sr.c

讲述linux的初始化过程

{
	check_disk_change(cdi->dev);

	if (MINOR(cdi->dev) >= sr_template.dev_max
	    || !scsi_CDs[MINOR(cdi->dev)].device) {
		return -ENXIO;	/* No such device */
	}
	/*
	 * If the device is in error recovery, wait until it is done.
	 * If the device is offline, then disallow any access to it.
	 */
	if (!scsi_block_when_processing_errors(scsi_CDs[MINOR(cdi->dev)].device)) {
		return -ENXIO;
	}
	scsi_CDs[MINOR(cdi->dev)].device->access_count++;
	if (scsi_CDs[MINOR(cdi->dev)].device->host->hostt->module)
		__MOD_INC_USE_COUNT(scsi_CDs[MINOR(cdi->dev)].device->host->hostt->module);
	if (sr_template.module)
		__MOD_INC_USE_COUNT(sr_template.module);

	/* If this device did not have media in the drive at boot time, then
	 * we would have been unable to get the sector size.  Check to see if
	 * this is the case, and try again.
	 */

	if (scsi_CDs[MINOR(cdi->dev)].needs_sector_size)
		get_sectorsize(MINOR(cdi->dev));

	return 0;
}

/*
 * do_sr_request() is the request handler function for the sr driver.
 * Its function in life is to take block device requests, and
 * translate them to SCSI commands.
 */


static int sr_detect(Scsi_Device * SDp)
{

	if (SDp->type != TYPE_ROM && SDp->type != TYPE_WORM)
		return 0;

	printk("Detected scsi CD-ROM sr%d at scsi%d, channel %d, id %d, lun %d\n",
	       sr_template.dev_noticed++,
	       SDp->host->host_no, SDp->channel, SDp->id, SDp->lun);

	return 1;
}

static int sr_attach(Scsi_Device * SDp)
{
	Scsi_CD *cpnt;
	int i;

	if (SDp->type != TYPE_ROM && SDp->type != TYPE_WORM)
		return 1;

	if (sr_template.nr_dev >= sr_template.dev_max) {
		SDp->attached--;
		return 1;
	}
	for (cpnt = scsi_CDs, i = 0; i < sr_template.dev_max; i++, cpnt++)
		if (!cpnt->device)
			break;

	if (i >= sr_template.dev_max)
		panic("scsi_devices corrupt (sr)");


	scsi_CDs[i].device = SDp;

	sr_template.nr_dev++;
	if (sr_template.nr_dev > sr_template.dev_max)
		panic("scsi_devices corrupt (sr)");
	return 0;
}


void get_sectorsize(int i)
{
	unsigned char cmd[10];
	unsigned char *buffer;
	int the_result, retries;
	int sector_size;
	Scsi_Request *SRpnt;

	buffer = (unsigned char *) scsi_malloc(512);
	SRpnt = scsi_allocate_request(scsi_CDs[i].device);
	
	if(buffer == NULL || SRpnt == NULL)
	{
		scsi_CDs[i].capacity = 0x1fffff;
		sector_size = 2048;	/* A guess, just in case */
		scsi_CDs[i].needs_sector_size = 1;
		if(buffer)
			scsi_free(buffer, 512);
		if(SRpnt)
			scsi_release_request(SRpnt);
		return;
	}	

	retries = 3;
	do {
		cmd[0] = READ_CAPACITY;
		cmd[1] = (scsi_CDs[i].device->lun << 5) & 0xe0;
		memset((void *) &cmd[2], 0, 8);
		SRpnt->sr_request.rq_status = RQ_SCSI_BUSY;	/* Mark as really busy */
		SRpnt->sr_cmd_len = 0;

		memset(buffer, 0, 8);

		/* Do the command and wait.. */

		SRpnt->sr_data_direction = SCSI_DATA_READ;
		scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
			      8, SR_TIMEOUT, MAX_RETRIES);

		the_result = SRpnt->sr_result;
		retries--;

	} while (the_result && retries);


	scsi_release_request(SRpnt);
	SRpnt = NULL;

	if (the_result) {
		scsi_CDs[i].capacity = 0x1fffff;
		sector_size = 2048;	/* A guess, just in case */
		scsi_CDs[i].needs_sector_size = 1;
	} else {
#if 0
		if (cdrom_get_last_written(MKDEV(MAJOR_NR, i),
					 (long *) &scsi_CDs[i].capacity))
#endif
			scsi_CDs[i].capacity = 1 + ((buffer[0] << 24) |
						    (buffer[1] << 16) |
						    (buffer[2] << 8) |
						    buffer[3]);
		sector_size = (buffer[4] << 24) |
		    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
		switch (sector_size) {
			/*
			 * HP 4020i CD-Recorder reports 2340 byte sectors
			 * Philips CD-Writers report 2352 byte sectors
			 *
			 * Use 2k sectors for them..
			 */
		case 0:
		case 2340:
		case 2352:
			sector_size = 2048;
			/* fall through */
		case 2048:
			scsi_CDs[i].capacity *= 4;
			/* fall through */
		case 512:
			break;
		default:
			printk("sr%d: unsupported sector size %d.\n",
			       i, sector_size);
			scsi_CDs[i].capacity = 0;
			scsi_CDs[i].needs_sector_size = 1;
		}

		scsi_CDs[i].device->sector_size = sector_size;

		/*
		 * Add this so that we have the ability to correctly gauge
		 * what the device is capable of.
		 */
		scsi_CDs[i].needs_sector_size = 0;
		sr_sizes[i] = scsi_CDs[i].capacity >> (BLOCK_SIZE_BITS - 9);
	};
	scsi_free(buffer, 512);
}

void get_capabilities(int i)
{
	unsigned char cmd[6];
	unsigned char *buffer;
	int rc, n;

	static char *loadmech[] =
	{
		"caddy",
		"tray",
		"pop-up",
		"",
		"changer",
		"cartridge changer",
		"",
		""
	};

	buffer = (unsigned char *) scsi_malloc(512);
	cmd[0] = MODE_SENSE;
	cmd[1] = (scsi_CDs[i].device->lun << 5) & 0xe0;
	cmd[2] = 0x2a;
	cmd[4] = 128;
	cmd[3] = cmd[5] = 0;
	rc = sr_do_ioctl(i, cmd, buffer, 128, 1, SCSI_DATA_READ, NULL);

	if (-EINVAL == rc) {
		/* failed, drive has'nt this mode page */
		scsi_CDs[i].cdi.speed = 1;
		/* disable speed select, drive probably can't do this either */
		scsi_CDs[i].cdi.mask |= CDC_SELECT_SPEED;
		scsi_free(buffer, 512);
		return;
	}
	n = buffer[3] + 4;
	scsi_CDs[i].cdi.speed = ((buffer[n + 8] << 8) + buffer[n + 9]) / 176;
	scsi_CDs[i].readcd_known = 1;
	scsi_CDs[i].readcd_cdda = buffer[n + 5] & 0x01;
	/* print some capability bits */
	printk("sr%i: scsi3-mmc drive: %dx/%dx %s%s%s%s%s%s\n", i,
	       ((buffer[n + 14] << 8) + buffer[n + 15]) / 176,
	       scsi_CDs[i].cdi.speed,
	       buffer[n + 3] & 0x01 ? "writer " : "",	/* CD Writer */
	       buffer[n + 3] & 0x20 ? "dvd-ram " : "",
	       buffer[n + 2] & 0x02 ? "cd/rw " : "",	/* can read rewriteable */
	       buffer[n + 4] & 0x20 ? "xa/form2 " : "",		/* can read xa/from2 */
	       buffer[n + 5] & 0x01 ? "cdda " : "",	/* can read audio data */
	       loadmech[buffer[n + 6] >> 5]);
	if ((buffer[n + 6] >> 5) == 0)
		/* caddy drives can't close tray... */
		scsi_CDs[i].cdi.mask |= CDC_CLOSE_TRAY;
	if ((buffer[n + 2] & 0x8) == 0)
		/* not a DVD drive */
		scsi_CDs[i].cdi.mask |= CDC_DVD;
	if ((buffer[n + 3] & 0x20) == 0) {
		/* can't write DVD-RAM media */
		scsi_CDs[i].cdi.mask |= CDC_DVD_RAM;
	} else {
		scsi_CDs[i].device->writeable = 1;
	}
	if ((buffer[n + 3] & 0x10) == 0)
		/* can't write DVD-R media */
		scsi_CDs[i].cdi.mask |= CDC_DVD_R;
	if ((buffer[n + 3] & 0x2) == 0)
		/* can't write CD-RW media */
		scsi_CDs[i].cdi.mask |= CDC_CD_RW;
	if ((buffer[n + 3] & 0x1) == 0)
		/* can't write CD-R media */
		scsi_CDs[i].cdi.mask |= CDC_CD_R;
	if ((buffer[n + 6] & 0x8) == 0)
		/* can't eject */
		scsi_CDs[i].cdi.mask |= CDC_OPEN_TRAY;

	if ((buffer[n + 6] >> 5) == mechtype_individual_changer ||
	    (buffer[n + 6] >> 5) == mechtype_cartridge_changer)
		scsi_CDs[i].cdi.capacity =
		    cdrom_number_of_slots(&(scsi_CDs[i].cdi));
	if (scsi_CDs[i].cdi.capacity <= 1)
		/* not a changer */
		scsi_CDs[i].cdi.mask |= CDC_SELECT_DISC;
	/*else    I don't think it can close its tray
	   scsi_CDs[i].cdi.mask |= CDC_CLOSE_TRAY; */

	scsi_free(buffer, 512);
}

/*
 * sr_packet() is the entry point for the generic commands generated
 * by the Uniform CD-ROM layer. 
 */
static int sr_packet(struct cdrom_device_info *cdi, struct cdrom_generic_command *cgc)
{
	Scsi_Device *device = scsi_CDs[MINOR(cdi->dev)].device;

	/* set the LUN */
	cgc->cmd[1] |= device->lun << 5;

	cgc->stat = sr_do_ioctl(MINOR(cdi->dev), cgc->cmd, cgc->buffer, cgc->buflen, cgc->quiet, cgc->data_direction, cgc->sense);

	return cgc->stat;
}

static int sr_registered;

static int sr_init()
{
	int i;

	if (sr_template.dev_noticed == 0)
		return 0;

	if (!sr_registered) {
		if (devfs_register_blkdev(MAJOR_NR, "sr", &cdrom_fops)) {
			printk("Unable to get major %d for SCSI-CD\n", MAJOR_NR);
			return 1;
		}
		sr_registered++;
	}
	if (scsi_CDs)
		return 0;

	sr_template.dev_max = sr_template.dev_noticed + SR_EXTRA_DEVS;
	scsi_CDs = kmalloc(sr_template.dev_max * sizeof(Scsi_CD), GFP_ATOMIC);
	if (!scsi_CDs)
		goto cleanup_devfs;
	memset(scsi_CDs, 0, sr_template.dev_max * sizeof(Scsi_CD));

	sr_sizes = kmalloc(sr_template.dev_max * sizeof(int), GFP_ATOMIC);
	if (!sr_sizes)
		goto cleanup_cds;
	memset(sr_sizes, 0, sr_template.dev_max * sizeof(int));

	sr_blocksizes = kmalloc(sr_template.dev_max * sizeof(int), GFP_ATOMIC);
	if (!sr_blocksizes)
		goto cleanup_sizes;

	sr_hardsizes = kmalloc(sr_template.dev_max * sizeof(int), GFP_ATOMIC);
	if (!sr_hardsizes)
		goto cleanup_blocksizes;
	/*
	 * These are good guesses for the time being.
	 */
	for (i = 0; i < sr_template.dev_max; i++) {
		sr_blocksizes[i] = 2048;
		sr_hardsizes[i] = 2048;
        }
	blksize_size[MAJOR_NR] = sr_blocksizes;
        hardsect_size[MAJOR_NR] = sr_hardsizes;
	return 0;
cleanup_blocksizes:
	kfree(sr_blocksizes);
cleanup_sizes:
	kfree(sr_sizes);
cleanup_cds:
	kfree(scsi_CDs);
cleanup_devfs:
	devfs_unregister_blkdev(MAJOR_NR, "sr");
	sr_registered--;
	return 1;
}

void sr_finish()
{
	int i;
	char name[6];

	blk_dev[MAJOR_NR].queue = sr_find_queue;
	blk_size[MAJOR_NR] = sr_sizes;

	for (i = 0; i < sr_template.nr_dev; ++i) {
		/* If we have already seen this, then skip it.  Comes up
		 * with loadable modules. */
		if (scsi_CDs[i].capacity)
			continue;
		scsi_CDs[i].capacity = 0x1fffff;
		scsi_CDs[i].device->sector_size = 2048;		/* A guess, just in case */
		scsi_CDs[i].needs_sector_size = 1;
		scsi_CDs[i].device->changed = 1;	/* force recheck CD type */
#if 0
		/* seems better to leave this for later */
		get_sectorsize(i);
		printk("Scd sectorsize = %d bytes.\n", scsi_CDs[i].sector_size);
#endif
		scsi_CDs[i].use = 1;

		scsi_CDs[i].device->ten = 1;
		scsi_CDs[i].device->remap = 1;
		scsi_CDs[i].readcd_known = 0;
		scsi_CDs[i].readcd_cdda = 0;
		sr_sizes[i] = scsi_CDs[i].capacity >> (BLOCK_SIZE_BITS - 9);

		scsi_CDs[i].cdi.ops = &sr_dops;
		scsi_CDs[i].cdi.handle = &scsi_CDs[i];
		scsi_CDs[i].cdi.dev = MKDEV(MAJOR_NR, i);
		scsi_CDs[i].cdi.mask = 0;
		scsi_CDs[i].cdi.capacity = 1;
		get_capabilities(i);
		sr_vendor_init(i);

		sprintf(name, "sr%d", i);
		strcpy(scsi_CDs[i].cdi.name, name);
                scsi_CDs[i].cdi.de =
                    devfs_register (scsi_CDs[i].device->de, "cd",
                                    DEVFS_FL_DEFAULT, MAJOR_NR, i,
                                    S_IFBLK | S_IRUGO | S_IWUGO,
                                    &cdrom_fops, NULL);
		register_cdrom(&scsi_CDs[i].cdi);
	}


	/* If our host adapter is capable of scatter-gather, then we increase
	 * the read-ahead to 16 blocks (32 sectors).  If not, we use
	 * a two block (4 sector) read ahead. */
	if (scsi_CDs[0].device && scsi_CDs[0].device->host->sg_tablesize)
		read_ahead[MAJOR_NR] = 32;	/* 32 sector read-ahead.  Always removable. */
	else
		read_ahead[MAJOR_NR] = 4;	/* 4 sector read-ahead */

	return;
}

static void sr_detach(Scsi_Device * SDp)
{
	Scsi_CD *cpnt;
	int i;

	for (cpnt = scsi_CDs, i = 0; i < sr_template.dev_max; i++, cpnt++)
		if (cpnt->device == SDp) {
			kdev_t devi = MKDEV(MAJOR_NR, i);
			struct super_block *sb = get_super(devi);

			/*
			 * Since the cdrom is read-only, no need to sync the device.
			 * We should be kind to our buffer cache, however.
			 */
			if (sb)
				invalidate_inodes(sb);
			invalidate_buffers(devi);

			/*
			 * Reset things back to a sane state so that one can re-load a new
			 * driver (perhaps the same one).
			 */
			unregister_cdrom(&(cpnt->cdi));
			cpnt->device = NULL;
			cpnt->capacity = 0;
			SDp->attached--;
			sr_template.nr_dev--;
			sr_template.dev_noticed--;
			sr_sizes[i] = 0;
			return;
		}
	return;
}

static int __init init_sr(void)
{
	sr_template.module = THIS_MODULE;
	return scsi_register_module(MODULE_SCSI_DEV, &sr_template);
}

static void __exit exit_sr(void)
{
	scsi_unregister_module(MODULE_SCSI_DEV, &sr_template);
	devfs_unregister_blkdev(MAJOR_NR, "sr");
	sr_registered--;
	if (scsi_CDs != NULL) {
		kfree(scsi_CDs);

		kfree(sr_sizes);
		sr_sizes = NULL;

		kfree(sr_blocksizes);
		sr_blocksizes = NULL;
		kfree(sr_hardsizes);
		sr_hardsizes = NULL;
	}
	blksize_size[MAJOR_NR] = NULL;
        hardsect_size[MAJOR_NR] = NULL;
	blk_size[MAJOR_NR] = NULL;
	read_ahead[MAJOR_NR] = 0;

	sr_template.dev_max = 0;
}

module_init(init_sr);
module_exit(exit_sr);