2 * Copyright (C) 2004 IBM Corporation
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>
9 * Copyright (C) 2013 Obsidian Research Corp
10 * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
12 * Device file system interface to the TPM
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
20 #include <linux/miscdevice.h>
21 #include <linux/slab.h>
22 #include <linux/uaccess.h>
26 struct tpm_chip *chip;
28 /* Data passed to and from the tpm via the read/write calls */
29 atomic_t data_pending;
30 struct mutex buffer_mutex;
32 struct timer_list user_read_timer; /* user needs to claim result */
33 struct work_struct work;
35 u8 data_buffer[TPM_BUFSIZE];
38 static void user_reader_timeout(unsigned long ptr)
40 struct file_priv *priv = (struct file_priv *)ptr;
42 schedule_work(&priv->work);
45 static void timeout_work(struct work_struct *work)
47 struct file_priv *priv = container_of(work, struct file_priv, work);
49 mutex_lock(&priv->buffer_mutex);
50 atomic_set(&priv->data_pending, 0);
51 memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
52 mutex_unlock(&priv->buffer_mutex);
55 static int tpm_open(struct inode *inode, struct file *file)
57 struct miscdevice *misc = file->private_data;
58 struct tpm_chip *chip = container_of(misc, struct tpm_chip,
60 struct file_priv *priv;
62 /* It's assured that the chip will be opened just once,
63 * by the check of is_open variable, which is protected
65 if (test_and_set_bit(0, &chip->is_open)) {
66 dev_dbg(chip->dev, "Another process owns this TPM\n");
70 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
72 clear_bit(0, &chip->is_open);
77 atomic_set(&priv->data_pending, 0);
78 mutex_init(&priv->buffer_mutex);
79 setup_timer(&priv->user_read_timer, user_reader_timeout,
81 INIT_WORK(&priv->work, timeout_work);
83 file->private_data = priv;
84 get_device(chip->dev);
88 static ssize_t tpm_read(struct file *file, char __user *buf,
89 size_t size, loff_t *off)
91 struct file_priv *priv = file->private_data;
95 del_singleshot_timer_sync(&priv->user_read_timer);
96 flush_work(&priv->work);
97 ret_size = atomic_read(&priv->data_pending);
98 if (ret_size > 0) { /* relay data */
99 ssize_t orig_ret_size = ret_size;
103 mutex_lock(&priv->buffer_mutex);
104 rc = copy_to_user(buf, priv->data_buffer, ret_size);
105 memset(priv->data_buffer, 0, orig_ret_size);
109 mutex_unlock(&priv->buffer_mutex);
112 atomic_set(&priv->data_pending, 0);
117 static ssize_t tpm_write(struct file *file, const char __user *buf,
118 size_t size, loff_t *off)
120 struct file_priv *priv = file->private_data;
121 size_t in_size = size;
124 /* cannot perform a write until the read has cleared
125 either via tpm_read or a user_read_timer timeout.
126 This also prevents splitted buffered writes from blocking here.
128 if (atomic_read(&priv->data_pending) != 0)
131 if (in_size > TPM_BUFSIZE)
134 mutex_lock(&priv->buffer_mutex);
137 (priv->data_buffer, (void __user *) buf, in_size)) {
138 mutex_unlock(&priv->buffer_mutex);
142 /* atomic tpm command send and result receive */
143 out_size = tpm_transmit(priv->chip, priv->data_buffer,
144 sizeof(priv->data_buffer));
146 mutex_unlock(&priv->buffer_mutex);
150 atomic_set(&priv->data_pending, out_size);
151 mutex_unlock(&priv->buffer_mutex);
153 /* Set a timeout by which the reader must come claim the result */
154 mod_timer(&priv->user_read_timer, jiffies + (60 * HZ));
160 * Called on file close
162 static int tpm_release(struct inode *inode, struct file *file)
164 struct file_priv *priv = file->private_data;
166 del_singleshot_timer_sync(&priv->user_read_timer);
167 flush_work(&priv->work);
168 file->private_data = NULL;
169 atomic_set(&priv->data_pending, 0);
170 clear_bit(0, &priv->chip->is_open);
171 put_device(priv->chip->dev);
176 static const struct file_operations tpm_fops = {
177 .owner = THIS_MODULE,
182 .release = tpm_release,
185 int tpm_dev_add_device(struct tpm_chip *chip)
189 chip->vendor.miscdev.fops = &tpm_fops;
190 if (chip->dev_num == 0)
191 chip->vendor.miscdev.minor = TPM_MINOR;
193 chip->vendor.miscdev.minor = MISC_DYNAMIC_MINOR;
195 chip->vendor.miscdev.name = chip->devname;
196 chip->vendor.miscdev.parent = chip->dev;
198 rc = misc_register(&chip->vendor.miscdev);
200 chip->vendor.miscdev.name = NULL;
202 "unable to misc_register %s, minor %d err=%d\n",
203 chip->vendor.miscdev.name,
204 chip->vendor.miscdev.minor, rc);
209 void tpm_dev_del_device(struct tpm_chip *chip)
211 if (chip->vendor.miscdev.name)
212 misc_deregister(&chip->vendor.miscdev);