drivers/char/tpm/tpm-dev.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2004 IBM Corporation
   4  * Authors:
   5  * Leendert van Doorn <leendert@watson.ibm.com>
   6  * Dave Safford <safford@watson.ibm.com>
   7  * Reiner Sailer <sailer@watson.ibm.com>
   8  * Kylene Hall <kjhall@us.ibm.com>
   9  *
  10  * Copyright (C) 2013 Obsidian Research Corp
  11  * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
  12  *
  13  * Device file system interface to the TPM
  14  */
  15 #include <linux/slab.h>
  16 #include "tpm-dev.h"
  17
  18 static int tpm_open(struct inode *inode, struct file *file)
  19 {
  20         struct tpm_chip *chip;
  21         struct file_priv *priv;
  22
  23         chip = container_of(inode->i_cdev, struct tpm_chip, cdev);
  24
  25         /* It's assured that the chip will be opened just once,
  26          * by the check of is_open variable, which is protected
  27          * by driver_lock. */
  28         if (test_and_set_bit(0, &chip->is_open)) {
  29                 dev_dbg(&chip->dev, "Another process owns this TPM\n");
  30                 return -EBUSY;
  31         }
  32
  33         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  34         if (priv == NULL)
  35                 goto out;
  36
  37         tpm_common_open(file, chip, priv, NULL);
  38
  39         return 0;
  40
  41  out:
  42         clear_bit(0, &chip->is_open);
  43         return -ENOMEM;
  44 }
  45
  46 /*
  47  * Called on file close
  48  */
  49 static int tpm_release(struct inode *inode, struct file *file)
  50 {
  51         struct file_priv *priv = file->private_data;
  52
  53         tpm_common_release(file, priv);
  54         clear_bit(0, &priv->chip->is_open);
  55         kfree(priv);
  56
  57         return 0;
  58 }
  59
  60 const struct file_operations tpm_fops = {
  61         .owner = THIS_MODULE,
  62         .llseek = no_llseek,
  63         .open = tpm_open,
  64         .read = tpm_common_read,
  65         .write = tpm_common_write,
  66         .poll = tpm_common_poll,
  67         .release = tpm_release,
  68 };