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/*

 * xor.c : Multiple Devices driver for Linux

 *

 * Copyright (C) 1996, 1997, 1998, 1999, 2000,

 * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.

 *

 * Dispatch optimized RAID-5 checksumming functions.

 *

 * 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, or (at your option)

 * any later version.

 *

 * You should have received a copy of the GNU General Public License

 * (for example /usr/src/linux/COPYING); if not, write to the Free

 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#define BH_TRACE 0

#include <linux/module.h>

#include <linux/raid/md.h>

#include <linux/raid/xor.h>

#include <asm/xor.h>

/* The xor routines to use.  */

static struct xor_block_template *active_template;

void

xor_block(unsigned int count, struct buffer_head **bh_ptr)

{

        unsigned long *p0, *p1, *p2, *p3, *p4;

        unsigned long bytes = bh_ptr[0]->b_size;

        p0 = (unsigned long *) bh_ptr[0]->b_data;

        p1 = (unsigned long *) bh_ptr[1]->b_data;

        if (count == 2) {

                active_template->do_2(bytes, p0, p1);

                return;

        }

        p2 = (unsigned long *) bh_ptr[2]->b_data;

        if (count == 3) {

                active_template->do_3(bytes, p0, p1, p2);

                return;

        }

        p3 = (unsigned long *) bh_ptr[3]->b_data;

        if (count == 4) {

                active_template->do_4(bytes, p0, p1, p2, p3);

                return;

        }

        p4 = (unsigned long *) bh_ptr[4]->b_data;

        active_template->do_5(bytes, p0, p1, p2, p3, p4);

}

/* Set of all registered templates.  */

static struct xor_block_template *template_list;

#define BENCH_SIZE (PAGE_SIZE)

static void

do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)

{

        int speed;

        unsigned long now;

        int i, count, max;

        tmpl->next = template_list;

        template_list = tmpl;

        /*

         * Count the number of XORs done during a whole jiffy, and use

         * this to calculate the speed of checksumming.  We use a 2-page

         * allocation to have guaranteed color L1-cache layout.

         */

        max = 0;

        for (i = 0; i < 5; i++) {

                now = jiffies;

                count = 0;

                while (jiffies == now) {

                        mb();

                        tmpl->do_2(BENCH_SIZE, b1, b2);

                        mb();

                        count++;

                        mb();

                }

                if (count > max)

                        max = count;

        }

        speed = max * (HZ * BENCH_SIZE / 1024);

        tmpl->speed = speed;

        printk("   %-10s: %5d.%03d MB/sec\n", tmpl->name,

               speed / 1000, speed % 1000);

}

static int

calibrate_xor_block(void)

{

        void *b1, *b2;

        struct xor_block_template *f, *fastest;

        b1 = (void *) md__get_free_pages(GFP_KERNEL, 2);

        if (! b1) {

                printk("raid5: Yikes!  No memory available.\n");

                return -ENOMEM;

        }

        b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;

        printk(KERN_INFO "raid5: measuring checksumming speed\n");

        sti();

#define xor_speed(templ)        do_xor_speed((templ), b1, b2)

        XOR_TRY_TEMPLATES;

#undef xor_speed

        free_pages((unsigned long)b1, 2);

        fastest = template_list;

        for (f = fastest; f; f = f->next)

                if (f->speed > fastest->speed)

                        fastest = f;

#ifdef XOR_SELECT_TEMPLATE

        fastest = XOR_SELECT_TEMPLATE(fastest);

#endif

        active_template = fastest;

        printk("raid5: using function: %s (%d.%03d MB/sec)\n",

               fastest->name, fastest->speed / 1000, fastest->speed % 1000);

        return 0;

}

MD_EXPORT_SYMBOL(xor_block);

MODULE_LICENSE("GPL");

module_init(calibrate_xor_block);