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
24 struct 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
virtual_nci_open(struct nci_dev * ndev)32 static 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
virtual_nci_close(struct nci_dev * ndev)40 static 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
virtual_nci_send(struct nci_dev * ndev,struct sk_buff * skb)53 static 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
76 static const struct nci_ops virtual_nci_ops = {
77 .open = virtual_nci_open,
78 .close = virtual_nci_close,
79 .send = virtual_nci_send
80 };
81
virtual_ncidev_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)82 static 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
virtual_ncidev_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)113 static 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 if (strnlen(skb->data, count) != count) {
129 kfree_skb(skb);
130 return -EINVAL;
131 }
132
133 nci_recv_frame(vdev->ndev, skb);
134 return count;
135 }
136
virtual_ncidev_open(struct inode * inode,struct file * file)137 static int virtual_ncidev_open(struct inode *inode, struct file *file)
138 {
139 int ret = 0;
140 struct virtual_nci_dev *vdev;
141
142 vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
143 if (!vdev)
144 return -ENOMEM;
145 vdev->ndev = nci_allocate_device(&virtual_nci_ops,
146 VIRTUAL_NFC_PROTOCOLS, 0, 0);
147 if (!vdev->ndev) {
148 kfree(vdev);
149 return -ENOMEM;
150 }
151
152 mutex_init(&vdev->mtx);
153 init_waitqueue_head(&vdev->wq);
154 file->private_data = vdev;
155 nci_set_drvdata(vdev->ndev, vdev);
156
157 ret = nci_register_device(vdev->ndev);
158 if (ret < 0) {
159 nci_free_device(vdev->ndev);
160 mutex_destroy(&vdev->mtx);
161 kfree(vdev);
162 return ret;
163 }
164
165 return 0;
166 }
167
virtual_ncidev_close(struct inode * inode,struct file * file)168 static int virtual_ncidev_close(struct inode *inode, struct file *file)
169 {
170 struct virtual_nci_dev *vdev = file->private_data;
171
172 nci_unregister_device(vdev->ndev);
173 nci_free_device(vdev->ndev);
174 mutex_destroy(&vdev->mtx);
175 kfree(vdev);
176
177 return 0;
178 }
179
virtual_ncidev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)180 static long virtual_ncidev_ioctl(struct file *file, unsigned int cmd,
181 unsigned long arg)
182 {
183 struct virtual_nci_dev *vdev = file->private_data;
184 const struct nfc_dev *nfc_dev = vdev->ndev->nfc_dev;
185 void __user *p = (void __user *)arg;
186
187 if (cmd != IOCTL_GET_NCIDEV_IDX)
188 return -ENOTTY;
189
190 if (copy_to_user(p, &nfc_dev->idx, sizeof(nfc_dev->idx)))
191 return -EFAULT;
192
193 return 0;
194 }
195
196 static const struct file_operations virtual_ncidev_fops = {
197 .owner = THIS_MODULE,
198 .read = virtual_ncidev_read,
199 .write = virtual_ncidev_write,
200 .open = virtual_ncidev_open,
201 .release = virtual_ncidev_close,
202 .unlocked_ioctl = virtual_ncidev_ioctl
203 };
204
205 static struct miscdevice miscdev = {
206 .minor = MISC_DYNAMIC_MINOR,
207 .name = "virtual_nci",
208 .fops = &virtual_ncidev_fops,
209 .mode = 0600,
210 };
211
212 module_misc_device(miscdev);
213
214 MODULE_LICENSE("GPL");
215 MODULE_DESCRIPTION("Virtual NCI device simulation driver");
216 MODULE_AUTHOR("Bongsu Jeon <bongsu.jeon@samsung.com>");
217