drivers/char/tpm/tpm-dev.c

   1 /*
   2  * Copyright (C) 2004 IBM Corporation
   3  * Authors:
   4  * Leendert van Doorn <leendert@watson.ibm.com>
   5  * Dave Safford <safford@watson.ibm.com>
   6  * Reiner Sailer <sailer@watson.ibm.com>
   7  * Kylene Hall <kjhall@us.ibm.com>
   8  *
   9  * Copyright (C) 2013 Obsidian Research Corp
  10  * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
  11  *
  12  * Device file system interface to the TPM
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License as
  16  * published by the Free Software Foundation, version 2 of the
  17  * License.
  18  *
  19  */
  20 #include <linux/slab.h>
  21 #include "tpm-dev.h"
  22
  23 static int tpm_open(struct inode *inode, struct file *file)
  24 {
  25         struct tpm_chip *chip;
  26         struct file_priv *priv;
  27
  28         chip = container_of(inode->i_cdev, struct tpm_chip, cdev);
  29
  30         /* It's assured that the chip will be opened just once,
  31          * by the check of is_open variable, which is protected
  32          * by driver_lock. */
  33         if (test_and_set_bit(0, &chip->is_open)) {
  34                 dev_dbg(&chip->dev, "Another process owns this TPM\n");
  35                 return -EBUSY;
  36         }
  37
  38         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  39         if (priv == NULL)
  40                 goto out;
  41
  42         tpm_common_open(file, chip, priv);
  43
  44         return 0;
  45
  46  out:
  47         clear_bit(0, &chip->is_open);
  48         return -ENOMEM;
  49 }
  50
  51 static ssize_t tpm_write(struct file *file, const char __user *buf,
  52                          size_t size, loff_t *off)
  53 {
  54         return tpm_common_write(file, buf, size, off, NULL);
  55 }
  56
  57 /*
  58  * Called on file close
  59  */
  60 static int tpm_release(struct inode *inode, struct file *file)
  61 {
  62         struct file_priv *priv = file->private_data;
  63
  64         tpm_common_release(file, priv);
  65         clear_bit(0, &priv->chip->is_open);
  66         kfree(priv);
  67
  68         return 0;
  69 }
  70
  71 const struct file_operations tpm_fops = {
  72         .owner = THIS_MODULE,
  73         .llseek = no_llseek,
  74         .open = tpm_open,
  75         .read = tpm_common_read,
  76         .write = tpm_write,
  77         .release = tpm_release,
  78 };