Driver Core: misc: add nodename support for misc devices.

This adds support for misc devices to report their requested nodename to
userspace. It also updates a number of misc drivers to provide the
needed subdirectory and device name to be used for them.

Signed-off-by: Kay Sievers <[e-mail]>
Signed-off-by: Jan Blunck <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

arch/x86/kernel/microcode_core.c

···
 static struct miscdevice microcode_dev = {
 	.minor			= MICROCODE_MINOR,
 	.name			= "microcode",
+	.devnode		= "cpu/microcode",
 	.fops			= &microcode_fops,
 };
 

drivers/char/hw_random/core.c

···
 static struct miscdevice rng_miscdev = {
 	.minor		= RNG_MISCDEV_MINOR,
 	.name		= RNG_MODULE_NAME,
+	.devnode	= "hwrng",
 	.fops		= &rng_chrdev_ops,
 };
 

drivers/char/misc.c

···
 	.open		= misc_open,
 };
 
-
 /**
  *	misc_register	-	register a miscellaneous device
  *	@misc: device structure
···
 		misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
 	dev = MKDEV(MISC_MAJOR, misc->minor);
 
-	misc->this_device = device_create(misc_class, misc->parent, dev, NULL,
-					  "%s", misc->name);
+	misc->this_device = device_create(misc_class, misc->parent, dev,
+					  misc, "%s", misc->name);
 	if (IS_ERR(misc->this_device)) {
 		err = PTR_ERR(misc->this_device);
 		goto out;
···
 EXPORT_SYMBOL(misc_register);
 EXPORT_SYMBOL(misc_deregister);
 
+static char *misc_nodename(struct device *dev)
+{
+	struct miscdevice *c = dev_get_drvdata(dev);
+
+	if (c->devnode)
+		return kstrdup(c->devnode, GFP_KERNEL);
+	return NULL;
+}
+
 static int __init misc_init(void)
 {
 	int err;
···
 	err = -EIO;
 	if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
 		goto fail_printk;
+	misc_class->nodename = misc_nodename;
 	return 0;
 
 fail_printk:

drivers/md/dm-ioctl.c

···
 static struct miscdevice _dm_misc = {
 	.minor 		= MISC_DYNAMIC_MINOR,
 	.name  		= DM_NAME,
+	.devnode	= "mapper/control",
 	.fops  		= &_ctl_fops
 };
 

drivers/net/tun.c

···
 static struct miscdevice tun_miscdev = {
 	.minor = TUN_MINOR,
 	.name = "tun",
+	.devnode = "net/tun",
 	.fops = &tun_fops,
 };
 

include/linux/miscdevice.h

···
 	struct list_head list;
 	struct device *parent;
 	struct device *this_device;
+	const char *devnode;
 };
 
 extern int misc_register(struct miscdevice * misc);