ide-scsi.c

讲述linux的初始化过程

	pc->current_position=pc->buffer;
	bcount = IDE_MIN (pc->request_transfer, 63 * 1024);		/* Request to transfer the entire buffer at once */

	if (drive->using_dma && rq->bh)
		dma_ok=!HWIF(drive)->dmaproc(test_bit (PC_WRITING, &pc->flags) ? ide_dma_write : ide_dma_read, drive);

	SELECT_DRIVE(HWIF(drive), drive);
	if (IDE_CONTROL_REG)
		OUT_BYTE (drive->ctl,IDE_CONTROL_REG);
	OUT_BYTE (dma_ok,IDE_FEATURE_REG);
	OUT_BYTE (bcount >> 8,IDE_BCOUNTH_REG);
	OUT_BYTE (bcount & 0xff,IDE_BCOUNTL_REG);

	if (dma_ok) {
		set_bit (PC_DMA_IN_PROGRESS, &pc->flags);
		(void) (HWIF(drive)->dmaproc(ide_dma_begin, drive));
	}
	if (test_bit (IDESCSI_DRQ_INTERRUPT, &scsi->flags)) {
		ide_set_handler (drive, &idescsi_transfer_pc, get_timeout(pc), NULL);
		OUT_BYTE (WIN_PACKETCMD, IDE_COMMAND_REG);		/* Issue the packet command */
		return ide_started;
	} else {
		OUT_BYTE (WIN_PACKETCMD, IDE_COMMAND_REG);
		return idescsi_transfer_pc (drive);
	}
}

/*
 *	idescsi_do_request is our request handling function.
 */
static ide_startstop_t idescsi_do_request (ide_drive_t *drive, struct request *rq, unsigned long block)
{
#if IDESCSI_DEBUG_LOG
	printk (KERN_INFO "rq_status: %d, rq_dev: %u, cmd: %d, errors: %d\n",rq->rq_status,(unsigned int) rq->rq_dev,rq->cmd,rq->errors);
	printk (KERN_INFO "sector: %ld, nr_sectors: %ld, current_nr_sectors: %ld\n",rq->sector,rq->nr_sectors,rq->current_nr_sectors);
#endif /* IDESCSI_DEBUG_LOG */

	if (rq->cmd == IDESCSI_PC_RQ) {
		return idescsi_issue_pc (drive, (idescsi_pc_t *) rq->buffer);
	}
	printk (KERN_ERR "ide-scsi: %s: unsupported command in request queue (%x)\n", drive->name, rq->cmd);
	idescsi_end_request (0,HWGROUP (drive));
	return ide_stopped;
}

static int idescsi_open (struct inode *inode, struct file *filp, ide_drive_t *drive)
{
	MOD_INC_USE_COUNT;
	return 0;
}

static void idescsi_ide_release (struct inode *inode, struct file *filp, ide_drive_t *drive)
{
	MOD_DEC_USE_COUNT;
}

static ide_drive_t *idescsi_drives[MAX_HWIFS * MAX_DRIVES];
static int idescsi_initialized = 0;

static void idescsi_add_settings(ide_drive_t *drive)
{
	idescsi_scsi_t *scsi = drive->driver_data;

/*
 *			drive	setting name	read/write	ioctl	ioctl		data type	min	max	mul_factor	div_factor	data pointer		set function
 */
	ide_add_setting(drive,	"bios_cyl",	SETTING_RW,	-1,	-1,		TYPE_INT,	0,	1023,	1,		1,		&drive->bios_cyl,	NULL);
	ide_add_setting(drive,	"bios_head",	SETTING_RW,	-1,	-1,		TYPE_BYTE,	0,	255,	1,		1,		&drive->bios_head,	NULL);
	ide_add_setting(drive,	"bios_sect",	SETTING_RW,	-1,	-1,		TYPE_BYTE,	0,	63,	1,		1,		&drive->bios_sect,	NULL);
	ide_add_setting(drive,	"transform",	SETTING_RW,	-1,	-1,		TYPE_INT,	0,	3,	1,		1,		&scsi->transform,	NULL);
	ide_add_setting(drive,	"log",		SETTING_RW,	-1,	-1,		TYPE_INT,	0,	1,	1,		1,		&scsi->log,		NULL);
}

/*
 *	Driver initialization.
 */
static void idescsi_setup (ide_drive_t *drive, idescsi_scsi_t *scsi, int id)
{
	DRIVER(drive)->busy++;
	idescsi_drives[id] = drive;
	drive->driver_data = scsi;
	drive->ready_stat = 0;
	memset (scsi, 0, sizeof (idescsi_scsi_t));
	scsi->drive = drive;
	if (drive->id && (drive->id->config & 0x0060) == 0x20)
		set_bit (IDESCSI_DRQ_INTERRUPT, &scsi->flags);
	set_bit(IDESCSI_TRANSFORM, &scsi->transform);
	clear_bit(IDESCSI_SG_TRANSFORM, &scsi->transform);
#if IDESCSI_DEBUG_LOG
	set_bit(IDESCSI_LOG_CMD, &scsi->log);
#endif /* IDESCSI_DEBUG_LOG */
	idescsi_add_settings(drive);
}

static int idescsi_cleanup (ide_drive_t *drive)
{
	idescsi_scsi_t *scsi = drive->driver_data;

	if (ide_unregister_subdriver (drive))
		return 1;
	drive->driver_data = NULL;
	kfree (scsi);
	return 0;
}

/*
 *	IDE subdriver functions, registered with ide.c
 */
static ide_driver_t idescsi_driver = {
	"ide-scsi",		/* name */
	IDESCSI_VERSION,	/* version */
	ide_scsi,		/* media */
	0,			/* busy */
	1,			/* supports_dma */
	0,			/* supports_dsc_overlap */
	idescsi_cleanup,	/* cleanup */
	idescsi_do_request,	/* do_request */
	idescsi_end_request,	/* end_request */
	NULL,			/* ioctl */
	idescsi_open,		/* open */
	idescsi_ide_release,	/* release */
	NULL,			/* media_change */
	NULL,			/* revalidate */
	NULL,			/* pre_reset */
	NULL,			/* capacity */
	NULL,			/* special */
	NULL			/* proc */
};

int idescsi_init (void);
static ide_module_t idescsi_module = {
	IDE_DRIVER_MODULE,
	idescsi_init,
	&idescsi_driver,
	NULL
};

/*
 *	idescsi_init will register the driver for each scsi.
 */
int idescsi_init (void)
{
	ide_drive_t *drive;
	idescsi_scsi_t *scsi;
	byte media[] = {TYPE_DISK, TYPE_TAPE, TYPE_PROCESSOR, TYPE_WORM, TYPE_ROM, TYPE_SCANNER, TYPE_MOD, 255};
	int i, failed, id;

	if (idescsi_initialized)
		return 0;
	idescsi_initialized = 1;
	for (i = 0; i < MAX_HWIFS * MAX_DRIVES; i++)
		idescsi_drives[i] = NULL;
	MOD_INC_USE_COUNT;
	for (i = 0; media[i] != 255; i++) {
		failed = 0;
		while ((drive = ide_scan_devices (media[i], idescsi_driver.name, NULL, failed++)) != NULL) {

			if ((scsi = (idescsi_scsi_t *) kmalloc (sizeof (idescsi_scsi_t), GFP_KERNEL)) == NULL) {
				printk (KERN_ERR "ide-scsi: %s: Can't allocate a scsi structure\n", drive->name);
				continue;
			}
			if (ide_register_subdriver (drive, &idescsi_driver, IDE_SUBDRIVER_VERSION)) {
				printk (KERN_ERR "ide-scsi: %s: Failed to register the driver with ide.c\n", drive->name);
				kfree (scsi);
				continue;
			}
			for (id = 0; id < MAX_HWIFS * MAX_DRIVES && idescsi_drives[id]; id++);
			idescsi_setup (drive, scsi, id);
			failed--;
		}
	}
	ide_register_module(&idescsi_module);
	MOD_DEC_USE_COUNT;
	return 0;
}

int idescsi_detect (Scsi_Host_Template *host_template)
{
	struct Scsi_Host *host;
	int id;
	int last_lun = 0;

	host_template->proc_name = "ide-scsi";
	host = scsi_register(host_template, 0);
	if(host == NULL)
		return 0;
		
	for (id = 0; id < MAX_HWIFS * MAX_DRIVES && idescsi_drives[id]; id++)
		last_lun = IDE_MAX(last_lun, idescsi_drives[id]->last_lun);
	host->max_id = id;
	host->max_lun = last_lun + 1;
	host->can_queue = host->cmd_per_lun * id;
	return 1;
}

int idescsi_release (struct Scsi_Host *host)
{
	ide_drive_t *drive;
	int id;

	for (id = 0; id < MAX_HWIFS * MAX_DRIVES; id++) {
		drive = idescsi_drives[id];
		if (drive)
			DRIVER(drive)->busy--;
	}
	return 0;
}

const char *idescsi_info (struct Scsi_Host *host)
{
	return "SCSI host adapter emulation for IDE ATAPI devices";
}

int idescsi_ioctl (Scsi_Device *dev, int cmd, void *arg)
{
	ide_drive_t *drive = idescsi_drives[dev->id];
	idescsi_scsi_t *scsi = drive->driver_data;

	if (cmd == SG_SET_TRANSFORM) {
		if (arg)
			set_bit(IDESCSI_SG_TRANSFORM, &scsi->transform);
		else
			clear_bit(IDESCSI_SG_TRANSFORM, &scsi->transform);
		return 0;
	} else if (cmd == SG_GET_TRANSFORM)
		return put_user(test_bit(IDESCSI_SG_TRANSFORM, &scsi->transform), (int *) arg);
	return -EINVAL;
}

static inline struct buffer_head *idescsi_kmalloc_bh (int count)
{
	struct buffer_head *bh, *bhp, *first_bh;

	if ((first_bh = bhp = bh = kmalloc (sizeof(struct buffer_head), GFP_ATOMIC)) == NULL)
		goto abort;
	memset (bh, 0, sizeof (struct buffer_head));
	bh->b_reqnext = NULL;
	while (--count) {
		if ((bh = kmalloc (sizeof(struct buffer_head), GFP_ATOMIC)) == NULL)
			goto abort;
		memset (bh, 0, sizeof (struct buffer_head));
		bhp->b_reqnext = bh;
		bhp = bh;
		bh->b_reqnext = NULL;
	}
	return first_bh;
abort:
	idescsi_free_bh (first_bh);
	return NULL;
}

static inline int idescsi_set_direction (idescsi_pc_t *pc)
{
	switch (pc->c[0]) {
		case READ_6: case READ_10: case READ_12:
			clear_bit (PC_WRITING, &pc->flags);
			return 0;
		case WRITE_6: case WRITE_10: case WRITE_12:
			set_bit (PC_WRITING, &pc->flags);
			return 0;
		default:
			return 1;
	}
}

static inline struct buffer_head *idescsi_dma_bh (ide_drive_t *drive, idescsi_pc_t *pc)
{
	struct buffer_head *bh = NULL, *first_bh = NULL;
	int segments = pc->scsi_cmd->use_sg;
	struct scatterlist *sg = pc->scsi_cmd->request_buffer;

	if (!drive->using_dma || !pc->request_transfer || pc->request_transfer % 1024)
		return NULL;
	if (idescsi_set_direction(pc))
		return NULL;
	if (segments) {
		if ((first_bh = bh = idescsi_kmalloc_bh (segments)) == NULL)
			return NULL;
#if IDESCSI_DEBUG_LOG
		printk ("ide-scsi: %s: building DMA table, %d segments, %dkB total\n", drive->name, segments, pc->request_transfer >> 10);
#endif /* IDESCSI_DEBUG_LOG */
		while (segments--) {
			bh->b_data = sg->address;
			bh->b_size = sg->length;
			bh = bh->b_reqnext;
			sg++;
		}
	} else {
		if ((first_bh = bh = idescsi_kmalloc_bh (1)) == NULL)
			return NULL;
#if IDESCSI_DEBUG_LOG
		printk ("ide-scsi: %s: building DMA table for a single buffer (%dkB)\n", drive->name, pc->request_transfer >> 10);
#endif /* IDESCSI_DEBUG_LOG */
		bh->b_data = pc->scsi_cmd->request_buffer;
		bh->b_size = pc->request_transfer;
	}
	return first_bh;
}

static inline int should_transform(ide_drive_t *drive, Scsi_Cmnd *cmd)
{
	idescsi_scsi_t *scsi = drive->driver_data;

	if (MAJOR(cmd->request.rq_dev) == SCSI_GENERIC_MAJOR)
		return test_bit(IDESCSI_SG_TRANSFORM, &scsi->transform);
	return test_bit(IDESCSI_TRANSFORM, &scsi->transform);
}

int idescsi_queue (Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
	ide_drive_t *drive = idescsi_drives[cmd->target];
	idescsi_scsi_t *scsi;
	struct request *rq = NULL;
	idescsi_pc_t *pc = NULL;

	if (!drive) {
		printk (KERN_ERR "ide-scsi: drive id %d not present\n", cmd->target);
		goto abort;
	}
	scsi = drive->driver_data;
	pc = kmalloc (sizeof (idescsi_pc_t), GFP_ATOMIC);
	rq = kmalloc (sizeof (struct request), GFP_ATOMIC);
	if (rq == NULL || pc == NULL) {
		printk (KERN_ERR "ide-scsi: %s: out of memory\n", drive->name);
		goto abort;
	}

	memset (pc->c, 0, 12);
	pc->flags = 0;
	pc->rq = rq;
	memcpy (pc->c, cmd->cmnd, cmd->cmd_len);
	if (cmd->use_sg) {
		pc->buffer = NULL;
		pc->sg = cmd->request_buffer;
	} else {
		pc->buffer = cmd->request_buffer;
		pc->sg = NULL;
	}
	pc->b_count = 0;
	pc->request_transfer = pc->buffer_size = cmd->request_bufflen;
	pc->scsi_cmd = cmd;
	pc->done = done;
	pc->timeout = jiffies + cmd->timeout_per_command;

	if (should_transform(drive, cmd))
		set_bit(PC_TRANSFORM, &pc->flags);
	idescsi_transform_pc1 (drive, pc);

	if (test_bit(IDESCSI_LOG_CMD, &scsi->log)) {
		printk ("ide-scsi: %s: que %lu, cmd = ", drive->name, cmd->serial_number);
		hexdump(cmd->cmnd, cmd->cmd_len);
		if (memcmp(pc->c, cmd->cmnd, cmd->cmd_len)) {
			printk ("ide-scsi: %s: que %lu, tsl = ", drive->name, cmd->serial_number);
			hexdump(pc->c, 12);
		}
	}

	ide_init_drive_cmd (rq);
	rq->buffer = (char *) pc;
	rq->bh = idescsi_dma_bh (drive, pc);
	rq->cmd = IDESCSI_PC_RQ;
	spin_unlock(&io_request_lock);
	(void) ide_do_drive_cmd (drive, rq, ide_end);
	spin_lock_irq(&io_request_lock);
	return 0;
abort:
	if (pc) kfree (pc);
	if (rq) kfree (rq);
	cmd->result = DID_ERROR << 16;
	done(cmd);
	return 0;
}

int idescsi_abort (Scsi_Cmnd *cmd)
{
	return SCSI_ABORT_SNOOZE;
}

int idescsi_reset (Scsi_Cmnd *cmd, unsigned int resetflags)
{
	return SCSI_RESET_SUCCESS;
}

int idescsi_bios (Disk *disk, kdev_t dev, int *parm)
{
	ide_drive_t *drive = idescsi_drives[disk->device->id];

	if (drive->bios_cyl && drive->bios_head && drive->bios_sect) {
		parm[0] = drive->bios_head;
		parm[1] = drive->bios_sect;
		parm[2] = drive->bios_cyl;
	}
	return 0;
}

static Scsi_Host_Template idescsi_template = IDESCSI;

static int __init init_idescsi_module(void)
{
	idescsi_init();
	idescsi_template.module = THIS_MODULE;
	scsi_register_module (MODULE_SCSI_HA, &idescsi_template);
	return 0;
}

static void __exit exit_idescsi_module(void)
{
	ide_drive_t *drive;
	byte media[] = {TYPE_DISK, TYPE_TAPE, TYPE_PROCESSOR, TYPE_WORM, TYPE_ROM, TYPE_SCANNER, TYPE_MOD, 255};
	int i, failed;

	scsi_unregister_module (MODULE_SCSI_HA, &idescsi_template);
	for (i = 0; media[i] != 255; i++) {
		failed = 0;
		while ((drive = ide_scan_devices (media[i], idescsi_driver.name, &idescsi_driver, failed)) != NULL)
			if (idescsi_cleanup (drive)) {
				printk ("%s: exit_idescsi_module() called while still busy\n", drive->name);
				failed++;
			}
	}
	ide_unregister_module(&idescsi_module);
}

module_init(init_idescsi_module);
module_exit(exit_idescsi_module);