lib: sbi_ecall: Add Kconfig option for each extension

For each SBI extension, we:

- Add a Kconfig option for it
- Add the extension to sbi_ecall_exts only if the extension is enabled
- Add the corresponding sbi_ecall_* object file only if the extension is
  enabled

Special cases are as follows:

- The legacy extensions are lumped together as one 'big' extension, as
  has always been the case in OpenSBI code.
- The platform-defined vendor extensions are regarded as one extension.
- The Base extension cannot be disabled.
- sbi_ecall_replace implements multiple extensions, so it's not easy to
  avoid linking it in. Enable it always, and use #ifdef to
  disable/enable individual extensions.

Signed-off-by: Vivian Wang <dramforever@live.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

Kconfig

@@ -18,6 +18,8 @@ menu "Platform Options"
 source "$(OPENSBI_PLATFORM_SRC_DIR)/Kconfig"
 endmenu
 
+source "$(OPENSBI_SRC_DIR)/lib/sbi/Kconfig"
+
 source "$(OPENSBI_SRC_DIR)/lib/utils/Kconfig"
 
 source "$(OPENSBI_SRC_DIR)/firmware/Kconfig"

lib/sbi/Kconfig

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: BSD-2-Clause
+
+menu "SBI Extension Support"
+
+config SBI_ECALL_TIME
+	bool "Timer extension"
+	default y
+
+config SBI_ECALL_RFENCE
+	bool "RFENCE extension"
+	default y
+
+config SBI_ECALL_IPI
+	bool "IPI extension"
+	default y
+
+config SBI_ECALL_HSM
+	bool "Hart State Management extension"
+	default y
+
+config SBI_ECALL_SRST
+	bool "System Reset extension"
+	default y
+
+config SBI_ECALL_PMU
+	bool "Performance Monitoring Unit extension"
+	default y
+
+config SBI_ECALL_LEGACY
+	bool "SBI v0.1 legacy extensions"
+	default y
+
+config SBI_ECALL_VENDOR
+	bool "Platform-defined vendor extensions"
+	default y
+
+endmenu

lib/sbi/objects.mk

@@ -16,22 +16,22 @@ libsbi-objs-y += sbi_ecall.o
 libsbi-objs-y += sbi_ecall_exts.o
 
 # The order of below extensions is performance optimized
-carray-sbi_ecall_exts-y += ecall_time
-carray-sbi_ecall_exts-y += ecall_rfence
-carray-sbi_ecall_exts-y += ecall_ipi
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_TIME) += ecall_time
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_RFENCE) += ecall_rfence
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_IPI) += ecall_ipi
 carray-sbi_ecall_exts-y += ecall_base
-carray-sbi_ecall_exts-y += ecall_hsm
-carray-sbi_ecall_exts-y += ecall_srst
-carray-sbi_ecall_exts-y += ecall_pmu
-carray-sbi_ecall_exts-y += ecall_legacy
-carray-sbi_ecall_exts-y += ecall_vendor
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_HSM) += ecall_hsm
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_SRST) += ecall_srst
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_PMU) += ecall_pmu
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_LEGACY) += ecall_legacy
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_VENDOR) += ecall_vendor
 
 libsbi-objs-y += sbi_ecall_base.o
-libsbi-objs-y += sbi_ecall_hsm.o
-libsbi-objs-y += sbi_ecall_legacy.o
-libsbi-objs-y += sbi_ecall_pmu.o
+libsbi-objs-$(CONFIG_SBI_ECALL_HSM) += sbi_ecall_hsm.o
+libsbi-objs-$(CONFIG_SBI_ECALL_LEGACY) += sbi_ecall_legacy.o
+libsbi-objs-$(CONFIG_SBI_ECALL_PMU) += sbi_ecall_pmu.o
 libsbi-objs-y += sbi_ecall_replace.o
-libsbi-objs-y += sbi_ecall_vendor.o
+libsbi-objs-$(CONFIG_SBI_ECALL_VENDOR) += sbi_ecall_vendor.o
 
 libsbi-objs-y += sbi_bitmap.o
 libsbi-objs-y += sbi_bitops.o

lib/sbi/sbi_ecall_replace.c

@@ -19,6 +19,7 @@
 #include <sbi/sbi_tlb.h>
 #include <sbi/sbi_trap.h>
 
+#ifdef CONFIG_SBI_ECALL_TIME
 static int sbi_ecall_time_handler(unsigned long extid, unsigned long funcid,
 				  const struct sbi_trap_regs *regs,
 				  unsigned long *out_val,
@@ -43,7 +44,9 @@ struct sbi_ecall_extension ecall_time = {
 	.extid_end = SBI_EXT_TIME,
 	.handle = sbi_ecall_time_handler,
 };
+#endif
 
+#ifdef CONFIG_SBI_ECALL_RFENCE
 static int sbi_ecall_rfence_handler(unsigned long extid, unsigned long funcid,
 				    const struct sbi_trap_regs *regs,
 				    unsigned long *out_val,
@@ -113,7 +116,9 @@ struct sbi_ecall_extension ecall_rfence = {
 	.extid_end = SBI_EXT_RFENCE,
 	.handle = sbi_ecall_rfence_handler,
 };
+#endif
 
+#ifdef CONFIG_SBI_ECALL_IPI
 static int sbi_ecall_ipi_handler(unsigned long extid, unsigned long funcid,
 				 const struct sbi_trap_regs *regs,
 				 unsigned long *out_val,
@@ -134,7 +139,9 @@ struct sbi_ecall_extension ecall_ipi = {
 	.extid_end = SBI_EXT_IPI,
 	.handle = sbi_ecall_ipi_handler,
 };
+#endif
 
+#ifdef CONFIG_SBI_ECALL_SRST
 static int sbi_ecall_srst_handler(unsigned long extid, unsigned long funcid,
 				  const struct sbi_trap_regs *regs,
 				  unsigned long *out_val,
@@ -194,3 +201,4 @@ struct sbi_ecall_extension ecall_srst = {
 	.handle = sbi_ecall_srst_handler,
 	.probe = sbi_ecall_srst_probe,
 };
+#endif