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tape_class.c
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1 /*
2  * Copyright IBM Corp. 2004
3  *
4  * Tape class device support
5  *
6  * Author: Stefan Bader <[email protected]>
7  * Based on simple class device code by Greg K-H
8  */
9 
10 #define KMSG_COMPONENT "tape"
11 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
12 
13 #include <linux/slab.h>
14 
15 #include "tape_class.h"
16 
17 MODULE_AUTHOR("Stefan Bader <[email protected]>");
18 MODULE_DESCRIPTION(
19  "Copyright IBM Corp. 2004 All Rights Reserved.\n"
20  "tape_class.c"
21 );
22 MODULE_LICENSE("GPL");
23 
24 static struct class *tape_class;
25 
26 /*
27  * Register a tape device and return a pointer to the cdev structure.
28  *
29  * device
30  * The pointer to the struct device of the physical (base) device.
31  * drivername
32  * The pointer to the drivers name for it's character devices.
33  * dev
34  * The intended major/minor number. The major number may be 0 to
35  * get a dynamic major number.
36  * fops
37  * The pointer to the drivers file operations for the tape device.
38  * devname
39  * The pointer to the name of the character device.
40  */
41 struct tape_class_device *register_tape_dev(
42  struct device * device,
43  dev_t dev,
44  const struct file_operations *fops,
45  char * device_name,
46  char * mode_name)
47 {
48  struct tape_class_device * tcd;
49  int rc;
50  char * s;
51 
52  tcd = kzalloc(sizeof(struct tape_class_device), GFP_KERNEL);
53  if (!tcd)
54  return ERR_PTR(-ENOMEM);
55 
56  strncpy(tcd->device_name, device_name, TAPECLASS_NAME_LEN);
57  for (s = strchr(tcd->device_name, '/'); s; s = strchr(s, '/'))
58  *s = '!';
59  strncpy(tcd->mode_name, mode_name, TAPECLASS_NAME_LEN);
60  for (s = strchr(tcd->mode_name, '/'); s; s = strchr(s, '/'))
61  *s = '!';
62 
63  tcd->char_device = cdev_alloc();
64  if (!tcd->char_device) {
65  rc = -ENOMEM;
66  goto fail_with_tcd;
67  }
68 
69  tcd->char_device->owner = fops->owner;
70  tcd->char_device->ops = fops;
71  tcd->char_device->dev = dev;
72 
73  rc = cdev_add(tcd->char_device, 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 = IS_ERR(tcd->class_device) ? PTR_ERR(tcd->class_device) : 0;
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 
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 
118 static int __init tape_init(void)
119 {
120  tape_class = class_create(THIS_MODULE, "tape390");
121 
122  return 0;
123 }
124 
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);
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