riscv: cpu: Add TH1520 CPU support

Introduce the SoC-specific code and corresponding Kconfig entries for
TH1520 SoC. Following features are implemented for TH1520,

- Cache enable/disable through customized CSR
- Invalidation of customized PMP entries
- DRAM driver probing for SPL

Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

arch/riscv/Kconfig

@@ -126,6 +126,7 @@ source "arch/riscv/cpu/generic/Kconfig"
 source "arch/riscv/cpu/jh7110/Kconfig"
 source "arch/riscv/cpu/k1/Kconfig"
 source "arch/riscv/cpu/k230/Kconfig"
+source "arch/riscv/cpu/th1520/Kconfig"
 
 # architecture-specific options below
 

arch/riscv/cpu/th1520/Kconfig

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+# Copyright (C) 2025, Yao Zi <ziyao@disroot.org>
+
+config THEAD_TH1520
+	bool
+	select ARCH_EARLY_INIT_R
+	select SYS_CACHE_SHIFT_6
+	select SUPPORT_SPL
+	select BINMAN if SPL
+	select SYS_CACHE_THEAD_CMO
+	imply CPU
+	imply CPU_RISCV
+	imply RISCV_TIMER if (RISCV_SMODE || SPL_RISCV_SMODE)
+	imply RISCV_ACLINT if RISCV_MMODE
+	imply SPL_RISCV_ACLINT if SPL_RISCV_MMODE
+	imply CMD_CPU
+	imply SPL_CPU
+	imply SPL_OPENSBI
+	imply SPL_LOAD_FIT

arch/riscv/cpu/th1520/Makefile

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2025, Yao Zi <ziyao@disroot.org>
+
+obj-y += cache.o
+obj-y += cpu.o
+obj-y += dram.o
+obj-y += spl.o

arch/riscv/cpu/th1520/cache.c

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2025 Yao Zi <ziyao@disroot.org>
+ */
+
+#include <asm/io.h>
+#include <cpu_func.h>
+#include <linux/bitops.h>
+
+#define CSR_MHCR		0x7c1
+#define  CSR_MHCR_IE		BIT(0)
+#define  CSR_MHCR_DE		BIT(1)
+
+void icache_enable(void)
+{
+	csr_write(CSR_MHCR, csr_read(CSR_MHCR) | CSR_MHCR_IE);
+}
+
+void dcache_enable(void)
+{
+	csr_write(CSR_MHCR, csr_read(CSR_MHCR) | CSR_MHCR_DE);
+}
+
+int icache_status(void)
+{
+	return (csr_read(CSR_MHCR) & CSR_MHCR_IE) != 0;
+}
+
+int dcache_status(void)
+{
+	return (csr_read(CSR_MHCR) & CSR_MHCR_DE) != 0;
+}

arch/riscv/cpu/th1520/cpu.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2025 Yao Zi <ziyao@disroot.org>
+ *
+ * TH1520 SoC has a set of undocumented customized PMP registers that are
+ * configured through MMIO operation. It must be disabled before entering
+ * the DRAM region, or an exception will be raised.
+ */
+
+#include <asm/io.h>
+#include <cpu_func.h>
+
+#define TH1520_PMP_BASE		(void *)0xffdc020000
+
+void th1520_invalidate_pmp(void)
+{
+	/* Invalidate the PMP configuration as in vendor U-Boot code */
+	writel(0x0, TH1520_PMP_BASE + 0x0);
+
+	invalidate_icache_all();
+}

arch/riscv/cpu/th1520/dram.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ */
+
+#include <fdtdec.h>
+#include <init.h>
+#include <asm/global_data.h>
+#include <linux/sizes.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int dram_init(void)
+{
+	return fdtdec_setup_mem_size_base();
+}
+
+int dram_init_banksize(void)
+{
+	return fdtdec_setup_memory_banksize();
+}

arch/riscv/cpu/th1520/spl.c

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2025 Yao Zi <ziyao@disroot.org>
+ */
+#include <dm.h>
+#include <linux/sizes.h>
+#include <log.h>
+#include <init.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int spl_dram_init(void)
+{
+	int ret;
+	struct udevice *dev;
+
+	ret = fdtdec_setup_mem_size_base();
+	if (ret) {
+		printf("failed to setup memory size and base: %d\n", ret);
+		return ret;
+	}
+
+	/* DDR init */
+	ret = uclass_get_device(UCLASS_RAM, 0, &dev);
+	if (ret) {
+		printf("DRAM init failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}

arch/riscv/include/asm/arch-th1520/cpu.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2025 Yao Zi <ziyao@disroot.org>
+ */
+
+#ifndef _ASM_TH1520_CPU_H_
+#define _ASM_TH1520_CPU_H_
+void th1520_invalidate_pmp(void);
+#endif /* _ASM_TH1520_CPU_H_ */

arch/riscv/include/asm/arch-th1520/spl.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2025 Yao Zi <ziyao@disroot.org>
+ */
+#ifndef _ASM_ARCH_TH1520_SPL_H_
+#define _ASM_ARCH_TH1520_SPL_H_
+
+void spl_dram_init(void);
+
+#endif // _ASM_ARCH_TH1520_SPL_H_