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>");