LXR linux/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
  23static 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
  51static 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 */
  60static 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
  71const 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};
  79