/* -*- linux-c -*- ------------------------------------------------------- *
   *
   *   Copyright 2002 H. Peter Anvin - All Rights Reserved
   *
   *   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, Inc., 53 Temple Place Ste 330,

   *   Boston MA 02111-1307, USA; either version 2 of the License, or

   *   (at your option) any later version; incorporated herein by reference.
   *
   * ----------------------------------------------------------------------- */
  
  /*

   * raid6/algos.c

   *
   * Algorithm list and algorithm selection for RAID-6
   */

  #include <linux/raid/pq.h>

  #ifndef __KERNEL__
  #include <sys/mman.h>

  #include <stdio.h>

  #else

  #include <linux/module.h>

  #include <linux/gfp.h>

  #if !RAID6_USE_EMPTY_ZERO_PAGE
  /* In .bss so it's zeroed */
  const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  EXPORT_SYMBOL(raid6_empty_zero_page);
  #endif

  #endif
  
  struct raid6_calls raid6_call;

  EXPORT_SYMBOL_GPL(raid6_call);

  const struct raid6_calls * const raid6_algos[] = {

  #if defined(__ia64__)
  	&raid6_intx16,
  	&raid6_intx32,
  #endif

  #if defined(__i386__) && !defined(__arch_um__)

  	&raid6_mmxx1,
  	&raid6_mmxx2,
  	&raid6_sse1x1,
  	&raid6_sse1x2,
  	&raid6_sse2x1,
  	&raid6_sse2x2,

  #ifdef CONFIG_AS_AVX2
  	&raid6_avx2x1,
  	&raid6_avx2x2,
  #endif

  #ifdef CONFIG_AS_AVX512
  	&raid6_avx512x1,
  	&raid6_avx512x2,
  #endif

  #endif

  #if defined(__x86_64__) && !defined(__arch_um__)

  	&raid6_sse2x1,
  	&raid6_sse2x2,
  	&raid6_sse2x4,

  #ifdef CONFIG_AS_AVX2
  	&raid6_avx2x1,
  	&raid6_avx2x2,
  	&raid6_avx2x4,
  #endif

  #ifdef CONFIG_AS_AVX512
  	&raid6_avx512x1,
  	&raid6_avx512x2,
  	&raid6_avx512x4,
  #endif

  #endif
  #ifdef CONFIG_ALTIVEC
  	&raid6_altivec1,
  	&raid6_altivec2,
  	&raid6_altivec4,
  	&raid6_altivec8,
  #endif

  #if defined(CONFIG_TILEGX)
  	&raid6_tilegx8,
  #endif

  #if defined(CONFIG_S390)
  	&raid6_s390vx8,
  #endif

  	&raid6_intx1,
  	&raid6_intx2,
  	&raid6_intx4,
  	&raid6_intx8,

  #ifdef CONFIG_KERNEL_MODE_NEON
  	&raid6_neonx1,
  	&raid6_neonx2,
  	&raid6_neonx4,
  	&raid6_neonx8,
  #endif

  	NULL
  };

  void (*raid6_2data_recov)(int, size_t, int, int, void **);
  EXPORT_SYMBOL_GPL(raid6_2data_recov);
  
  void (*raid6_datap_recov)(int, size_t, int, void **);
  EXPORT_SYMBOL_GPL(raid6_datap_recov);
  
  const struct raid6_recov_calls *const raid6_recov_algos[] = {

  #ifdef CONFIG_AS_AVX512
  	&raid6_recov_avx512,
  #endif

  #ifdef CONFIG_AS_AVX2
  	&raid6_recov_avx2,
  #endif

  #ifdef CONFIG_AS_SSSE3

  	&raid6_recov_ssse3,
  #endif

  #ifdef CONFIG_S390
  	&raid6_recov_s390xc,
  #endif

  #if defined(CONFIG_KERNEL_MODE_NEON)
  	&raid6_recov_neon,
  #endif

  	&raid6_recov_intx1,
  	NULL
  };

  #ifdef __KERNEL__
  #define RAID6_TIME_JIFFIES_LG2	4
  #else
  /* Need more time to be stable in userspace */
  #define RAID6_TIME_JIFFIES_LG2	9

  #define time_before(x, y) ((x) < (y))

  #endif

  static inline const struct raid6_recov_calls *raid6_choose_recov(void)

  {
  	const struct raid6_recov_calls *const *algo;
  	const struct raid6_recov_calls *best;
  
  	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
  		if (!best || (*algo)->priority > best->priority)
  			if (!(*algo)->valid || (*algo)->valid())
  				best = *algo;
  
  	if (best) {
  		raid6_2data_recov = best->data2;
  		raid6_datap_recov = best->datap;

  		pr_info("raid6: using %s recovery algorithm
  ", best->name);

  	} else

  		pr_err("raid6: Yikes! No recovery algorithm found!
  ");

  	return best;
  }

  static inline const struct raid6_calls *raid6_choose_gen(
  	void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)

  {

  	unsigned long perf, bestgenperf, bestxorperf, j0, j1;
  	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */

  	const struct raid6_calls *const *algo;
  	const struct raid6_calls *best;

  	for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {

  		if (!best || (*algo)->prefer >= best->prefer) {
  			if ((*algo)->valid && !(*algo)->valid())
  				continue;

  			perf = 0;
  
  			preempt_disable();
  			j0 = jiffies;

  			while ((j1 = jiffies) == j0)

  				cpu_relax();

  			while (time_before(jiffies,
  					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {

  				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);

  				perf++;
  			}
  			preempt_enable();

  			if (perf > bestgenperf) {
  				bestgenperf = perf;

  				best = *algo;

  			}

  			pr_info("raid6: %-8s gen() %5ld MB/s
  ", (*algo)->name,

  			       (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));

  
  			if (!(*algo)->xor_syndrome)
  				continue;
  
  			perf = 0;
  
  			preempt_disable();
  			j0 = jiffies;
  			while ((j1 = jiffies) == j0)
  				cpu_relax();
  			while (time_before(jiffies,
  					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
  				(*algo)->xor_syndrome(disks, start, stop,
  						      PAGE_SIZE, *dptrs);
  				perf++;
  			}
  			preempt_enable();
  
  			if (best == *algo)
  				bestxorperf = perf;
  
  			pr_info("raid6: %-8s xor() %5ld MB/s
  ", (*algo)->name,
  				(perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));

  		}
  	}

  	if (best) {

  		pr_info("raid6: using algorithm %s gen() %ld MB/s
  ",

  		       best->name,

  		       (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
  		if (best->xor_syndrome)
  			pr_info("raid6: .... xor() %ld MB/s, rmw enabled
  ",
  			       (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));

  		raid6_call = *best;
  	} else

  		pr_err("raid6: Yikes!  No algorithm found!
  ");

  	return best;
  }
  
  
  /* Try to pick the best algorithm */
  /* This code uses the gfmul table as convenient data set to abuse */
  
  int __init raid6_select_algo(void)
  {
  	const int disks = (65536/PAGE_SIZE)+2;
  
  	const struct raid6_calls *gen_best;
  	const struct raid6_recov_calls *rec_best;
  	char *syndromes;
  	void *dptrs[(65536/PAGE_SIZE)+2];
  	int i;
  
  	for (i = 0; i < disks-2; i++)
  		dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
  
  	/* Normal code - use a 2-page allocation to avoid D$ conflict */
  	syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
  
  	if (!syndromes) {

  		pr_err("raid6: Yikes!  No memory available.
  ");

  		return -ENOMEM;
  	}
  
  	dptrs[disks-2] = syndromes;
  	dptrs[disks-1] = syndromes + PAGE_SIZE;
  
  	/* select raid gen_syndrome function */
  	gen_best = raid6_choose_gen(&dptrs, disks);

  	/* select raid recover functions */

  	rec_best = raid6_choose_recov();
  
  	free_pages((unsigned long)syndromes, 1);

  	return gen_best && rec_best ? 0 : -EINVAL;

  }

  
  static void raid6_exit(void)
  {
  	do { } while (0);
  }
  
  subsys_initcall(raid6_select_algo);
  module_exit(raid6_exit);
  MODULE_LICENSE("GPL");

  MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");