sr.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

		};
		if (((long) sgpnt[count].address) + sgpnt[count].length - 1 >
		    ISA_DMA_THRESHOLD && SCpnt->host->unchecked_isa_dma) {
		    sgpnt[count].alt_address = sgpnt[count].address;
		    /* We try to avoid exhausting the DMA pool, since it is easier
		     * to control usage here.  In other places we might have a more
		     * pressing need, and we would be screwed if we ran out */
		    if(dma_free_sectors < (sgpnt[count].length >> 9) + 5) {
			sgpnt[count].address = NULL;
		    } else {
			sgpnt[count].address = (char *) scsi_malloc(sgpnt[count].length);
		    };
		    /* If we start running low on DMA buffers, we abort the scatter-gather
		     * operation, and free all of the memory we have allocated.  We want to
		     * ensure that all scsi operations are able to do at least a non-scatter/gather
		     * operation */
		    if(sgpnt[count].address == NULL){ /* Out of dma memory */
			printk("Warning: Running low on SCSI DMA buffers");
			/* Try switching back to a non scatter-gather operation. */
			while(--count >= 0){
			    if(sgpnt[count].alt_address) 
				scsi_free(sgpnt[count].address, sgpnt[count].length);
			};
			SCpnt->use_sg = 0;
			scsi_free(buffer, SCpnt->sglist_len);
			break;
		    }; /* if address == NULL */
		};  /* if need DMA fixup */
	    };  /* for loop to fill list */
#ifdef DEBUG
	    printk("SR: %d %d %d %d %d *** ",SCpnt->use_sg, SCpnt->request.sector,
		   this_count, 
		   SCpnt->request.current_nr_sectors,
		   SCpnt->request.nr_sectors);
	    for(count=0; count<SCpnt->use_sg; count++)
		printk("SGlist: %d %x %x %x\n", count,
		       sgpnt[count].address, 
		       sgpnt[count].alt_address, 
		       sgpnt[count].length);
#endif
	};  /* Able to allocate scatter-gather list */
	};
	
	if (SCpnt->use_sg == 0){
	/* We cannot use scatter-gather.  Do this the old fashion way */
	if (!SCpnt->request.bh)  	
	    this_count = SCpnt->request.nr_sectors;
	else
	    this_count = (SCpnt->request.bh->b_size >> 9);
	
	start = block % 4;
	if (start)
	    {				  
	    this_count = ((this_count > 4 - start) ? 
			  (4 - start) : (this_count));
	    buffer = (unsigned char *) scsi_malloc(2048);
	    } 
	else if (this_count < 4)
	    {
	    buffer = (unsigned char *) scsi_malloc(2048);
	    }
	else
	    {
	    this_count -= this_count % 4;
	    buffer = (unsigned char *) SCpnt->request.buffer;
	    if (((long) buffer) + (this_count << 9) > ISA_DMA_THRESHOLD &&
		SCpnt->host->unchecked_isa_dma)
		buffer = (unsigned char *) scsi_malloc(this_count << 9);
	    }
	};
    
	if (scsi_CDs[dev].sector_size == 2048)
	block = block >> 2; /* These are the sectors that the cdrom uses */
	else
	block = block & 0xfffffffc;
    
	realcount = (this_count + 3) / 4;
    
	if (scsi_CDs[dev].sector_size == 512) realcount = realcount << 2;
    
	if (((realcount > 0xff) || (block > 0x1fffff)) && scsi_CDs[dev].ten) 
    {
		if (realcount > 0xffff)
	{
			realcount = 0xffff;
			this_count = realcount * (scsi_CDs[dev].sector_size >> 9);
	}
	
		cmd[0] += READ_10 - READ_6 ;
		cmd[2] = (unsigned char) (block >> 24) & 0xff;
		cmd[3] = (unsigned char) (block >> 16) & 0xff;
		cmd[4] = (unsigned char) (block >> 8) & 0xff;
		cmd[5] = (unsigned char) block & 0xff;
		cmd[6] = cmd[9] = 0;
		cmd[7] = (unsigned char) (realcount >> 8) & 0xff;
		cmd[8] = (unsigned char) realcount & 0xff;
    }
	else
    {
	if (realcount > 0xff)
	{
	    realcount = 0xff;
	    this_count = realcount * (scsi_CDs[dev].sector_size >> 9);
	}
	
	cmd[1] |= (unsigned char) ((block >> 16) & 0x1f);
	cmd[2] = (unsigned char) ((block >> 8) & 0xff);
	cmd[3] = (unsigned char) block & 0xff;
	cmd[4] = (unsigned char) realcount;
	cmd[5] = 0;
    }   
    
#ifdef DEBUG
    { 
	int i;
	printk("ReadCD: %d %d %d %d\n",block, realcount, buffer, this_count);
	printk("Use sg: %d\n", SCpnt->use_sg);
	printk("Dumping command: ");
	for(i=0; i<12; i++) printk("%2.2x ", cmd[i]);
	printk("\n");
    };
#endif
    
    /* Some dumb host adapters can speed transfers by knowing the
     * minimum transfersize in advance.
     *
     * We shouldn't disconnect in the middle of a sector, but the cdrom
     * sector size can be larger than the size of a buffer and the
     * transfer may be split to the size of a buffer.  So it's safe to
     * assume that we can at least transfer the minimum of the buffer
     * size (1024) and the sector size between each connect / disconnect.
     */
    
    SCpnt->transfersize = (scsi_CDs[dev].sector_size > 1024) ?
	1024 : scsi_CDs[dev].sector_size;
    
	SCpnt->this_count = this_count;
	scsi_do_cmd (SCpnt, (void *) cmd, buffer, 
		 realcount * scsi_CDs[dev].sector_size, 
		 rw_intr, SR_TIMEOUT, MAX_RETRIES);
}

static int sr_detect(Scsi_Device * SDp){
    
    if(SDp->type != TYPE_ROM && SDp->type != TYPE_WORM) return 0;

#ifdef MACH
    printk("Detected scsi CD-ROM cd%d at scsi%d, channel %d, id %d, lun %d\n",
#else
    printk("Detected scsi CD-ROM sr%d at scsi%d, channel %d, id %d, lun %d\n",
#endif
	   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)");
    
    SDp->scsi_request_fn = do_sr_request;
    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;
}


static void sr_init_done (Scsi_Cmnd * SCpnt)
{
    struct request * req;
    
    req = &SCpnt->request;
    req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
    
    if (req->sem != NULL) {
	up(req->sem);
    }
}

void get_sectorsize(int i){
    unsigned char cmd[10];
    unsigned char *buffer;
    int the_result, retries;
    Scsi_Cmnd * SCpnt;
    
    buffer = (unsigned char *) scsi_malloc(512);
    SCpnt = allocate_device(NULL, scsi_CDs[i].device, 1);
    
    retries = 3;
    do {
	cmd[0] = READ_CAPACITY;
	cmd[1] = (scsi_CDs[i].device->lun << 5) & 0xe0;
	memset ((void *) &cmd[2], 0, 8);
	SCpnt->request.rq_status = RQ_SCSI_BUSY;  /* Mark as really busy */
	SCpnt->cmd_len = 0;
	
	memset(buffer, 0, 8);

	/* Do the command and wait.. */
	{
	    struct semaphore sem = MUTEX_LOCKED;
	    SCpnt->request.sem = &sem;
	    scsi_do_cmd (SCpnt,
			 (void *) cmd, (void *) buffer,
			 512, sr_init_done,  SR_TIMEOUT,
			 MAX_RETRIES);
	    down(&sem);
	}
	
	the_result = SCpnt->result;
	retries--;
	
    } while(the_result && retries);
    
    SCpnt->request.rq_status = RQ_INACTIVE;  /* Mark as not busy */
    
    wake_up(&SCpnt->device->device_wait); 
    
    if (the_result) {
	scsi_CDs[i].capacity = 0x1fffff;
	scsi_CDs[i].sector_size = 2048;  /* A guess, just in case */
	scsi_CDs[i].needs_sector_size = 1;
    } else {
	scsi_CDs[i].capacity = 1 + ((buffer[0] << 24) |
				    (buffer[1] << 16) |
				    (buffer[2] << 8) |
				    buffer[3]);
	scsi_CDs[i].sector_size = (buffer[4] << 24) |
	    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
	switch (scsi_CDs[i].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:
			scsi_CDs[i].sector_size = 2048;
			/* fall through */
		case 2048:
			scsi_CDs[i].capacity *= 4;
			/* fall through */
		case 512:
			break;
		default:
#ifdef MACH
			printk ("cd%d : unsupported sector size %d.\n",
				i, scsi_CDs[i].sector_size);
#else
			printk ("scd%d : unsupported sector size %d.\n",
				i, scsi_CDs[i].sector_size);
#endif
			scsi_CDs[i].capacity = 0;
			scsi_CDs[i].needs_sector_size = 1;
	}
	scsi_CDs[i].needs_sector_size = 0;
	sr_sizes[i] = scsi_CDs[i].capacity >> (BLOCK_SIZE_BITS - 9);
    };
    scsi_free(buffer, 512);
}

static int sr_registered = 0;

static int sr_init()
{
    int i;

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

    if(!sr_registered) {
	if (register_blkdev(MAJOR_NR,"sr",&sr_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 = (Scsi_CD *) scsi_init_malloc(sr_template.dev_max * sizeof(Scsi_CD), GFP_ATOMIC);
    memset(scsi_CDs, 0, sr_template.dev_max * sizeof(Scsi_CD));

    sr_sizes = (int *) scsi_init_malloc(sr_template.dev_max * sizeof(int), GFP_ATOMIC);
    memset(sr_sizes, 0, sr_template.dev_max * sizeof(int));

    sr_blocksizes = (int *) scsi_init_malloc(sr_template.dev_max * 
					 sizeof(int), GFP_ATOMIC);
    for(i=0;i<sr_template.dev_max;i++) sr_blocksizes[i] = 2048;
    blksize_size[MAJOR_NR] = sr_blocksizes;
    return 0;
}

void sr_finish()
{
    int i;
    
    blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
    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].sector_size = 2048;  /* A guess, just in case */
	scsi_CDs[i].needs_sector_size = 1;
#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].ten = 1;
	scsi_CDs[i].remap = 1;
	scsi_CDs[i].auto_eject = 0; /* Default is not to eject upon unmount. */
	sr_sizes[i] = scsi_CDs[i].capacity >> (BLOCK_SIZE_BITS - 9);
    }
    
    
    /* 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);

	    /*
	     * Since the cdrom is read-only, no need to sync the device.
	     * We should be kind to our buffer cache, however.
	     */
	    invalidate_inodes(devi);
	    invalidate_buffers(devi);
	    
	    /*
	     * Reset things back to a sane state so that one can re-load a new
	     * driver (perhaps the same one).
	     */
	    cpnt->device = NULL;
	    cpnt->capacity = 0;
	    SDp->attached--;
	    sr_template.nr_dev--;
	    sr_template.dev_noticed--;
	    sr_sizes[i] = 0;
	    return;
	}
    return;
}


#ifdef MODULE

int init_module(void) {
    sr_template.usage_count = &mod_use_count_;
    return scsi_register_module(MODULE_SCSI_DEV, &sr_template);
}

void cleanup_module( void) 
{
    scsi_unregister_module(MODULE_SCSI_DEV, &sr_template);
    unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
    sr_registered--;
    if(scsi_CDs != NULL) {
	scsi_init_free((char *) scsi_CDs,
		       (sr_template.dev_noticed + SR_EXTRA_DEVS) 
		       * sizeof(Scsi_CD));
	
	scsi_init_free((char *) sr_sizes, sr_template.dev_max * sizeof(int));
	scsi_init_free((char *) sr_blocksizes, sr_template.dev_max * sizeof(int));
    }
    
    blksize_size[MAJOR_NR] = NULL;
    blk_dev[MAJOR_NR].request_fn = NULL;
    blk_size[MAJOR_NR] = NULL;	
    read_ahead[MAJOR_NR] = 0;
    
    sr_template.dev_max = 0;
}
#endif /* MODULE */

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 4
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -4
 * c-argdecl-indent: 4
 * c-label-offset: -4
 * c-continued-statement-offset: 4
 * c-continued-brace-offset: 0
 * indent-tabs-mode: nil
 * tab-width: 8
 * End:
 */