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