1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright IBM Corp. 2004
4  *
5  * Tape class device support
6  *
7  * Author: Stefan Bader <shbader@de.ibm.com>
8  * Based on simple class device code by Greg K-H
9  */
10 
11 #define KMSG_COMPONENT "tape"
12 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
13 
14 #include <linux/slab.h>
15 
16 #include "tape_class.h"
17 
18 MODULE_AUTHOR("Stefan Bader <shbader@de.ibm.com>");
19 MODULE_DESCRIPTION(
20 	"Copyright IBM Corp. 2004   All Rights Reserved.\n"
21 	"tape_class.c"
22 );
23 MODULE_LICENSE("GPL");
24 
25 static struct class *tape_class;
26 
27 /*
28  * Register a tape device and return a pointer to the cdev structure.
29  *
30  * device
31  *	The pointer to the struct device of the physical (base) device.
32  * drivername
33  *	The pointer to the drivers name for it's character devices.
34  * dev
35  *	The intended major/minor number. The major number may be 0 to
36  *	get a dynamic major number.
37  * fops
38  *	The pointer to the drivers file operations for the tape device.
39  * devname
40  *	The pointer to the name of the character device.
41  */
register_tape_dev(struct device * device,dev_t dev,const struct file_operations * fops,char * device_name,char * mode_name)42 struct tape_class_device *register_tape_dev(
43 	struct device *		device,
44 	dev_t			dev,
45 	const struct file_operations *fops,
46 	char *			device_name,
47 	char *			mode_name)
48 {
49 	struct tape_class_device *	tcd;
50 	int		rc;
51 	char *		s;
52 
53 	tcd = kzalloc(sizeof(struct tape_class_device), GFP_KERNEL);
54 	if (!tcd)
55 		return ERR_PTR(-ENOMEM);
56 
57 	strscpy(tcd->device_name, device_name, TAPECLASS_NAME_LEN);
58 	for (s = strchr(tcd->device_name, '/'); s; s = strchr(s, '/'))
59 		*s = '!';
60 	strscpy(tcd->mode_name, mode_name, TAPECLASS_NAME_LEN);
61 	for (s = strchr(tcd->mode_name, '/'); s; s = strchr(s, '/'))
62 		*s = '!';
63 
64 	tcd->char_device = cdev_alloc();
65 	if (!tcd->char_device) {
66 		rc = -ENOMEM;
67 		goto fail_with_tcd;
68 	}
69 
70 	tcd->char_device->owner = fops->owner;
71 	tcd->char_device->ops   = fops;
72 
73 	rc = cdev_add(tcd->char_device, dev, 1);
74 	if (rc)
75 		goto fail_with_cdev;
76 
77 	tcd->class_device = device_create(tape_class, device,
78 					  tcd->char_device->dev, NULL,
79 					  "%s", tcd->device_name);
80 	rc = PTR_ERR_OR_ZERO(tcd->class_device);
81 	if (rc)
82 		goto fail_with_cdev;
83 	rc = sysfs_create_link(
84 		&device->kobj,
85 		&tcd->class_device->kobj,
86 		tcd->mode_name
87 	);
88 	if (rc)
89 		goto fail_with_class_device;
90 
91 	return tcd;
92 
93 fail_with_class_device:
94 	device_destroy(tape_class, tcd->char_device->dev);
95 
96 fail_with_cdev:
97 	cdev_del(tcd->char_device);
98 
99 fail_with_tcd:
100 	kfree(tcd);
101 
102 	return ERR_PTR(rc);
103 }
104 EXPORT_SYMBOL(register_tape_dev);
105 
unregister_tape_dev(struct device * device,struct tape_class_device * tcd)106 void unregister_tape_dev(struct device *device, struct tape_class_device *tcd)
107 {
108 	if (tcd != NULL && !IS_ERR(tcd)) {
109 		sysfs_remove_link(&device->kobj, tcd->mode_name);
110 		device_destroy(tape_class, tcd->char_device->dev);
111 		cdev_del(tcd->char_device);
112 		kfree(tcd);
113 	}
114 }
115 EXPORT_SYMBOL(unregister_tape_dev);
116 
117 
tape_init(void)118 static int __init tape_init(void)
119 {
120 	tape_class = class_create(THIS_MODULE, "tape390");
121 
122 	return 0;
123 }
124 
tape_exit(void)125 static void __exit tape_exit(void)
126 {
127 	class_destroy(tape_class);
128 	tape_class = NULL;
129 }
130 
131 postcore_initcall(tape_init);
132 module_exit(tape_exit);
133