1 files changed, 213 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
new file mode 100644
index 000000000000..d9b774e02a1f
--- /dev/null
+++ b/drivers/char/tpm/tpm-dev.c
@@ -0,0 +1,213 @@
+/*
+ * 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/miscdevice.h>
+#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 miscdevice *misc = file->private_data;
+	struct tpm_chip *chip = container_of(misc, struct tpm_chip,
+					     vendor.miscdev);
+	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->dev, "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->dev);
+	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->dev);
+	kfree(priv);
+	return 0;
+}
+
+static const struct file_operations tpm_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.open = tpm_open,
+	.read = tpm_read,
+	.write = tpm_write,
+	.release = tpm_release,
+};
+
+int tpm_dev_add_device(struct tpm_chip *chip)
+{
+	int rc;
+
+	chip->vendor.miscdev.fops = &tpm_fops;
+	if (chip->dev_num == 0)
+		chip->vendor.miscdev.minor = TPM_MINOR;
+	else
+		chip->vendor.miscdev.minor = MISC_DYNAMIC_MINOR;
+
+	chip->vendor.miscdev.name = chip->devname;
+	chip->vendor.miscdev.parent = chip->dev;
+
+	rc = misc_register(&chip->vendor.miscdev);
+	if (rc) {
+		chip->vendor.miscdev.name = NULL;
+		dev_err(chip->dev,
+			"unable to misc_register %s, minor %d err=%d\n",
+			chip->vendor.miscdev.name,
+			chip->vendor.miscdev.minor, rc);
+	}
+	return rc;
+}
+
+void tpm_dev_del_device(struct tpm_chip *chip)
+{
+	if (chip->vendor.miscdev.name)
+		misc_deregister(&chip->vendor.miscdev);
+}