/*
 * Driver for Alauda-based card readers
 *
 * Current development and maintenance by:
 *   (c) 2005 Daniel Drake <dsd@gentoo.org>
 *
 * The 'Alauda' is a chip manufacturered by RATOC for OEM use.
 *
 * Alauda implements a vendor-specific command set to access two media reader
 * ports (XD, SmartMedia). This driver converts SCSI commands to the commands
 * which are accepted by these devices.
 *
 * The driver was developed through reverse-engineering, with the help of the
 * sddr09 driver which has many similarities, and with some help from the
 * (very old) vendor-supplied GPL sma03 driver.
 *
 * For protocol info, see http://alauda.sourceforge.net
 *
 * 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.
 *
 * 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; if not, write to the Free Software Foundation, Inc.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/slab.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>

#include "usb.h"
#include "transport.h"
#include "protocol.h"
#include "debug.h"

MODULE_DESCRIPTION("Driver for Alauda-based card readers");
MODULE_AUTHOR("Daniel Drake <dsd@gentoo.org>");
MODULE_LICENSE("GPL");

/*
 * Status bytes
 */
#define ALAUDA_STATUS_ERROR             0x01
#define ALAUDA_STATUS_READY             0x40

/*
 * Control opcodes (for request field)
 */
#define ALAUDA_GET_XD_MEDIA_STATUS      0x08
#define ALAUDA_GET_SM_MEDIA_STATUS      0x98
#define ALAUDA_ACK_XD_MEDIA_CHANGE      0x0a
#define ALAUDA_ACK_SM_MEDIA_CHANGE      0x9a
#define ALAUDA_GET_XD_MEDIA_SIG         0x86
#define ALAUDA_GET_SM_MEDIA_SIG         0x96

/*
 * Bulk command identity (byte 0)
 */
#define ALAUDA_BULK_CMD                 0x40

/*
 * Bulk opcodes (byte 1)
 */
#define ALAUDA_BULK_GET_REDU_DATA       0x85
#define ALAUDA_BULK_READ_BLOCK          0x94
#define ALAUDA_BULK_ERASE_BLOCK         0xa3
#define ALAUDA_BULK_WRITE_BLOCK         0xb4
#define ALAUDA_BULK_GET_STATUS2         0xb7
#define ALAUDA_BULK_RESET_MEDIA         0xe0

/*
 * Port to operate on (byte 8)
 */
#define ALAUDA_PORT_XD                  0x00
#define ALAUDA_PORT_SM                  0x01

/*
 * LBA and PBA are unsigned ints. Special values.
 */
#define UNDEF    0xffff
#define SPARE    0xfffe
#define UNUSABLE 0xfffd

struct alauda_media_info {
        unsigned long capacity;         /* total media size in bytes */
        unsigned int pagesize;          /* page size in bytes */
        unsigned int blocksize;         /* number of pages per block */
        unsigned int uzonesize;         /* number of usable blocks per zone */
        unsigned int zonesize;          /* number of blocks per zone */
        unsigned int blockmask;         /* mask to get page from address */

        unsigned char pageshift;
        unsigned char blockshift;
        unsigned char zoneshift;

        u16 **lba_to_pba;               /* logical to physical block map */
        u16 **pba_to_lba;               /* physical to logical block map */
};

struct alauda_info {
        struct alauda_media_info port[2];
        int wr_ep;                      /* endpoint to write data out of */

        unsigned char sense_key;
        unsigned long sense_asc;        /* additional sense code */
        unsigned long sense_ascq;       /* additional sense code qualifier */
};

#define short_pack(lsb,msb) ( ((u16)(lsb)) | ( ((u16)(msb))<<8 ) )
#define LSB_of(s) ((s)&0xFF)
#define MSB_of(s) ((s)>>8)

#define MEDIA_PORT(us) us->srb->device->lun
#define MEDIA_INFO(us) ((struct alauda_info *)us->extra)->port[MEDIA_PORT(us)]

#define PBA_LO(pba) ((pba & 0xF) << 5)
#define PBA_HI(pba) (pba >> 3)
#define PBA_ZONE(pba) (pba >> 11)

static int init_alauda(struct us_data *us);


/*
 * The table of devices
 */
#define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \
                    vendorName, productName, useProtocol, useTransport, \
                    initFunction, flags) \
{ USB_DEVICE_VER(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax), \
  .driver_info = (flags) }

static struct usb_device_id alauda_usb_ids[] = {
#       include "unusual_alauda.h"
        { }             /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, alauda_usb_ids);

#undef UNUSUAL_DEV

/*
 * The flags table
 */
#define UNUSUAL_DEV(idVendor, idProduct, bcdDeviceMin, bcdDeviceMax, \
                    vendor_name, product_name, use_protocol, use_transport, \
                    init_function, Flags) \
{ \
        .vendorName = vendor_name,      \
        .productName = product_name,    \
        .useProtocol = use_protocol,    \
        .useTransport = use_transport,  \
        .initFunction = init_function,  \
}

static struct us_unusual_dev alauda_unusual_dev_list[] = {
#       include "unusual_alauda.h"
        { }             /* Terminating entry */
};

#undef UNUSUAL_DEV


/*
 * Media handling
 */

struct alauda_card_info {
        unsigned char id;               /* id byte */
        unsigned char chipshift;        /* 1<<cs bytes total capacity */
        unsigned char pageshift;        /* 1<<ps bytes in a page */
        unsigned char blockshift;       /* 1<<bs pages per block */
        unsigned char zoneshift;        /* 1<<zs blocks per zone */
};

static struct alauda_card_info alauda_card_ids[] = {
        /* NAND flash */
        { 0x6e, 20, 8, 4, 8},   /* 1 MB */
        { 0xe8, 20, 8, 4, 8},   /* 1 MB */
        { 0xec, 20, 8, 4, 8},   /* 1 MB */
        { 0x64, 21, 8, 4, 9},   /* 2 MB */
        { 0xea, 21, 8, 4, 9},   /* 2 MB */
        { 0x6b, 22, 9, 4, 9},   /* 4 MB */
        { 0xe3, 22, 9, 4, 9},   /* 4 MB */
        { 0xe5, 22, 9, 4, 9},   /* 4 MB */
        { 0xe6, 23, 9, 4, 10},  /* 8 MB */
        { 0x73, 24, 9, 5, 10},  /* 16 MB */
        { 0x75, 25, 9, 5, 10},  /* 32 MB */
        { 0x76, 26, 9, 5, 10},  /* 64 MB */
        { 0x79, 27, 9, 5, 10},  /* 128 MB */
        { 0x71, 28, 9, 5, 10},  /* 256 MB */

        /* MASK ROM */
        { 0x5d, 21, 9, 4, 8},   /* 2 MB */
        { 0xd5, 22, 9, 4, 9},   /* 4 MB */
        { 0xd6, 23, 9, 4, 10},  /* 8 MB */
        { 0x57, 24, 9, 4, 11},  /* 16 MB */
        { 0x58, 25, 9, 4, 12},  /* 32 MB */
        { 0,}
};

static struct alauda_card_info *alauda_card_find_id(unsigned char id) {
        int i;

        for (i = 0; alauda_card_ids[i].id != 0; i++)
                if (alauda_card_ids[i].id == id)
                        return &(alauda_card_ids[i]);
        return NULL;
}

/*
 * ECC computation.
 */

static unsigned char parity[256];
static unsigned char ecc2[256];

static void nand_init_ecc(void) {
        int i, j, a;

        parity[0] = 0;
        for (i = 1; i < 256; i++)
                parity[i] = (parity[i&(i-1)] ^ 1);

        for (i = 0; i < 256; i++) {
                a = 0;
                for (j = 0; j < 8; j++) {
                        if (i & (1<<j)) {
                                if ((j & 1) == 0)
                                        a ^= 0x04;
                                if ((j & 2) == 0)
                                        a ^= 0x10;
                                if ((j & 4) == 0)
                                        a ^= 0x40;
                        }
                }
                ecc2[i] = ~(a ^ (a<<1) ^ (parity[i] ? 0xa8 : 0));
        }
}

/* compute 3-byte ecc on 256 bytes */
static void nand_compute_ecc(unsigned char *data, unsigned char *ecc) {
        int i, j, a;
        unsigned char par = 0, bit, bits[8] = {0};

        /* collect 16 checksum bits */
        for (i = 0; i < 256; i++) {
                par ^= data[i];
                bit = parity[data[i]];
                for (j = 0; j < 8; j++)
                        if ((i & (1<<j)) == 0)
                                bits[j] ^= bit;
        }

        /* put 4+4+4 = 12 bits in the ecc */
        a = (bits[3] << 6) + (bits[2] << 4) + (bits[1] << 2) + bits[0];
        ecc[0] = ~(a ^ (a<<1) ^ (parity[par] ? 0xaa : 0));

        a = (bits[7] << 6) + (bits[6] << 4) + (bits[5] << 2) + bits[4];
        ecc[1] = ~(a ^ (a<<1) ^ (parity[par] ? 0xaa : 0));

        ecc[2] = ecc2[par];
}

static int nand_compare_ecc(unsigned char *data, unsigned char *ecc) {
        return (data[0] == ecc[0] && data[1] == ecc[1] && data[2] == ecc[2]);
}

static void nand_store_ecc(unsigned char *data, unsigned char *ecc) {
        memcpy(data, ecc, 3);
}

/*
 * Alauda driver
 */

/*
 * Forget our PBA <---> LBA mappings for a particular port
 */
static void alauda_free_maps (struct alauda_media_info *media_info)
{
        unsigned int shift = media_info->zoneshift
                + media_info->blockshift + media_info->pageshift;
        unsigned int num_zones = media_info->capacity >> shift;
        unsigned int i;

        if (media_info->lba_to_pba != NULL)
                for (i = 0; i < num_zones; i++) {
                        kfree(media_info->lba_to_pba[i]);
                        media_info->lba_to_pba[i] = NULL;
                }

        if (media_info->pba_to_lba != NULL)
                for (i = 0; i < num_zones; i++) {
                        kfree(media_info->pba_to_lba[i]);
                        media_info->pba_to_lba[i] = NULL;
                }
}

/*
 * Returns 2 bytes of status data
 * The first byte describes media status, and second byte describes door status
 */
static int alauda_get_media_status(struct us_data *us, unsigned char *data)
{
        int rc;
        unsigned char command;

        if (MEDIA_PORT(us) == ALAUDA_PORT_XD)
                command = ALAUDA_GET_XD_MEDIA_STATUS;
        else
                command = ALAUDA_GET_SM_MEDIA_STATUS;

        rc = usb_stor_ctrl_transfer(us, us->recv_ctrl_pipe,
                command, 0xc0, 0, 1, data, 2);

        usb_stor_dbg(us, "Media status %02X %02X\n", data[0], data[1]);

        return rc;
}

/*
 * Clears the "media was changed" bit so that we know when it changes again
 * in the future.
 */
static int alauda_ack_media(struct us_data *us)
{
        unsigned char command;

        if (MEDIA_PORT(us) == ALAUDA_PORT_XD)
                command = ALAUDA_ACK_XD_MEDIA_CHANGE;
        else
                command = ALAUDA_ACK_SM_MEDIA_CHANGE;

        return usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
                command, 0x40, 0, 1, NULL, 0);
}

/*
 * Retrieves a 4-byte media signature, which indicates manufacturer, capacity,
 * and some other details.
 */
static int alauda_get_media_signature(struct us_data *us, unsigned char *data)
{
        unsigned char command;

        if (MEDIA_PORT(us) == ALAUDA_PORT_XD)
                command = ALAUDA_GET_XD_MEDIA_SIG;
        else
                command = ALAUDA_GET_SM_MEDIA_SIG;

        return usb_stor_ctrl_transfer(us, us->recv_ctrl_pipe,
                command, 0xc0, 0, 0, data, 4);
}

/*
 * Resets the media status (but not the whole device?)
 */
static int alauda_reset_media(struct us_data *us)
{
        unsigned char *command = us->iobuf;

        memset(command, 0, 9);
        command[0] = ALAUDA_BULK_CMD;
        command[1] = ALAUDA_BULK_RESET_MEDIA;
        command[8] = MEDIA_PORT(us);

        return usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
}

/*
 * Examines the media and deduces capacity, etc.
 */
static int alauda_init_media(struct us_data *us)
{
        unsigned char *data = us->iobuf;
        int ready = 0;
        struct alauda_card_info *media_info;
        unsigned int num_zones;

        while (ready == 0) {
                msleep(20);

                if (alauda_get_media_status(us, data) != USB_STOR_XFER_GOOD)
                        return USB_STOR_TRANSPORT_ERROR;

                if (data[0] & 0x10)
                        ready = 1;
        }

        usb_stor_dbg(us, "We are ready for action!\n");

        if (alauda_ack_media(us) != USB_STOR_XFER_GOOD)
                return USB_STOR_TRANSPORT_ERROR;

        msleep(10);

        if (alauda_get_media_status(us, data) != USB_STOR_XFER_GOOD)
                return USB_STOR_TRANSPORT_ERROR;

        if (data[0] != 0x14) {
                usb_stor_dbg(us, "Media not ready after ack\n");
                return USB_STOR_TRANSPORT_ERROR;
        }

        if (alauda_get_media_signature(us, data) != USB_STOR_XFER_GOOD)
                return USB_STOR_TRANSPORT_ERROR;

        usb_stor_dbg(us, "Media signature: %02X %02X %02X %02X\n",
                     data[0], data[1], data[2], data[3]);
        media_info = alauda_card_find_id(data[1]);
        if (media_info == NULL) {
                printk(KERN_WARNING
                        "alauda_init_media: Unrecognised media signature: "
                        "%02X %02X %02X %02X\n",
                        data[0], data[1], data[2], data[3]);
                return USB_STOR_TRANSPORT_ERROR;
        }

        MEDIA_INFO(us).capacity = 1 << media_info->chipshift;
        usb_stor_dbg(us, "Found media with capacity: %ldMB\n",
                     MEDIA_INFO(us).capacity >> 20);

        MEDIA_INFO(us).pageshift = media_info->pageshift;
        MEDIA_INFO(us).blockshift = media_info->blockshift;
        MEDIA_INFO(us).zoneshift = media_info->zoneshift;

        MEDIA_INFO(us).pagesize = 1 << media_info->pageshift;
        MEDIA_INFO(us).blocksize = 1 << media_info->blockshift;
        MEDIA_INFO(us).zonesize = 1 << media_info->zoneshift;

        MEDIA_INFO(us).uzonesize = ((1 << media_info->zoneshift) / 128) * 125;
        MEDIA_INFO(us).blockmask = MEDIA_INFO(us).blocksize - 1;

        num_zones = MEDIA_INFO(us).capacity >> (MEDIA_INFO(us).zoneshift
                + MEDIA_INFO(us).blockshift + MEDIA_INFO(us).pageshift);
        MEDIA_INFO(us).pba_to_lba = kcalloc(num_zones, sizeof(u16*), GFP_NOIO);
        MEDIA_INFO(us).lba_to_pba = kcalloc(num_zones, sizeof(u16*), GFP_NOIO);

        if (alauda_reset_media(us) != USB_STOR_XFER_GOOD)
                return USB_STOR_TRANSPORT_ERROR;

        return USB_STOR_TRANSPORT_GOOD;
}

/*
 * Examines the media status and does the right thing when the media has gone,
 * appeared, or changed.
 */
static int alauda_check_media(struct us_data *us)
{
        struct alauda_info *info = (struct alauda_info *) us->extra;
        unsigned char status[2];
        int rc;

        rc = alauda_get_media_status(us, status);

        /* Check for no media or door open */
        if ((status[0] & 0x80) || ((status[0] & 0x1F) == 0x10)
                || ((status[1] & 0x01) == 0)) {
                usb_stor_dbg(us, "No media, or door open\n");
                alauda_free_maps(&MEDIA_INFO(us));
                info->sense_key = 0x02;
                info->sense_asc = 0x3A;
                info->sense_ascq = 0x00;
                return USB_STOR_TRANSPORT_FAILED;
        }

        /* Check for media change */
        if (status[0] & 0x08) {
                usb_stor_dbg(us, "Media change detected\n");
                alauda_free_maps(&MEDIA_INFO(us));
                alauda_init_media(us);

                info->sense_key = UNIT_ATTENTION;
                info->sense_asc = 0x28;
                info->sense_ascq = 0x00;
                return USB_STOR_TRANSPORT_FAILED;
        }

        return USB_STOR_TRANSPORT_GOOD;
}

/*
 * Checks the status from the 2nd status register
 * Returns 3 bytes of status data, only the first is known
 */
static int alauda_check_status2(struct us_data *us)
{
        int rc;
        unsigned char command[] = {
                ALAUDA_BULK_CMD, ALAUDA_BULK_GET_STATUS2,
                0, 0, 0, 0, 3, 0, MEDIA_PORT(us)
        };
        unsigned char data[3];

        rc = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        rc = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                data, 3, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        usb_stor_dbg(us, "%02X %02X %02X\n", data[0], data[1], data[2]);
        if (data[0] & ALAUDA_STATUS_ERROR)
                return USB_STOR_XFER_ERROR;

        return USB_STOR_XFER_GOOD;
}

/*
 * Gets the redundancy data for the first page of a PBA
 * Returns 16 bytes.
 */
static int alauda_get_redu_data(struct us_data *us, u16 pba, unsigned char *data)
{
        int rc;
        unsigned char command[] = {
                ALAUDA_BULK_CMD, ALAUDA_BULK_GET_REDU_DATA,
                PBA_HI(pba), PBA_ZONE(pba), 0, PBA_LO(pba), 0, 0, MEDIA_PORT(us)
        };

        rc = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        return usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                data, 16, NULL);
}

/*
 * Finds the first unused PBA in a zone
 * Returns the absolute PBA of an unused PBA, or 0 if none found.
 */
static u16 alauda_find_unused_pba(struct alauda_media_info *info,
        unsigned int zone)
{
        u16 *pba_to_lba = info->pba_to_lba[zone];
        unsigned int i;

        for (i = 0; i < info->zonesize; i++)
                if (pba_to_lba[i] == UNDEF)
                        return (zone << info->zoneshift) + i;

        return 0;
}

/*
 * Reads the redundancy data for all PBA's in a zone
 * Produces lba <--> pba mappings
 */
static int alauda_read_map(struct us_data *us, unsigned int zone)
{
        unsigned char *data = us->iobuf;
        int result;
        int i, j;
        unsigned int zonesize = MEDIA_INFO(us).zonesize;
        unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
        unsigned int lba_offset, lba_real, blocknum;
        unsigned int zone_base_lba = zone * uzonesize;
        unsigned int zone_base_pba = zone * zonesize;
        u16 *lba_to_pba = kcalloc(zonesize, sizeof(u16), GFP_NOIO);
        u16 *pba_to_lba = kcalloc(zonesize, sizeof(u16), GFP_NOIO);
        if (lba_to_pba == NULL || pba_to_lba == NULL) {
                result = USB_STOR_TRANSPORT_ERROR;
                goto error;
        }

        usb_stor_dbg(us, "Mapping blocks for zone %d\n", zone);

        /* 1024 PBA's per zone */
        for (i = 0; i < zonesize; i++)
                lba_to_pba[i] = pba_to_lba[i] = UNDEF;

        for (i = 0; i < zonesize; i++) {
                blocknum = zone_base_pba + i;

                result = alauda_get_redu_data(us, blocknum, data);
                if (result != USB_STOR_XFER_GOOD) {
                        result = USB_STOR_TRANSPORT_ERROR;
                        goto error;
                }

                /* special PBAs have control field 0^16 */
                for (j = 0; j < 16; j++)
                        if (data[j] != 0)
                                goto nonz;
                pba_to_lba[i] = UNUSABLE;
                usb_stor_dbg(us, "PBA %d has no logical mapping\n", blocknum);
                continue;

        nonz:
                /* unwritten PBAs have control field FF^16 */
                for (j = 0; j < 16; j++)
                        if (data[j] != 0xff)
                                goto nonff;
                continue;

        nonff:
                /* normal PBAs start with six FFs */
                if (j < 6) {
                        usb_stor_dbg(us, "PBA %d has no logical mapping: reserved area = %02X%02X%02X%02X data status %02X block status %02X\n",
                                     blocknum,
                                     data[0], data[1], data[2], data[3],
                                     data[4], data[5]);
                        pba_to_lba[i] = UNUSABLE;
                        continue;
                }

                if ((data[6] >> 4) != 0x01) {
                        usb_stor_dbg(us, "PBA %d has invalid address field %02X%02X/%02X%02X\n",
                                     blocknum, data[6], data[7],
                                     data[11], data[12]);
                        pba_to_lba[i] = UNUSABLE;
                        continue;
                }

                /* check even parity */
                if (parity[data[6] ^ data[7]]) {
                        printk(KERN_WARNING
                               "alauda_read_map: Bad parity in LBA for block %d"
                               " (%02X %02X)\n", i, data[6], data[7]);
                        pba_to_lba[i] = UNUSABLE;
                        continue;
                }

                lba_offset = short_pack(data[7], data[6]);
                lba_offset = (lba_offset & 0x07FF) >> 1;
                lba_real = lba_offset + zone_base_lba;

                /*
                 * Every 1024 physical blocks ("zone"), the LBA numbers
                 * go back to zero, but are within a higher block of LBA's.
                 * Also, there is a maximum of 1000 LBA's per zone.
                 * In other words, in PBA 1024-2047 you will find LBA 0-999
                 * which are really LBA 1000-1999. This allows for 24 bad
                 * or special physical blocks per zone.
                 */

                if (lba_offset >= uzonesize) {
                        printk(KERN_WARNING
                               "alauda_read_map: Bad low LBA %d for block %d\n",
                               lba_real, blocknum);
                        continue;
                }

                if (lba_to_pba[lba_offset] != UNDEF) {
                        printk(KERN_WARNING
                               "alauda_read_map: "
                               "LBA %d seen for PBA %d and %d\n",
                               lba_real, lba_to_pba[lba_offset], blocknum);
                        continue;
                }

                pba_to_lba[i] = lba_real;
                lba_to_pba[lba_offset] = blocknum;
                continue;
        }

        MEDIA_INFO(us).lba_to_pba[zone] = lba_to_pba;
        MEDIA_INFO(us).pba_to_lba[zone] = pba_to_lba;
        result = 0;
        goto out;

error:
        kfree(lba_to_pba);
        kfree(pba_to_lba);
out:
        return result;
}

/*
 * Checks to see whether we have already mapped a certain zone
 * If we haven't, the map is generated
 */
static void alauda_ensure_map_for_zone(struct us_data *us, unsigned int zone)
{
        if (MEDIA_INFO(us).lba_to_pba[zone] == NULL
                || MEDIA_INFO(us).pba_to_lba[zone] == NULL)
                alauda_read_map(us, zone);
}

/*
 * Erases an entire block
 */
static int alauda_erase_block(struct us_data *us, u16 pba)
{
        int rc;
        unsigned char command[] = {
                ALAUDA_BULK_CMD, ALAUDA_BULK_ERASE_BLOCK, PBA_HI(pba),
                PBA_ZONE(pba), 0, PBA_LO(pba), 0x02, 0, MEDIA_PORT(us)
        };
        unsigned char buf[2];

        usb_stor_dbg(us, "Erasing PBA %d\n", pba);

        rc = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        rc = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                buf, 2, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        usb_stor_dbg(us, "Erase result: %02X %02X\n", buf[0], buf[1]);
        return rc;
}

/*
 * Reads data from a certain offset page inside a PBA, including interleaved
 * redundancy data. Returns (pagesize+64)*pages bytes in data.
 */
static int alauda_read_block_raw(struct us_data *us, u16 pba,
                unsigned int page, unsigned int pages, unsigned char *data)
{
        int rc;
        unsigned char command[] = {
                ALAUDA_BULK_CMD, ALAUDA_BULK_READ_BLOCK, PBA_HI(pba),
                PBA_ZONE(pba), 0, PBA_LO(pba) + page, pages, 0, MEDIA_PORT(us)
        };

        usb_stor_dbg(us, "pba %d page %d count %d\n", pba, page, pages);

        rc = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        return usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
                data, (MEDIA_INFO(us).pagesize + 64) * pages, NULL);
}

/*
 * Reads data from a certain offset page inside a PBA, excluding redundancy
 * data. Returns pagesize*pages bytes in data. Note that data must be big enough
 * to hold (pagesize+64)*pages bytes of data, but you can ignore those 'extra'
 * trailing bytes outside this function.
 */
static int alauda_read_block(struct us_data *us, u16 pba,
                unsigned int page, unsigned int pages, unsigned char *data)
{
        int i, rc;
        unsigned int pagesize = MEDIA_INFO(us).pagesize;

        rc = alauda_read_block_raw(us, pba, page, pages, data);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        /* Cut out the redundancy data */
        for (i = 0; i < pages; i++) {
                int dest_offset = i * pagesize;
                int src_offset = i * (pagesize + 64);
                memmove(data + dest_offset, data + src_offset, pagesize);
        }

        return rc;
}

/*
 * Writes an entire block of data and checks status after write.
 * Redundancy data must be already included in data. Data should be
 * (pagesize+64)*blocksize bytes in length.
 */
static int alauda_write_block(struct us_data *us, u16 pba, unsigned char *data)
{
        int rc;
        struct alauda_info *info = (struct alauda_info *) us->extra;
        unsigned char command[] = {
                ALAUDA_BULK_CMD, ALAUDA_BULK_WRITE_BLOCK, PBA_HI(pba),
                PBA_ZONE(pba), 0, PBA_LO(pba), 32, 0, MEDIA_PORT(us)
        };

        usb_stor_dbg(us, "pba %d\n", pba);

        rc = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
                command, 9, NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        rc = usb_stor_bulk_transfer_buf(us, info->wr_ep, data,
                (MEDIA_INFO(us).pagesize + 64) * MEDIA_INFO(us).blocksize,
                NULL);
        if (rc != USB_STOR_XFER_GOOD)
                return rc;

        return alauda_check_status2(us);
}

/*
 * Write some data to a specific LBA.
 */
static int alauda_write_lba(struct us_data *us, u16 lba,
                 unsigned int page, unsigned int pages,
                 unsigned char *ptr, unsigned char *blockbuffer)
{
        u16 pba, lbap, new_pba;
        unsigned char *bptr, *cptr, *xptr;
        unsigned char ecc[3];
        int i, result;
        unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
        unsigned int zonesize = MEDIA_INFO(us).zonesize;
        unsigned int pagesize = MEDIA_INFO(us).pagesize;
        unsigned int blocksize = MEDIA_INFO(us).blocksize;
        unsigned int lba_offset = lba % uzonesize;
        unsigned int new_pba_offset;
        unsigned int zone = lba / uzonesize;

        alauda_ensure_map_for_zone(us, zone);

        pba = MEDIA_INFO(us).lba_to_pba[zone][lba_offset];
        if (pba == 1) {
                /* Maybe it is impossible to write to PBA 1.
                   Fake success, but don't do anything. */
                printk(KERN_WARNING
                       "alauda_write_lba: avoid writing to pba 1\n");
                return USB_STOR_TRANSPORT_GOOD;
        }

        new_pba = alauda_find_unused_pba(&MEDIA_INFO(us), zone);
        if (!new_pba) {
                printk(KERN_WARNING
                       "alauda_write_lba: Out of unused blocks\n");
                return USB_STOR_TRANSPORT_ERROR;
        }

        /* read old contents */
        if (pba != UNDEF) {
                result = alauda_read_block_raw(us, pba, 0,
                        blocksize, blockbuffer);
                if (result != USB_STOR_XFER_GOOD)
                        return result;
        } else {
                memset(blockbuffer, 0, blocksize * (pagesize + 64));
        }

        lbap = (lba_offset << 1) | 0x1000;
        if (parity[MSB_of(lbap) ^ LSB_of(lbap)])
                lbap ^= 1;

        /* check old contents and fill lba */
        for (i = 0; i < blocksize; i++) {
                bptr = blockbuffer + (i * (pagesize + 64));
                cptr = bptr + pagesize;
                nand_compute_ecc(bptr, ecc);
                if (!nand_compare_ecc(cptr+13, ecc)) {
                        usb_stor_dbg(us, "Warning: bad ecc in page %d- of pba %d\n",
                                     i, pba);
                        nand_store_ecc(cptr+13, ecc);
                }
                nand_compute_ecc(bptr + (pagesize / 2), ecc);
                if (!nand_compare_ecc(cptr+8, ecc)) {
                        usb_stor_dbg(us, "Warning: bad ecc in page %d+ of pba %d\n",
                                     i, pba);
                        nand_store_ecc(cptr+8, ecc);
                }
                cptr[6] = cptr[11] = MSB_of(lbap);
                cptr[7] = cptr[12] = LSB_of(lbap);
        }

        /* copy in new stuff and compute ECC */
        xptr = ptr;
        for (i = page; i < page+pages; i++) {
                bptr = blockbuffer + (i * (pagesize + 64));
                cptr = bptr + pagesize;
                memcpy(bptr, xptr, pagesize);
                xptr += pagesize;
                nand_compute_ecc(bptr, ecc);
                nand_store_ecc(cptr+13, ecc);
                nand_compute_ecc(bptr + (pagesize / 2), ecc);
                nand_store_ecc(cptr+8, ecc);
        }

        result = alauda_write_block(us, new_pba, blockbuffer);
        if (result != USB_STOR_XFER_GOOD)
                return result;

        new_pba_offset = new_pba - (zone * zonesize);
        MEDIA_INFO(us).pba_to_lba[zone][new_pba_offset] = lba;
        MEDIA_INFO(us).lba_to_pba[zone][lba_offset] = new_pba;
        usb_stor_dbg(us, "Remapped LBA %d to PBA %d\n", lba, new_pba);

        if (pba != UNDEF) {
                unsigned int pba_offset = pba - (zone * zonesize);
                result = alauda_erase_block(us, pba);
                if (result != USB_STOR_XFER_GOOD)
                        return result;
                MEDIA_INFO(us).pba_to_lba[zone][pba_offset] = UNDEF;
        }

        return USB_STOR_TRANSPORT_GOOD;
}

/*
 * Read data from a specific sector address
 */
static int alauda_read_data(struct us_data *us, unsigned long address,
                unsigned int sectors)
{
        unsigned char *buffer;
        u16 lba, max_lba;
        unsigned int page, len, offset;
        unsigned int blockshift = MEDIA_INFO(us).blockshift;
        unsigned int pageshift = MEDIA_INFO(us).pageshift;
        unsigned int blocksize = MEDIA_INFO(us).blocksize;
        unsigned int pagesize = MEDIA_INFO(us).pagesize;
        unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
        struct scatterlist *sg;
        int result;

        /*
         * Since we only read in one block at a time, we have to create
         * a bounce buffer and move the data a piece at a time between the
         * bounce buffer and the actual transfer buffer.
         * We make this buffer big enough to hold temporary redundancy data,
         * which we use when reading the data blocks.
         */

        len = min(sectors, blocksize) * (pagesize + 64);
        buffer = kmalloc(len, GFP_NOIO);
        if (buffer == NULL) {
                printk(KERN_WARNING "alauda_read_data: Out of memory\n");
                return USB_STOR_TRANSPORT_ERROR;
        }

        /* Figure out the initial LBA and page */
        lba = address >> blockshift;
        page = (address & MEDIA_INFO(us).blockmask);
        max_lba = MEDIA_INFO(us).capacity >> (blockshift + pageshift);

        result = USB_STOR_TRANSPORT_GOOD;
        offset = 0;
        sg = NULL;

        while (sectors > 0) {
                unsigned int zone = lba / uzonesize; /* integer division */
                unsigned int lba_offset = lba - (zone * uzonesize);
                unsigned int pages;
                u16 pba;
                alauda_ensure_map_for_zone(us, zone);

                /* Not overflowing capacity? */
                if (lba >= max_lba) {
                        usb_stor_dbg(us, "Error: Requested lba %u exceeds maximum %u\n",
                                     lba, max_lba);
                        result = USB_STOR_TRANSPORT_ERROR;
                        break;
                }

                /* Find number of pages we can read in this block */
                pages = min(sectors, blocksize - page);
                len = pages << pageshift;

                /* Find where this lba lives on disk */
                pba = MEDIA_INFO(us).lba_to_pba[zone][lba_offset];

                if (pba == UNDEF) {     /* this lba was never written */
                        usb_stor_dbg(us, "Read %d zero pages (LBA %d) page %d\n",
                                     pages, lba, page);

                        /* This is not really an error. It just means
                           that the block has never been written.
                           Instead of returning USB_STOR_TRANSPORT_ERROR
                           it is better to return all zero data. */

                        memset(buffer, 0, len);
                } else {
                        usb_stor_dbg(us, "Read %d pages, from PBA %d (LBA %d) page %d\n",
                                     pages, pba, lba, page);

                        result = alauda_read_block(us, pba, page, pages, buffer);
                        if (result != USB_STOR_TRANSPORT_GOOD)
                                break;
                }

                /* Store the data in the transfer buffer */
                usb_stor_access_xfer_buf(buffer, len, us->srb,
                                &sg, &offset, TO_XFER_BUF);

                page = 0;
                lba++;
                sectors -= pages;
        }

        kfree(buffer);
        return result;

}

/*
 * Write data to a specific sector address
 */
static int alauda_write_data(struct us_data *us, unsigned long address,
                unsigned int sectors)
{
        unsigned char *buffer, *blockbuffer;
        unsigned int page, len, offset;
        unsigned int blockshift = MEDIA_INFO(us).blockshift;
        unsigned int pageshift = MEDIA_INFO(us).pageshift;
        unsigned int blocksize = MEDIA_INFO(us).blocksize;
        unsigned int pagesize = MEDIA_INFO(us).pagesize;
        struct scatterlist *sg;
        u16 lba, max_lba;
        int result;

        /*
         * Since we don't write the user data directly to the device,
         * we have to create a bounce buffer and move the data a piece
         * at a time between the bounce buffer and the actual transfer buffer.
         */

        len = min(sectors, blocksize) * pagesize;
        buffer = kmalloc(len, GFP_NOIO);
        if (buffer == NULL) {
                printk(KERN_WARNING "alauda_write_data: Out of memory\n");
                return USB_STOR_TRANSPORT_ERROR;
        }

        /*
         * We also need a temporary block buffer, where we read in the old data,
         * overwrite parts with the new data, and manipulate the redundancy data
         */
        blockbuffer = kmalloc((pagesize + 64) * blocksize, GFP_NOIO);
        if (blockbuffer == NULL) {
                printk(KERN_WARNING "alauda_write_data: Out of memory\n");
                kfree(buffer);
                return USB_STOR_TRANSPORT_ERROR;
        }

        /* Figure out the initial LBA and page */
        lba = address >> blockshift;
        page = (address & MEDIA_INFO(us).blockmask);
        max_lba = MEDIA_INFO(us).capacity >> (pageshift + blockshift);

        result = USB_STOR_TRANSPORT_GOOD;
        offset = 0;
        sg = NULL;

        while (sectors > 0) {
                /* Write as many sectors as possible in this block */
                unsigned int pages = min(sectors, blocksize - page);
                len = pages << pageshift;

                /* Not overflowing capacity? */
                if (lba >= max_lba) {
                        usb_stor_dbg(us, "Requested lba %u exceeds maximum %u\n",
                                     lba, max_lba);
                        result = USB_STOR_TRANSPORT_ERROR;
                        break;
                }

                /* Get the data from the transfer buffer */
                usb_stor_access_xfer_buf(buffer, len, us->srb,
                                &sg, &offset, FROM_XFER_BUF);

                result = alauda_write_lba(us, lba, page, pages, buffer,
                        blockbuffer);
                if (result != USB_STOR_TRANSPORT_GOOD)
                        break;

                page = 0;
                lba++;
                sectors -= pages;
        }

        kfree(buffer);
        kfree(blockbuffer);
        return result;
}

/*
 * Our interface with the rest of the world
 */

static void alauda_info_destructor(void *extra)
{
        struct alauda_info *info = (struct alauda_info *) extra;
        int port;

        if (!info)
                return;

        for (port = 0; port < 2; port++) {
                struct alauda_media_info *media_info = &info->port[port];

                alauda_free_maps(media_info);
                kfree(media_info->lba_to_pba);
                kfree(media_info->pba_to_lba);
        }
}

/*
 * Initialize alauda_info struct and find the data-write endpoint
 */
static int init_alauda(struct us_data *us)
{
        struct alauda_info *info;
        struct usb_host_interface *altsetting = us->pusb_intf->cur_altsetting;
        nand_init_ecc();

        us->extra = kzalloc(sizeof(struct alauda_info), GFP_NOIO);
        if (!us->extra)
                return USB_STOR_TRANSPORT_ERROR;

        info = (struct alauda_info *) us->extra;
        us->extra_destructor = alauda_info_destructor;

        info->wr_ep = usb_sndbulkpipe(us->pusb_dev,
                altsetting->endpoint[0].desc.bEndpointAddress
                & USB_ENDPOINT_NUMBER_MASK);

        return USB_STOR_TRANSPORT_GOOD;
}

static int alauda_transport(struct scsi_cmnd *srb, struct us_data *us)
{
        int rc;
        struct alauda_info *info = (struct alauda_info *) us->extra;
        unsigned char *ptr = us->iobuf;
        static unsigned char inquiry_response[36] = {
                0x00, 0x80, 0x00, 0x01, 0x1F, 0x00, 0x00, 0x00
        };

        if (srb->cmnd[0] == INQUIRY) {
                usb_stor_dbg(us, "INQUIRY - Returning bogus response\n");
                memcpy(ptr, inquiry_response, sizeof(inquiry_response));
                fill_inquiry_response(us, ptr, 36);
                return USB_STOR_TRANSPORT_GOOD;
        }

        if (srb->cmnd[0] == TEST_UNIT_READY) {
                usb_stor_dbg(us, "TEST_UNIT_READY\n");
                return alauda_check_media(us);
        }

        if (srb->cmnd[0] == READ_CAPACITY) {
                unsigned int num_zones;
                unsigned long capacity;

                rc = alauda_check_media(us);
                if (rc != USB_STOR_TRANSPORT_GOOD)
                        return rc;

                num_zones = MEDIA_INFO(us).capacity >> (MEDIA_INFO(us).zoneshift
                        + MEDIA_INFO(us).blockshift + MEDIA_INFO(us).pageshift);

                capacity = num_zones * MEDIA_INFO(us).uzonesize
                        * MEDIA_INFO(us).blocksize;

                /* Report capacity and page size */
                ((__be32 *) ptr)[0] = cpu_to_be32(capacity - 1);
                ((__be32 *) ptr)[1] = cpu_to_be32(512);

                usb_stor_set_xfer_buf(ptr, 8, srb);
                return USB_STOR_TRANSPORT_GOOD;
        }

        if (srb->cmnd[0] == READ_10) {
                unsigned int page, pages;

                rc = alauda_check_media(us);
                if (rc != USB_STOR_TRANSPORT_GOOD)
                        return rc;

                page = short_pack(srb->cmnd[3], srb->cmnd[2]);
                page <<= 16;
                page |= short_pack(srb->cmnd[5], srb->cmnd[4]);
                pages = short_pack(srb->cmnd[8], srb->cmnd[7]);

                usb_stor_dbg(us, "READ_10: page %d pagect %d\n", page, pages);

                return alauda_read_data(us, page, pages);
        }

        if (srb->cmnd[0] == WRITE_10) {
                unsigned int page, pages;

                rc = alauda_check_media(us);
                if (rc != USB_STOR_TRANSPORT_GOOD)
                        return rc;

                page = short_pack(srb->cmnd[3], srb->cmnd[2]);
                page <<= 16;
                page |= short_pack(srb->cmnd[5], srb->cmnd[4]);
                pages = short_pack(srb->cmnd[8], srb->cmnd[7]);

                usb_stor_dbg(us, "WRITE_10: page %d pagect %d\n", page, pages);

                return alauda_write_data(us, page, pages);
        }

        if (srb->cmnd[0] == REQUEST_SENSE) {
                usb_stor_dbg(us, "REQUEST_SENSE\n");

                memset(ptr, 0, 18);
                ptr[0] = 0xF0;
                ptr[2] = info->sense_key;
                ptr[7] = 11;
                ptr[12] = info->sense_asc;
                ptr[13] = info->sense_ascq;
                usb_stor_set_xfer_buf(ptr, 18, srb);

                return USB_STOR_TRANSPORT_GOOD;
        }

        if (srb->cmnd[0] == ALLOW_MEDIUM_REMOVAL) {
                /* sure.  whatever.  not like we can stop the user from popping
                   the media out of the device (no locking doors, etc) */
                return USB_STOR_TRANSPORT_GOOD;
        }

        usb_stor_dbg(us, "Gah! Unknown command: %d (0x%x)\n",
                     srb->cmnd[0], srb->cmnd[0]);
        info->sense_key = 0x05;
        info->sense_asc = 0x20;
        info->sense_ascq = 0x00;
        return USB_STOR_TRANSPORT_FAILED;
}

static int alauda_probe(struct usb_interface *intf,
                         const struct usb_device_id *id)
{
        struct us_data *us;
        int result;

        result = usb_stor_probe1(&us, intf, id,
                        (id - alauda_usb_ids) + alauda_unusual_dev_list);
        if (result)
                return result;

        us->transport_name  = "Alauda Control/Bulk";
        us->transport = alauda_transport;
        us->transport_reset = usb_stor_Bulk_reset;
        us->max_lun = 1;

        result = usb_stor_probe2(us);
        return result;
}

static struct usb_driver alauda_driver = {
        .name =         "ums-alauda",
        .probe =        alauda_probe,
        .disconnect =   usb_stor_disconnect,
        .suspend =      usb_stor_suspend,
        .resume =       usb_stor_resume,
        .reset_resume = usb_stor_reset_resume,
        .pre_reset =    usb_stor_pre_reset,
        .post_reset =   usb_stor_post_reset,
        .id_table =     alauda_usb_ids,
        .soft_unbind =  1,
        .no_dynamic_id = 1,
};

module_usb_driver(alauda_driver);