st.c

讲述linux的初始化过程

                   dev, debugging);)
}


static int st_set_options(Scsi_Tape *STp, long options)
{
	int value;
	long code;
	ST_mode *STm;
	int dev = TAPE_NR(STp->devt);

	STm = &(STp->modes[STp->current_mode]);
	if (!STm->defined) {
		memcpy(STm, &(STp->modes[0]), sizeof(ST_mode));
		modes_defined = TRUE;
                DEBC(printk(ST_DEB_MSG
                            "st%d: Initialized mode %d definition from mode 0\n",
                            dev, STp->current_mode));
	}

	code = options & MT_ST_OPTIONS;
	if (code == MT_ST_BOOLEANS) {
		STm->do_buffer_writes = (options & MT_ST_BUFFER_WRITES) != 0;
		STm->do_async_writes = (options & MT_ST_ASYNC_WRITES) != 0;
		STm->defaults_for_writes = (options & MT_ST_DEF_WRITES) != 0;
		STm->do_read_ahead = (options & MT_ST_READ_AHEAD) != 0;
		STp->two_fm = (options & MT_ST_TWO_FM) != 0;
		STp->fast_mteom = (options & MT_ST_FAST_MTEOM) != 0;
		STp->do_auto_lock = (options & MT_ST_AUTO_LOCK) != 0;
		STp->can_bsr = (options & MT_ST_CAN_BSR) != 0;
		STp->omit_blklims = (options & MT_ST_NO_BLKLIMS) != 0;
		if ((STp->device)->scsi_level >= SCSI_2)
			STp->can_partitions = (options & MT_ST_CAN_PARTITIONS) != 0;
		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
		STm->sysv = (options & MT_ST_SYSV) != 0;
		DEB( debugging = (options & MT_ST_DEBUGGING) != 0; )
		st_log_options(STp, STm, dev);
	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
		value = (code == MT_ST_SETBOOLEANS);
		if ((options & MT_ST_BUFFER_WRITES) != 0)
			STm->do_buffer_writes = value;
		if ((options & MT_ST_ASYNC_WRITES) != 0)
			STm->do_async_writes = value;
		if ((options & MT_ST_DEF_WRITES) != 0)
			STm->defaults_for_writes = value;
		if ((options & MT_ST_READ_AHEAD) != 0)
			STm->do_read_ahead = value;
		if ((options & MT_ST_TWO_FM) != 0)
			STp->two_fm = value;
		if ((options & MT_ST_FAST_MTEOM) != 0)
			STp->fast_mteom = value;
		if ((options & MT_ST_AUTO_LOCK) != 0)
			STp->do_auto_lock = value;
		if ((options & MT_ST_CAN_BSR) != 0)
			STp->can_bsr = value;
		if ((options & MT_ST_NO_BLKLIMS) != 0)
			STp->omit_blklims = value;
		if ((STp->device)->scsi_level >= SCSI_2 &&
		    (options & MT_ST_CAN_PARTITIONS) != 0)
			STp->can_partitions = value;
		if ((options & MT_ST_SCSI2LOGICAL) != 0)
			STp->scsi2_logical = value;
		if ((options & MT_ST_SYSV) != 0)
			STm->sysv = value;
                DEB(
		if ((options & MT_ST_DEBUGGING) != 0)
			debugging = value; )
		st_log_options(STp, STm, dev);
	} else if (code == MT_ST_WRITE_THRESHOLD) {
		value = (options & ~MT_ST_OPTIONS) * ST_KILOBYTE;
		if (value < 1 || value > st_buffer_size) {
			printk(KERN_WARNING
                               "st%d: Write threshold %d too small or too large.\n",
			       dev, value);
			return (-EIO);
		}
		STp->write_threshold = value;
		printk(KERN_INFO "st%d: Write threshold set to %d bytes.\n",
		       dev, value);
	} else if (code == MT_ST_DEF_BLKSIZE) {
		value = (options & ~MT_ST_OPTIONS);
		if (value == ~MT_ST_OPTIONS) {
			STm->default_blksize = (-1);
			printk(KERN_INFO "st%d: Default block size disabled.\n", dev);
		} else {
			STm->default_blksize = value;
			printk(KERN_INFO "st%d: Default block size set to %d bytes.\n",
			       dev, STm->default_blksize);
		}
	} else if (code == MT_ST_TIMEOUTS) {
		value = (options & ~MT_ST_OPTIONS);
		if ((value & MT_ST_SET_LONG_TIMEOUT) != 0) {
			STp->long_timeout = (value & ~MT_ST_SET_LONG_TIMEOUT) * HZ;
			printk(KERN_INFO "st%d: Long timeout set to %d seconds.\n", dev,
			       (value & ~MT_ST_SET_LONG_TIMEOUT));
		} else {
			STp->timeout = value * HZ;
			printk(KERN_INFO "st%d: Normal timeout set to %d seconds.\n",
                               dev, value);
		}
	} else if (code == MT_ST_DEF_OPTIONS) {
		code = (options & ~MT_ST_CLEAR_DEFAULT);
		value = (options & MT_ST_CLEAR_DEFAULT);
		if (code == MT_ST_DEF_DENSITY) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STm->default_density = (-1);
				printk(KERN_INFO "st%d: Density default disabled.\n",
                                       dev);
			} else {
				STm->default_density = value & 0xff;
				printk(KERN_INFO "st%d: Density default set to %x\n",
				       dev, STm->default_density);
			}
		} else if (code == MT_ST_DEF_DRVBUFFER) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STp->default_drvbuffer = 0xff;
				printk(KERN_INFO
                                       "st%d: Drive buffer default disabled.\n", dev);
			} else {
				STp->default_drvbuffer = value & 7;
				printk(KERN_INFO
                                       "st%d: Drive buffer default set to %x\n",
				       dev, STp->default_drvbuffer);
			}
		} else if (code == MT_ST_DEF_COMPRESSION) {
			if (value == MT_ST_CLEAR_DEFAULT) {
				STm->default_compression = ST_DONT_TOUCH;
				printk(KERN_INFO
                                       "st%d: Compression default disabled.\n", dev);
			} else {
				STm->default_compression = (value & 1 ? ST_YES : ST_NO);
				printk(KERN_INFO "st%d: Compression default set to %x\n",
				       dev, (value & 1));
			}
		}
	} else
		return (-EIO);

	return 0;
}

#define MODE_HEADER_LENGTH  4

/* Mode header and page byte offsets */
#define MH_OFF_DATA_LENGTH     0
#define MH_OFF_MEDIUM_TYPE     1
#define MH_OFF_DEV_SPECIFIC    2
#define MH_OFF_BDESCS_LENGTH   3
#define MP_OFF_PAGE_NBR        0
#define MP_OFF_PAGE_LENGTH     1

/* Mode header and page bit masks */
#define MH_BIT_WP              0x80
#define MP_MSK_PAGE_NBR        0x3f

/* Don't return block descriptors */
#define MODE_SENSE_OMIT_BDESCS 0x08

#define MODE_SELECT_PAGE_FORMAT 0x10

/* Read a mode page into the tape buffer. The block descriptors are included
   if incl_block_descs is true. */
static int read_mode_page(Scsi_Tape *STp, int page, int omit_block_descs)
{
	unsigned char cmd[MAX_COMMAND_SIZE];
	Scsi_Request *SRpnt = NULL;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SENSE;
	if (omit_block_descs)
		cmd[1] = MODE_SENSE_OMIT_BDESCS;
	cmd[2] = page;
	cmd[4] = 255;

	SRpnt = st_do_scsi(SRpnt, STp, cmd, cmd[4], SCSI_DATA_READ,
			   STp->timeout, 0, TRUE);
	if (SRpnt == NULL)
		return (STp->buffer)->syscall_result;

	scsi_release_request(SRpnt);

	return (STp->buffer)->syscall_result;
}


/* Send the mode page in the tape buffer to the drive. Assumes that the mode data
   in the buffer is correctly formatted. */
static int write_mode_page(Scsi_Tape *STp, int page)
{
	int pgo;
	unsigned char cmd[MAX_COMMAND_SIZE];
	Scsi_Request *SRpnt = NULL;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	cmd[0] = MODE_SELECT;
	cmd[1] = MODE_SELECT_PAGE_FORMAT;
	pgo = MODE_HEADER_LENGTH + (STp->buffer)->b_data[MH_OFF_BDESCS_LENGTH];
	cmd[4] = pgo + (STp->buffer)->b_data[pgo + MP_OFF_PAGE_LENGTH] + 2;

	/* Clear reserved fields */
	(STp->buffer)->b_data[MH_OFF_DATA_LENGTH] = 0;
	(STp->buffer)->b_data[MH_OFF_MEDIUM_TYPE] = 0;
	(STp->buffer)->b_data[MH_OFF_DEV_SPECIFIC] &= ~MH_BIT_WP;
	(STp->buffer)->b_data[pgo + MP_OFF_PAGE_NBR] &= MP_MSK_PAGE_NBR;

	SRpnt = st_do_scsi(SRpnt, STp, cmd, cmd[4], SCSI_DATA_WRITE,
			   STp->timeout, 0, TRUE);
	if (SRpnt == NULL)
		return (STp->buffer)->syscall_result;

	scsi_release_request(SRpnt);

	return (STp->buffer)->syscall_result;
}


#define COMPRESSION_PAGE        0x0f
#define COMPRESSION_PAGE_LENGTH 16

#define CP_OFF_DCE_DCC          2

#define DCE_MASK  0x80
#define DCC_MASK  0x40
#define RED_MASK  0x60


/* Control the compression with mode page 15. Algorithm not changed if zero.

   The block descriptors are read and written because Sony SDT-7000 does not
   work without this (suggestion from Michael Schaefer <[e-mail]>).
   Including block descriptors should not cause any harm to other drives. */

static int st_compression(Scsi_Tape * STp, int state)
{
	int retval;
	int mpoffs;  /* Offset to mode page start */
	unsigned char *b_data = (STp->buffer)->b_data;
	DEB( int dev = TAPE_NR(STp->devt); )

	if (STp->ready != ST_READY)
		return (-EIO);

	/* Read the current page contents */
	retval = read_mode_page(STp, COMPRESSION_PAGE, FALSE);
	if (retval) {
                DEBC(printk(ST_DEB_MSG "st%d: Compression mode page not supported.\n",
                            dev));
		return (-EIO);
	}

	mpoffs = MODE_HEADER_LENGTH + b_data[MH_OFF_BDESCS_LENGTH];
        DEBC(printk(ST_DEB_MSG "st%d: Compression state is %d.\n", dev,
                    (b_data[mpoffs + CP_OFF_DCE_DCC] & DCE_MASK ? 1 : 0)));

	/* Check if compression can be changed */
	if ((b_data[mpoffs + 2] & DCC_MASK) == 0) {
                DEBC(printk(ST_DEB_MSG "st%d: Compression not supported.\n", dev));
		return (-EIO);
	}

	/* Do the change */
	if (state)
		b_data[mpoffs + CP_OFF_DCE_DCC] |= DCE_MASK;
	else
		b_data[mpoffs + CP_OFF_DCE_DCC] &= ~DCE_MASK;

	retval = write_mode_page(STp, COMPRESSION_PAGE);
	if (retval) {
                DEBC(printk(ST_DEB_MSG "st%d: Compression change failed.\n", dev));
		return (-EIO);
	}
        DEBC(printk(ST_DEB_MSG "st%d: Compression state changed to %d.\n",
		       dev, state));

	STp->compression_changed = TRUE;
	return 0;
}


/* Internal ioctl function */
static int st_int_ioctl(Scsi_Tape *STp, unsigned int cmd_in, unsigned long arg)
{
	int timeout;
	long ltmp;
	int i, ioctl_result;
	int chg_eof = TRUE;
	unsigned char cmd[MAX_COMMAND_SIZE];
	Scsi_Request *SRpnt;
	ST_partstat *STps;
	int fileno, blkno, at_sm, undone;
	int datalen = 0, direction = SCSI_DATA_NONE;
	int dev = TAPE_NR(STp->devt);

	if (STp->ready != ST_READY && cmd_in != MTLOAD) {
		if (STp->ready == ST_NO_TAPE)
			return (-ENOMEDIUM);
		else
			return (-EIO);
	}
	timeout = STp->long_timeout;
	STps = &(STp->ps[STp->partition]);
	fileno = STps->drv_file;
	blkno = STps->drv_block;
	at_sm = STps->at_sm;

	memset(cmd, 0, MAX_COMMAND_SIZE);
	switch (cmd_in) {
	case MTFSFM:
		chg_eof = FALSE;	/* Changed from the FSF after this */
	case MTFSF:
		cmd[0] = SPACE;
		cmd[1] = 0x01;	/* Space FileMarks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(printk(ST_DEB_MSG "st%d: Spacing tape forward over %d filemarks.\n",
			    dev, cmd[2] * 65536 + cmd[3] * 256 + cmd[4]));
		if (fileno >= 0)
			fileno += arg;
		blkno = 0;
		at_sm &= (arg == 0);
		break;
	case MTBSFM:
		chg_eof = FALSE;	/* Changed from the FSF after this */
	case MTBSF:
		cmd[0] = SPACE;
		cmd[1] = 0x01;	/* Space FileMarks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(
                     if (cmd[2] & 0x80)
                     	ltmp = 0xff000000;
                     ltmp = ltmp | (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
                     printk(ST_DEB_MSG
                            "st%d: Spacing tape backward over %ld filemarks.\n",
                            dev, (-ltmp));
		)
		if (fileno >= 0)
			fileno -= arg;
		blkno = (-1);	/* We can't know the block number */
		at_sm &= (arg == 0);
		break;
	case MTFSR:
		cmd[0] = SPACE;
		cmd[1] = 0x00;	/* Space Blocks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(printk(ST_DEB_MSG "st%d: Spacing tape forward %d blocks.\n", dev,
			       cmd[2] * 65536 + cmd[3] * 256 + cmd[4]));
		if (blkno >= 0)
			blkno += arg;
		at_sm &= (arg == 0);
		break;
	case MTBSR:
		cmd[0] = SPACE;
		cmd[1] = 0x00;	/* Space Blocks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(
                     if (cmd[2] & 0x80)
                          ltmp = 0xff000000;
                     ltmp = ltmp | (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
                     printk(ST_DEB_MSG
                            "st%d: Spacing tape backward %ld blocks.\n", dev, (-ltmp));
		)
		if (blkno >= 0)
			blkno -= arg;
		at_sm &= (arg == 0);
		break;
	case MTFSS:
		cmd[0] = SPACE;
		cmd[1] = 0x04;	/* Space Setmarks */
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
                DEBC(printk(ST_DEB_MSG "st%d: Spacing tape forward %d setmarks.\n", dev,
                            cmd[2] * 65536 + cmd[3] * 256 + cmd[4]));
		if (arg != 0) {
			blkno = fileno = (-1);
			at_sm = 1;
		}
		break;
	case MTBSS:
		cmd[0] = SPACE;
		cmd[1] = 0x04;	/* Space Setmarks */
		ltmp = (-arg);
		cmd[2] = (ltmp >> 16);
		cmd[3] = (ltmp >> 8);
		cmd[4] = ltmp;
                DEBC(
                     if (cmd[2] & 0x80)
				ltmp = 0xff000000;
                     ltmp = ltmp | (cmd[2] << 16) | (cmd[3] << 8) | cmd[4];
                     printk(ST_DEB_MSG "st%d: Spacing tape backward %ld setmarks.\n",
                            dev, (-ltmp));
		)
		if (arg != 0) {
			blkno = fileno = (-1);
			at_sm = 1;
		}
		break;
	case MTWEOF:
	case MTWSM:
		if (STp->write_prot)
			return (-EACCES);
		cmd[0] = WRITE_FILEMARKS;
		if (cmd_in == MTWSM)
			cmd[1] = 2;
		cmd[2] = (arg >> 16);
		cmd[3] = (arg >> 8);
		cmd[4] = arg;
		timeout = STp->timeout;
                DEBC(
                     if (cmd_in == MTWEOF)
                               printk(ST_DEB_MSG "st%d: Writing %d filemarks.\n", dev,
				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
                     else
				printk(ST_DEB_MSG "st%d: Writing %d setmarks.\n", dev,
				 cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
		)
		if (fileno >= 0)
			fileno += arg;
		blkno = 0;
		at_sm = (cmd_in == MTWSM);
		break;
	case MTREW:
		cmd[0] = REZERO_UNIT;
#if ST_NOWAIT
		cmd[1] = 1;	/* Don't wait for completion */
		timeout = STp->timeout;
#endif
                DEBC(printk(ST_DEB_MSG "st%d: Rewinding tape.\n", dev));
		fileno = blkno = at_sm = 0;
		break;
	case MTOFFL:
	case MTLOAD:
	case MTUNLOAD:
		cmd[0] = START_STOP;
		if (cmd_in == MTLOAD)
			cmd[4] |= 1;
		/*
		 * If arg >= 1 && arg <= 6 Enhanced load/unload in HP C1553A
		 */
		if (cmd_in != MTOFFL &&
		    arg >= 1 + MT_ST_HPLOADER_OFFSET
		    && arg <= 6 + MT_ST_HPLOADER_OFFSET) {
                        DEBC(printk(ST_DEB_MSG "st%d: Enhanced %sload slot %2ld.\n",