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+/*
+ * Copyright 2017, Matt Brown, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * vpermxor$#.c
+ *
+ * Based on H. Peter Anvin's paper - The mathematics of RAID-6
+ *
+ * $#-way unrolled portable integer math RAID-6 instruction set
+ * This file is postprocessed using unroll.awk
+ *
+ * vpermxor$#.c makes use of the vpermxor instruction to optimise the RAID6 Q
+ * syndrome calculations.
+ * This can be run on systems which have both Altivec and vpermxor instruction.
+ *
+ * This instruction was introduced in POWER8 - ISA v2.07.
+ */
+
+#include <linux/raid/pq.h>
+#ifdef CONFIG_ALTIVEC
+
+#include <altivec.h>
+#include <asm/ppc-opcode.h>
+#ifdef __KERNEL__
+#include <asm/cputable.h>
+#include <asm/switch_to.h>
+#endif
+
+typedef vector unsigned char unative_t;
+#define NSIZE sizeof(unative_t)
+
+static const vector unsigned char gf_low = {0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14,
+ 0x12, 0x10, 0x0e, 0x0c, 0x0a, 0x08,
+ 0x06, 0x04, 0x02,0x00};
+static const vector unsigned char gf_high = {0xfd, 0xdd, 0xbd, 0x9d, 0x7d, 0x5d,
+ 0x3d, 0x1d, 0xe0, 0xc0, 0xa0, 0x80,
+ 0x60, 0x40, 0x20, 0x00};
+
+static void noinline raid6_vpermxor$#_gen_syndrome_real(int disks, size_t bytes,
+ void **ptrs)
+{
+ u8 **dptr = (u8 **)ptrs;
+ u8 *p, *q;
+ int d, z, z0;
+ unative_t wp$$, wq$$, wd$$;
+
+ z0 = disks - 3; /* Highest data disk */
+ p = dptr[z0+1]; /* XOR parity */
+ q = dptr[z0+2]; /* RS syndrome */
+
+ for (d = 0; d < bytes; d += NSIZE*$#) {
+ wp$$ = wq$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
+
+ for (z = z0-1; z>=0; z--) {
+ wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
+ /* P syndrome */
+ wp$$ = vec_xor(wp$$, wd$$);
+
+ /* Q syndrome */
+ asm(VPERMXOR(%0,%1,%2,%3):"=v"(wq$$):"v"(gf_high), "v"(gf_low), "v"(wq$$));
+ wq$$ = vec_xor(wq$$, wd$$);
+ }
+ *(unative_t *)&p[d+NSIZE*$$] = wp$$;
+ *(unative_t *)&q[d+NSIZE*$$] = wq$$;
+ }
+}
+
+static void raid6_vpermxor$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+
+ raid6_vpermxor$#_gen_syndrome_real(disks, bytes, ptrs);
+
+ disable_kernel_altivec();
+ preempt_enable();
+}
+
+int raid6_have_altivec_vpermxor(void);
+#if $# == 1
+int raid6_have_altivec_vpermxor(void)
+{
+ /* Check if arch has both altivec and the vpermxor instructions */
+# ifdef __KERNEL__
+ return (cpu_has_feature(CPU_FTR_ALTIVEC_COMP) &&
+ cpu_has_feature(CPU_FTR_ARCH_207S));
+# else
+ return 1;
+#endif
+
+}
+#endif
+
+const struct raid6_calls raid6_vpermxor$# = {
+ raid6_vpermxor$#_gen_syndrome,
+ NULL,
+ raid6_have_altivec_vpermxor,
+ "vpermxor$#",
+ 0
+};
+#endif