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