/*
 * SCSI functions used by both the initiator and the target code.
 */

#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <asm/unaligned.h>
#include <scsi/scsi_common.h>

/* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
 * You may not alter any existing entry (although adding new ones is
 * encouraged once assigned by ANSI/INCITS T10
 */
static const char *const scsi_device_types[] = {
        "Direct-Access    ",
        "Sequential-Access",
        "Printer          ",
        "Processor        ",
        "WORM             ",
        "CD-ROM           ",
        "Scanner          ",
        "Optical Device   ",
        "Medium Changer   ",
        "Communications   ",
        "ASC IT8          ",
        "ASC IT8          ",
        "RAID             ",
        "Enclosure        ",
        "Direct-Access-RBC",
        "Optical card     ",
        "Bridge controller",
        "Object storage   ",
        "Automation/Drive ",
        "Security Manager ",
        "Direct-Access-ZBC",
};

/**
 * scsi_device_type - Return 17 char string indicating device type.
 * @type: type number to look up
 */
const char *scsi_device_type(unsigned type)
{
        if (type == 0x1e)
                return "Well-known LUN   ";
        if (type == 0x1f)
                return "No Device        ";
        if (type >= ARRAY_SIZE(scsi_device_types))
                return "Unknown          ";
        return scsi_device_types[type];
}
EXPORT_SYMBOL(scsi_device_type);

/**
 * scsilun_to_int - convert a scsi_lun to an int
 * @scsilun:    struct scsi_lun to be converted.
 *
 * Description:
 *     Convert @scsilun from a struct scsi_lun to a four byte host byte-ordered
 *     integer, and return the result. The caller must check for
 *     truncation before using this function.
 *
 * Notes:
 *     For a description of the LUN format, post SCSI-3 see the SCSI
 *     Architecture Model, for SCSI-3 see the SCSI Controller Commands.
 *
 *     Given a struct scsi_lun of: d2 04 0b 03 00 00 00 00, this function
 *     returns the integer: 0x0b03d204
 *
 *     This encoding will return a standard integer LUN for LUNs smaller
 *     than 256, which typically use a single level LUN structure with
 *     addressing method 0.
 */
u64 scsilun_to_int(struct scsi_lun *scsilun)
{
        int i;
        u64 lun;

        lun = 0;
        for (i = 0; i < sizeof(lun); i += 2)
                lun = lun | (((u64)scsilun->scsi_lun[i] << ((i + 1) * 8)) |
                             ((u64)scsilun->scsi_lun[i + 1] << (i * 8)));
        return lun;
}
EXPORT_SYMBOL(scsilun_to_int);

/**
 * int_to_scsilun - reverts an int into a scsi_lun
 * @lun:        integer to be reverted
 * @scsilun:    struct scsi_lun to be set.
 *
 * Description:
 *     Reverts the functionality of the scsilun_to_int, which packed
 *     an 8-byte lun value into an int. This routine unpacks the int
 *     back into the lun value.
 *
 * Notes:
 *     Given an integer : 0x0b03d204,  this function returns a
 *     struct scsi_lun of: d2 04 0b 03 00 00 00 00
 *
 */
void int_to_scsilun(u64 lun, struct scsi_lun *scsilun)
{
        int i;

        memset(scsilun->scsi_lun, 0, sizeof(scsilun->scsi_lun));

        for (i = 0; i < sizeof(lun); i += 2) {
                scsilun->scsi_lun[i] = (lun >> 8) & 0xFF;
                scsilun->scsi_lun[i+1] = lun & 0xFF;
                lun = lun >> 16;
        }
}
EXPORT_SYMBOL(int_to_scsilun);

/**
 * scsi_normalize_sense - normalize main elements from either fixed or
 *                      descriptor sense data format into a common format.
 *
 * @sense_buffer:       byte array containing sense data returned by device
 * @sb_len:             number of valid bytes in sense_buffer
 * @sshdr:              pointer to instance of structure that common
 *                      elements are written to.
 *
 * Notes:
 *      The "main elements" from sense data are: response_code, sense_key,
 *      asc, ascq and additional_length (only for descriptor format).
 *
 *      Typically this function can be called after a device has
 *      responded to a SCSI command with the CHECK_CONDITION status.
 *
 * Return value:
 *      true if valid sense data information found, else false;
 */
bool scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
                          struct scsi_sense_hdr *sshdr)
{
        if (!sense_buffer || !sb_len)
                return false;

        memset(sshdr, 0, sizeof(struct scsi_sense_hdr));

        sshdr->response_code = (sense_buffer[0] & 0x7f);

        if (!scsi_sense_valid(sshdr))
                return false;

        if (sshdr->response_code >= 0x72) {
                /*
                 * descriptor format
                 */
                if (sb_len > 1)
                        sshdr->sense_key = (sense_buffer[1] & 0xf);
                if (sb_len > 2)
                        sshdr->asc = sense_buffer[2];
                if (sb_len > 3)
                        sshdr->ascq = sense_buffer[3];
                if (sb_len > 7)
                        sshdr->additional_length = sense_buffer[7];
        } else {
                /*
                 * fixed format
                 */
                if (sb_len > 2)
                        sshdr->sense_key = (sense_buffer[2] & 0xf);
                if (sb_len > 7) {
                        sb_len = (sb_len < (sense_buffer[7] + 8)) ?
                                         sb_len : (sense_buffer[7] + 8);
                        if (sb_len > 12)
                                sshdr->asc = sense_buffer[12];
                        if (sb_len > 13)
                                sshdr->ascq = sense_buffer[13];
                }
        }

        return true;
}
EXPORT_SYMBOL(scsi_normalize_sense);

/**
 * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
 * @sense_buffer:       byte array of descriptor format sense data
 * @sb_len:             number of valid bytes in sense_buffer
 * @desc_type:          value of descriptor type to find
 *                      (e.g. 0 -> information)
 *
 * Notes:
 *      only valid when sense data is in descriptor format
 *
 * Return value:
 *      pointer to start of (first) descriptor if found else NULL
 */
const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
                                int desc_type)
{
        int add_sen_len, add_len, desc_len, k;
        const u8 * descp;

        if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
                return NULL;
        if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
                return NULL;
        add_sen_len = (add_sen_len < (sb_len - 8)) ?
                        add_sen_len : (sb_len - 8);
        descp = &sense_buffer[8];
        for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
                descp += desc_len;
                add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
                desc_len = add_len + 2;
                if (descp[0] == desc_type)
                        return descp;
                if (add_len < 0) // short descriptor ??
                        break;
        }
        return NULL;
}
EXPORT_SYMBOL(scsi_sense_desc_find);

/**
 * scsi_build_sense_buffer - build sense data in a buffer
 * @desc:       Sense format (non zero == descriptor format,
 *              0 == fixed format)
 * @buf:        Where to build sense data
 * @key:        Sense key
 * @asc:        Additional sense code
 * @ascq:       Additional sense code qualifier
 *
 **/
void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
{
        if (desc) {
                buf[0] = 0x72;  /* descriptor, current */
                buf[1] = key;
                buf[2] = asc;
                buf[3] = ascq;
                buf[7] = 0;
        } else {
                buf[0] = 0x70;  /* fixed, current */
                buf[2] = key;
                buf[7] = 0xa;
                buf[12] = asc;
                buf[13] = ascq;
        }
}
EXPORT_SYMBOL(scsi_build_sense_buffer);

/**
 * scsi_set_sense_information - set the information field in a
 *              formatted sense data buffer
 * @buf:        Where to build sense data
 * @buf_len:    buffer length
 * @info:       64-bit information value to be set
 *
 * Return value:
 *      0 on success or EINVAL for invalid sense buffer length
 **/
int scsi_set_sense_information(u8 *buf, int buf_len, u64 info)
{
        if ((buf[0] & 0x7f) == 0x72) {
                u8 *ucp, len;

                len = buf[7];
                ucp = (char *)scsi_sense_desc_find(buf, len + 8, 0);
                if (!ucp) {
                        buf[7] = len + 0xc;
                        ucp = buf + 8 + len;
                }

                if (buf_len < len + 0xc)
                        /* Not enough room for info */
                        return -EINVAL;

                ucp[0] = 0;
                ucp[1] = 0xa;
                ucp[2] = 0x80; /* Valid bit */
                ucp[3] = 0;
                put_unaligned_be64(info, &ucp[4]);
        } else if ((buf[0] & 0x7f) == 0x70) {
                /*
                 * Only set the 'VALID' bit if we can represent the value
                 * correctly; otherwise just fill out the lower bytes and
                 * clear the 'VALID' flag.
                 */
                if (info <= 0xffffffffUL)
                        buf[0] |= 0x80;
                else
                        buf[0] &= 0x7f;
                put_unaligned_be32((u32)info, &buf[3]);
        }

        return 0;
}
EXPORT_SYMBOL(scsi_set_sense_information);

/**
 * scsi_set_sense_field_pointer - set the field pointer sense key
 *              specific information in a formatted sense data buffer
 * @buf:        Where to build sense data
 * @buf_len:    buffer length
 * @fp:         field pointer to be set
 * @bp:         bit pointer to be set
 * @cd:         command/data bit
 *
 * Return value:
 *      0 on success or EINVAL for invalid sense buffer length
 */
int scsi_set_sense_field_pointer(u8 *buf, int buf_len, u16 fp, u8 bp, bool cd)
{
        u8 *ucp, len;

        if ((buf[0] & 0x7f) == 0x72) {
                len = buf[7];
                ucp = (char *)scsi_sense_desc_find(buf, len + 8, 2);
                if (!ucp) {
                        buf[7] = len + 8;
                        ucp = buf + 8 + len;
                }

                if (buf_len < len + 8)
                        /* Not enough room for info */
                        return -EINVAL;

                ucp[0] = 2;
                ucp[1] = 6;
                ucp[4] = 0x80; /* Valid bit */
                if (cd)
                        ucp[4] |= 0x40;
                if (bp < 0x8)
                        ucp[4] |= 0x8 | bp;
                put_unaligned_be16(fp, &ucp[5]);
        } else if ((buf[0] & 0x7f) == 0x70) {
                len = buf[7];
                if (len < 18)
                        buf[7] = 18;

                buf[15] = 0x80;
                if (cd)
                        buf[15] |= 0x40;
                if (bp < 0x8)
                        buf[15] |= 0x8 | bp;
                put_unaligned_be16(fp, &buf[16]);
        }

        return 0;
}
EXPORT_SYMBOL(scsi_set_sense_field_pointer);