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  * $#-way unrolled portable integer math RAID-6 instruction set
  17  *
  18  * This file is postprocessed using unroll.pl
  19  *
  20  * <benh> hpa: in process,
  21  * you can just "steal" the vec unit with enable_kernel_altivec() (but
  22  * bracked this with preempt_disable/enable or in a lock)
  23  */
  24
  25 #include "raid6.h"
  26
  27 #ifdef CONFIG_ALTIVEC
  28
  29 #include <altivec.h>
  30 #include <asm/system.h>
  31 #include <asm/cputable.h>
  32
  33 /*
  34  * This is the C data type to use
  35  */
  36
  37 typedef vector unsigned char unative_t;
  38
  39 #define NBYTES(x) ((vector unsigned char) {x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
  40 #define NSIZE   sizeof(unative_t)
  41
  42 /*
  43  * The SHLBYTE() operation shifts each byte left by 1, *not*
  44  * rolling over into the next byte
  45  */
  46 static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  47 {
  48         return vec_add(v,v);
  49 }
  50
  51 /*
  52  * The MASK() operation returns 0xFF in any byte for which the high
  53  * bit is 1, 0x00 for any byte for which the high bit is 0.
  54  */
  55 static inline __attribute_const__ unative_t MASK(unative_t v)
  56 {
  57         unative_t zv = NBYTES(0);
  58
  59         /* vec_cmpgt returns a vector bool char; thus the need for the cast */
  60         return (unative_t)vec_cmpgt(zv, v);
  61 }
  62
  63
  64 /* This is noinline to make damned sure that gcc doesn't move any of the
  65    Altivec code around the enable/disable code */
  66 static void noinline
  67 raid6_altivec$#_gen_syndrome_real(int disks, size_t bytes, void **ptrs)
  68 {
  69         u8 **dptr = (u8 **)ptrs;
  70         u8 *p, *q;
  71         int d, z, z0;
  72
  73         unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
  74         unative_t x1d = NBYTES(0x1d);
  75
  76         z0 = disks - 3;         /* Highest data disk */
  77         p = dptr[z0+1];         /* XOR parity */
  78         q = dptr[z0+2];         /* RS syndrome */
  79
  80         for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
  81                 wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
  82                 for ( z = z0-1 ; z >= 0 ; z-- ) {
  83                         wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
  84                         wp$$ = vec_xor(wp$$, wd$$);
  85                         w2$$ = MASK(wq$$);
  86                         w1$$ = SHLBYTE(wq$$);
  87                         w2$$ = vec_and(w2$$, x1d);
  88                         w1$$ = vec_xor(w1$$, w2$$);
  89                         wq$$ = vec_xor(w1$$, wd$$);
  90                 }
  91                 *(unative_t *)&p[d+NSIZE*$$] = wp$$;
  92                 *(unative_t *)&q[d+NSIZE*$$] = wq$$;
  93         }
  94 }
  95
  96 static void raid6_altivec$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
  97 {
  98         preempt_disable();
  99         enable_kernel_altivec();
 100
 101         raid6_altivec$#_gen_syndrome_real(disks, bytes, ptrs);
 102
 103         preempt_enable();
 104 }
 105
 106 int raid6_have_altivec(void);
 107 #if $# == 1
 108 int raid6_have_altivec(void)
 109 {
 110         /* This assumes either all CPUs have Altivec or none does */
 111         return cpu_has_feature(CPU_FTR_ALTIVEC);
 112 }
 113 #endif
 114
 115 const struct raid6_calls raid6_altivec$# = {
 116         raid6_altivec$#_gen_syndrome,
 117         raid6_have_altivec,
 118         "altivecx$#",
 119         0
 120 };
 121
 122 #endif /* CONFIG_ALTIVEC */