Merge patch series "riscv: Add bfloat16 instruction support"

Inochi Amaoto <inochiama@gmail.com> says:

Add description for the BFloat16 precision Floating-Point ISA extension,
(Zfbfmin, Zvfbfmin, Zvfbfwma). which was ratified in commit 4dc23d62
("Added Chapter title to BF16") of the riscv-isa-manual.

* patches from https://lore.kernel.org/r/20250213003849.147358-1-inochiama@gmail.com:
  riscv: hwprobe: export bfloat16 ISA extension
  riscv: add ISA extension parsing for bfloat16 ISA extension
  dt-bindings: riscv: add bfloat16 ISA extension description

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250213003849.147358-1-inochiama@gmail.com

Documentation/arch/riscv/hwprobe.rst

@@ -248,6 +248,18 @@ The following keys are defined:
   * :c:macro:`RISCV_HWPROBE_EXT_SUPM`: The Supm extension is supported as
        defined in version 1.0 of the RISC-V Pointer Masking extensions.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZFBFMIN`: The Zfbfmin extension is supported as
+       defined in the RISC-V ISA manual starting from commit 4dc23d6229de
+       ("Added Chapter title to BF16").
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVFBFMIN`: The Zvfbfmin extension is supported as
+       defined in the RISC-V ISA manual starting from commit 4dc23d6229de
+       ("Added Chapter title to BF16").
+
+  * :c:macro:`RISCV_HWPROBE_EXT_ZVFBFWMA`: The Zvfbfwma extension is supported as
+       defined in the RISC-V ISA manual starting from commit 4dc23d6229de
+       ("Added Chapter title to BF16").
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated.  Returns similar values to
      :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was
      mistakenly classified as a bitmask rather than a value.

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -329,6 +329,12 @@ properties:
             instructions, as ratified in commit 056b6ff ("Zfa is ratified") of
             riscv-isa-manual.
 
+        - const: zfbfmin
+          description:
+            The standard Zfbfmin extension which provides minimal support for
+            16-bit half-precision brain floating-point instructions, as ratified
+            in commit 4dc23d62 ("Added Chapter title to BF16") of riscv-isa-manual.
+
         - const: zfh
           description:
             The standard Zfh extension for 16-bit half-precision binary
@@ -525,6 +531,18 @@ properties:
             in commit 6f702a2 ("Vector extensions are now ratified") of
             riscv-v-spec.
 
+        - const: zvfbfmin
+          description:
+            The standard Zvfbfmin extension for minimal support for vectored
+            16-bit half-precision brain floating-point instructions, as ratified
+            in commit 4dc23d62 ("Added Chapter title to BF16") of riscv-isa-manual.
+
+        - const: zvfbfwma
+          description:
+            The standard Zvfbfwma extension for vectored half-precision brain
+            floating-point widening multiply-accumulate instructions, as ratified
+            in commit 4dc23d62 ("Added Chapter title to BF16") of riscv-isa-manual.
+
         - const: zvfh
           description:
             The standard Zvfh extension for vectored half-precision
@@ -673,6 +691,33 @@ properties:
         then:
           contains:
             const: zca
+      # Zfbfmin depends on F
+      - if:
+          contains:
+            const: zfbfmin
+        then:
+          contains:
+            const: f
+      # Zvfbfmin depends on V or Zve32f
+      - if:
+          contains:
+            const: zvfbfmin
+        then:
+          oneOf:
+            - contains:
+                const: v
+            - contains:
+                const: zve32f
+      # Zvfbfwma depends on Zfbfmin and Zvfbfmin
+      - if:
+          contains:
+            const: zvfbfwma
+        then:
+          allOf:
+            - contains:
+                const: zfbfmin
+            - contains:
+                const: zvfbfmin
 
 allOf:
   # Zcf extension does not exist on rv64

arch/riscv/include/asm/hwcap.h

@@ -100,6 +100,9 @@
 #define RISCV_ISA_EXT_ZICCRSE		91
 #define RISCV_ISA_EXT_SVADE		92
 #define RISCV_ISA_EXT_SVADU		93
+#define RISCV_ISA_EXT_ZFBFMIN		94
+#define RISCV_ISA_EXT_ZVFBFMIN		95
+#define RISCV_ISA_EXT_ZVFBFWMA		96
 
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 

arch/riscv/include/uapi/asm/hwprobe.h

@@ -75,6 +75,9 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_SUPM		(1ULL << 49)
 #define		RISCV_HWPROBE_EXT_ZICNTR	(1ULL << 50)
 #define		RISCV_HWPROBE_EXT_ZIHPM		(1ULL << 51)
+#define		RISCV_HWPROBE_EXT_ZFBFMIN	(1ULL << 52)
+#define		RISCV_HWPROBE_EXT_ZVFBFMIN	(1ULL << 53)
+#define		RISCV_HWPROBE_EXT_ZVFBFWMA	(1ULL << 54)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)

arch/riscv/kernel/cpufeature.c

@@ -80,6 +80,15 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned i
 }
 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
 
+static int riscv_ext_f_depends(const struct riscv_isa_ext_data *data,
+			       const unsigned long *isa_bitmap)
+{
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_f))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
 static int riscv_ext_zicbom_validate(const struct riscv_isa_ext_data *data,
 				     const unsigned long *isa_bitmap)
 {
@@ -140,6 +149,28 @@ static int riscv_ext_zcf_validate(const struct riscv_isa_ext_data *data,
 	return -EPROBE_DEFER;
 }
 
+static int riscv_vector_f_validate(const struct riscv_isa_ext_data *data,
+				   const unsigned long *isa_bitmap)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_V))
+		return -EINVAL;
+
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZVE32F))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
+static int riscv_ext_zvfbfwma_validate(const struct riscv_isa_ext_data *data,
+				       const unsigned long *isa_bitmap)
+{
+	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZFBFMIN) &&
+	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZVFBFMIN))
+		return 0;
+
+	return -EPROBE_DEFER;
+}
+
 static int riscv_ext_svadu_validate(const struct riscv_isa_ext_data *data,
 				    const unsigned long *isa_bitmap)
 {
@@ -345,6 +376,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(zacas, RISCV_ISA_EXT_ZACAS),
 	__RISCV_ISA_EXT_DATA(zawrs, RISCV_ISA_EXT_ZAWRS),
 	__RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zfbfmin, RISCV_ISA_EXT_ZFBFMIN, riscv_ext_f_depends),
 	__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),
@@ -377,6 +409,9 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_SUPERSET(zve64d, RISCV_ISA_EXT_ZVE64D, riscv_zve64d_exts),
 	__RISCV_ISA_EXT_SUPERSET(zve64f, RISCV_ISA_EXT_ZVE64F, riscv_zve64f_exts),
 	__RISCV_ISA_EXT_SUPERSET(zve64x, RISCV_ISA_EXT_ZVE64X, riscv_zve64x_exts),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvfbfmin, RISCV_ISA_EXT_ZVFBFMIN, riscv_vector_f_validate),
+	__RISCV_ISA_EXT_DATA_VALIDATE(zvfbfwma, RISCV_ISA_EXT_ZVFBFWMA,
+				      riscv_ext_zvfbfwma_validate),
 	__RISCV_ISA_EXT_DATA(zvfh, RISCV_ISA_EXT_ZVFH),
 	__RISCV_ISA_EXT_DATA(zvfhmin, RISCV_ISA_EXT_ZVFHMIN),
 	__RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),

arch/riscv/kernel/sys_hwprobe.c

@@ -134,6 +134,8 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 			EXT_KEY(ZVE64D);
 			EXT_KEY(ZVE64F);
 			EXT_KEY(ZVE64X);
+			EXT_KEY(ZVFBFMIN);
+			EXT_KEY(ZVFBFWMA);
 			EXT_KEY(ZVFH);
 			EXT_KEY(ZVFHMIN);
 			EXT_KEY(ZVKB);
@@ -150,6 +152,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 			EXT_KEY(ZCD);
 			EXT_KEY(ZCF);
 			EXT_KEY(ZFA);
+			EXT_KEY(ZFBFMIN);
 			EXT_KEY(ZFH);
 			EXT_KEY(ZFHMIN);
 		}