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/hazards.h>
  21 #include <asm/processor.h>
  22 #include <asm/current.h>
  23
  24 #ifdef CONFIG_MIPS_MT_FPAFF
  25 #include <asm/mips_mt.h>
  26 #endif
  27
  28 struct sigcontext;
  29 struct sigcontext32;
  30
  31 extern void fpu_emulator_init_fpu(void);
  32 extern void _init_fpu(void);
  33 extern void _save_fp(struct task_struct *);
  34 extern void _restore_fp(struct task_struct *);
  35
  36 /*
  37  * This enum specifies a mode in which we want the FPU to operate, for cores
  38  * which implement the Status.FR bit. Note that FPU_32BIT & FPU_64BIT
  39  * purposefully have the values 0 & 1 respectively, so that an integer value
  40  * of Status.FR can be trivially casted to the corresponding enum fpu_mode.
  41  */
  42 enum fpu_mode {
  43         FPU_32BIT = 0,          /* FR = 0 */
  44         FPU_64BIT,              /* FR = 1 */
  45         FPU_AS_IS,
  46 };
  47
  48 static inline int __enable_fpu(enum fpu_mode mode)
  49 {
  50         int fr;
  51
  52         switch (mode) {
  53         case FPU_AS_IS:
  54                 /* just enable the FPU in its current mode */
  55                 set_c0_status(ST0_CU1);
  56                 enable_fpu_hazard();
  57                 return 0;
  58
  59         case FPU_64BIT:
  60 #if !(defined(CONFIG_CPU_MIPS32_R2) || defined(CONFIG_64BIT))
  61                 /* we only have a 32-bit FPU */
  62                 return SIGFPE;
  63 #endif
  64                 /* fall through */
  65         case FPU_32BIT:
  66                 /* set CU1 & change FR appropriately */
  67                 fr = (int)mode;
  68                 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
  69                 enable_fpu_hazard();
  70
  71                 /* check FR has the desired value */
  72                 return (!!(read_c0_status() & ST0_FR) == !!fr) ? 0 : SIGFPE;
  73
  74         default:
  75                 BUG();
  76         }
  77
  78         return SIGFPE;
  79 }
  80
  81 #define __disable_fpu()                                                 \
  82 do {                                                                    \
  83         clear_c0_status(ST0_CU1);                                       \
  84         disable_fpu_hazard();                                           \
  85 } while (0)
  86
  87 #define clear_fpu_owner()       clear_thread_flag(TIF_USEDFPU)
  88
  89 static inline int __is_fpu_owner(void)
  90 {
  91         return test_thread_flag(TIF_USEDFPU);
  92 }
  93
  94 static inline int is_fpu_owner(void)
  95 {
  96         return cpu_has_fpu && __is_fpu_owner();
  97 }
  98
  99 static inline int __own_fpu(void)
 100 {
 101         enum fpu_mode mode;
 102         int ret;
 103
 104         mode = !test_thread_flag(TIF_32BIT_FPREGS);
 105         ret = __enable_fpu(mode);
 106         if (ret)
 107                 return ret;
 108
 109         KSTK_STATUS(current) |= ST0_CU1;
 110         if (mode == FPU_64BIT)
 111                 KSTK_STATUS(current) |= ST0_FR;
 112         else /* mode == FPU_32BIT */
 113                 KSTK_STATUS(current) &= ~ST0_FR;
 114
 115         set_thread_flag(TIF_USEDFPU);
 116         return 0;
 117 }
 118
 119 static inline int own_fpu_inatomic(int restore)
 120 {
 121         int ret = 0;
 122
 123         if (cpu_has_fpu && !__is_fpu_owner()) {
 124                 ret = __own_fpu();
 125                 if (restore && !ret)
 126                         _restore_fp(current);
 127         }
 128         return ret;
 129 }
 130
 131 static inline int own_fpu(int restore)
 132 {
 133         int ret;
 134
 135         preempt_disable();
 136         ret = own_fpu_inatomic(restore);
 137         preempt_enable();
 138         return ret;
 139 }
 140
 141 static inline void lose_fpu(int save)
 142 {
 143         preempt_disable();
 144         if (is_fpu_owner()) {
 145                 if (save)
 146                         _save_fp(current);
 147                 KSTK_STATUS(current) &= ~ST0_CU1;
 148                 clear_thread_flag(TIF_USEDFPU);
 149                 __disable_fpu();
 150         }
 151         preempt_enable();
 152 }
 153
 154 static inline int init_fpu(void)
 155 {
 156         int ret = 0;
 157
 158         preempt_disable();
 159         if (cpu_has_fpu) {
 160                 ret = __own_fpu();
 161                 if (!ret)
 162                         _init_fpu();
 163         } else {
 164                 fpu_emulator_init_fpu();
 165         }
 166
 167         preempt_enable();
 168         return ret;
 169 }
 170
 171 static inline void save_fp(struct task_struct *tsk)
 172 {
 173         if (cpu_has_fpu)
 174                 _save_fp(tsk);
 175 }
 176
 177 static inline void restore_fp(struct task_struct *tsk)
 178 {
 179         if (cpu_has_fpu)
 180                 _restore_fp(tsk);
 181 }
 182
 183 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
 184 {
 185         if (tsk == current) {
 186                 preempt_disable();
 187                 if (is_fpu_owner())
 188                         _save_fp(current);
 189                 preempt_enable();
 190         }
 191
 192         return tsk->thread.fpu.fpr;
 193 }
 194
 195 #endif /* _ASM_FPU_H */