[PATCH v6 08/16] riscv: add ISA parsing for Zca, Zcf, Zcd and Zcb

[Clément Léger]

The Zc* standard extension for code reduction introduces new extensions.
This patch adds support for Zca, Zcf, Zcd and Zcb. Zce, Zcmt and Zcmp
are left out of this patch since they are targeting microcontrollers/
embedded CPUs instead of application processors.

Signed-off-by: Clément Léger <cleger at rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley at microchip.com>
---
 arch/riscv/include/asm/hwcap.h |  5 +++-
 arch/riscv/kernel/cpufeature.c | 55 +++++++++++++++++++++++++++++++++-
 2 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 543e3ea2da0e..3915c9cb088b 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -82,7 +82,10 @@
 #define RISCV_ISA_EXT_ZACAS		73
 #define RISCV_ISA_EXT_XANDESPMU		74
 #define RISCV_ISA_EXT_ZIMOP		75
-
+#define RISCV_ISA_EXT_ZCA		76
+#define RISCV_ISA_EXT_ZCB		77
+#define RISCV_ISA_EXT_ZCD		78
+#define RISCV_ISA_EXT_ZCF		79
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 
 #define RISCV_ISA_EXT_MAX		128
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index d20e236cec8b..53c7ca590a22 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -111,6 +111,9 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,
 
 #define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, NULL)
 
+#define __RISCV_ISA_EXT_DATA_VALIDATE(_name, _id, _validate) \
+			_RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, _validate)
+
 /* Used to declare pure "lasso" extension (Zk for instance) */
 #define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
 	_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
@@ -122,6 +125,37 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,
 #define __RISCV_ISA_EXT_SUPERSET_VALIDATE(_name, _id, _sub_exts, _validate) \
 	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), _validate)
 
+static int riscv_ext_zca_depends(const struct riscv_isa_ext_data *data,
+				 const unsigned long *isa_bitmap)
+{
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+static int riscv_ext_zcd_validate(const struct riscv_isa_ext_data *data,
+				  const unsigned long *isa_bitmap)
+{
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA) &&
+	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_d))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
+static int riscv_ext_zcf_validate(const struct riscv_isa_ext_data *data,
+				  const unsigned long *isa_bitmap)
+{
+	if (IS_ENABLED(CONFIG_64BIT))
+		return -EINVAL;
+
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA) &&
+	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_f))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
 static const unsigned int riscv_zk_bundled_exts[] = {
 	RISCV_ISA_EXT_ZBKB,
 	RISCV_ISA_EXT_ZBKC,
@@ -202,6 +236,21 @@ static const unsigned int riscv_xlinuxenvcfg_exts[] = {
 	RISCV_ISA_EXT_XLINUXENVCFG
 };
 
+/*
+ * Zc* spec states that:
+ * - C always implies Zca
+ * - C+F implies Zcf (RV32 only)
+ * - C+D implies Zcd
+ *
+ * These extensions will be enabled and then validated depending on the
+ * availability of F/D RV32.
+ */
+static const unsigned int riscv_c_exts[] = {
+	RISCV_ISA_EXT_ZCA,
+	RISCV_ISA_EXT_ZCF,
+	RISCV_ISA_EXT_ZCD,
+};
+
 /*
  * The canonical order of ISA extension names in the ISA string is defined in
  * chapter 27 of the unprivileged specification.
@@ -248,7 +297,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(f, RISCV_ISA_EXT_f),
 	__RISCV_ISA_EXT_DATA(d, RISCV_ISA_EXT_d),
 	__RISCV_ISA_EXT_DATA(q, RISCV_ISA_EXT_q),
-	__RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c),
+	__RISCV_ISA_EXT_SUPERSET(c, RISCV_ISA_EXT_c, riscv_c_exts),
 	__RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v),
 	__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
 	__RISCV_ISA_EXT_SUPERSET_VALIDATE(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts,
@@ -267,6 +316,10 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA),
 	__RISCV_ISA_EXT_DATA(zfh, RISCV_ISA_EXT_ZFH),
 	__RISCV_ISA_EXT_DATA(zfhmin, RISCV_ISA_EXT_ZFHMIN),
+	__RISCV_ISA_EXT_DATA(zca, RISCV_ISA_EXT_ZCA),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zcb, RISCV_ISA_EXT_ZCB, riscv_ext_zca_depends),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zcd, RISCV_ISA_EXT_ZCD, riscv_ext_zcd_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zcf, RISCV_ISA_EXT_ZCF, riscv_ext_zcf_validate),
 	__RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
 	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
 	__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
-- 
2.45.1