[PATCH v2 02/16] spacemit: k1: enable SPL with debug UART

[Raymond Mao <raymondmaoca@gmail.com>]

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

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

Signed-off-by: Raymond Mao <raymond.mao@riscstar.com>
---
 arch/riscv/cpu/k1/Kconfig     |  2 ++
 arch/riscv/dts/Makefile       |  1 +
 arch/riscv/dts/k1-spl.dts     | 25 +++++++++++++++++++++++++
 arch/riscv/dts/k1.dtsi        |  2 +-
 board/spacemit/k1/Makefile    |  2 ++
 board/spacemit/k1/spl.c       | 24 ++++++++++++++++++++++++
 configs/spacemit_k1_defconfig | 21 ++++++++++++++++++++-
 include/configs/k1.h          |  7 +++++--
 8 files changed, 80 insertions(+), 4 deletions(-)
 create mode 100644 arch/riscv/dts/k1-spl.dts
 create mode 100644 board/spacemit/k1/spl.c

diff --git a/arch/riscv/cpu/k1/Kconfig b/arch/riscv/cpu/k1/Kconfig
index 4b621158334..011fc89557e 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@gmail.com>
+# Copyright (C) 2025-2026, RISCstar Ltd.
 
 if ARCH_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/Makefile b/arch/riscv/dts/Makefile
index 9b347fc3b50..e942ef95142 100644
--- a/arch/riscv/dts/Makefile
+++ b/arch/riscv/dts/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0+
 
+dtb-$(CONFIG_ARCH_K1) += k1-spl.dtb
 dtb-$(CONFIG_TARGET_ANDES_AE350) += ae350_32.dtb ae350_64.dtb
 dtb-$(CONFIG_TARGET_ANDES_VOYAGER) += qilai-voyager.dtb
 dtb-$(CONFIG_TARGET_BANANAPI_F3) += k1-bananapi-f3.dtb
diff --git a/arch/riscv/dts/k1-spl.dts b/arch/riscv/dts/k1-spl.dts
new file mode 100644
index 00000000000..c7196c2d722
--- /dev/null
+++ b/arch/riscv/dts/k1-spl.dts
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+/*
+ * Copyright (C) 2023-2026 Spacemit, Inc
+ * Copyright (C) 2025-2026 RISCstar Ltd.
+ */
+
+/dts-v1/;
+#include "k1.dtsi"
+#include "binman.dtsi"
+
+/ {
+	model = "spacemit k1 spl";
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+};
+
+&soc {
+	bootph-all;
+	serial@d4017000 {
+		status = "okay";
+		bootph-pre-ram;
+	};
+};
diff --git a/arch/riscv/dts/k1.dtsi b/arch/riscv/dts/k1.dtsi
index a633e43da32..9c203eb4b79 100644
--- a/arch/riscv/dts/k1.dtsi
+++ b/arch/riscv/dts/k1.dtsi
@@ -318,7 +318,7 @@
 		};
 	};
 
-	soc {
+	soc: soc {
 		compatible = "simple-bus";
 		interrupt-parent = <&plic>;
 		#address-cells = <2>;
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@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 0bdc3c800f0..d794170bc5b 100644
--- a/configs/spacemit_k1_defconfig
+++ b/configs/spacemit_k1_defconfig
@@ -3,7 +3,19 @@ CONFIG_SYS_MALLOC_LEN=0x1000000
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
 CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x1000000
-CONFIG_DEFAULT_DEVICE_TREE="k1-bananapi-f3"
+CONFIG_DEFAULT_DEVICE_TREE="k1-spl"
+CONFIG_SPL=y
+CONFIG_SPL_TEXT_BASE=0xc0801000
+CONFIG_SPL_MAX_SIZE=0x33000
+CONFIG_SPL_BSS_START_ADDR=0xc0837000
+CONFIG_SPL_BSS_MAX_SIZE=0x2000
+# CONFIG_SPL_SHARES_INIT_SP_ADDR is not set
+CONFIG_SPL_HAVE_INIT_STACK=y
+CONFIG_SPL_STACK=0xc0840000
+CONFIG_SPL_SIZE_LIMIT=0x31000
+CONFIG_SPL_FIT_SIGNATURE=y
+CONFIG_SPL_LOAD_FIT_ADDRESS=0x08000000
+CONFIG_STACK_SIZE=0x100000
 CONFIG_SYS_BOOTM_LEN=0xa000000
 CONFIG_SYS_LOAD_ADDR=0x200000
 CONFIG_ARCH_RV64I=y
@@ -23,3 +35,10 @@ CONFIG_PINCTRL_SINGLE=y
 CONFIG_RESET_SPACEMIT_K1=y
 CONFIG_SYS_NS16550=y
 CONFIG_SYS_NS16550_MEM32=y
+CONFIG_DEBUG_UART=y
+CONFIG_DEBUG_UART_BASE=0xd4017000
+CONFIG_DEBUG_UART_CLOCK=14700000
+CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_DEBUG_UART_NS16550=y
+CONFIG_DEBUG_UART_ANNOUNCE=y
+# CONFIG_DEBUG_SBI_CONSOLE is not set
diff --git a/include/configs/k1.h b/include/configs/k1.h
index 97cf4d72df0..e0b05c50b70 100644
--- a/include/configs/k1.h
+++ b/include/configs/k1.h
@@ -1,13 +1,16 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * Copyright (c) 2024, Kongyang Liu <seashell11234455@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_SDRAM_BASE	    0x0
+
+#define CFG_SYS_NS16550_CLK	    14700000
+#define CFG_SYS_NS16550_IER	    0x40 /* UART Unit Enable */
 
 #endif /* __CONFIG_H */
-- 
2.25.1