/*
 * 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.
 */

#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>

#define PRINT_PREF KERN_INFO "mtd_torturetest: "
#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;
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);
}

/*
 * Erase eraseblock number @ebnum.
 */
static inline int erase_eraseblock(int ebnum)
{
	int err;
	struct erase_info ei;
	loff_t addr = ebnum * mtd->erasesize;

	memset(&ei, 0, sizeof(struct erase_info));
	ei.mtd  = mtd;
	ei.addr = addr;
	ei.len  = mtd->erasesize;

	err = mtd->erase(mtd, &ei);
	if (err) {
		printk(PRINT_PREF "error %d while erasing EB %d\n", err, ebnum);
		return err;
	}

	if (ei.state == MTD_ERASE_FAILED) {
		printk(PRINT_PREF "some erase error occurred at EB %d\n",
		       ebnum);
		return -EIO;
	}

	return 0;
}

/*
 * 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 = 0;
	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 (err == -EUCLEAN)
		printk(PRINT_PREF "single bit flip occurred at EB %d "
		       "MTD reported that it was fixed.\n", ebnum);
	else if (err) {
		printk(PRINT_PREF "error %d while reading EB %d, "
		       "read %zd\n", err, ebnum, read);
		return err;
	}

	if (read != len) {
		printk(PRINT_PREF "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)) {
		printk(PRINT_PREF "read wrong data from EB %d\n", ebnum);
		report_corrupt(check_buf, buf);

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

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

	return 0;
}

static inline int write_pattern(int ebnum, void *buf)
{
	int err;
	size_t written = 0;
	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) {
		printk(PRINT_PREF "error %d while writing EB %d, written %zd"
		      " bytes\n", err, ebnum, written);
		return err;
	}
	if (written != len) {
		printk(PRINT_PREF "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;
	int bad_ebs[ebcnt];

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

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

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

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

	err = -ENOMEM;
	patt_5A5 = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!patt_5A5) {
		printk(PRINT_PREF "error: cannot allocate memory\n");
		goto out_mtd;
	}

	patt_A5A = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!patt_A5A) {
		printk(PRINT_PREF "error: cannot allocate memory\n");
		goto out_patt_5A5;
	}

	patt_FF = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!patt_FF) {
		printk(PRINT_PREF "error: cannot allocate memory\n");
		goto out_patt_A5A;
	}

	check_buf = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!check_buf) {
		printk(PRINT_PREF "error: cannot allocate memory\n");
		goto out_patt_FF;
	}

	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);
		}
	}

	/*
	 * Check if there is a bad eraseblock among those we are going to test.
	 */
	memset(&bad_ebs[0], 0, sizeof(int) * ebcnt);
	if (mtd->block_isbad) {
		for (i = eb; i < eb + ebcnt; i++) {
			err = mtd->block_isbad(mtd,
					       (loff_t)i * mtd->erasesize);

			if (err < 0) {
				printk(PRINT_PREF "block_isbad() returned %d "
				       "for EB %d\n", err, i);
				goto out;
			}

			if (err) {
				printk("EB %d is bad. Skip it.\n", i);
				bad_ebs[i - eb] = 1;
			}
		}
	}

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

		/* Erase all eraseblocks */
		for (i = eb; i < eb + ebcnt; i++) {
			if (bad_ebs[i - eb])
				continue;
			err = erase_eraseblock(i);
			if (err)
				goto out;
			cond_resched();
		}

		/* 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) {
					printk(PRINT_PREF "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) {
					printk(PRINT_PREF "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;
			printk(PRINT_PREF "%08u erase cycles done, took %lu "
			       "milliseconds (%lu seconds)\n",
			       erase_cycles, ms, ms / 1000);
			start_timing();
		}

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

	printk(PRINT_PREF "finished after %u erase cycles\n",
	       erase_cycles);
	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)
		printk(PRINT_PREF "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++;

	printk(PRINT_PREF "verify fails on %d pages, %d bytes/%d bits\n",
	       pages, bytes, bits);
	printk(PRINT_PREF "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");

		printk(PRINT_PREF "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");