1 // SPDX-License-Identifier: GPL-2.0
14  * Made things a lot mode modular - easy to compile in just one or two
17  * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
20  *		Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
22  * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
24  * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
34  * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au>  10-Jan-1998
61  * Assigned numbers, used for dynamic minors
63 #define DYNAMIC_MINORS 128 /* like dynamic majors */
70 	ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);  in misc_minor_alloc()
72 		ret = DYNAMIC_MINORS - ret - 1;  in misc_minor_alloc()
83 		ida_free(&misc_minors_ida, DYNAMIC_MINORS - minor - 1);  in misc_minor_free()
109 	seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");  in misc_seq_show()
126 	int err = -ENODEV;  in misc_open()
132 		if (iter->minor != minor)  in misc_open()
135 		new_fops = fops_get(iter->fops);  in misc_open()
141 		request_module("char-major-%d-%d", MISC_MAJOR, minor);  in misc_open()
145 			if (iter->minor != minor)  in misc_open()
148 			new_fops = fops_get(iter->fops);  in misc_open()
158 	 * file operations, including f_op->open below  in misc_open()
160 	file->private_data = c;  in misc_open()
164 	if (file->f_op->open)  in misc_open()
165 		err = file->f_op->open(inode, file);  in misc_open()
171 static char *misc_devnode(const struct device *dev, umode_t *mode)  in misc_devnode()  argument
175 	if (mode && c->mode)  in misc_devnode()
176 		*mode = c->mode;  in misc_devnode()
177 	if (c->nodename)  in misc_devnode()
178 		return kstrdup(c->nodename, GFP_KERNEL);  in misc_devnode()
194  *	misc_register	-	register a miscellaneous device
204  *	syscall to the device sets file->private_data to point to the
215 	bool is_dynamic = (misc->minor == MISC_DYNAMIC_MINOR);  in misc_register()
217 	INIT_LIST_HEAD(&misc->list);  in misc_register()
225 			err = -EBUSY;  in misc_register()
228 		misc->minor = i;  in misc_register()
233 			if (c->minor == misc->minor) {  in misc_register()
234 				err = -EBUSY;  in misc_register()
240 	dev = MKDEV(MISC_MAJOR, misc->minor);  in misc_register()
242 	misc->this_device =  in misc_register()
243 		device_create_with_groups(&misc_class, misc->parent, dev,  in misc_register()
244 					  misc, misc->groups, "%s", misc->name);  in misc_register()
245 	if (IS_ERR(misc->this_device)) {  in misc_register()
247 			misc_minor_free(misc->minor);  in misc_register()
248 			misc->minor = MISC_DYNAMIC_MINOR;  in misc_register()
250 		err = PTR_ERR(misc->this_device);  in misc_register()
258 	list_add(&misc->list, &misc_list);  in misc_register()
266  *	misc_deregister - unregister a miscellaneous device
275 	if (WARN_ON(list_empty(&misc->list)))  in misc_deregister()
279 	list_del(&misc->list);  in misc_deregister()
280 	device_destroy(&misc_class, MKDEV(MISC_MAJOR, misc->minor));  in misc_deregister()
281 	misc_minor_free(misc->minor);  in misc_deregister()
296 	err = -EIO;  in misc_init()