LXR linux/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
  18static 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 */
  49static 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
  60const 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};
  69