MIPS: cpu-probe: move fpu probing/handling into its own file
authorThomas Bogendoerfer <tsbogend@alpha.franken.de>
Thu, 8 Oct 2020 21:33:25 +0000 (23:33 +0200)
committerThomas Bogendoerfer <tsbogend@alpha.franken.de>
Mon, 12 Oct 2020 10:04:50 +0000 (12:04 +0200)
cpu-probe.c has grown when supporting more and more CPUs and there
are use cases where probing for all the CPUs isn't useful like
running on a R3k system. But still the fpu handling is nearly
the same. For sharing put the fpu code into it's own file.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
arch/mips/kernel/Makefile
arch/mips/kernel/cpu-probe.c
arch/mips/kernel/fpu-probe.c [new file with mode: 0644]
arch/mips/kernel/fpu-probe.h [new file with mode: 0644]

index 13a26d25482987596cbf18dfe8a3977022f1052c..026801c21724ce8d95d56ae6b53d299e8b47d9a1 100644 (file)
@@ -42,6 +42,7 @@ sw-$(CONFIG_CPU_TX39XX)               := r2300_switch.o
 sw-$(CONFIG_CPU_CAVIUM_OCTEON) := octeon_switch.o
 obj-y                          += $(sw-y)
 
+obj-$(CONFIG_MIPS_FP_SUPPORT)  += fpu-probe.o
 obj-$(CONFIG_CPU_R2300_FPU)    += r2300_fpu.o
 obj-$(CONFIG_CPU_R4K_FPU)      += r4k_fpu.o
 
index 6be23f205e7411f8b2ed28c984cd76de45461945..b8e073772bdb69f0a4ab129cab32330281122e3d 100644 (file)
 #include <asm/spram.h>
 #include <linux/uaccess.h>
 
+#include "fpu-probe.h"
+
 #include <asm/mach-loongson64/cpucfg-emul.h>
 
 /* Hardware capabilities */
 unsigned int elf_hwcap __read_mostly;
 EXPORT_SYMBOL_GPL(elf_hwcap);
 
-#ifdef CONFIG_MIPS_FP_SUPPORT
-
-/*
- * Get the FPU Implementation/Revision.
- */
-static inline unsigned long cpu_get_fpu_id(void)
-{
-       unsigned long tmp, fpu_id;
-
-       tmp = read_c0_status();
-       __enable_fpu(FPU_AS_IS);
-       fpu_id = read_32bit_cp1_register(CP1_REVISION);
-       write_c0_status(tmp);
-       return fpu_id;
-}
-
-/*
- * Check if the CPU has an external FPU.
- */
-static inline int __cpu_has_fpu(void)
-{
-       return (cpu_get_fpu_id() & FPIR_IMP_MASK) != FPIR_IMP_NONE;
-}
-
-/*
- * Determine the FCSR mask for FPU hardware.
- */
-static inline void cpu_set_fpu_fcsr_mask(struct cpuinfo_mips *c)
-{
-       unsigned long sr, mask, fcsr, fcsr0, fcsr1;
-
-       fcsr = c->fpu_csr31;
-       mask = FPU_CSR_ALL_X | FPU_CSR_ALL_E | FPU_CSR_ALL_S | FPU_CSR_RM;
-
-       sr = read_c0_status();
-       __enable_fpu(FPU_AS_IS);
-
-       fcsr0 = fcsr & mask;
-       write_32bit_cp1_register(CP1_STATUS, fcsr0);
-       fcsr0 = read_32bit_cp1_register(CP1_STATUS);
-
-       fcsr1 = fcsr | ~mask;
-       write_32bit_cp1_register(CP1_STATUS, fcsr1);
-       fcsr1 = read_32bit_cp1_register(CP1_STATUS);
-
-       write_32bit_cp1_register(CP1_STATUS, fcsr);
-
-       write_c0_status(sr);
-
-       c->fpu_msk31 = ~(fcsr0 ^ fcsr1) & ~mask;
-}
-
-/*
- * Determine the IEEE 754 NaN encodings and ABS.fmt/NEG.fmt execution modes
- * supported by FPU hardware.
- */
-static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
-{
-       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
-                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
-                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
-                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
-               unsigned long sr, fir, fcsr, fcsr0, fcsr1;
-
-               sr = read_c0_status();
-               __enable_fpu(FPU_AS_IS);
-
-               fir = read_32bit_cp1_register(CP1_REVISION);
-               if (fir & MIPS_FPIR_HAS2008) {
-                       fcsr = read_32bit_cp1_register(CP1_STATUS);
-
-                       /*
-                        * MAC2008 toolchain never landed in real world, so we're only
-                        * testing wether it can be disabled and don't try to enabled
-                        * it.
-                        */
-                       fcsr0 = fcsr & ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008 | FPU_CSR_MAC2008);
-                       write_32bit_cp1_register(CP1_STATUS, fcsr0);
-                       fcsr0 = read_32bit_cp1_register(CP1_STATUS);
-
-                       fcsr1 = fcsr | FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
-                       write_32bit_cp1_register(CP1_STATUS, fcsr1);
-                       fcsr1 = read_32bit_cp1_register(CP1_STATUS);
-
-                       write_32bit_cp1_register(CP1_STATUS, fcsr);
-
-                       if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2)) {
-                               /*
-                                * The bit for MAC2008 might be reused by R6 in future,
-                                * so we only test for R2-R5.
-                                */
-                               if (fcsr0 & FPU_CSR_MAC2008)
-                                       c->options |= MIPS_CPU_MAC_2008_ONLY;
-                       }
-
-                       if (!(fcsr0 & FPU_CSR_NAN2008))
-                               c->options |= MIPS_CPU_NAN_LEGACY;
-                       if (fcsr1 & FPU_CSR_NAN2008)
-                               c->options |= MIPS_CPU_NAN_2008;
-
-                       if ((fcsr0 ^ fcsr1) & FPU_CSR_ABS2008)
-                               c->fpu_msk31 &= ~FPU_CSR_ABS2008;
-                       else
-                               c->fpu_csr31 |= fcsr & FPU_CSR_ABS2008;
-
-                       if ((fcsr0 ^ fcsr1) & FPU_CSR_NAN2008)
-                               c->fpu_msk31 &= ~FPU_CSR_NAN2008;
-                       else
-                               c->fpu_csr31 |= fcsr & FPU_CSR_NAN2008;
-               } else {
-                       c->options |= MIPS_CPU_NAN_LEGACY;
-               }
-
-               write_c0_status(sr);
-       } else {
-               c->options |= MIPS_CPU_NAN_LEGACY;
-       }
-}
-
-/*
- * IEEE 754 conformance mode to use.  Affects the NaN encoding and the
- * ABS.fmt/NEG.fmt execution mode.
- */
-static enum { STRICT, LEGACY, STD2008, RELAXED } ieee754 = STRICT;
-
-/*
- * Set the IEEE 754 NaN encodings and the ABS.fmt/NEG.fmt execution modes
- * to support by the FPU emulator according to the IEEE 754 conformance
- * mode selected.  Note that "relaxed" straps the emulator so that it
- * allows 2008-NaN binaries even for legacy processors.
- */
-static void cpu_set_nofpu_2008(struct cpuinfo_mips *c)
-{
-       c->options &= ~(MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY);
-       c->fpu_csr31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
-       c->fpu_msk31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
-
-       switch (ieee754) {
-       case STRICT:
-               if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
-                                   MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
-                                   MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
-                                   MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
-                       c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
-               } else {
-                       c->options |= MIPS_CPU_NAN_LEGACY;
-                       c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
-               }
-               break;
-       case LEGACY:
-               c->options |= MIPS_CPU_NAN_LEGACY;
-               c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
-               break;
-       case STD2008:
-               c->options |= MIPS_CPU_NAN_2008;
-               c->fpu_csr31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
-               c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
-               break;
-       case RELAXED:
-               c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
-               break;
-       }
-}
-
-/*
- * Override the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode
- * according to the "ieee754=" parameter.
- */
-static void cpu_set_nan_2008(struct cpuinfo_mips *c)
-{
-       switch (ieee754) {
-       case STRICT:
-               mips_use_nan_legacy = !!cpu_has_nan_legacy;
-               mips_use_nan_2008 = !!cpu_has_nan_2008;
-               break;
-       case LEGACY:
-               mips_use_nan_legacy = !!cpu_has_nan_legacy;
-               mips_use_nan_2008 = !cpu_has_nan_legacy;
-               break;
-       case STD2008:
-               mips_use_nan_legacy = !cpu_has_nan_2008;
-               mips_use_nan_2008 = !!cpu_has_nan_2008;
-               break;
-       case RELAXED:
-               mips_use_nan_legacy = true;
-               mips_use_nan_2008 = true;
-               break;
-       }
-}
-
-/*
- * IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode override
- * settings:
- *
- * strict:  accept binaries that request a NaN encoding supported by the FPU
- * legacy:  only accept legacy-NaN binaries
- * 2008:    only accept 2008-NaN binaries
- * relaxed: accept any binaries regardless of whether supported by the FPU
- */
-static int __init ieee754_setup(char *s)
-{
-       if (!s)
-               return -1;
-       else if (!strcmp(s, "strict"))
-               ieee754 = STRICT;
-       else if (!strcmp(s, "legacy"))
-               ieee754 = LEGACY;
-       else if (!strcmp(s, "2008"))
-               ieee754 = STD2008;
-       else if (!strcmp(s, "relaxed"))
-               ieee754 = RELAXED;
-       else
-               return -1;
-
-       if (!(boot_cpu_data.options & MIPS_CPU_FPU))
-               cpu_set_nofpu_2008(&boot_cpu_data);
-       cpu_set_nan_2008(&boot_cpu_data);
-
-       return 0;
-}
-
-early_param("ieee754", ieee754_setup);
-
-/*
- * Set the FIR feature flags for the FPU emulator.
- */
-static void cpu_set_nofpu_id(struct cpuinfo_mips *c)
-{
-       u32 value;
-
-       value = 0;
-       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
-                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
-                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
-                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
-               value |= MIPS_FPIR_D | MIPS_FPIR_S;
-       if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
-                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
-                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
-               value |= MIPS_FPIR_F64 | MIPS_FPIR_L | MIPS_FPIR_W;
-       if (c->options & MIPS_CPU_NAN_2008)
-               value |= MIPS_FPIR_HAS2008;
-       c->fpu_id = value;
-}
-
-/* Determined FPU emulator mask to use for the boot CPU with "nofpu".  */
-static unsigned int mips_nofpu_msk31;
-
-/*
- * Set options for FPU hardware.
- */
-static void cpu_set_fpu_opts(struct cpuinfo_mips *c)
-{
-       c->fpu_id = cpu_get_fpu_id();
-       mips_nofpu_msk31 = c->fpu_msk31;
-
-       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
-                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
-                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
-                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
-               if (c->fpu_id & MIPS_FPIR_3D)
-                       c->ases |= MIPS_ASE_MIPS3D;
-               if (c->fpu_id & MIPS_FPIR_UFRP)
-                       c->options |= MIPS_CPU_UFR;
-               if (c->fpu_id & MIPS_FPIR_FREP)
-                       c->options |= MIPS_CPU_FRE;
-       }
-
-       cpu_set_fpu_fcsr_mask(c);
-       cpu_set_fpu_2008(c);
-       cpu_set_nan_2008(c);
-}
-
-/*
- * Set options for the FPU emulator.
- */
-static void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
-{
-       c->options &= ~MIPS_CPU_FPU;
-       c->fpu_msk31 = mips_nofpu_msk31;
-
-       cpu_set_nofpu_2008(c);
-       cpu_set_nan_2008(c);
-       cpu_set_nofpu_id(c);
-}
-
-static int mips_fpu_disabled;
-
-static int __init fpu_disable(char *s)
-{
-       cpu_set_nofpu_opts(&boot_cpu_data);
-       mips_fpu_disabled = 1;
-
-       return 1;
-}
-
-__setup("nofpu", fpu_disable);
-
-#else /* !CONFIG_MIPS_FP_SUPPORT */
-
-#define mips_fpu_disabled 1
-
-static inline unsigned long cpu_get_fpu_id(void)
-{
-       return FPIR_IMP_NONE;
-}
-
-static inline int __cpu_has_fpu(void)
-{
-       return 0;
-}
-
-static void cpu_set_fpu_opts(struct cpuinfo_mips *c)
-{
-       /* no-op */
-}
-
-static void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
-{
-       /* no-op */
-}
-
-#endif /* CONFIG_MIPS_FP_SUPPORT */
-
 static inline unsigned long cpu_get_msa_id(void)
 {
        unsigned long status, msa_id;
diff --git a/arch/mips/kernel/fpu-probe.c b/arch/mips/kernel/fpu-probe.c
new file mode 100644 (file)
index 0000000..e689d6a
--- /dev/null
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Processor capabilities determination functions.
+ *
+ * Copyright (C) xxxx  the Anonymous
+ * Copyright (C) 1994 - 2006 Ralf Baechle
+ * Copyright (C) 2003, 2004  Maciej W. Rozycki
+ * Copyright (C) 2001, 2004, 2011, 2012         MIPS Technologies, Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+
+#include <asm/bugs.h>
+#include <asm/cpu.h>
+#include <asm/cpu-features.h>
+#include <asm/cpu-type.h>
+#include <asm/elf.h>
+#include <asm/fpu.h>
+#include <asm/mipsregs.h>
+
+#include "fpu-probe.h"
+
+/*
+ * Get the FPU Implementation/Revision.
+ */
+static inline unsigned long cpu_get_fpu_id(void)
+{
+       unsigned long tmp, fpu_id;
+
+       tmp = read_c0_status();
+       __enable_fpu(FPU_AS_IS);
+       fpu_id = read_32bit_cp1_register(CP1_REVISION);
+       write_c0_status(tmp);
+       return fpu_id;
+}
+
+/*
+ * Check if the CPU has an external FPU.
+ */
+int __cpu_has_fpu(void)
+{
+       return (cpu_get_fpu_id() & FPIR_IMP_MASK) != FPIR_IMP_NONE;
+}
+
+/*
+ * Determine the FCSR mask for FPU hardware.
+ */
+static inline void cpu_set_fpu_fcsr_mask(struct cpuinfo_mips *c)
+{
+       unsigned long sr, mask, fcsr, fcsr0, fcsr1;
+
+       fcsr = c->fpu_csr31;
+       mask = FPU_CSR_ALL_X | FPU_CSR_ALL_E | FPU_CSR_ALL_S | FPU_CSR_RM;
+
+       sr = read_c0_status();
+       __enable_fpu(FPU_AS_IS);
+
+       fcsr0 = fcsr & mask;
+       write_32bit_cp1_register(CP1_STATUS, fcsr0);
+       fcsr0 = read_32bit_cp1_register(CP1_STATUS);
+
+       fcsr1 = fcsr | ~mask;
+       write_32bit_cp1_register(CP1_STATUS, fcsr1);
+       fcsr1 = read_32bit_cp1_register(CP1_STATUS);
+
+       write_32bit_cp1_register(CP1_STATUS, fcsr);
+
+       write_c0_status(sr);
+
+       c->fpu_msk31 = ~(fcsr0 ^ fcsr1) & ~mask;
+}
+
+/*
+ * Determine the IEEE 754 NaN encodings and ABS.fmt/NEG.fmt execution modes
+ * supported by FPU hardware.
+ */
+static void cpu_set_fpu_2008(struct cpuinfo_mips *c)
+{
+       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
+                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
+               unsigned long sr, fir, fcsr, fcsr0, fcsr1;
+
+               sr = read_c0_status();
+               __enable_fpu(FPU_AS_IS);
+
+               fir = read_32bit_cp1_register(CP1_REVISION);
+               if (fir & MIPS_FPIR_HAS2008) {
+                       fcsr = read_32bit_cp1_register(CP1_STATUS);
+
+                       /*
+                        * MAC2008 toolchain never landed in real world, so
+                        * we're only testing whether it can be disabled and
+                        *  don't try to enabled it.
+                        */
+                       fcsr0 = fcsr & ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008 |
+                                        FPU_CSR_MAC2008);
+                       write_32bit_cp1_register(CP1_STATUS, fcsr0);
+                       fcsr0 = read_32bit_cp1_register(CP1_STATUS);
+
+                       fcsr1 = fcsr | FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+                       write_32bit_cp1_register(CP1_STATUS, fcsr1);
+                       fcsr1 = read_32bit_cp1_register(CP1_STATUS);
+
+                       write_32bit_cp1_register(CP1_STATUS, fcsr);
+
+                       if (c->isa_level & (MIPS_CPU_ISA_M32R2 |
+                                           MIPS_CPU_ISA_M64R2)) {
+                               /*
+                                * The bit for MAC2008 might be reused by R6
+                                * in future, so we only test for R2-R5.
+                                */
+                               if (fcsr0 & FPU_CSR_MAC2008)
+                                       c->options |= MIPS_CPU_MAC_2008_ONLY;
+                       }
+
+                       if (!(fcsr0 & FPU_CSR_NAN2008))
+                               c->options |= MIPS_CPU_NAN_LEGACY;
+                       if (fcsr1 & FPU_CSR_NAN2008)
+                               c->options |= MIPS_CPU_NAN_2008;
+
+                       if ((fcsr0 ^ fcsr1) & FPU_CSR_ABS2008)
+                               c->fpu_msk31 &= ~FPU_CSR_ABS2008;
+                       else
+                               c->fpu_csr31 |= fcsr & FPU_CSR_ABS2008;
+
+                       if ((fcsr0 ^ fcsr1) & FPU_CSR_NAN2008)
+                               c->fpu_msk31 &= ~FPU_CSR_NAN2008;
+                       else
+                               c->fpu_csr31 |= fcsr & FPU_CSR_NAN2008;
+               } else {
+                       c->options |= MIPS_CPU_NAN_LEGACY;
+               }
+
+               write_c0_status(sr);
+       } else {
+               c->options |= MIPS_CPU_NAN_LEGACY;
+       }
+}
+
+/*
+ * IEEE 754 conformance mode to use.  Affects the NaN encoding and the
+ * ABS.fmt/NEG.fmt execution mode.
+ */
+static enum { STRICT, LEGACY, STD2008, RELAXED } ieee754 = STRICT;
+
+/*
+ * Set the IEEE 754 NaN encodings and the ABS.fmt/NEG.fmt execution modes
+ * to support by the FPU emulator according to the IEEE 754 conformance
+ * mode selected.  Note that "relaxed" straps the emulator so that it
+ * allows 2008-NaN binaries even for legacy processors.
+ */
+static void cpu_set_nofpu_2008(struct cpuinfo_mips *c)
+{
+       c->options &= ~(MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY);
+       c->fpu_csr31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
+       c->fpu_msk31 &= ~(FPU_CSR_ABS2008 | FPU_CSR_NAN2008);
+
+       switch (ieee754) {
+       case STRICT:
+               if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+                                   MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+                                   MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
+                                   MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
+                       c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
+               } else {
+                       c->options |= MIPS_CPU_NAN_LEGACY;
+                       c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+               }
+               break;
+       case LEGACY:
+               c->options |= MIPS_CPU_NAN_LEGACY;
+               c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+               break;
+       case STD2008:
+               c->options |= MIPS_CPU_NAN_2008;
+               c->fpu_csr31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+               c->fpu_msk31 |= FPU_CSR_ABS2008 | FPU_CSR_NAN2008;
+               break;
+       case RELAXED:
+               c->options |= MIPS_CPU_NAN_2008 | MIPS_CPU_NAN_LEGACY;
+               break;
+       }
+}
+
+/*
+ * Override the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode
+ * according to the "ieee754=" parameter.
+ */
+static void cpu_set_nan_2008(struct cpuinfo_mips *c)
+{
+       switch (ieee754) {
+       case STRICT:
+               mips_use_nan_legacy = !!cpu_has_nan_legacy;
+               mips_use_nan_2008 = !!cpu_has_nan_2008;
+               break;
+       case LEGACY:
+               mips_use_nan_legacy = !!cpu_has_nan_legacy;
+               mips_use_nan_2008 = !cpu_has_nan_legacy;
+               break;
+       case STD2008:
+               mips_use_nan_legacy = !cpu_has_nan_2008;
+               mips_use_nan_2008 = !!cpu_has_nan_2008;
+               break;
+       case RELAXED:
+               mips_use_nan_legacy = true;
+               mips_use_nan_2008 = true;
+               break;
+       }
+}
+
+/*
+ * IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode override
+ * settings:
+ *
+ * strict:  accept binaries that request a NaN encoding supported by the FPU
+ * legacy:  only accept legacy-NaN binaries
+ * 2008:    only accept 2008-NaN binaries
+ * relaxed: accept any binaries regardless of whether supported by the FPU
+ */
+static int __init ieee754_setup(char *s)
+{
+       if (!s)
+               return -1;
+       else if (!strcmp(s, "strict"))
+               ieee754 = STRICT;
+       else if (!strcmp(s, "legacy"))
+               ieee754 = LEGACY;
+       else if (!strcmp(s, "2008"))
+               ieee754 = STD2008;
+       else if (!strcmp(s, "relaxed"))
+               ieee754 = RELAXED;
+       else
+               return -1;
+
+       if (!(boot_cpu_data.options & MIPS_CPU_FPU))
+               cpu_set_nofpu_2008(&boot_cpu_data);
+       cpu_set_nan_2008(&boot_cpu_data);
+
+       return 0;
+}
+
+early_param("ieee754", ieee754_setup);
+
+/*
+ * Set the FIR feature flags for the FPU emulator.
+ */
+static void cpu_set_nofpu_id(struct cpuinfo_mips *c)
+{
+       u32 value;
+
+       value = 0;
+       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
+                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
+               value |= MIPS_FPIR_D | MIPS_FPIR_S;
+       if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
+                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
+               value |= MIPS_FPIR_F64 | MIPS_FPIR_L | MIPS_FPIR_W;
+       if (c->options & MIPS_CPU_NAN_2008)
+               value |= MIPS_FPIR_HAS2008;
+       c->fpu_id = value;
+}
+
+/* Determined FPU emulator mask to use for the boot CPU with "nofpu".  */
+static unsigned int mips_nofpu_msk31;
+
+/*
+ * Set options for FPU hardware.
+ */
+void cpu_set_fpu_opts(struct cpuinfo_mips *c)
+{
+       c->fpu_id = cpu_get_fpu_id();
+       mips_nofpu_msk31 = c->fpu_msk31;
+
+       if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+                           MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+                           MIPS_CPU_ISA_M32R5 | MIPS_CPU_ISA_M64R5 |
+                           MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6)) {
+               if (c->fpu_id & MIPS_FPIR_3D)
+                       c->ases |= MIPS_ASE_MIPS3D;
+               if (c->fpu_id & MIPS_FPIR_UFRP)
+                       c->options |= MIPS_CPU_UFR;
+               if (c->fpu_id & MIPS_FPIR_FREP)
+                       c->options |= MIPS_CPU_FRE;
+       }
+
+       cpu_set_fpu_fcsr_mask(c);
+       cpu_set_fpu_2008(c);
+       cpu_set_nan_2008(c);
+}
+
+/*
+ * Set options for the FPU emulator.
+ */
+void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
+{
+       c->options &= ~MIPS_CPU_FPU;
+       c->fpu_msk31 = mips_nofpu_msk31;
+
+       cpu_set_nofpu_2008(c);
+       cpu_set_nan_2008(c);
+       cpu_set_nofpu_id(c);
+}
+
+int mips_fpu_disabled;
+
+static int __init fpu_disable(char *s)
+{
+       cpu_set_nofpu_opts(&boot_cpu_data);
+       mips_fpu_disabled = 1;
+
+       return 1;
+}
+
+__setup("nofpu", fpu_disable);
+
diff --git a/arch/mips/kernel/fpu-probe.h b/arch/mips/kernel/fpu-probe.h
new file mode 100644 (file)
index 0000000..951ce50
--- /dev/null
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <linux/kernel.h>
+
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+
+#ifdef CONFIG_MIPS_FP_SUPPORT
+
+extern int mips_fpu_disabled;
+
+int __cpu_has_fpu(void);
+void cpu_set_fpu_opts(struct cpuinfo_mips *c);
+void cpu_set_nofpu_opts(struct cpuinfo_mips *c);
+
+#else /* !CONFIG_MIPS_FP_SUPPORT */
+
+#define mips_fpu_disabled 1
+
+static inline unsigned long cpu_get_fpu_id(void)
+{
+       return FPIR_IMP_NONE;
+}
+
+static inline int __cpu_has_fpu(void)
+{
+       return 0;
+}
+
+static inline void cpu_set_fpu_opts(struct cpuinfo_mips *c)
+{
+       /* no-op */
+}
+
+static inline void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
+{
+       /* no-op */
+}
+
+#endif /* CONFIG_MIPS_FP_SUPPORT */