[PATCH RFC 3/3] lib: sbi: Add VIRQ ecall extension

[Raymond Mao]

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

Add vendor SBI extension ecall for VIRQ.
This allows S-mode payload to pop/complete the next pending VIRQ has
couried into the current domain.

Signed-off-by: Raymond Mao <raymond.mao at riscstar.com>
---
 include/sbi/sbi_ecall_interface.h | 18 ++++++++++
 lib/sbi/Kconfig                   |  5 +++
 lib/sbi/objects.mk                |  3 ++
 lib/sbi/sbi_ecall_virq.c          | 57 +++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 lib/sbi/sbi_ecall_virq.c

diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
index 76624e3f..9cb9a7eb 100644
--- a/include/sbi/sbi_ecall_interface.h
+++ b/include/sbi/sbi_ecall_interface.h
@@ -126,6 +126,24 @@
 #define SBI_EXT_FWFT_SET		0x0
 #define SBI_EXT_FWFT_GET		0x1
 
+#ifdef CONFIG_SBI_ECALL_VIRQ
+
+/* Vendor extension base range is defined by the SBI spec. Choose a private ID. */
+#define SBI_EXT_VIRQ			0x0900524d
+
+/* Function IDs for SBI_EXT_VIRQ */
+#define SBI_EXT_VIRQ_POP		0
+#define SBI_EXT_VIRQ_COMPLETE		1
+
+/*
+ * SBI_EXT_VIRQ_POP
+ * Returns:
+ *   a0: SBI error code (0 for success)
+ *   a1: next pending hwirq (0 if none pending)
+ */
+
+#endif
+
 enum sbi_fwft_feature_t {
 	SBI_FWFT_MISALIGNED_EXC_DELEG		= 0x0,
 	SBI_FWFT_LANDING_PAD			= 0x1,
diff --git a/lib/sbi/Kconfig b/lib/sbi/Kconfig
index c6cc04bc..8479f861 100644
--- a/lib/sbi/Kconfig
+++ b/lib/sbi/Kconfig
@@ -69,4 +69,9 @@ config SBI_ECALL_SSE
 config SBI_ECALL_MPXY
 	bool "MPXY extension"
 	default y
+
+config SBI_ECALL_VIRQ
+	bool "VIRQ extension"
+	default y
+
 endmenu
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 07d13229..18e590ab 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -64,6 +64,9 @@ libsbi-objs-$(CONFIG_SBI_ECALL_SSE) += sbi_ecall_sse.o
 carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_MPXY) += ecall_mpxy
 libsbi-objs-$(CONFIG_SBI_ECALL_MPXY) += sbi_ecall_mpxy.o
 
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_VIRQ) += ecall_virq
+libsbi-objs-$(CONFIG_SBI_ECALL_VIRQ) += sbi_ecall_virq.o
+
 libsbi-objs-y += sbi_bitmap.o
 libsbi-objs-y += sbi_bitops.o
 libsbi-objs-y += sbi_console.o
diff --git a/lib/sbi/sbi_ecall_virq.c b/lib/sbi/sbi_ecall_virq.c
new file mode 100644
index 00000000..b192598e
--- /dev/null
+++ b/lib/sbi/sbi_ecall_virq.c
@@ -0,0 +1,57 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026 RISCstar Solutions.
+ *
+ * Author: Raymond Mao <raymond.mao at riscstar.com>
+ */
+
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_ecall.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_trap.h>
+#include <sbi/sbi_virq.h>
+
+static int sbi_ecall_virq_handler(unsigned long extid,
+				  unsigned long funcid,
+				  struct sbi_trap_regs *regs,
+				  struct sbi_ecall_return *out)
+{
+	(void)extid;
+
+	sbi_printf("[ECALL VIRQ] VIRQ ecall handler, funcid: %ld\n", funcid);
+
+	switch (funcid) {
+	case SBI_EXT_VIRQ_POP:
+		out->value = (unsigned long)sbi_virq_pop_thishart();
+		return SBI_OK;
+	case SBI_EXT_VIRQ_COMPLETE:
+		u32 hwirq = (u32)regs->a0;
+
+		sbi_virq_complete_thishart(hwirq);
+		regs->a0 = 0;
+		return SBI_OK;
+	default:
+		return SBI_ENOTSUPP;
+	}
+}
+
+struct sbi_ecall_extension ecall_virq;
+
+static int sbi_ecall_virq_register_extensions(void)
+{
+	int ret;
+
+	ret = sbi_ecall_register_extension(&ecall_virq);
+	sbi_printf("[ECALL VIRQ] register VIRQ ecall extensions, ret=%d\n", ret);
+	return ret;
+}
+
+struct sbi_ecall_extension ecall_virq = {
+	.name        = "virq",
+	.extid_start = SBI_EXT_VIRQ,
+	.extid_end   = SBI_EXT_VIRQ,
+	.register_extensions    = sbi_ecall_virq_register_extensions,
+	.handle      = sbi_ecall_virq_handler,
+};
-- 
2.25.1