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 <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 enum virtual_ncidev_mode {
  17         virtual_ncidev_enabled,
  18         virtual_ncidev_disabled,
  19         virtual_ncidev_disabling,
  20 };
  21
  22 #define IOCTL_GET_NCIDEV_IDX    0
  23 #define VIRTUAL_NFC_PROTOCOLS   (NFC_PROTO_JEWEL_MASK | \
  24                                  NFC_PROTO_MIFARE_MASK | \
  25                                  NFC_PROTO_FELICA_MASK | \
  26                                  NFC_PROTO_ISO14443_MASK | \
  27                                  NFC_PROTO_ISO14443_B_MASK | \
  28                                  NFC_PROTO_ISO15693_MASK)
  29
  30 static enum virtual_ncidev_mode state;
  31 static DECLARE_WAIT_QUEUE_HEAD(wq);
  32 static struct miscdevice miscdev;
  33 static struct sk_buff *send_buff;
  34 static struct nci_dev *ndev;
  35 static DEFINE_MUTEX(nci_mutex);
  36
  37 static int virtual_nci_open(struct nci_dev *ndev)
  38 {
  39         return 0;
  40 }
  41
  42 static int virtual_nci_close(struct nci_dev *ndev)
  43 {
  44         mutex_lock(&nci_mutex);
  45         kfree_skb(send_buff);
  46         send_buff = NULL;
  47         mutex_unlock(&nci_mutex);
  48
  49         return 0;
  50 }
  51
  52 static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
  53 {
  54         mutex_lock(&nci_mutex);
  55         if (state != virtual_ncidev_enabled) {
  56                 mutex_unlock(&nci_mutex);
  57                 kfree_skb(skb);
  58                 return 0;
  59         }
  60
  61         if (send_buff) {
  62                 mutex_unlock(&nci_mutex);
  63                 kfree_skb(skb);
  64                 return -1;
  65         }
  66         send_buff = skb_copy(skb, GFP_KERNEL);
  67         mutex_unlock(&nci_mutex);
  68         wake_up_interruptible(&wq);
  69         consume_skb(skb);
  70
  71         return 0;
  72 }
  73
  74 static const struct nci_ops virtual_nci_ops = {
  75         .open = virtual_nci_open,
  76         .close = virtual_nci_close,
  77         .send = virtual_nci_send
  78 };
  79
  80 static ssize_t virtual_ncidev_read(struct file *file, char __user *buf,
  81                                    size_t count, loff_t *ppos)
  82 {
  83         size_t actual_len;
  84
  85         mutex_lock(&nci_mutex);
  86         while (!send_buff) {
  87                 mutex_unlock(&nci_mutex);
  88                 if (wait_event_interruptible(wq, send_buff))
  89                         return -EFAULT;
  90                 mutex_lock(&nci_mutex);
  91         }
  92
  93         actual_len = min_t(size_t, count, send_buff->len);
  94
  95         if (copy_to_user(buf, send_buff->data, actual_len)) {
  96                 mutex_unlock(&nci_mutex);
  97                 return -EFAULT;
  98         }
  99
 100         skb_pull(send_buff, actual_len);
 101         if (send_buff->len == 0) {
 102                 consume_skb(send_buff);
 103                 send_buff = NULL;
 104         }
 105         mutex_unlock(&nci_mutex);
 106
 107         return actual_len;
 108 }
 109
 110 static ssize_t virtual_ncidev_write(struct file *file,
 111                                     const char __user *buf,
 112                                     size_t count, loff_t *ppos)
 113 {
 114         struct sk_buff *skb;
 115
 116         skb = alloc_skb(count, GFP_KERNEL);
 117         if (!skb)
 118                 return -ENOMEM;
 119
 120         if (copy_from_user(skb_put(skb, count), buf, count)) {
 121                 kfree_skb(skb);
 122                 return -EFAULT;
 123         }
 124
 125         nci_recv_frame(ndev, skb);
 126         return count;
 127 }
 128
 129 static int virtual_ncidev_open(struct inode *inode, struct file *file)
 130 {
 131         int ret = 0;
 132
 133         mutex_lock(&nci_mutex);
 134         if (state != virtual_ncidev_disabled) {
 135                 mutex_unlock(&nci_mutex);
 136                 return -EBUSY;
 137         }
 138
 139         ndev = nci_allocate_device(&virtual_nci_ops, VIRTUAL_NFC_PROTOCOLS,
 140                                    0, 0);
 141         if (!ndev) {
 142                 mutex_unlock(&nci_mutex);
 143                 return -ENOMEM;
 144         }
 145
 146         ret = nci_register_device(ndev);
 147         if (ret < 0) {
 148                 nci_free_device(ndev);
 149                 mutex_unlock(&nci_mutex);
 150                 return ret;
 151         }
 152         state = virtual_ncidev_enabled;
 153         mutex_unlock(&nci_mutex);
 154
 155         return 0;
 156 }
 157
 158 static int virtual_ncidev_close(struct inode *inode, struct file *file)
 159 {
 160         mutex_lock(&nci_mutex);
 161
 162         if (state == virtual_ncidev_enabled) {
 163                 state = virtual_ncidev_disabling;
 164                 mutex_unlock(&nci_mutex);
 165
 166                 nci_unregister_device(ndev);
 167                 nci_free_device(ndev);
 168
 169                 mutex_lock(&nci_mutex);
 170         }
 171
 172         state = virtual_ncidev_disabled;
 173         mutex_unlock(&nci_mutex);
 174
 175         return 0;
 176 }
 177
 178 static long virtual_ncidev_ioctl(struct file *flip, unsigned int cmd,
 179                                  unsigned long arg)
 180 {
 181         const struct nfc_dev *nfc_dev = ndev->nfc_dev;
 182         void __user *p = (void __user *)arg;
 183
 184         if (cmd != IOCTL_GET_NCIDEV_IDX)
 185                 return -ENOTTY;
 186
 187         if (copy_to_user(p, &nfc_dev->idx, sizeof(nfc_dev->idx)))
 188                 return -EFAULT;
 189
 190         return 0;
 191 }
 192
 193 static const struct file_operations virtual_ncidev_fops = {
 194         .owner = THIS_MODULE,
 195         .read = virtual_ncidev_read,
 196         .write = virtual_ncidev_write,
 197         .open = virtual_ncidev_open,
 198         .release = virtual_ncidev_close,
 199         .unlocked_ioctl = virtual_ncidev_ioctl
 200 };
 201
 202 static int __init virtual_ncidev_init(void)
 203 {
 204         state = virtual_ncidev_disabled;
 205         miscdev.minor = MISC_DYNAMIC_MINOR;
 206         miscdev.name = "virtual_nci";
 207         miscdev.fops = &virtual_ncidev_fops;
 208         miscdev.mode = 0600;
 209
 210         return misc_register(&miscdev);
 211 }
 212
 213 static void __exit virtual_ncidev_exit(void)
 214 {
 215         misc_deregister(&miscdev);
 216 }
 217
 218 module_init(virtual_ncidev_init);
 219 module_exit(virtual_ncidev_exit);
 220
 221 MODULE_LICENSE("GPL");
 222 MODULE_DESCRIPTION("Virtual NCI device simulation driver");
 223 MODULE_AUTHOR("Bongsu Jeon <bongsu.jeon@samsung.com>");