drivers/nfc/virtual_ncidev.c

   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 <[email protected]>
   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
  15 enum 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
  29 static enum virtual_ncidev_mode state;
  30 static struct miscdevice miscdev;
  31 static struct sk_buff *send_buff;
  32 static struct nci_dev *ndev;
  33 static DEFINE_MUTEX(nci_mutex);
  34
  35 static int virtual_nci_open(struct nci_dev *ndev)
  36 {
  37         return 0;
  38 }
  39
  40 static 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
  50 static 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
  68 static struct nci_ops virtual_nci_ops = {
  69         .open = virtual_nci_open,
  70         .close = virtual_nci_close,
  71         .send = virtual_nci_send
  72 };
  73
  74 static 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
 102 static 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
 121 static 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
 150 static 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
 170 static 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
 185 static 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
 194 static 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
 205 static void __exit virtual_ncidev_exit(void)
 206 {
 207         misc_deregister(&miscdev);
 208 }
 209
 210 module_init(virtual_ncidev_init);
 211 module_exit(virtual_ncidev_exit);
 212
 213 MODULE_LICENSE("GPL");
 214 MODULE_DESCRIPTION("Virtual NCI device simulation driver");
 215 MODULE_AUTHOR("Bongsu Jeon <[email protected]>");