arch/alpha/include/asm/fpu.h

   1 #ifndef __ASM_ALPHA_FPU_H
   2 #define __ASM_ALPHA_FPU_H
   3
   4 /*
   5  * Alpha floating-point control register defines:
   6  */
   7 #define FPCR_DNOD       (1UL<<47)       /* denorm INV trap disable */
   8 #define FPCR_DNZ        (1UL<<48)       /* denorms to zero */
   9 #define FPCR_INVD       (1UL<<49)       /* invalid op disable (opt.) */
  10 #define FPCR_DZED       (1UL<<50)       /* division by zero disable (opt.) */
  11 #define FPCR_OVFD       (1UL<<51)       /* overflow disable (optional) */
  12 #define FPCR_INV        (1UL<<52)       /* invalid operation */
  13 #define FPCR_DZE        (1UL<<53)       /* division by zero */
  14 #define FPCR_OVF        (1UL<<54)       /* overflow */
  15 #define FPCR_UNF        (1UL<<55)       /* underflow */
  16 #define FPCR_INE        (1UL<<56)       /* inexact */
  17 #define FPCR_IOV        (1UL<<57)       /* integer overflow */
  18 #define FPCR_UNDZ       (1UL<<60)       /* underflow to zero (opt.) */
  19 #define FPCR_UNFD       (1UL<<61)       /* underflow disable (opt.) */
  20 #define FPCR_INED       (1UL<<62)       /* inexact disable (opt.) */
  21 #define FPCR_SUM        (1UL<<63)       /* summary bit */
  22
  23 #define FPCR_DYN_SHIFT  58              /* first dynamic rounding mode bit */
  24 #define FPCR_DYN_CHOPPED (0x0UL << FPCR_DYN_SHIFT)      /* towards 0 */
  25 #define FPCR_DYN_MINUS   (0x1UL << FPCR_DYN_SHIFT)      /* towards -INF */
  26 #define FPCR_DYN_NORMAL  (0x2UL << FPCR_DYN_SHIFT)      /* towards nearest */
  27 #define FPCR_DYN_PLUS    (0x3UL << FPCR_DYN_SHIFT)      /* towards +INF */
  28 #define FPCR_DYN_MASK    (0x3UL << FPCR_DYN_SHIFT)
  29
  30 #define FPCR_MASK       0xffff800000000000L
  31
  32 /*
  33  * IEEE trap enables are implemented in software.  These per-thread
  34  * bits are stored in the "ieee_state" field of "struct thread_info".
  35  * Thus, the bits are defined so as not to conflict with the
  36  * floating-point enable bit (which is architected).  On top of that,
  37  * we want to make these bits compatible with OSF/1 so
  38  * ieee_set_fp_control() etc. can be implemented easily and
  39  * compatibly.  The corresponding definitions are in
  40  * /usr/include/machine/fpu.h under OSF/1.
  41  */
  42 #define IEEE_TRAP_ENABLE_INV    (1UL<<1)        /* invalid op */
  43 #define IEEE_TRAP_ENABLE_DZE    (1UL<<2)        /* division by zero */
  44 #define IEEE_TRAP_ENABLE_OVF    (1UL<<3)        /* overflow */
  45 #define IEEE_TRAP_ENABLE_UNF    (1UL<<4)        /* underflow */
  46 #define IEEE_TRAP_ENABLE_INE    (1UL<<5)        /* inexact */
  47 #define IEEE_TRAP_ENABLE_DNO    (1UL<<6)        /* denorm */
  48 #define IEEE_TRAP_ENABLE_MASK   (IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE |\
  49                                  IEEE_TRAP_ENABLE_OVF | IEEE_TRAP_ENABLE_UNF |\
  50                                  IEEE_TRAP_ENABLE_INE | IEEE_TRAP_ENABLE_DNO)
  51
  52 /* Denorm and Underflow flushing */
  53 #define IEEE_MAP_DMZ            (1UL<<12)       /* Map denorm inputs to zero */
  54 #define IEEE_MAP_UMZ            (1UL<<13)       /* Map underflowed outputs to zero */
  55
  56 #define IEEE_MAP_MASK           (IEEE_MAP_DMZ | IEEE_MAP_UMZ)
  57
  58 /* status bits coming from fpcr: */
  59 #define IEEE_STATUS_INV         (1UL<<17)
  60 #define IEEE_STATUS_DZE         (1UL<<18)
  61 #define IEEE_STATUS_OVF         (1UL<<19)
  62 #define IEEE_STATUS_UNF         (1UL<<20)
  63 #define IEEE_STATUS_INE         (1UL<<21)
  64 #define IEEE_STATUS_DNO         (1UL<<22)
  65
  66 #define IEEE_STATUS_MASK        (IEEE_STATUS_INV | IEEE_STATUS_DZE |    \
  67                                  IEEE_STATUS_OVF | IEEE_STATUS_UNF |    \
  68                                  IEEE_STATUS_INE | IEEE_STATUS_DNO)
  69
  70 #define IEEE_SW_MASK            (IEEE_TRAP_ENABLE_MASK |                \
  71                                  IEEE_STATUS_MASK | IEEE_MAP_MASK)
  72
  73 #define IEEE_CURRENT_RM_SHIFT   32
  74 #define IEEE_CURRENT_RM_MASK    (3UL<<IEEE_CURRENT_RM_SHIFT)
  75
  76 #define IEEE_STATUS_TO_EXCSUM_SHIFT     16
  77
  78 #define IEEE_INHERIT    (1UL<<63)       /* inherit on thread create? */
  79
  80 /*
  81  * Convert the software IEEE trap enable and status bits into the
  82  * hardware fpcr format.
  83  *
  84  * Digital Unix engineers receive my thanks for not defining the
  85  * software bits identical to the hardware bits.  The chip designers
  86  * receive my thanks for making all the not-implemented fpcr bits
  87  * RAZ forcing us to use system calls to read/write this value.
  88  */
  89
  90 static inline unsigned long
  91 ieee_swcr_to_fpcr(unsigned long sw)
  92 {
  93         unsigned long fp;
  94         fp = (sw & IEEE_STATUS_MASK) << 35;
  95         fp |= (sw & IEEE_MAP_DMZ) << 36;
  96         fp |= (sw & IEEE_STATUS_MASK ? FPCR_SUM : 0);
  97         fp |= (~sw & (IEEE_TRAP_ENABLE_INV
  98                       | IEEE_TRAP_ENABLE_DZE
  99                       | IEEE_TRAP_ENABLE_OVF)) << 48;
 100         fp |= (~sw & (IEEE_TRAP_ENABLE_UNF | IEEE_TRAP_ENABLE_INE)) << 57;
 101         fp |= (sw & IEEE_MAP_UMZ ? FPCR_UNDZ | FPCR_UNFD : 0);
 102         fp |= (~sw & IEEE_TRAP_ENABLE_DNO) << 41;
 103         return fp;
 104 }
 105
 106 static inline unsigned long
 107 ieee_fpcr_to_swcr(unsigned long fp)
 108 {
 109         unsigned long sw;
 110         sw = (fp >> 35) & IEEE_STATUS_MASK;
 111         sw |= (fp >> 36) & IEEE_MAP_DMZ;
 112         sw |= (~fp >> 48) & (IEEE_TRAP_ENABLE_INV
 113                              | IEEE_TRAP_ENABLE_DZE
 114                              | IEEE_TRAP_ENABLE_OVF);
 115         sw |= (~fp >> 57) & (IEEE_TRAP_ENABLE_UNF | IEEE_TRAP_ENABLE_INE);
 116         sw |= (fp >> 47) & IEEE_MAP_UMZ;
 117         sw |= (~fp >> 41) & IEEE_TRAP_ENABLE_DNO;
 118         return sw;
 119 }
 120
 121 #ifdef __KERNEL__
 122
 123 /* The following two functions don't need trapb/excb instructions
 124    around the mf_fpcr/mt_fpcr instructions because (a) the kernel
 125    never generates arithmetic faults and (b) call_pal instructions
 126    are implied trap barriers.  */
 127
 128 static inline unsigned long
 129 rdfpcr(void)
 130 {
 131         unsigned long tmp, ret;
 132
 133 #if defined(CONFIG_ALPHA_EV6) || defined(CONFIG_ALPHA_EV67)
 134         __asm__ __volatile__ (
 135                 "ftoit $f0,%0\n\t"
 136                 "mf_fpcr $f0\n\t"
 137                 "ftoit $f0,%1\n\t"
 138                 "itoft %0,$f0"
 139                 : "=r"(tmp), "=r"(ret));
 140 #else
 141         __asm__ __volatile__ (
 142                 "stt $f0,%0\n\t"
 143                 "mf_fpcr $f0\n\t"
 144                 "stt $f0,%1\n\t"
 145                 "ldt $f0,%0"
 146                 : "=m"(tmp), "=m"(ret));
 147 #endif
 148
 149         return ret;
 150 }
 151
 152 static inline void
 153 wrfpcr(unsigned long val)
 154 {
 155         unsigned long tmp;
 156
 157 #if defined(CONFIG_ALPHA_EV6) || defined(CONFIG_ALPHA_EV67)
 158         __asm__ __volatile__ (
 159                 "ftoit $f0,%0\n\t"
 160                 "itoft %1,$f0\n\t"
 161                 "mt_fpcr $f0\n\t"
 162                 "itoft %0,$f0"
 163                 : "=&r"(tmp) : "r"(val));
 164 #else
 165         __asm__ __volatile__ (
 166                 "stt $f0,%0\n\t"
 167                 "ldt $f0,%1\n\t"
 168                 "mt_fpcr $f0\n\t"
 169                 "ldt $f0,%0"
 170                 : "=m"(tmp) : "m"(val));
 171 #endif
 172 }
 173
 174 static inline unsigned long
 175 swcr_update_status(unsigned long swcr, unsigned long fpcr)
 176 {
 177         /* EV6 implements most of the bits in hardware.  Collect
 178            the acrued exception bits from the real fpcr.  */
 179         if (implver() == IMPLVER_EV6) {
 180                 swcr &= ~IEEE_STATUS_MASK;
 181                 swcr |= (fpcr >> 35) & IEEE_STATUS_MASK;
 182         }
 183         return swcr;
 184 }
 185
 186 extern unsigned long alpha_read_fp_reg (unsigned long reg);
 187 extern void alpha_write_fp_reg (unsigned long reg, unsigned long val);
 188 extern unsigned long alpha_read_fp_reg_s (unsigned long reg);
 189 extern void alpha_write_fp_reg_s (unsigned long reg, unsigned long val);
 190
 191 #endif /* __KERNEL__ */
 192
 193 #endif /* __ASM_ALPHA_FPU_H */