drivers/md/raid6altivec.uc

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Bostom MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * raid6altivec$#.c
  15  *
  16  * $#-way unrolled portable integer math RAID-6 instruction set
  17  *
  18  * This file is postprocessed using unroll.pl
  19  *
  20  * <benh> hpa: in process,
  21  * you can just "steal" the vec unit with enable_kernel_altivec() (but
  22  * bracked this with preempt_disable/enable or in a lock)
  23  */
  24
  25 #include "raid6.h"
  26
  27 #ifdef CONFIG_ALTIVEC
  28
  29 #include <altivec.h>
  30 #ifdef __KERNEL__
  31 # include <asm/system.h>
  32 # include <asm/cputable.h>
  33 #endif
  34
  35 /*
  36  * This is the C data type to use.  We use a vector of
  37  * signed char so vec_cmpgt() will generate the right
  38  * instruction.
  39  */
  40
  41 typedef vector signed char unative_t;
  42
  43 #define NBYTES(x) ((vector signed char) {x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
  44 #define NSIZE   sizeof(unative_t)
  45
  46 /*
  47  * The SHLBYTE() operation shifts each byte left by 1, *not*
  48  * rolling over into the next byte
  49  */
  50 static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  51 {
  52         return vec_add(v,v);
  53 }
  54
  55 /*
  56  * The MASK() operation returns 0xFF in any byte for which the high
  57  * bit is 1, 0x00 for any byte for which the high bit is 0.
  58  */
  59 static inline __attribute_const__ unative_t MASK(unative_t v)
  60 {
  61         unative_t zv = NBYTES(0);
  62
  63         /* vec_cmpgt returns a vector bool char; thus the need for the cast */
  64         return (unative_t)vec_cmpgt(zv, v);
  65 }
  66
  67
  68 /* This is noinline to make damned sure that gcc doesn't move any of the
  69    Altivec code around the enable/disable code */
  70 static void noinline
  71 raid6_altivec$#_gen_syndrome_real(int disks, size_t bytes, void **ptrs)
  72 {
  73         u8 **dptr = (u8 **)ptrs;
  74         u8 *p, *q;
  75         int d, z, z0;
  76
  77         unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
  78         unative_t x1d = NBYTES(0x1d);
  79
  80         z0 = disks - 3;         /* Highest data disk */
  81         p = dptr[z0+1];         /* XOR parity */
  82         q = dptr[z0+2];         /* RS syndrome */
  83
  84         for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
  85                 wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
  86                 for ( z = z0-1 ; z >= 0 ; z-- ) {
  87                         wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
  88                         wp$$ = vec_xor(wp$$, wd$$);
  89                         w2$$ = MASK(wq$$);
  90                         w1$$ = SHLBYTE(wq$$);
  91                         w2$$ = vec_and(w2$$, x1d);
  92                         w1$$ = vec_xor(w1$$, w2$$);
  93                         wq$$ = vec_xor(w1$$, wd$$);
  94                 }
  95                 *(unative_t *)&p[d+NSIZE*$$] = wp$$;
  96                 *(unative_t *)&q[d+NSIZE*$$] = wq$$;
  97         }
  98 }
  99
 100 static void raid6_altivec$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
 101 {
 102         preempt_disable();
 103         enable_kernel_altivec();
 104
 105         raid6_altivec$#_gen_syndrome_real(disks, bytes, ptrs);
 106
 107         preempt_enable();
 108 }
 109
 110 int raid6_have_altivec(void);
 111 #if $# == 1
 112 int raid6_have_altivec(void)
 113 {
 114         /* This assumes either all CPUs have Altivec or none does */
 115 # ifdef __KERNEL__
 116         return cpu_has_feature(CPU_FTR_ALTIVEC);
 117 # else
 118         return 1;
 119 # endif
 120 }
 121 #endif
 122
 123 const struct raid6_calls raid6_altivec$# = {
 124         raid6_altivec$#_gen_syndrome,
 125         raid6_have_altivec,
 126         "altivecx$#",
 127         0
 128 };
 129
 130 #endif /* CONFIG_ALTIVEC */