/*
 * Copyright (C) 2006-2008 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; see the file COPYING. If not, write to the Free Software
 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Test random reads, writes and erases on MTD device.
 *
 * Author: Adrian Hunter <ext-adrian.hunter@nokia.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/err.h>
#include <linux/mtd/mtd.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <linux/random.h>

#include "mtd_test.h"

static int dev = -EINVAL;
module_param(dev, int, S_IRUGO);
MODULE_PARM_DESC(dev, "MTD device number to use");

static int count = 10000;
module_param(count, int, S_IRUGO);
MODULE_PARM_DESC(count, "Number of operations to do (default is 10000)");

static struct mtd_info *mtd;
static unsigned char *writebuf;
static unsigned char *readbuf;
static unsigned char *bbt;
static int *offsets;

static int pgsize;
static int bufsize;
static int ebcnt;
static int pgcnt;

static int rand_eb(void)
{
        unsigned int eb;

again:
        eb = prandom_u32();
        /* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
        eb %= (ebcnt - 1);
        if (bbt[eb])
                goto again;
        return eb;
}

static int rand_offs(void)
{
        unsigned int offs;

        offs = prandom_u32();
        offs %= bufsize;
        return offs;
}

static int rand_len(int offs)
{
        unsigned int len;

        len = prandom_u32();
        len %= (bufsize - offs);
        return len;
}

static int do_read(void)
{
        int eb = rand_eb();
        int offs = rand_offs();
        int len = rand_len(offs);
        loff_t addr;

        if (bbt[eb + 1]) {
                if (offs >= mtd->erasesize)
                        offs -= mtd->erasesize;
                if (offs + len > mtd->erasesize)
                        len = mtd->erasesize - offs;
        }
        addr = eb * mtd->erasesize + offs;
        return mtdtest_read(mtd, addr, len, readbuf);
}

static int do_write(void)
{
        int eb = rand_eb(), offs, err, len;
        loff_t addr;

        offs = offsets[eb];
        if (offs >= mtd->erasesize) {
                err = mtdtest_erase_eraseblock(mtd, eb);
                if (err)
                        return err;
                offs = offsets[eb] = 0;
        }
        len = rand_len(offs);
        len = ((len + pgsize - 1) / pgsize) * pgsize;
        if (offs + len > mtd->erasesize) {
                if (bbt[eb + 1])
                        len = mtd->erasesize - offs;
                else {
                        err = mtdtest_erase_eraseblock(mtd, eb + 1);
                        if (err)
                                return err;
                        offsets[eb + 1] = 0;
                }
        }
        addr = eb * mtd->erasesize + offs;
        err = mtdtest_write(mtd, addr, len, writebuf);
        if (unlikely(err))
                return err;
        offs += len;
        while (offs > mtd->erasesize) {
                offsets[eb++] = mtd->erasesize;
                offs -= mtd->erasesize;
        }
        offsets[eb] = offs;
        return 0;
}

static int do_operation(void)
{
        if (prandom_u32() & 1)
                return do_read();
        else
                return do_write();
}

static int __init mtd_stresstest_init(void)
{
        int err;
        int i, op;
        uint64_t tmp;

        printk(KERN_INFO "\n");
        printk(KERN_INFO "=================================================\n");

        if (dev < 0) {
                pr_info("Please specify a valid mtd-device via module parameter\n");
                pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
                return -EINVAL;
        }

        pr_info("MTD device: %d\n", dev);

        mtd = get_mtd_device(NULL, dev);
        if (IS_ERR(mtd)) {
                err = PTR_ERR(mtd);
                pr_err("error: cannot get MTD device\n");
                return err;
        }

        if (mtd->writesize == 1) {
                pr_info("not NAND flash, assume page size is 512 "
                       "bytes.\n");
                pgsize = 512;
        } else
                pgsize = mtd->writesize;

        tmp = mtd->size;
        do_div(tmp, mtd->erasesize);
        ebcnt = tmp;
        pgcnt = mtd->erasesize / pgsize;

        pr_info("MTD device size %llu, eraseblock size %u, "
               "page size %u, count of eraseblocks %u, pages per "
               "eraseblock %u, OOB size %u\n",
               (unsigned long long)mtd->size, mtd->erasesize,
               pgsize, ebcnt, pgcnt, mtd->oobsize);

        if (ebcnt < 2) {
                pr_err("error: need at least 2 eraseblocks\n");
                err = -ENOSPC;
                goto out_put_mtd;
        }

        /* Read or write up 2 eraseblocks at a time */
        bufsize = mtd->erasesize * 2;

        err = -ENOMEM;
        readbuf = vmalloc(bufsize);
        writebuf = vmalloc(bufsize);
        offsets = kmalloc(ebcnt * sizeof(int), GFP_KERNEL);
        if (!readbuf || !writebuf || !offsets)
                goto out;
        for (i = 0; i < ebcnt; i++)
                offsets[i] = mtd->erasesize;
        prandom_bytes(writebuf, bufsize);

        bbt = kzalloc(ebcnt, GFP_KERNEL);
        if (!bbt)
                goto out;
        err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
        if (err)
                goto out;

        /* Do operations */
        pr_info("doing operations\n");
        for (op = 0; op < count; op++) {
                if ((op & 1023) == 0)
                        pr_info("%d operations done\n", op);
                err = do_operation();
                if (err)
                        goto out;
                cond_resched();
        }
        pr_info("finished, %d operations done\n", op);

out:
        kfree(offsets);
        kfree(bbt);
        vfree(writebuf);
        vfree(readbuf);
out_put_mtd:
        put_mtd_device(mtd);
        if (err)
                pr_info("error %d occurred\n", err);
        printk(KERN_INFO "=================================================\n");
        return err;
}
module_init(mtd_stresstest_init);

static void __exit mtd_stresstest_exit(void)
{
        return;
}
module_exit(mtd_stresstest_exit);

MODULE_DESCRIPTION("Stress test module");
MODULE_AUTHOR("Adrian Hunter");
MODULE_LICENSE("GPL");