diff options
Diffstat (limited to 'drivers/char/tpm/tpm-dev.c')
| -rw-r--r-- | drivers/char/tpm/tpm-dev.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c new file mode 100644 index 000000000..de0337ebd --- /dev/null +++ b/drivers/char/tpm/tpm-dev.c @@ -0,0 +1,183 @@ +/* + * Copyright (C) 2004 IBM Corporation + * Authors: + * Leendert van Doorn <leendert@watson.ibm.com> + * Dave Safford <safford@watson.ibm.com> + * Reiner Sailer <sailer@watson.ibm.com> + * Kylene Hall <kjhall@us.ibm.com> + * + * Copyright (C) 2013 Obsidian Research Corp + * Jason Gunthorpe <jgunthorpe@obsidianresearch.com> + * + * Device file system interface to the TPM + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, version 2 of the + * License. + * + */ +#include <linux/slab.h> +#include <linux/uaccess.h> +#include "tpm.h" + +struct file_priv { + struct tpm_chip *chip; + + /* Data passed to and from the tpm via the read/write calls */ + atomic_t data_pending; + struct mutex buffer_mutex; + + struct timer_list user_read_timer; /* user needs to claim result */ + struct work_struct work; + + u8 data_buffer[TPM_BUFSIZE]; +}; + +static void user_reader_timeout(unsigned long ptr) +{ + struct file_priv *priv = (struct file_priv *)ptr; + + schedule_work(&priv->work); +} + +static void timeout_work(struct work_struct *work) +{ + struct file_priv *priv = container_of(work, struct file_priv, work); + + mutex_lock(&priv->buffer_mutex); + atomic_set(&priv->data_pending, 0); + memset(priv->data_buffer, 0, sizeof(priv->data_buffer)); + mutex_unlock(&priv->buffer_mutex); +} + +static int tpm_open(struct inode *inode, struct file *file) +{ + struct tpm_chip *chip = + container_of(inode->i_cdev, struct tpm_chip, cdev); + struct file_priv *priv; + + /* It's assured that the chip will be opened just once, + * by the check of is_open variable, which is protected + * by driver_lock. */ + if (test_and_set_bit(0, &chip->is_open)) { + dev_dbg(chip->pdev, "Another process owns this TPM\n"); + return -EBUSY; + } + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (priv == NULL) { + clear_bit(0, &chip->is_open); + return -ENOMEM; + } + + priv->chip = chip; + atomic_set(&priv->data_pending, 0); + mutex_init(&priv->buffer_mutex); + setup_timer(&priv->user_read_timer, user_reader_timeout, + (unsigned long)priv); + INIT_WORK(&priv->work, timeout_work); + + file->private_data = priv; + get_device(chip->pdev); + return 0; +} + +static ssize_t tpm_read(struct file *file, char __user *buf, + size_t size, loff_t *off) +{ + struct file_priv *priv = file->private_data; + ssize_t ret_size; + int rc; + + del_singleshot_timer_sync(&priv->user_read_timer); + flush_work(&priv->work); + ret_size = atomic_read(&priv->data_pending); + if (ret_size > 0) { /* relay data */ + ssize_t orig_ret_size = ret_size; + if (size < ret_size) + ret_size = size; + + mutex_lock(&priv->buffer_mutex); + rc = copy_to_user(buf, priv->data_buffer, ret_size); + memset(priv->data_buffer, 0, orig_ret_size); + if (rc) + ret_size = -EFAULT; + + mutex_unlock(&priv->buffer_mutex); + } + + atomic_set(&priv->data_pending, 0); + + return ret_size; +} + +static ssize_t tpm_write(struct file *file, const char __user *buf, + size_t size, loff_t *off) +{ + struct file_priv *priv = file->private_data; + size_t in_size = size; + ssize_t out_size; + + /* cannot perform a write until the read has cleared + either via tpm_read or a user_read_timer timeout. + This also prevents splitted buffered writes from blocking here. + */ + if (atomic_read(&priv->data_pending) != 0) + return -EBUSY; + + if (in_size > TPM_BUFSIZE) + return -E2BIG; + + mutex_lock(&priv->buffer_mutex); + + if (copy_from_user + (priv->data_buffer, (void __user *) buf, in_size)) { + mutex_unlock(&priv->buffer_mutex); + return -EFAULT; + } + + /* atomic tpm command send and result receive */ + out_size = tpm_transmit(priv->chip, priv->data_buffer, + sizeof(priv->data_buffer)); + if (out_size < 0) { + mutex_unlock(&priv->buffer_mutex); + return out_size; + } + + atomic_set(&priv->data_pending, out_size); + mutex_unlock(&priv->buffer_mutex); + + /* Set a timeout by which the reader must come claim the result */ + mod_timer(&priv->user_read_timer, jiffies + (60 * HZ)); + + return in_size; +} + +/* + * Called on file close + */ +static int tpm_release(struct inode *inode, struct file *file) +{ + struct file_priv *priv = file->private_data; + + del_singleshot_timer_sync(&priv->user_read_timer); + flush_work(&priv->work); + file->private_data = NULL; + atomic_set(&priv->data_pending, 0); + clear_bit(0, &priv->chip->is_open); + put_device(priv->chip->pdev); + kfree(priv); + return 0; +} + +const struct file_operations tpm_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .open = tpm_open, + .read = tpm_read, + .write = tpm_write, + .release = tpm_release, +}; + + |