powerpc/axonram: Use only one block device major number

Axonram module registers one block device for each DDR2 DIMM found
on a system. This means that each DDR2 DIMM becomes its own block device
major number. This patch lets axonram module to register the only one
block device for all DDR2 DIMMs which also spares kernel resources.

Signed-off-by: Maxim Shchetynin <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

arch/powerpc/sysdev/axonram.c

···
 #define AXON_RAM_SECTOR_SIZE		1 << AXON_RAM_SECTOR_SHIFT
 #define AXON_RAM_IRQ_FLAGS		IRQF_SHARED | IRQF_TRIGGER_RISING
 
+static int azfs_major, azfs_minor;
+
 struct axon_ram_bank {
 	struct of_device	*device;
 	struct gendisk		*disk;
···
 		goto failed;
 	}
 
-	bank->disk->first_minor = 0;
+	bank->disk->major = azfs_major;
+	bank->disk->first_minor = azfs_minor;
 	bank->disk->fops = &axon_ram_devops;
 	bank->disk->private_data = bank;
 	bank->disk->driverfs_dev = &device->dev;
 
 	sprintf(bank->disk->disk_name, "%s%d",
 			AXON_RAM_DEVICE_NAME, axon_ram_bank_id);
-	bank->disk->major = register_blkdev(0, bank->disk->disk_name);
-	if (bank->disk->major < 0) {
-		dev_err(&device->dev, "Cannot register block device\n");
-		rc = -EFAULT;
-		goto failed;
-	}
 
 	bank->disk->queue = blk_alloc_queue(GFP_KERNEL);
 	if (bank->disk->queue == NULL) {
···
 		goto failed;
 	}
 
+	azfs_minor += bank->disk->minors;
+
 	return 0;
 
 failed:
···
 
 	device_remove_file(&device->dev, &dev_attr_ecc);
 	free_irq(bank->irq_id, device);
-	unregister_blkdev(bank->disk->major, bank->disk->disk_name);
 	del_gendisk(bank->disk);
 	iounmap((void __iomem *) bank->io_addr);
 	kfree(bank);
···
 static int __init
 axon_ram_init(void)
 {
+	azfs_major = register_blkdev(azfs_major, AXON_RAM_DEVICE_NAME);
+	if (azfs_major < 0) {
+		printk(KERN_ERR "%s cannot become block device major number\n",
+				AXON_RAM_MODULE_NAME);
+		return -EFAULT;
+	}
+	azfs_minor = 0;
+
 	return of_register_platform_driver(&axon_ram_driver);
 }
 
···
 axon_ram_exit(void)
 {
 	of_unregister_platform_driver(&axon_ram_driver);
+	unregister_blkdev(azfs_major, AXON_RAM_DEVICE_NAME);
 }
 
 module_init(axon_ram_init);