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