[PATCH v3 4/4] lib: sbi: implement SBI FWFT extension

[Clément Léger <cleger@rivosinc.com>]

The SBI FWFT extension defines a set of function that can be called to
control the configuration of some platform features (misaligned
trap delegation, etc). This patch implements sbi_fwft_set() and
sbi_fwft_get() as defined in the specification [1].

Link: https://lists.riscv.org/g/tech-prs/message/924 [1]
Signed-off-by: Cl?ment L?ger <cleger@rivosinc.com>
---
 lib/sbi/Kconfig          |  4 ++++
 lib/sbi/objects.mk       |  3 +++
 lib/sbi/sbi_ecall_fwft.c | 49 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 lib/sbi/sbi_ecall_fwft.c

diff --git a/lib/sbi/Kconfig b/lib/sbi/Kconfig
index cc8e031..6cf54ce 100644
--- a/lib/sbi/Kconfig
+++ b/lib/sbi/Kconfig
@@ -38,6 +38,10 @@ config SBI_ECALL_CPPC
 	bool "CPPC extension"
 	default y
 
+config SBI_ECALL_FWFT
+	bool "Firmware Feature extension"
+	default y
+
 config SBI_ECALL_LEGACY
 	bool "SBI v0.1 legacy extensions"
 	default y
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 221e72c..211abad 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -46,6 +46,9 @@ libsbi-objs-$(CONFIG_SBI_ECALL_DBCN) += sbi_ecall_dbcn.o
 carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_CPPC) += ecall_cppc
 libsbi-objs-$(CONFIG_SBI_ECALL_CPPC) += sbi_ecall_cppc.o
 
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_FWFT) += ecall_fwft
+libsbi-objs-$(CONFIG_SBI_ECALL_FWFT) += sbi_ecall_fwft.o
+
 carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_LEGACY) += ecall_legacy
 libsbi-objs-$(CONFIG_SBI_ECALL_LEGACY) += sbi_ecall_legacy.o
 
diff --git a/lib/sbi/sbi_ecall_fwft.c b/lib/sbi/sbi_ecall_fwft.c
new file mode 100644
index 0000000..267cbab
--- /dev/null
+++ b/lib/sbi/sbi_ecall_fwft.c
@@ -0,0 +1,49 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Rivos Inc.
+ *
+ * Authors:
+ *   Cl?ment L?ger <cleger@rivosinc.com>
+ */
+
+#include <sbi/sbi_ecall.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_fwft.h>
+#include <sbi/sbi_trap.h>
+
+static int sbi_ecall_fwft_handler(unsigned long extid, unsigned long funcid,
+				 struct sbi_trap_regs *regs,
+				 struct sbi_ecall_return *out)
+{
+	int ret = 0;
+
+	switch (funcid) {
+	case SBI_EXT_FWFT_SET:
+		ret = sbi_fwft_set(regs->a0, regs->a1, regs->a2);
+		break;
+	case SBI_EXT_FWFT_GET:
+		ret = sbi_fwft_get(regs->a0, &out->value);
+		break;
+	default:
+		ret = SBI_ENOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+
+struct sbi_ecall_extension ecall_fwft;
+
+static int sbi_ecall_fwft_register_extensions(void)
+{
+	return sbi_ecall_register_extension(&ecall_fwft);
+}
+
+struct sbi_ecall_extension ecall_fwft = {
+	.extid_start = SBI_EXT_FWFT,
+	.extid_end = SBI_EXT_FWFT,
+	.register_extensions = sbi_ecall_fwft_register_extensions,
+	.handle = sbi_ecall_fwft_handler,
+};
-- 
2.45.2