tape_class.c

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