/*
 * Copyright (C) 2006-2008 Artem Bityutskiy
 * Copyright (C) 2006-2008 Jarkko Lavinen
 * Copyright (C) 2006-2008 Adrian Hunter
 *
 * 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.
 *
 * Authors: Artem Bityutskiy, Jarkko Lavinen, Adria Hunter
 *
 * WARNING: this test program may kill your flash and your device. Do not
 * use it unless you know what you do. Authors are not responsible for any
 * damage caused by this program.
 */

#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 "mtd_test.h"

#define RETRIES 3

static int eb = 8;
module_param(eb, int, S_IRUGO);
MODULE_PARM_DESC(eb, "eraseblock number within the selected MTD device");

static int ebcnt = 32;
module_param(ebcnt, int, S_IRUGO);
MODULE_PARM_DESC(ebcnt, "number of consecutive eraseblocks to torture");

static int pgcnt;
module_param(pgcnt, int, S_IRUGO);
MODULE_PARM_DESC(pgcnt, "number of pages per eraseblock to torture (0 => all)");

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

static int gran = 512;
module_param(gran, int, S_IRUGO);
MODULE_PARM_DESC(gran, "how often the status information should be printed");

static int check = 1;
module_param(check, int, S_IRUGO);
MODULE_PARM_DESC(check, "if the written data should be checked");

static unsigned int cycles_count;
module_param(cycles_count, uint, S_IRUGO);
MODULE_PARM_DESC(cycles_count, "how many erase cycles to do "
                               "(infinite by default)");

static struct mtd_info *mtd;

/* This buffer contains 0x555555...0xAAAAAA... pattern */
static unsigned char *patt_5A5;
/* This buffer contains 0xAAAAAA...0x555555... pattern */
static unsigned char *patt_A5A;
/* This buffer contains all 0xFF bytes */
static unsigned char *patt_FF;
/* This a temporary buffer is use when checking data */
static unsigned char *check_buf;
/* How many erase cycles were done */
static unsigned int erase_cycles;

static int pgsize;
static struct timeval start, finish;

static void report_corrupt(unsigned char *read, unsigned char *written);

static inline void start_timing(void)
{
        do_gettimeofday(&start);
}

static inline void stop_timing(void)
{
        do_gettimeofday(&finish);
}

/*
 * Check that the contents of eraseblock number @enbum is equivalent to the
 * @buf buffer.
 */
static inline int check_eraseblock(int ebnum, unsigned char *buf)
{
        int err, retries = 0;
        size_t read;
        loff_t addr = ebnum * mtd->erasesize;
        size_t len = mtd->erasesize;

        if (pgcnt) {
                addr = (ebnum + 1) * mtd->erasesize - pgcnt * pgsize;
                len = pgcnt * pgsize;
        }

retry:
        err = mtd_read(mtd, addr, len, &read, check_buf);
        if (mtd_is_bitflip(err))
                pr_err("single bit flip occurred at EB %d "
                       "MTD reported that it was fixed.\n", ebnum);
        else if (err) {
                pr_err("error %d while reading EB %d, "
                       "read %zd\n", err, ebnum, read);
                return err;
        }

        if (read != len) {
                pr_err("failed to read %zd bytes from EB %d, "
                       "read only %zd, but no error reported\n",
                       len, ebnum, read);
                return -EIO;
        }

        if (memcmp(buf, check_buf, len)) {
                pr_err("read wrong data from EB %d\n", ebnum);
                report_corrupt(check_buf, buf);

                if (retries++ < RETRIES) {
                        /* Try read again */
                        yield();
                        pr_info("re-try reading data from EB %d\n",
                               ebnum);
                        goto retry;
                } else {
                        pr_info("retried %d times, still errors, "
                               "give-up\n", RETRIES);
                        return -EINVAL;
                }
        }

        if (retries != 0)
                pr_info("only attempt number %d was OK (!!!)\n",
                       retries);

        return 0;
}

static inline int write_pattern(int ebnum, void *buf)
{
        int err;
        size_t written;
        loff_t addr = ebnum * mtd->erasesize;
        size_t len = mtd->erasesize;

        if (pgcnt) {
                addr = (ebnum + 1) * mtd->erasesize - pgcnt * pgsize;
                len = pgcnt * pgsize;
        }
        err = mtd_write(mtd, addr, len, &written, buf);
        if (err) {
                pr_err("error %d while writing EB %d, written %zd"
                      " bytes\n", err, ebnum, written);
                return err;
        }
        if (written != len) {
                pr_info("written only %zd bytes of %zd, but no error"
                       " reported\n", written, len);
                return -EIO;
        }

        return 0;
}

static int __init tort_init(void)
{
        int err = 0, i, infinite = !cycles_count;
        unsigned char *bad_ebs;

        printk(KERN_INFO "\n");
        printk(KERN_INFO "=================================================\n");
        pr_info("Warning: this program is trying to wear out your "
               "flash, stop it if this is not wanted.\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);
        pr_info("torture %d eraseblocks (%d-%d) of mtd%d\n",
               ebcnt, eb, eb + ebcnt - 1, dev);
        if (pgcnt)
                pr_info("torturing just %d pages per eraseblock\n",
                        pgcnt);
        pr_info("write verify %s\n", check ? "enabled" : "disabled");

        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;

        if (pgcnt && (pgcnt > mtd->erasesize / pgsize || pgcnt < 0)) {
                pr_err("error: invalid pgcnt value %d\n", pgcnt);
                goto out_mtd;
        }

        err = -ENOMEM;
        patt_5A5 = kmalloc(mtd->erasesize, GFP_KERNEL);
        if (!patt_5A5)
                goto out_mtd;

        patt_A5A = kmalloc(mtd->erasesize, GFP_KERNEL);
        if (!patt_A5A)
                goto out_patt_5A5;

        patt_FF = kmalloc(mtd->erasesize, GFP_KERNEL);
        if (!patt_FF)
                goto out_patt_A5A;

        check_buf = kmalloc(mtd->erasesize, GFP_KERNEL);
        if (!check_buf)
                goto out_patt_FF;

        bad_ebs = kzalloc(ebcnt, GFP_KERNEL);
        if (!bad_ebs)
                goto out_check_buf;

        err = 0;

        /* Initialize patterns */
        memset(patt_FF, 0xFF, mtd->erasesize);
        for (i = 0; i < mtd->erasesize / pgsize; i++) {
                if (!(i & 1)) {
                        memset(patt_5A5 + i * pgsize, 0x55, pgsize);
                        memset(patt_A5A + i * pgsize, 0xAA, pgsize);
                } else {
                        memset(patt_5A5 + i * pgsize, 0xAA, pgsize);
                        memset(patt_A5A + i * pgsize, 0x55, pgsize);
                }
        }

        err = mtdtest_scan_for_bad_eraseblocks(mtd, bad_ebs, eb, ebcnt);
        if (err)
                goto out;

        start_timing();
        while (1) {
                int i;
                void *patt;

                mtdtest_erase_good_eraseblocks(mtd, bad_ebs, eb, ebcnt);

                /* Check if the eraseblocks contain only 0xFF bytes */
                if (check) {
                        for (i = eb; i < eb + ebcnt; i++) {
                                if (bad_ebs[i - eb])
                                        continue;
                                err = check_eraseblock(i, patt_FF);
                                if (err) {
                                        pr_info("verify failed"
                                               " for 0xFF... pattern\n");
                                        goto out;
                                }
                                cond_resched();
                        }
                }

                /* Write the pattern */
                for (i = eb; i < eb + ebcnt; i++) {
                        if (bad_ebs[i - eb])
                                continue;
                        if ((eb + erase_cycles) & 1)
                                patt = patt_5A5;
                        else
                                patt = patt_A5A;
                        err = write_pattern(i, patt);
                        if (err)
                                goto out;
                        cond_resched();
                }

                /* Verify what we wrote */
                if (check) {
                        for (i = eb; i < eb + ebcnt; i++) {
                                if (bad_ebs[i - eb])
                                        continue;
                                if ((eb + erase_cycles) & 1)
                                        patt = patt_5A5;
                                else
                                        patt = patt_A5A;
                                err = check_eraseblock(i, patt);
                                if (err) {
                                        pr_info("verify failed for %s"
                                               " pattern\n",
                                               ((eb + erase_cycles) & 1) ?
                                               "0x55AA55..." : "0xAA55AA...");
                                        goto out;
                                }
                                cond_resched();
                        }
                }

                erase_cycles += 1;

                if (erase_cycles % gran == 0) {
                        long ms;

                        stop_timing();
                        ms = (finish.tv_sec - start.tv_sec) * 1000 +
                             (finish.tv_usec - start.tv_usec) / 1000;
                        pr_info("%08u erase cycles done, took %lu "
                               "milliseconds (%lu seconds)\n",
                               erase_cycles, ms, ms / 1000);
                        start_timing();
                }

                if (!infinite && --cycles_count == 0)
                        break;
        }
out:

        pr_info("finished after %u erase cycles\n",
               erase_cycles);
        kfree(bad_ebs);
out_check_buf:
        kfree(check_buf);
out_patt_FF:
        kfree(patt_FF);
out_patt_A5A:
        kfree(patt_A5A);
out_patt_5A5:
        kfree(patt_5A5);
out_mtd:
        put_mtd_device(mtd);
        if (err)
                pr_info("error %d occurred during torturing\n", err);
        printk(KERN_INFO "=================================================\n");
        return err;
}
module_init(tort_init);

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

static int countdiffs(unsigned char *buf, unsigned char *check_buf,
                      unsigned offset, unsigned len, unsigned *bytesp,
                      unsigned *bitsp);
static void print_bufs(unsigned char *read, unsigned char *written, int start,
                       int len);

/*
 * Report the detailed information about how the read EB differs from what was
 * written.
 */
static void report_corrupt(unsigned char *read, unsigned char *written)
{
        int i;
        int bytes, bits, pages, first;
        int offset, len;
        size_t check_len = mtd->erasesize;

        if (pgcnt)
                check_len = pgcnt * pgsize;

        bytes = bits = pages = 0;
        for (i = 0; i < check_len; i += pgsize)
                if (countdiffs(written, read, i, pgsize, &bytes,
                               &bits) >= 0)
                        pages++;

        pr_info("verify fails on %d pages, %d bytes/%d bits\n",
               pages, bytes, bits);
        pr_info("The following is a list of all differences between"
               " what was read from flash and what was expected\n");

        for (i = 0; i < check_len; i += pgsize) {
                cond_resched();
                bytes = bits = 0;
                first = countdiffs(written, read, i, pgsize, &bytes,
                                   &bits);
                if (first < 0)
                        continue;

                printk("-------------------------------------------------------"
                       "----------------------------------\n");

                pr_info("Page %zd has %d bytes/%d bits failing verify,"
                       " starting at offset 0x%x\n",
                       (mtd->erasesize - check_len + i) / pgsize,
                       bytes, bits, first);

                offset = first & ~0x7;
                len = ((first + bytes) | 0x7) + 1 - offset;

                print_bufs(read, written, offset, len);
        }
}

static void print_bufs(unsigned char *read, unsigned char *written, int start,
                       int len)
{
        int i = 0, j1, j2;
        char *diff;

        printk("Offset       Read                          Written\n");
        while (i < len) {
                printk("0x%08x: ", start + i);
                diff = "   ";
                for (j1 = 0; j1 < 8 && i + j1 < len; j1++) {
                        printk(" %02x", read[start + i + j1]);
                        if (read[start + i + j1] != written[start + i + j1])
                                diff = "***";
                }

                while (j1 < 8) {
                        printk(" ");
                        j1 += 1;
                }

                printk("  %s ", diff);

                for (j2 = 0; j2 < 8 && i + j2 < len; j2++)
                        printk(" %02x", written[start + i + j2]);
                printk("\n");
                i += 8;
        }
}

/*
 * Count the number of differing bytes and bits and return the first differing
 * offset.
 */
static int countdiffs(unsigned char *buf, unsigned char *check_buf,
                      unsigned offset, unsigned len, unsigned *bytesp,
                      unsigned *bitsp)
{
        unsigned i, bit;
        int first = -1;

        for (i = offset; i < offset + len; i++)
                if (buf[i] != check_buf[i]) {
                        first = i;
                        break;
                }

        while (i < offset + len) {
                if (buf[i] != check_buf[i]) {
                        (*bytesp)++;
                        bit = 1;
                        while (bit < 256) {
                                if ((buf[i] & bit) != (check_buf[i] & bit))
                                        (*bitsp)++;
                                bit <<= 1;
                        }
                }
                i++;
        }

        return first;
}

MODULE_DESCRIPTION("Eraseblock torturing module");
MODULE_AUTHOR("Artem Bityutskiy, Jarkko Lavinen, Adrian Hunter");
MODULE_LICENSE("GPL");