mtd: Add new SmartMedia/xD FTL

This implements new readwrite SmartMedia/xd FTL.

mtd driver must have support proper ECC and badblock verification
based on oob parts for 512 bytes nand.

Also mtd driver must define read_oob and write_oob, which are used
to read and write both data and oob together.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 1284 insertions, 0 deletions

diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c
new file mode 100644
index 000000000000..a59ebb48cae1
--- /dev/null
+++ b/drivers/mtd/sm_ftl.c
@@ -0,0 +1,1284 @@
+/*
+ * Copyright © 2009 - Maxim Levitsky
+ * SmartMedia/xD translation layer
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/hdreg.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/sysfs.h>
+#include <linux/bitops.h>
+#include "nand/sm_common.h"
+#include "sm_ftl.h"
+
+#ifdef CONFIG_SM_FTL_MUSEUM
+#include <linux/mtd/nand_ecc.h>
+#endif
+
+
+struct workqueue_struct *cache_flush_workqueue;
+
+static int cache_timeout = 1000;
+module_param(cache_timeout, bool, S_IRUGO);
+MODULE_PARM_DESC(cache_timeout,
+        "Timeout (in ms) for cache flush (1000 ms default");
+
+static int debug;
+module_param(debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug level (0-2)");
+
+
+/* ------------------- sysfs attributtes ---------------------------------- */
+struct sm_sysfs_attribute {
+        struct device_attribute dev_attr;
+        char *data;
+        int len;
+};
+
+ssize_t sm_attr_show(struct device *dev, struct device_attribute *attr,
+                     char *buf)
+{
+        struct sm_sysfs_attribute *sm_attr =
+                container_of(attr, struct sm_sysfs_attribute, dev_attr);
+
+        strncpy(buf, sm_attr->data, sm_attr->len);
+        return sm_attr->len;
+}
+
+
+#define NUM_ATTRIBUTES 1
+#define SM_CIS_VENDOR_OFFSET 0x59
+struct attribute_group *sm_create_sysfs_attributes(struct sm_ftl *ftl)
+{
+        struct attribute_group *attr_group;
+        struct attribute **attributes;
+        struct sm_sysfs_attribute *vendor_attribute;
+
+        int vendor_len = strnlen(ftl->cis_buffer + SM_CIS_VENDOR_OFFSET,
+                                        SM_SMALL_PAGE - SM_CIS_VENDOR_OFFSET);
+
+        char *vendor = kmalloc(vendor_len, GFP_KERNEL);
+        memcpy(vendor, ftl->cis_buffer + SM_CIS_VENDOR_OFFSET, vendor_len);
+        vendor[vendor_len] = 0;
+
+        /* Initialize sysfs attributes */
+        vendor_attribute =
+                kzalloc(sizeof(struct sm_sysfs_attribute), GFP_KERNEL);
+
+        vendor_attribute->data = vendor;
+        vendor_attribute->len = vendor_len;
+        vendor_attribute->dev_attr.attr.name = "vendor";
+        vendor_attribute->dev_attr.attr.mode = S_IRUGO;
+        vendor_attribute->dev_attr.show = sm_attr_show;
+
+
+        /* Create array of pointers to the attributes */
+        attributes = kzalloc(sizeof(struct attribute *) * (NUM_ATTRIBUTES + 1),
+                                                                GFP_KERNEL);
+        attributes[0] = &vendor_attribute->dev_attr.attr;
+
+        /* Finally create the attribute group */
+        attr_group = kzalloc(sizeof(struct attribute_group), GFP_KERNEL);
+        attr_group->attrs = attributes;
+        return attr_group;
+}
+
+void sm_delete_sysfs_attributes(struct sm_ftl *ftl)
+{
+        struct attribute **attributes = ftl->disk_attributes->attrs;
+        int i;
+
+        for (i = 0; attributes[i] ; i++) {
+
+                struct device_attribute *dev_attr = container_of(attributes[i],
+                        struct device_attribute, attr);
+
+                struct sm_sysfs_attribute *sm_attr =
+                        container_of(dev_attr,
+                                struct sm_sysfs_attribute, dev_attr);
+
+                kfree(sm_attr->data);
+                kfree(sm_attr);
+        }
+
+        kfree(ftl->disk_attributes->attrs);
+        kfree(ftl->disk_attributes);
+}
+
+
+/* ----------------------- oob helpers -------------------------------------- */
+
+static int sm_get_lba(uint8_t *lba)
+{
+        /* check fixed bits */
+        if ((lba[0] & 0xF8) != 0x10)
+                return -2;
+
+        /* check parity - endianess doesn't matter */
+        if (hweight16(*(uint16_t *)lba) & 1)
+                return -2;
+
+        return (lba[1] >> 1) | ((lba[0] & 0x07) << 7);
+}
+
+
+/*
+ * Read LBA asscociated with block
+ * returns -1, if block is erased
+ * returns -2 if error happens
+ */
+static int sm_read_lba(struct sm_oob *oob)
+{
+        static const uint32_t erased_pattern[4] = {
+                0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
+
+        uint16_t lba_test;
+        int lba;
+
+        /* First test for erased block */
+        if (!memcmp(oob, erased_pattern, SM_OOB_SIZE))
+                return -1;
+
+        /* Now check is both copies of the LBA differ too much */
+        lba_test = *(uint16_t *)oob->lba_copy1 ^ *(uint16_t*)oob->lba_copy2;
+        if (lba_test && !is_power_of_2(lba_test))
+                return -2;
+
+        /* And read it */
+        lba = sm_get_lba(oob->lba_copy1);
+
+        if (lba == -2)
+                lba = sm_get_lba(oob->lba_copy2);
+
+        return lba;
+}
+
+static void sm_write_lba(struct sm_oob *oob, uint16_t lba)
+{
+        uint8_t tmp[2];
+
+        WARN_ON(lba >= 1000);
+
+        tmp[0] = 0x10 | ((lba >> 7) & 0x07);
+        tmp[1] = (lba << 1) & 0xFF;
+
+        if (hweight16(*(uint16_t *)tmp) & 0x01)
+                tmp[1] |= 1;
+
+        oob->lba_copy1[0] = oob->lba_copy2[0] = tmp[0];
+        oob->lba_copy1[1] = oob->lba_copy2[1] = tmp[1];
+}
+
+
+/* Make offset from parts */
+static loff_t sm_mkoffset(struct sm_ftl *ftl, int zone, int block, int boffset)
+{
+        WARN_ON(boffset & (SM_SECTOR_SIZE - 1));
+        WARN_ON(zone < 0 || zone >= ftl->zone_count);
+        WARN_ON(block >= ftl->zone_size);
+        WARN_ON(boffset >= ftl->block_size);
+
+        if (block == -1)
+                return -1;
+
+        return (zone * SM_MAX_ZONE_SIZE + block) * ftl->block_size + boffset;
+}
+
+/* Breaks offset into parts */
+static void sm_break_offset(struct sm_ftl *ftl, loff_t offset,
+                            int *zone, int *block, int *boffset)
+{
+        *boffset = do_div(offset, ftl->block_size);
+        *block = do_div(offset, ftl->max_lba);
+        *zone = offset >= ftl->zone_count ? -1 : offset;
+}
+
+/* ---------------------- low level IO ------------------------------------- */
+
+static int sm_correct_sector(uint8_t *buffer, struct sm_oob *oob)
+{
+#ifdef CONFIG_SM_FTL_MUSEUM
+        uint8_t ecc[3];
+
+        __nand_calculate_ecc(buffer, SM_SMALL_PAGE, ecc);
+        if (__nand_correct_data(buffer, ecc, oob->ecc1, SM_SMALL_PAGE) < 0)
+                return -EIO;
+
+        buffer += SM_SMALL_PAGE;
+
+        __nand_calculate_ecc(buffer, SM_SMALL_PAGE, ecc);
+        if (__nand_correct_data(buffer, ecc, oob->ecc2, SM_SMALL_PAGE) < 0)
+                return -EIO;
+#endif
+        return 0;
+}
+
+/* Reads a sector + oob*/
+static int sm_read_sector(struct sm_ftl *ftl,
+                          int zone, int block, int boffset,
+                          uint8_t *buffer, struct sm_oob *oob)
+{
+        struct mtd_info *mtd = ftl->trans->mtd;
+        struct mtd_oob_ops ops;
+        struct sm_oob tmp_oob;
+        int ret;
+        int try = 0;
+
+        /* FTL can contain -1 entries that are by default filled with bits */
+        if (block == -1) {
+                memset(buffer, 0xFF, SM_SECTOR_SIZE);
+                return 0;
+        }
+
+        /* User might not need the oob, but we do for data vertification */
+        if (!oob)
+                oob = &tmp_oob;
+
+        ops.mode = ftl->smallpagenand ? MTD_OOB_RAW : MTD_OOB_PLACE;
+        ops.ooboffs = 0;
+        ops.ooblen = SM_OOB_SIZE;
+        ops.oobbuf = (void *)oob;
+        ops.len = SM_SECTOR_SIZE;
+        ops.datbuf = buffer;
+
+again:
+        if (try++) {
+                /* Avoid infinite recursion on CIS reads, sm_recheck_media
+                        won't help anyway */
+                if (zone == 0 && block == ftl->cis_block && boffset ==
+                        ftl->cis_boffset)
+                        return ret;
+
+                /* Test if media is stable */
+                if (try == 3 || sm_recheck_media(ftl))
+                        return ret;
+        }
+
+        /* Unfortunelly, oob read will _always_ succeed,
+                despite card removal..... */
+        ret = mtd->read_oob(mtd, sm_mkoffset(ftl, zone, block, boffset), &ops);
+
+        /* Test for unknown errors */
+        if (ret != 0 && ret != -EUCLEAN && ret != -EBADMSG) {
+                dbg("read of block %d at zone %d, failed due to error (%d)",
+                        block, zone, ret);
+                goto again;
+        }
+
+        /* Do a basic test on the oob, to guard against returned garbage */
+        if (oob->reserved != 0xFFFFFFFF && !is_power_of_2(~oob->reserved))
+                goto again;
+
+        /* This should never happen, unless there is a bug in the mtd driver */
+        WARN_ON(ops.oobretlen != SM_OOB_SIZE);
+        WARN_ON(buffer && ops.retlen != SM_SECTOR_SIZE);
+
+        if (!buffer)
+                return 0;
+
+        /* Test if sector marked as bad */
+        if (!sm_sector_valid(oob)) {
+                dbg("read of block %d at zone %d, failed because it is marked"
+                        " as bad" , block, zone);
+                goto again;
+        }
+
+        /* Test ECC*/
+        if (ret == -EBADMSG ||
+                (ftl->smallpagenand && sm_correct_sector(buffer, oob))) {
+
+                dbg("read of block %d at zone %d, failed due to ECC error",
+                        block, zone);
+                goto again;
+        }
+
+        return 0;
+}
+
+/* Writes a sector to media */
+static int sm_write_sector(struct sm_ftl *ftl,
+                           int zone, int block, int boffset,
+                           uint8_t *buffer, struct sm_oob *oob)
+{
+        struct mtd_oob_ops ops;
+        struct mtd_info *mtd = ftl->trans->mtd;
+        int ret;
+
+        BUG_ON(ftl->readonly);
+
+        if (zone == 0 && (block == ftl->cis_block || block == 0)) {
+                dbg("attempted to write the CIS!");
+                return -EIO;
+        }
+
+        if (ftl->unstable)
+                return -EIO;
+
+        ops.mode = ftl->smallpagenand ? MTD_OOB_RAW : MTD_OOB_PLACE;
+        ops.len = SM_SECTOR_SIZE;
+        ops.datbuf = buffer;
+        ops.ooboffs = 0;
+        ops.ooblen = SM_OOB_SIZE;
+        ops.oobbuf = (void *)oob;
+
+        ret = mtd->write_oob(mtd, sm_mkoffset(ftl, zone, block, boffset), &ops);
+
+        /* Now we assume that hardware will catch write bitflip errors */
+        /* If you are paranoid, use CONFIG_MTD_NAND_VERIFY_WRITE */
+
+        if (ret) {
+                dbg("write to block %d at zone %d, failed with error %d",
+                        block, zone, ret);
+
+                sm_recheck_media(ftl);
+                return ret;
+        }
+
+        /* This should never happen, unless there is a bug in the driver */
+        WARN_ON(ops.oobretlen != SM_OOB_SIZE);
+        WARN_ON(buffer && ops.retlen != SM_SECTOR_SIZE);
+
+        return 0;
+}
+
+/* ------------------------ block IO ------------------------------------- */
+
+/* Write a block using data and lba, and invalid sector bitmap */
+static int sm_write_block(struct sm_ftl *ftl, uint8_t *buf,
+                          int zone, int block, int lba,
+                          unsigned long invalid_bitmap)
+{
+        struct sm_oob oob;
+        int boffset;
+        int retry = 0;
+
+        /* Initialize the oob with requested values */
+        memset(&oob, 0xFF, SM_OOB_SIZE);
+        sm_write_lba(&oob, lba);
+restart:
+        if (ftl->unstable)
+                return -EIO;
+
+        for (boffset = 0; boffset < ftl->block_size;
+                                boffset += SM_SECTOR_SIZE) {
+
+                oob.data_status = 0xFF;
+
+                if (test_bit(boffset / SM_SECTOR_SIZE, &invalid_bitmap)) {
+
+                        sm_printk("sector %d of block at LBA %d of zone %d"
+                                " coudn't be read, marking it as invalid",
+                                boffset / SM_SECTOR_SIZE, lba, zone);
+
+                        oob.data_status = 0;
+                }
+
+#ifdef CONFIG_SM_FTL_MUSEUM
+                if (ftl->smallpagenand) {
+                        __nand_calculate_ecc(buf + boffset,
+                                                SM_SMALL_PAGE, oob.ecc1);
+
+                        __nand_calculate_ecc(buf + boffset + SM_SMALL_PAGE,
+                                                SM_SMALL_PAGE, oob.ecc2);
+                }
+#endif
+                if (!sm_write_sector(ftl, zone, block, boffset,
+                                                        buf + boffset, &oob))
+                        continue;
+
+                if (!retry) {
+
+                        /* If write fails. try to erase the block */
+                        /* This is safe, because we never write in blocks
+                                that contain valuable data.
+                        This is intended to repair block that are marked
+                        as erased, but that isn't fully erased*/
+
+                        if (sm_erase_block(ftl, zone, block, 0))
+                                return -EIO;
+
+                        retry = 1;
+                        goto restart;
+                } else {
+                        sm_mark_block_bad(ftl, zone, block);
+                        return -EIO;
+                }
+        }
+        return 0;
+}
+
+
+/* Mark whole block at offset 'offs' as bad. */
+static void sm_mark_block_bad(struct sm_ftl *ftl, int zone, int block)
+{
+        struct sm_oob oob;
+        int boffset;
+
+        memset(&oob, 0xFF, SM_OOB_SIZE);
+        oob.block_status = 0xF0;
+
+        if (ftl->unstable)
+                return;
+
+        if (sm_recheck_media(ftl))
+                return;
+
+        sm_printk("marking block %d of zone %d as bad", block, zone);
+
+        /* We aren't checking the return value, because we don't care */
+        /* This also fails on fake xD cards, but I guess these won't expose
+                any bad blocks till fail completly */
+        for (boffset = 0; boffset < ftl->block_size; boffset += SM_SECTOR_SIZE)
+                sm_write_sector(ftl, zone, block, boffset, NULL, &oob);
+}
+
+/*
+ * Erase a block within a zone
+ * If erase succedes, it updates free block fifo, otherwise marks block as bad
+ */
+static int sm_erase_block(struct sm_ftl *ftl, int zone_num, uint16_t block,
+                          int put_free)
+{
+        struct ftl_zone *zone = &ftl->zones[zone_num];
+        struct mtd_info *mtd = ftl->trans->mtd;
+        struct erase_info erase;
+
+        erase.mtd = mtd;
+        erase.callback = sm_erase_callback;
+        erase.addr = sm_mkoffset(ftl, zone_num, block, 0);
+        erase.len = ftl->block_size;
+        erase.priv = (u_long)ftl;
+
+        if (ftl->unstable)
+                return -EIO;
+
+        BUG_ON(ftl->readonly);
+
+        if (zone_num == 0 && (block == ftl->cis_block || block == 0)) {
+                sm_printk("attempted to erase the CIS!");
+                return -EIO;
+        }
+
+        if (mtd->erase(mtd, &erase)) {
+                sm_printk("erase of block %d in zone %d failed",
+                                                        block, zone_num);
+                goto error;
+        }
+
+        if (erase.state == MTD_ERASE_PENDING)
+                wait_for_completion(&ftl->erase_completion);
+
+        if (erase.state != MTD_ERASE_DONE) {
+                sm_printk("erase of block %d in zone %d failed after wait",
+                        block, zone_num);
+                goto error;
+        }
+
+        if (put_free)
+                kfifo_in(&zone->free_sectors,
+                        (const unsigned char *)&block, sizeof(block));
+
+        return 0;
+error:
+        sm_mark_block_bad(ftl, zone_num, block);
+        return -EIO;
+}
+
+static void sm_erase_callback(struct erase_info *self)
+{
+        struct sm_ftl *ftl = (struct sm_ftl *)self->priv;
+        complete(&ftl->erase_completion);
+}
+
+/* Throughtly test that block is valid. */
+static int sm_check_block(struct sm_ftl *ftl, int zone, int block)
+{
+        int boffset;
+        struct sm_oob oob;
+        int lbas[] = { -3, 0, 0, 0 };
+        int i = 0;
+        int test_lba;
+
+
+        /* First just check that block doesn't look fishy */
+        /* Only blocks that are valid or are sliced in two parts, are
+                accepted */
+        for (boffset = 0; boffset < ftl->block_size;
+                                        boffset += SM_SECTOR_SIZE) {
+
+                /* This shoudn't happen anyway */
+                if (sm_read_sector(ftl, zone, block, boffset, NULL, &oob))
+                        return -2;
+
+                test_lba = sm_read_lba(&oob);
+
+                if (lbas[i] != test_lba)
+                        lbas[++i] = test_lba;
+
+                /* If we found three different LBAs, something is fishy */
+                if (i == 3)
+                        return -EIO;
+        }
+
+        /* If the block is sliced (partialy erased usually) erase it */
+        if (i == 2) {
+                sm_erase_block(ftl, zone, block, 1);
+                return 1;
+        }
+
+        return 0;
+}
+
+/* ----------------- media scanning --------------------------------- */
+static const struct chs_entry chs_table[] = {
+        { 1,    125,  4,  4  },
+        { 2,    125,  4,  8  },
+        { 4,    250,  4,  8  },
+        { 8,    250,  4,  16 },
+        { 16,   500,  4,  16 },
+        { 32,   500,  8,  16 },
+        { 64,   500,  8,  32 },
+        { 128,  500,  16, 32 },
+        { 256,  1000, 16, 32 },
+        { 512,  1015, 32, 63 },
+        { 1024, 985,  33, 63 },
+        { 2048, 985,  33, 63 },
+        { 0 },
+};
+
+
+static const uint8_t cis_signature[] = {
+        0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
+};
+/* Find out media parameters.
+ * This ideally has to be based on nand id, but for now device size is enough */
+int sm_get_media_info(struct sm_ftl *ftl, struct mtd_info *mtd)
+{
+        int i;
+        int size_in_megs = mtd->size / (1024 * 1024);
+
+        ftl->readonly = mtd->type == MTD_ROM;
+
+        /* Manual settings for very old devices */
+        ftl->zone_count = 1;
+        ftl->smallpagenand = 0;
+
+        switch (size_in_megs) {
+        case 1:
+                /* 1 MiB flash/rom SmartMedia card (256 byte pages)*/
+                ftl->zone_size = 256;
+                ftl->max_lba = 250;
+                ftl->block_size = 8 * SM_SECTOR_SIZE;
+                ftl->smallpagenand = 1;
+
+                break;
+        case 2:
+                /* 2 MiB flash SmartMedia (256 byte pages)*/
+                if (mtd->writesize == SM_SMALL_PAGE) {
+                        ftl->zone_size = 512;
+                        ftl->max_lba = 500;
+                        ftl->block_size = 8 * SM_SECTOR_SIZE;
+                        ftl->smallpagenand = 1;
+                /* 2 MiB rom SmartMedia */
+                } else {
+
+                        if (!ftl->readonly)
+                                return -ENODEV;
+
+                        ftl->zone_size = 256;
+                        ftl->max_lba = 250;
+                        ftl->block_size = 16 * SM_SECTOR_SIZE;
+                }
+                break;
+        case 4:
+                /* 4 MiB flash/rom SmartMedia device */
+                ftl->zone_size = 512;
+                ftl->max_lba = 500;
+                ftl->block_size = 16 * SM_SECTOR_SIZE;
+                break;
+        case 8:
+                /* 8 MiB flash/rom SmartMedia device */
+                ftl->zone_size = 1024;
+                ftl->max_lba = 1000;
+                ftl->block_size = 16 * SM_SECTOR_SIZE;
+        }
+
+        /* Minimum xD size is 16MiB. Also, all xD cards have standard zone
+           sizes. SmartMedia cards exist up to 128 MiB and have same layout*/
+        if (size_in_megs >= 16) {
+                ftl->zone_count = size_in_megs / 16;
+                ftl->zone_size = 1024;
+                ftl->max_lba = 1000;
+                ftl->block_size = 32 * SM_SECTOR_SIZE;
+        }
+
+        /* Test for proper write,erase and oob sizes */
+        if (mtd->erasesize > ftl->block_size)
+                return -ENODEV;
+
+        if (mtd->writesize > SM_SECTOR_SIZE)
+                return -ENODEV;
+
+        if (ftl->smallpagenand && mtd->oobsize < SM_SMALL_OOB_SIZE)
+                return -ENODEV;
+
+        if (!ftl->smallpagenand && mtd->oobsize < SM_OOB_SIZE)
+                return -ENODEV;
+
+        /* We use these functions for IO */
+        if (!mtd->read_oob || !mtd->write_oob)
+                return -ENODEV;
+
+        /* Find geometry information */
+        for (i = 0 ; i < ARRAY_SIZE(chs_table) ; i++) {
+                if (chs_table[i].size == size_in_megs) {
+                        ftl->cylinders = chs_table[i].cyl;
+                        ftl->heads = chs_table[i].head;
+                        ftl->sectors = chs_table[i].sec;
+                        return 0;
+                }
+        }
+
+        sm_printk("media has unknown size : %dMiB", size_in_megs);
+        ftl->cylinders = 985;
+        ftl->heads =  33;
+        ftl->sectors = 63;
+        return 0;
+}
+
+/* Validate the CIS */
+static int sm_read_cis(struct sm_ftl *ftl)
+{
+        struct sm_oob oob;
+
+        if (sm_read_sector(ftl,
+                0, ftl->cis_block, ftl->cis_boffset, ftl->cis_buffer, &oob))
+                        return -EIO;
+
+        if (!sm_sector_valid(&oob) || !sm_block_valid(&oob))
+                return -EIO;
+
+        if (!memcmp(ftl->cis_buffer + ftl->cis_page_offset,
+                        cis_signature, sizeof(cis_signature))) {
+                return 0;
+        }
+
+        return -EIO;
+}
+
+/* Scan the media for the CIS */
+static int sm_find_cis(struct sm_ftl *ftl)
+{
+        struct sm_oob oob;
+        int block, boffset;
+        int block_found = 0;
+        int cis_found = 0;
+
+        /* Search for first valid block */
+        for (block = 0 ; block < ftl->zone_size - ftl->max_lba ; block++) {
+
+                if (sm_read_sector(ftl, 0, block, 0, NULL, &oob))
+                        continue;
+
+                if (!sm_block_valid(&oob))
+                        continue;
+                block_found = 1;
+                break;
+        }
+
+        if (!block_found)
+                return -EIO;
+
+        /* Search for first valid sector in this block */
+        for (boffset = 0 ; boffset < ftl->block_size;
+                                                boffset += SM_SECTOR_SIZE) {
+
+                if (sm_read_sector(ftl, 0, block, boffset, NULL, &oob))
+                        continue;
+
+                if (!sm_sector_valid(&oob))
+                        continue;
+                break;
+        }
+
+        if (boffset == ftl->block_size)
+                return -EIO;
+
+        ftl->cis_block = block;
+        ftl->cis_boffset = boffset;
+        ftl->cis_page_offset = 0;
+
+        cis_found = !sm_read_cis(ftl);
+
+        if (!cis_found) {
+                ftl->cis_page_offset = SM_SMALL_PAGE;
+                cis_found = !sm_read_cis(ftl);
+        }
+
+        if (cis_found) {
+                dbg("CIS block found at offset %x",
+                        block * ftl->block_size +
+                                boffset + ftl->cis_page_offset);
+                return 0;
+        }
+        return -EIO;
+}
+
+/* Basic test to determine if underlying mtd device if functional */
+static int sm_recheck_media(struct sm_ftl *ftl)
+{
+        if (sm_read_cis(ftl)) {
+
+                if (!ftl->unstable) {
+                        sm_printk("media unstable, not allowing writes");
+                        ftl->unstable = 1;
+                }
+                return -EIO;
+        }
+        return 0;
+}
+
+/* Initialize a FTL zone */
+static int sm_init_zone(struct sm_ftl *ftl, int zone_num)
+{
+        struct ftl_zone *zone = &ftl->zones[zone_num];
+        struct sm_oob oob;
+        uint16_t block;
+        int lba;
+        int i = 0;
+
+        dbg("initializing zone %d", zone_num);
+
+        /* Allocate memory for FTL table */
+        zone->lba_to_phys_table = kmalloc(ftl->max_lba * 2, GFP_KERNEL);
+
+        if (!zone->lba_to_phys_table)
+                return -ENOMEM;
+        memset(zone->lba_to_phys_table, -1, ftl->max_lba * 2);
+
+
+        /* Allocate memory for free sectors FIFO */
+        if (kfifo_alloc(&zone->free_sectors, ftl->zone_size * 2, GFP_KERNEL)) {
+                kfree(zone->lba_to_phys_table);
+                return -ENOMEM;
+        }
+
+        /* Now scan the zone */
+        for (block = 0 ; block < ftl->zone_size ; block++) {
+
+                /* Skip blocks till the CIS (including) */
+                if (zone_num == 0 && block <= ftl->cis_block)
+                        continue;
+
+                /* Read the oob of first sector */
+                if (sm_read_sector(ftl, zone_num, block, 0, NULL, &oob))
+                        return -EIO;
+
+                /* Test to see if block is erased. It is enough to test
+                        first sector, because erase happens in one shot */
+                if (sm_block_erased(&oob)) {
+                        kfifo_in(&zone->free_sectors,
+                                (unsigned char *)&block, 2);
+                        continue;
+                }
+
+                /* If block is marked as bad, skip it */
+                /* This assumes we can trust first sector*/
+                /* However the way the block valid status is defined, ensures
+                        very low probability of failure here */
+                if (!sm_block_valid(&oob)) {
+                        dbg("PH %04d <-> <marked bad>", block);
+                        continue;
+                }
+
+
+                lba = sm_read_lba(&oob);
+
+                /* Invalid LBA means that block is damaged. */
+                /* We can try to erase it, or mark it as bad, but
+                        lets leave that to recovery application */
+                if (lba == -2 || lba >= ftl->max_lba) {
+                        dbg("PH %04d <-> LBA %04d(bad)", block, lba);
+                        continue;
+                }
+
+
+                /* If there is no collision,
+                        just put the sector in the FTL table */
+                if (zone->lba_to_phys_table[lba] < 0) {
+                        dbg_verbose("PH %04d <-> LBA %04d", block, lba);
+                        zone->lba_to_phys_table[lba] = block;
+                        continue;
+                }
+
+                sm_printk("collision"
+                        " of LBA %d between blocks %d and %d in zone %d",
+                        lba, zone->lba_to_phys_table[lba], block, zone_num);
+
+                /* Test that this block is valid*/
+                if (sm_check_block(ftl, zone_num, block))
+                        continue;
+
+                /* Test now the old block */
+                if (sm_check_block(ftl, zone_num,
+                                        zone->lba_to_phys_table[lba])) {
+                        zone->lba_to_phys_table[lba] = block;
+                        continue;
+                }
+
+                /* If both blocks are valid and share same LBA, it means that
+                        they hold different versions of same data. It not
+                        known which is more recent, thus just erase one of them
+                */
+                sm_printk("both blocks are valid, erasing the later");
+                sm_erase_block(ftl, zone_num, block, 1);
+        }
+
+        dbg("zone initialized");
+        zone->initialized = 1;
+
+        /* No free sectors, means that the zone is heavily damaged, write won't
+                work, but it can still can be (partially) read */
+        if (!kfifo_len(&zone->free_sectors)) {
+                sm_printk("no free blocks in zone %d", zone_num);
+                return 0;
+        }
+
+        /* Randomize first block we write to */
+        get_random_bytes(&i, 2);
+        i %= (kfifo_len(&zone->free_sectors) / 2);
+
+        while (i--) {
+                kfifo_out(&zone->free_sectors, (unsigned char *)&block, 2);
+                kfifo_in(&zone->free_sectors, (const unsigned char *)&block, 2);
+        }
+        return 0;
+}
+
+/* Get and automaticly initialize an FTL mapping for one zone */
+struct ftl_zone *sm_get_zone(struct sm_ftl *ftl, int zone_num)
+{
+        struct ftl_zone *zone;
+        int error;
+
+        BUG_ON(zone_num >= ftl->zone_count);
+        zone = &ftl->zones[zone_num];
+
+        if (!zone->initialized) {
+                error = sm_init_zone(ftl, zone_num);
+
+                if (error)
+                        return ERR_PTR(error);
+        }
+        return zone;
+}
+
+
+/* ----------------- cache handling ------------------------------------------*/
+
+/* Initialize the one block cache */
+void sm_cache_init(struct sm_ftl *ftl)
+{
+        ftl->cache_data_invalid_bitmap = 0xFFFFFFFF;
+        ftl->cache_clean = 1;
+        ftl->cache_zone = -1;
+        ftl->cache_block = -1;
+        /*memset(ftl->cache_data, 0xAA, ftl->block_size);*/
+}
+
+/* Put sector in one block cache */
+void sm_cache_put(struct sm_ftl *ftl, char *buffer, int boffset)
+{
+        memcpy(ftl->cache_data + boffset, buffer, SM_SECTOR_SIZE);
+        clear_bit(boffset / SM_SECTOR_SIZE, &ftl->cache_data_invalid_bitmap);
+        ftl->cache_clean = 0;
+}
+
+/* Read a sector from the cache */
+int sm_cache_get(struct sm_ftl *ftl, char *buffer, int boffset)
+{
+        if (test_bit(boffset / SM_SECTOR_SIZE,
+                &ftl->cache_data_invalid_bitmap))
+                        return -1;
+
+        memcpy(buffer, ftl->cache_data + boffset, SM_SECTOR_SIZE);
+        return 0;
+}
+
+/* Write the cache to hardware */
+int sm_cache_flush(struct sm_ftl *ftl)
+{
+        struct ftl_zone *zone;
+
+        int sector_num;
+        uint16_t write_sector;
+        int zone_num = ftl->cache_zone;
+        int block_num;
+
+        if (ftl->cache_clean)
+                return 0;
+
+        if (ftl->unstable)
+                return -EIO;
+
+        BUG_ON(zone_num < 0);
+        zone = &ftl->zones[zone_num];
+        block_num = zone->lba_to_phys_table[ftl->cache_block];
+
+
+        /* Try to read all unread areas of the cache block*/
+        for_each_bit(sector_num, &ftl->cache_data_invalid_bitmap,
+                ftl->block_size / SM_SECTOR_SIZE) {
+
+                if (!sm_read_sector(ftl,
+                        zone_num, block_num, sector_num * SM_SECTOR_SIZE,
+                        ftl->cache_data + sector_num * SM_SECTOR_SIZE, NULL))
+                                clear_bit(sector_num,
+                                        &ftl->cache_data_invalid_bitmap);
+        }
+restart:
+
+        if (ftl->unstable)
+                return -EIO;
+        /* No spare blocks */
+        /* We could still continue by erasing the current block,
+                but for such worn out media it doesn't worth the trouble,
+                        and the dangers */
+
+        if (!kfifo_len(&zone->free_sectors)) {
+                dbg("no free sectors for write!");
+                return -EIO;
+        }
+
+        kfifo_out(&zone->free_sectors, (unsigned char *)&write_sector, 2);
+
+        if (sm_write_block(ftl, ftl->cache_data, zone_num, write_sector,
+                ftl->cache_block, ftl->cache_data_invalid_bitmap))
+                        goto restart;
+
+        /* Update the FTL table */
+        zone->lba_to_phys_table[ftl->cache_block] = write_sector;
+
+        /* Write succesfull, so erase and free the old block */
+        if (block_num > 0)
+                sm_erase_block(ftl, zone_num, block_num, 1);
+
+        sm_cache_init(ftl);
+        return 0;
+}
+
+
+/* flush timer, runs a second after last write */
+static void sm_cache_flush_timer(unsigned long data)
+{
+        struct sm_ftl *ftl = (struct sm_ftl *)data;
+        queue_work(cache_flush_workqueue, &ftl->flush_work);
+}
+
+/* cache flush work, kicked by timer */
+static void sm_cache_flush_work(struct work_struct *work)
+{
+        struct sm_ftl *ftl = container_of(work, struct sm_ftl, flush_work);
+        mutex_lock(&ftl->mutex);
+        sm_cache_flush(ftl);
+        mutex_unlock(&ftl->mutex);
+        return;
+}
+
+/* ---------------- outside interface -------------------------------------- */
+
+/* outside interface: read a sector */
+static int sm_read(struct mtd_blktrans_dev *dev,
+                   unsigned long sect_no, char *buf)
+{
+        struct sm_ftl *ftl = dev->priv;
+        struct ftl_zone *zone;
+        int error = 0, in_cache = 0;
+        int zone_num, block, boffset;
+
+        sm_break_offset(ftl, sect_no << 9, &zone_num, &block, &boffset);
+        mutex_lock(&ftl->mutex);
+
+
+        zone = sm_get_zone(ftl, zone_num);
+        if (IS_ERR(zone)) {
+                error = PTR_ERR(zone);
+                goto unlock;
+        }
+
+        /* Have to look at cache first */
+        if (ftl->cache_zone == zone_num && ftl->cache_block == block) {
+                in_cache = 1;
+                if (!sm_cache_get(ftl, buf, boffset))
+                        goto unlock;
+        }
+
+        /* Translate the block and return if doesn't exist in the table */
+        block = zone->lba_to_phys_table[block];
+
+        if (block == -1) {
+                memset(buf, 0xFF, SM_SECTOR_SIZE);
+                goto unlock;
+        }
+
+        if (sm_read_sector(ftl, zone_num, block, boffset, buf, NULL)) {
+                error = -EIO;
+                goto unlock;
+        }
+
+        if (in_cache)
+                sm_cache_put(ftl, buf, boffset);
+unlock:
+        mutex_unlock(&ftl->mutex);
+        return error;
+}
+
+/* outside interface: write a sector */
+static int sm_write(struct mtd_blktrans_dev *dev,
+                                unsigned long sec_no, char *buf)
+{
+        struct sm_ftl *ftl = dev->priv;
+        struct ftl_zone *zone;
+        int error, zone_num, block, boffset;
+
+        BUG_ON(ftl->readonly);
+        sm_break_offset(ftl, sec_no << 9, &zone_num, &block, &boffset);
+
+        /* No need in flush thread running now */
+        del_timer(&ftl->timer);
+        mutex_lock(&ftl->mutex);
+
+        zone = sm_get_zone(ftl, zone_num);
+        if (IS_ERR(zone)) {
+                error = PTR_ERR(zone);
+                goto unlock;
+        }
+
+        /* If entry is not in cache, flush it */
+        if (ftl->cache_block != block || ftl->cache_zone != zone_num) {
+
+                error = sm_cache_flush(ftl);
+                if (error)
+                        goto unlock;
+
+                ftl->cache_block = block;
+                ftl->cache_zone = zone_num;
+        }
+
+        sm_cache_put(ftl, buf, boffset);
+unlock:
+        mod_timer(&ftl->timer, jiffies + msecs_to_jiffies(cache_timeout));
+        mutex_unlock(&ftl->mutex);
+        return error;
+}
+
+/* outside interface: flush everything */
+static int sm_flush(struct mtd_blktrans_dev *dev)
+{
+        struct sm_ftl *ftl = dev->priv;
+        int retval;
+
+        mutex_lock(&ftl->mutex);
+        retval =  sm_cache_flush(ftl);
+        mutex_unlock(&ftl->mutex);
+        return retval;
+}
+
+/* outside interface: device is released */
+static int sm_release(struct mtd_blktrans_dev *dev)
+{
+        struct sm_ftl *ftl = dev->priv;
+
+        mutex_lock(&ftl->mutex);
+        del_timer_sync(&ftl->timer);
+        cancel_work_sync(&ftl->flush_work);
+        sm_cache_flush(ftl);
+        mutex_unlock(&ftl->mutex);
+        return 0;
+}
+
+/* outside interface: get geometry */
+static int sm_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
+{
+        struct sm_ftl *ftl = dev->priv;
+        geo->heads = ftl->heads;
+        geo->sectors = ftl->sectors;
+        geo->cylinders = ftl->cylinders;
+        return 0;
+}
+
+/* external interface: main initialization function */
+static void sm_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+        struct mtd_blktrans_dev *trans;
+        struct sm_ftl *ftl;
+
+        /* Allocate & initialize our private structure */
+        ftl = kzalloc(sizeof(struct sm_ftl), GFP_KERNEL);
+        if (!ftl)
+                goto error1;
+
+
+        mutex_init(&ftl->mutex);
+        setup_timer(&ftl->timer, sm_cache_flush_timer, (unsigned long)ftl);
+        INIT_WORK(&ftl->flush_work, sm_cache_flush_work);
+        init_completion(&ftl->erase_completion);
+
+        /* Read media information */
+        if (sm_get_media_info(ftl, mtd)) {
+                dbg("found unsupported mtd device, aborting");
+                goto error2;
+        }
+
+
+        /* Allocate temporary CIS buffer for read retry support */
+        ftl->cis_buffer = kzalloc(SM_SECTOR_SIZE, GFP_KERNEL);
+        if (!ftl->cis_buffer)
+                goto error2;
+
+        /* Allocate zone array, it will be initialized on demand */
+        ftl->zones = kzalloc(sizeof(struct ftl_zone) * ftl->zone_count,
+                                                                GFP_KERNEL);
+        if (!ftl->zones)
+                goto error3;
+
+        /* Allocate the cache*/
+        ftl->cache_data = kzalloc(ftl->block_size, GFP_KERNEL);
+
+        if (!ftl->cache_data)
+                goto error4;
+
+        sm_cache_init(ftl);
+
+
+        /* Allocate upper layer structure and initialize it */
+        trans = kzalloc(sizeof(struct mtd_blktrans_dev), GFP_KERNEL);
+        if (!trans)
+                goto error5;
+
+        ftl->trans = trans;
+        trans->priv = ftl;
+
+        trans->tr = tr;
+        trans->mtd = mtd;
+        trans->devnum = -1;
+        trans->size = (ftl->block_size * ftl->max_lba * ftl->zone_count) >> 9;
+        trans->readonly = ftl->readonly;
+
+        if (sm_find_cis(ftl)) {
+                dbg("CIS not found on mtd device, aborting");
+                goto error6;
+        }
+
+        ftl->disk_attributes = sm_create_sysfs_attributes(ftl);
+        trans->disk_attributes = ftl->disk_attributes;
+
+        sm_printk("Found %d MiB xD/SmartMedia FTL on mtd%d",
+                (int)(mtd->size / (1024 * 1024)), mtd->index);
+
+        dbg("FTL layout:");
+        dbg("%d zone(s), each consists of %d blocks (+%d spares)",
+                ftl->zone_count, ftl->max_lba,
+                ftl->zone_size - ftl->max_lba);
+        dbg("each block consists of %d bytes",
+                ftl->block_size);
+
+
+        /* Register device*/
+        if (add_mtd_blktrans_dev(trans)) {
+                dbg("error in mtdblktrans layer");
+                goto error6;
+        }
+        return;
+error6:
+        kfree(trans);
+error5:
+        kfree(ftl->cache_data);
+error4:
+        kfree(ftl->zones);
+error3:
+        kfree(ftl->cis_buffer);
+error2:
+        kfree(ftl);
+error1:
+        return;
+}
+
+/* main interface: device {surprise,} removal */
+static void sm_remove_dev(struct mtd_blktrans_dev *dev)
+{
+        struct sm_ftl *ftl = dev->priv;
+        int i;
+
+        del_mtd_blktrans_dev(dev);
+        ftl->trans = NULL;
+
+        for (i = 0 ; i < ftl->zone_count; i++) {
+
+                if (!ftl->zones[i].initialized)
+                        continue;
+
+                kfree(ftl->zones[i].lba_to_phys_table);
+                kfifo_free(&ftl->zones[i].free_sectors);
+        }
+
+        sm_delete_sysfs_attributes(ftl);
+        kfree(ftl->cis_buffer);
+        kfree(ftl->zones);
+        kfree(ftl->cache_data);
+        kfree(ftl);
+}
+
+static struct mtd_blktrans_ops sm_ftl_ops = {
+        .name           = "smblk",
+        .major          = -1,
+        .part_bits      = SM_FTL_PARTN_BITS,
+        .blksize        = SM_SECTOR_SIZE,
+        .getgeo         = sm_getgeo,
+
+        .add_mtd        = sm_add_mtd,
+        .remove_dev     = sm_remove_dev,
+
+        .readsect       = sm_read,
+        .writesect      = sm_write,
+
+        .flush          = sm_flush,
+        .release        = sm_release,
+
+        .owner          = THIS_MODULE,
+};
+
+static __init int sm_module_init(void)
+{
+        int error = 0;
+        cache_flush_workqueue = create_freezeable_workqueue("smflush");
+
+        if (IS_ERR(cache_flush_workqueue))
+                return PTR_ERR(cache_flush_workqueue);
+
+        error = register_mtd_blktrans(&sm_ftl_ops);
+        if (error)
+                destroy_workqueue(cache_flush_workqueue);
+        return error;
+
+}
+
+static void __exit sm_module_exit(void)
+{
+        destroy_workqueue(cache_flush_workqueue);
+        deregister_mtd_blktrans(&sm_ftl_ops);
+}
+
+module_init(sm_module_init);
+module_exit(sm_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Maxim Levitsky <maximlevitsky@gmail.com>");
+MODULE_DESCRIPTION("Smartmedia/xD mtd translation layer");