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