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