCH_RV64I=y
 CONFIG_RISCV_SMODE=y
+CONFIG_STACK_SIZE=0x100000
 CONFIG_FIT=y
+CONFIG_SPL_FIT_SIGNATURE=y
 CONFIG_SUPPORT_RAW_INITRD=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_SYS_CBSIZE=256
 CONFIG_SYS_PBSIZE=276
 # CONFIG_BOARD_INIT is not set
+CONFIG_SPL_MAX_SIZE=0x33000
+# CONFIG_SPL_SHARES_INIT_SP_ADDR is not set
+CONFIG_SPL_HAVE_INIT_STACK=y
 CONFIG_HUSH_PARSER=y
 CONFIG_OF_UPSTREAM=y
 CONFIG_ENV_OVERWRITE=y
@@ -22,5 +35,8 @@ CONFIG_CLK_SPACEMIT=y
 CONFIG_CLK_SPACEMIT_K1=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_SINGLE=y
+CONFIG_DEBUG_UART_NS16550=y
+CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_DEBUG_UART_ANNOUNCE=y
 CONFIG_SYS_NS16550=y
 CONFIG_SYS_NS16550_MEM32=y
diff --git a/include/configs/k1.h b/include/configs/k1.h
index 97cf4d72df0..15a40f2128f 100644
--- a/include/configs/k1.h
+++ b/include/configs/k1.h
@@ -1,13 +1,15 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * Copyright (c) 2024, Kongyang Liu <seashell11234455 at gmail.com>
+ * Copyright (C) 2025-2026, RISCstar Ltd.
  *
  */
 
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
-#define CFG_SYS_SDRAM_BASE         0x0
-#define CFG_SYS_NS16550_IER        0x40 /* UART Unit Enable */
+#define CFG_SYS_NS16550_CLK	    14700000
+#define CFG_SYS_NS16550_IER	    0x40 /* UART Unit Enable */
+#define CFG_SYS_SDRAM_BASE	    0x0
 
 #endif /* __CONFIG_H */

-- 
2.43.0