[PATCH RFC 04/12] RISC-V: add Zbc extension detection

[Heiko Stuebner]

From: Heiko Stuebner <heiko.stuebner@xxxxxxxx>

Add handling for Zbc extension.

Zbc provides instruction for carry-less multiplication.

Signed-off-by: Heiko Stuebner <heiko.stuebner@xxxxxxxx>
---
 arch/riscv/Kconfig             | 22 ++++++++++++++++++++++
 arch/riscv/include/asm/hwcap.h |  1 +
 arch/riscv/kernel/cpu.c        |  1 +
 arch/riscv/kernel/cpufeature.c |  1 +
 4 files changed, 25 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index f4b0e0144516..05b92bcb7bfe 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -449,6 +449,28 @@ config RISCV_ISA_ZBB
 
 	   If you don't know what to do here, say Y.
 
+config TOOLCHAIN_HAS_ZBC
+	bool
+	default y
+	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbc)
+	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
+	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on AS_IS_GNU
+
+config RISCV_ISA_ZBC
+	bool "Zbc extension support for bit manipulation instructions"
+	depends on TOOLCHAIN_HAS_ZBC
+	depends on !XIP_KERNEL && MMU
+	default y
+	help
+	   Adds support to dynamically detect the presence of the ZBC
+	   extension (carry-less multiplication) and enable its usage.
+
+	   The Zbc extension provides instructions clmul, clmulh and clmulr
+	   to accelerate carry-less multiplications.
+
+	   If you don't know what to do here, say Y.
+
 config TOOLCHAIN_HAS_ZICBOM
 	bool
 	default y
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index c8c69b49f0ad..8673c2146d20 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -60,6 +60,7 @@ enum riscv_isa_ext_id {
 	RISCV_ISA_EXT_SVINVAL,
 	RISCV_ISA_EXT_SVPBMT,
 	RISCV_ISA_EXT_ZBB,
+	RISCV_ISA_EXT_ZBC,
 	RISCV_ISA_EXT_ZICBOM,
 	RISCV_ISA_EXT_ZIHINTPAUSE,
 	RISCV_ISA_EXT_ID_MAX
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 420228e219f7..995462a0de86 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -186,6 +186,7 @@ arch_initcall(riscv_cpuinfo_init);
  */
 static struct riscv_isa_ext_data isa_ext_arr[] = {
 	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
+	__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
 	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
 	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 33938f91cbbf..ba74f3fa2310 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -235,6 +235,7 @@ printk("!!!! isa-string: %s\n\n\n", isa);
 				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
 				SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB);
+				SET_ISA_EXT_MAP("zbc", RISCV_ISA_EXT_ZBC);
 				SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
 				SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
 			}
-- 
2.39.0