arch/mips/include/asm/fpu.h

   1 /*
   2  * Copyright (C) 2002 MontaVista Software Inc.
   3  * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation;  either version 2 of the  License, or (at your
   8  * option) any later version.
   9  */
  10 #ifndef _ASM_FPU_H
  11 #define _ASM_FPU_H
  12
  13 #include <linux/sched.h>
  14 #include <linux/thread_info.h>
  15 #include <linux/bitops.h>
  16
  17 #include <asm/mipsregs.h>
  18 #include <asm/cpu.h>
  19 #include <asm/cpu-features.h>
  20 #include <asm/fpu_emulator.h>
  21 #include <asm/hazards.h>
  22 #include <asm/processor.h>
  23 #include <asm/current.h>
  24 #include <asm/msa.h>
  25
  26 #ifdef CONFIG_MIPS_MT_FPAFF
  27 #include <asm/mips_mt.h>
  28 #endif
  29
  30 struct sigcontext;
  31 struct sigcontext32;
  32
  33 extern void _init_fpu(unsigned int);
  34 extern void _save_fp(struct task_struct *);
  35 extern void _restore_fp(struct task_struct *);
  36
  37 /*
  38  * This enum specifies a mode in which we want the FPU to operate, for cores
  39  * which implement the Status.FR bit. Note that the bottom bit of the value
  40  * purposefully matches the desired value of the Status.FR bit.
  41  */
  42 enum fpu_mode {
  43         FPU_32BIT = 0,          /* FR = 0 */
  44         FPU_64BIT,              /* FR = 1, FRE = 0 */
  45         FPU_AS_IS,
  46         FPU_HYBRID,             /* FR = 1, FRE = 1 */
  47
  48 #define FPU_FR_MASK             0x1
  49 };
  50
  51 #define __disable_fpu()                                                 \
  52 do {                                                                    \
  53         clear_c0_status(ST0_CU1);                                       \
  54         disable_fpu_hazard();                                           \
  55 } while (0)
  56
  57 static inline int __enable_fpu(enum fpu_mode mode)
  58 {
  59         int fr;
  60
  61         switch (mode) {
  62         case FPU_AS_IS:
  63                 /* just enable the FPU in its current mode */
  64                 set_c0_status(ST0_CU1);
  65                 enable_fpu_hazard();
  66                 return 0;
  67
  68         case FPU_HYBRID:
  69                 if (!cpu_has_fre)
  70                         return SIGFPE;
  71
  72                 /* set FRE */
  73                 set_c0_config5(MIPS_CONF5_FRE);
  74                 goto fr_common;
  75
  76         case FPU_64BIT:
  77 #if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
  78       || defined(CONFIG_64BIT))
  79                 /* we only have a 32-bit FPU */
  80                 return SIGFPE;
  81 #endif
  82                 /* fall through */
  83         case FPU_32BIT:
  84                 if (cpu_has_fre) {
  85                         /* clear FRE */
  86                         clear_c0_config5(MIPS_CONF5_FRE);
  87                 }
  88 fr_common:
  89                 /* set CU1 & change FR appropriately */
  90                 fr = (int)mode & FPU_FR_MASK;
  91                 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
  92                 enable_fpu_hazard();
  93
  94                 /* check FR has the desired value */
  95                 if (!!(read_c0_status() & ST0_FR) == !!fr)
  96                         return 0;
  97
  98                 /* unsupported FR value */
  99                 __disable_fpu();
 100                 return SIGFPE;
 101
 102         default:
 103                 BUG();
 104         }
 105
 106         return SIGFPE;
 107 }
 108
 109 #define clear_fpu_owner()       clear_thread_flag(TIF_USEDFPU)
 110
 111 static inline int __is_fpu_owner(void)
 112 {
 113         return test_thread_flag(TIF_USEDFPU);
 114 }
 115
 116 static inline int is_fpu_owner(void)
 117 {
 118         return cpu_has_fpu && __is_fpu_owner();
 119 }
 120
 121 static inline int __own_fpu(void)
 122 {
 123         enum fpu_mode mode;
 124         int ret;
 125
 126         if (test_thread_flag(TIF_HYBRID_FPREGS))
 127                 mode = FPU_HYBRID;
 128         else
 129                 mode = !test_thread_flag(TIF_32BIT_FPREGS);
 130
 131         ret = __enable_fpu(mode);
 132         if (ret)
 133                 return ret;
 134
 135         KSTK_STATUS(current) |= ST0_CU1;
 136         if (mode == FPU_64BIT || mode == FPU_HYBRID)
 137                 KSTK_STATUS(current) |= ST0_FR;
 138         else /* mode == FPU_32BIT */
 139                 KSTK_STATUS(current) &= ~ST0_FR;
 140
 141         set_thread_flag(TIF_USEDFPU);
 142         return 0;
 143 }
 144
 145 static inline int own_fpu_inatomic(int restore)
 146 {
 147         int ret = 0;
 148
 149         if (cpu_has_fpu && !__is_fpu_owner()) {
 150                 ret = __own_fpu();
 151                 if (restore && !ret)
 152                         _restore_fp(current);
 153         }
 154         return ret;
 155 }
 156
 157 static inline int own_fpu(int restore)
 158 {
 159         int ret;
 160
 161         preempt_disable();
 162         ret = own_fpu_inatomic(restore);
 163         preempt_enable();
 164         return ret;
 165 }
 166
 167 static inline void lose_fpu(int save)
 168 {
 169         preempt_disable();
 170         if (is_msa_enabled()) {
 171                 if (save) {
 172                         save_msa(current);
 173                         current->thread.fpu.fcr31 =
 174                                         read_32bit_cp1_register(CP1_STATUS);
 175                 }
 176                 disable_msa();
 177                 clear_thread_flag(TIF_USEDMSA);
 178                 __disable_fpu();
 179         } else if (is_fpu_owner()) {
 180                 if (save)
 181                         _save_fp(current);
 182                 __disable_fpu();
 183         }
 184         KSTK_STATUS(current) &= ~ST0_CU1;
 185         clear_thread_flag(TIF_USEDFPU);
 186         preempt_enable();
 187 }
 188
 189 static inline int init_fpu(void)
 190 {
 191         unsigned int fcr31 = current->thread.fpu.fcr31;
 192         int ret = 0;
 193
 194         if (cpu_has_fpu) {
 195                 unsigned int config5;
 196
 197                 ret = __own_fpu();
 198                 if (ret)
 199                         return ret;
 200
 201                 if (!cpu_has_fre) {
 202                         _init_fpu(fcr31);
 203
 204                         return 0;
 205                 }
 206
 207                 /*
 208                  * Ensure FRE is clear whilst running _init_fpu, since
 209                  * single precision FP instructions are used. If FRE
 210                  * was set then we'll just end up initialising all 32
 211                  * 64b registers.
 212                  */
 213                 config5 = clear_c0_config5(MIPS_CONF5_FRE);
 214                 enable_fpu_hazard();
 215
 216                 _init_fpu(fcr31);
 217
 218                 /* Restore FRE */
 219                 write_c0_config5(config5);
 220                 enable_fpu_hazard();
 221         } else
 222                 fpu_emulator_init_fpu();
 223
 224         return ret;
 225 }
 226
 227 static inline void save_fp(struct task_struct *tsk)
 228 {
 229         if (cpu_has_fpu)
 230                 _save_fp(tsk);
 231 }
 232
 233 static inline void restore_fp(struct task_struct *tsk)
 234 {
 235         if (cpu_has_fpu)
 236                 _restore_fp(tsk);
 237 }
 238
 239 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
 240 {
 241         if (tsk == current) {
 242                 preempt_disable();
 243                 if (is_fpu_owner())
 244                         _save_fp(current);
 245                 preempt_enable();
 246         }
 247
 248         return tsk->thread.fpu.fpr;
 249 }
 250
 251 #endif /* _ASM_FPU_H */