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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Virtual NCI device simulation driver
*
* Copyright (C) 2020 Samsung Electrnoics
* Bongsu Jeon <bongsu.jeon@samsung.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <linux/wait.h>
#include <net/nfc/nci_core.h>
enum virtual_ncidev_mode {
virtual_ncidev_enabled,
virtual_ncidev_disabled,
virtual_ncidev_disabling,
};
#define IOCTL_GET_NCIDEV_IDX 0
#define VIRTUAL_NFC_PROTOCOLS (NFC_PROTO_JEWEL_MASK | \
NFC_PROTO_MIFARE_MASK | \
NFC_PROTO_FELICA_MASK | \
NFC_PROTO_ISO14443_MASK | \
NFC_PROTO_ISO14443_B_MASK | \
NFC_PROTO_ISO15693_MASK)
static enum virtual_ncidev_mode state;
static DECLARE_WAIT_QUEUE_HEAD(wq);
static struct miscdevice miscdev;
static struct sk_buff *send_buff;
static struct nci_dev *ndev;
static DEFINE_MUTEX(nci_mutex);
static int virtual_nci_open(struct nci_dev *ndev)
{
return 0;
}
static int virtual_nci_close(struct nci_dev *ndev)
{
mutex_lock(&nci_mutex);
kfree_skb(send_buff);
send_buff = NULL;
mutex_unlock(&nci_mutex);
return 0;
}
static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
{
mutex_lock(&nci_mutex);
if (state != virtual_ncidev_enabled) {
mutex_unlock(&nci_mutex);
kfree_skb(skb);
return 0;
}
if (send_buff) {
mutex_unlock(&nci_mutex);
kfree_skb(skb);
return -1;
}
send_buff = skb_copy(skb, GFP_KERNEL);
mutex_unlock(&nci_mutex);
wake_up_interruptible(&wq);
consume_skb(skb);
return 0;
}
static const struct nci_ops virtual_nci_ops = {
.open = virtual_nci_open,
.close = virtual_nci_close,
.send = virtual_nci_send
};
static ssize_t virtual_ncidev_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
size_t actual_len;
mutex_lock(&nci_mutex);
while (!send_buff) {
mutex_unlock(&nci_mutex);
if (wait_event_interruptible(wq, send_buff))
return -EFAULT;
mutex_lock(&nci_mutex);
}
actual_len = min_t(size_t, count, send_buff->len);
if (copy_to_user(buf, send_buff->data, actual_len)) {
mutex_unlock(&nci_mutex);
return -EFAULT;
}
skb_pull(send_buff, actual_len);
if (send_buff->len == 0) {
consume_skb(send_buff);
send_buff = NULL;
}
mutex_unlock(&nci_mutex);
return actual_len;
}
static ssize_t virtual_ncidev_write(struct file *file,
const char __user *buf,
size_t count, loff_t *ppos)
{
struct sk_buff *skb;
skb = alloc_skb(count, GFP_KERNEL);
if (!skb)
return -ENOMEM;
if (copy_from_user(skb_put(skb, count), buf, count)) {
kfree_skb(skb);
return -EFAULT;
}
if (strnlen(skb->data, count) != count) {
kfree_skb(skb);
return -EINVAL;
}
nci_recv_frame(ndev, skb);
return count;
}
static int virtual_ncidev_open(struct inode *inode, struct file *file)
{
int ret = 0;
mutex_lock(&nci_mutex);
if (state != virtual_ncidev_disabled) {
mutex_unlock(&nci_mutex);
return -EBUSY;
}
ndev = nci_allocate_device(&virtual_nci_ops, VIRTUAL_NFC_PROTOCOLS,
0, 0);
if (!ndev) {
mutex_unlock(&nci_mutex);
return -ENOMEM;
}
ret = nci_register_device(ndev);
if (ret < 0) {
nci_free_device(ndev);
mutex_unlock(&nci_mutex);
return ret;
}
state = virtual_ncidev_enabled;
mutex_unlock(&nci_mutex);
return 0;
}
static int virtual_ncidev_close(struct inode *inode, struct file *file)
{
mutex_lock(&nci_mutex);
if (state == virtual_ncidev_enabled) {
state = virtual_ncidev_disabling;
mutex_unlock(&nci_mutex);
nci_unregister_device(ndev);
nci_free_device(ndev);
mutex_lock(&nci_mutex);
}
state = virtual_ncidev_disabled;
mutex_unlock(&nci_mutex);
return 0;
}
static long virtual_ncidev_ioctl(struct file *flip, unsigned int cmd,
unsigned long arg)
{
const struct nfc_dev *nfc_dev = ndev->nfc_dev;
void __user *p = (void __user *)arg;
if (cmd != IOCTL_GET_NCIDEV_IDX)
return -ENOTTY;
if (copy_to_user(p, &nfc_dev->idx, sizeof(nfc_dev->idx)))
return -EFAULT;
return 0;
}
static const struct file_operations virtual_ncidev_fops = {
.owner = THIS_MODULE,
.read = virtual_ncidev_read,
.write = virtual_ncidev_write,
.open = virtual_ncidev_open,
.release = virtual_ncidev_close,
.unlocked_ioctl = virtual_ncidev_ioctl
};
static int __init virtual_ncidev_init(void)
{
state = virtual_ncidev_disabled;
miscdev.minor = MISC_DYNAMIC_MINOR;
miscdev.name = "virtual_nci";
miscdev.fops = &virtual_ncidev_fops;
miscdev.mode = 0600;
return misc_register(&miscdev);
}
static void __exit virtual_ncidev_exit(void)
{
misc_deregister(&miscdev);
}
module_init(virtual_ncidev_init);
module_exit(virtual_ncidev_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Virtual NCI device simulation driver");
MODULE_AUTHOR("Bongsu Jeon <bongsu.jeon@samsung.com>");
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