1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Virtual NCI device simulation driver
  4 *
  5 * Copyright (C) 2020 Samsung Electrnoics
  6 * Bongsu Jeon <bongsu.jeon@samsung.com>
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/module.h>
 11#include <linux/miscdevice.h>
 12#include <linux/mutex.h>
 13#include <linux/wait.h>
 14#include <net/nfc/nci_core.h>
 15
 16#define IOCTL_GET_NCIDEV_IDX    0
 17#define VIRTUAL_NFC_PROTOCOLS	(NFC_PROTO_JEWEL_MASK | \
 18				 NFC_PROTO_MIFARE_MASK | \
 19				 NFC_PROTO_FELICA_MASK | \
 20				 NFC_PROTO_ISO14443_MASK | \
 21				 NFC_PROTO_ISO14443_B_MASK | \
 22				 NFC_PROTO_ISO15693_MASK)
 23
 24struct virtual_nci_dev {
 25	struct nci_dev *ndev;
 26	struct mutex mtx;
 27	struct sk_buff *send_buff;
 28	struct wait_queue_head wq;
 29};
 30
 31static int virtual_nci_open(struct nci_dev *ndev)
 32{
 33	return 0;
 34}
 35
 36static int virtual_nci_close(struct nci_dev *ndev)
 37{
 38	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
 39
 40	mutex_lock(&vdev->mtx);
 41	kfree_skb(vdev->send_buff);
 42	vdev->send_buff = NULL;
 43	mutex_unlock(&vdev->mtx);
 44
 45	return 0;
 46}
 47
 48static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
 49{
 50	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
 51
 52	mutex_lock(&vdev->mtx);
 53	if (vdev->send_buff) {
 54		mutex_unlock(&vdev->mtx);
 55		kfree_skb(skb);
 56		return -1;
 57	}
 58	vdev->send_buff = skb_copy(skb, GFP_KERNEL);
 59	if (!vdev->send_buff) {
 60		mutex_unlock(&vdev->mtx);
 61		kfree_skb(skb);
 62		return -1;
 63	}
 64	mutex_unlock(&vdev->mtx);
 65	wake_up_interruptible(&vdev->wq);
 66	consume_skb(skb);
 67
 68	return 0;
 69}
 70
 71static const struct nci_ops virtual_nci_ops = {
 72	.open = virtual_nci_open,
 73	.close = virtual_nci_close,
 74	.send = virtual_nci_send
 75};
 76
 77static ssize_t virtual_ncidev_read(struct file *file, char __user *buf,
 78				   size_t count, loff_t *ppos)
 79{
 80	struct virtual_nci_dev *vdev = file->private_data;
 81	size_t actual_len;
 82
 83	mutex_lock(&vdev->mtx);
 84	while (!vdev->send_buff) {
 85		mutex_unlock(&vdev->mtx);
 86		if (wait_event_interruptible(vdev->wq, vdev->send_buff))
 87			return -EFAULT;
 88		mutex_lock(&vdev->mtx);
 89	}
 90
 91	actual_len = min_t(size_t, count, vdev->send_buff->len);
 92
 93	if (copy_to_user(buf, vdev->send_buff->data, actual_len)) {
 94		mutex_unlock(&vdev->mtx);
 95		return -EFAULT;
 96	}
 97
 98	skb_pull(vdev->send_buff, actual_len);
 99	if (vdev->send_buff->len == 0) {
100		consume_skb(vdev->send_buff);
101		vdev->send_buff = NULL;
102	}
103	mutex_unlock(&vdev->mtx);
104
105	return actual_len;
106}
107
108static ssize_t virtual_ncidev_write(struct file *file,
109				    const char __user *buf,
110				    size_t count, loff_t *ppos)
111{
112	struct virtual_nci_dev *vdev = file->private_data;
113	struct sk_buff *skb;
114
115	skb = alloc_skb(count, GFP_KERNEL);
116	if (!skb)
117		return -ENOMEM;
118
119	if (copy_from_user(skb_put(skb, count), buf, count)) {
120		kfree_skb(skb);
121		return -EFAULT;
122	}
123
124	nci_recv_frame(vdev->ndev, skb);
125	return count;
126}
127
128static int virtual_ncidev_open(struct inode *inode, struct file *file)
129{
130	int ret = 0;
131	struct virtual_nci_dev *vdev;
132
133	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
134	if (!vdev)
135		return -ENOMEM;
136	vdev->ndev = nci_allocate_device(&virtual_nci_ops,
137		VIRTUAL_NFC_PROTOCOLS, 0, 0);
138	if (!vdev->ndev) {
139		kfree(vdev);
140		return -ENOMEM;
141	}
142
143	mutex_init(&vdev->mtx);
144	init_waitqueue_head(&vdev->wq);
145	file->private_data = vdev;
146	nci_set_drvdata(vdev->ndev, vdev);
147
148	ret = nci_register_device(vdev->ndev);
149	if (ret < 0) {
150		nci_free_device(vdev->ndev);
151		mutex_destroy(&vdev->mtx);
152		kfree(vdev);
153		return ret;
154	}
155
156	return 0;
157}
158
159static int virtual_ncidev_close(struct inode *inode, struct file *file)
160{
161	struct virtual_nci_dev *vdev = file->private_data;
162
163	nci_unregister_device(vdev->ndev);
164	nci_free_device(vdev->ndev);
165	mutex_destroy(&vdev->mtx);
166	kfree(vdev);
167
168	return 0;
169}
170
171static long virtual_ncidev_ioctl(struct file *file, unsigned int cmd,
172				 unsigned long arg)
173{
174	struct virtual_nci_dev *vdev = file->private_data;
175	const struct nfc_dev *nfc_dev = vdev->ndev->nfc_dev;
176	void __user *p = (void __user *)arg;
177
178	if (cmd != IOCTL_GET_NCIDEV_IDX)
179		return -ENOTTY;
180
181	if (copy_to_user(p, &nfc_dev->idx, sizeof(nfc_dev->idx)))
182		return -EFAULT;
183
184	return 0;
185}
186
187static const struct file_operations virtual_ncidev_fops = {
188	.owner = THIS_MODULE,
189	.read = virtual_ncidev_read,
190	.write = virtual_ncidev_write,
191	.open = virtual_ncidev_open,
192	.release = virtual_ncidev_close,
193	.unlocked_ioctl = virtual_ncidev_ioctl
194};
195
196static struct miscdevice miscdev = {
197	.minor = MISC_DYNAMIC_MINOR,
198	.name = "virtual_nci",
199	.fops = &virtual_ncidev_fops,
200	.mode = 0600,
201};
202
203static int __init virtual_ncidev_init(void)
204{
205	return misc_register(&miscdev);
206}
207
208static void __exit virtual_ncidev_exit(void)
209{
210	misc_deregister(&miscdev);
211}
212
213module_init(virtual_ncidev_init);
214module_exit(virtual_ncidev_exit);
215
216MODULE_LICENSE("GPL");
217MODULE_DESCRIPTION("Virtual NCI device simulation driver");
218MODULE_AUTHOR("Bongsu Jeon <bongsu.jeon@samsung.com>");