opensbi: generic: add cv181x reset support

This allows certain secondary program loaders and other
payloads to utilize SBI reboot ecalls.

opensbi/platform/generic/cvitek_cv181x.c

@@ -0,0 +1,71 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 Thomas Makin.
+ *
+ * Authors:
+ *   Thomas Makin <[email protected]>
+ */
+
+#include <platform_override.h>
+#include <sbi/sbi_system.h>
+#include <sbi/riscv_io.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+
+static inline void cv_writel(u32 value, uintptr_t base, u32 reg) {
+	writel(value, (volatile void *)(base + reg));
+}
+
+static inline u32 cv_readl(uintptr_t base, u32 reg) {
+	return readl((volatile void *)(base + reg));
+}
+
+static int cv_system_reset_check(u32 type, u32 reason)
+{
+	return 1;
+}
+
+#define REG_RTC_CTRL_BASE 0x05025000
+#define   RTC_CTRL0_UNLOCKKEY 0x4
+#define   RTC_CTRL0           0x8
+
+#define REG_RTC_BASE 0x05026000
+#define   RTC_EN_WARM_RST_REQ 0xCC
+
+static void cv_system_reset(u32 type, u32 reason)
+{
+	u32 val;
+
+	cv_writel(0x01, REG_RTC_BASE, RTC_EN_WARM_RST_REQ);
+	while (cv_readl(REG_RTC_BASE, RTC_EN_WARM_RST_REQ) != 0x01);
+	cv_writel(0xAB18, REG_RTC_CTRL_BASE, RTC_CTRL0_UNLOCKKEY);
+	val = cv_readl(REG_RTC_CTRL_BASE, + RTC_CTRL0);
+	val |= (0xFFFF0800 | (0x1 << 4));
+	cv_writel(val, REG_RTC_CTRL_BASE, RTC_CTRL0);
+
+	while (1);
+}
+
+static struct sbi_system_reset_device cv_reset = {
+	.name = "cv_reset",
+	.system_reset_check = cv_system_reset_check,
+	.system_reset = cv_system_reset
+};
+
+static int cv_early_init(bool cold_boot, const struct fdt_match *match)
+{
+	if (cold_boot)
+		sbi_system_reset_set_device(&cv_reset);
+
+	return 0;
+}
+
+static const struct fdt_match cvitek_cv181x_match[] = {
+	{ .compatible = "cvitek,cv181x" },
+	{ },
+};
+
+const struct platform_override cvitek_cv181x = {
+	.match_table = cvitek_cv181x_match,
+	.early_init = cv_early_init,
+};

opensbi/platform/generic/objects.mk

@@ -9,3 +9,4 @@
 
 platform-objs-y += platform.o
 platform-objs-y += sifive_fu540.o
+platform-objs-y += cvitek_cv181x.o

opensbi/platform/generic/platform.c

@@ -23,9 +23,11 @@
 #include <sbi_utils/reset/fdt_reset.h>
 
 extern const struct platform_override sifive_fu540;
+extern const struct platform_override cvitek_cv181x;
 
 static const struct platform_override *special_platforms[] = {
 	&sifive_fu540,
+	&cvitek_cv181x,
 };
 
 static const struct platform_override *generic_plat = NULL;