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path: root/drivers/char/tpm/tpm-dev.c
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Diffstat (limited to 'drivers/char/tpm/tpm-dev.c')
-rw-r--r--drivers/char/tpm/tpm-dev.c183
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,
+};
+
+