v4.19.13 snapshot.
diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
new file mode 100644
index 0000000..e4a04b2
--- /dev/null
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -0,0 +1,149 @@
+/*
+ * 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"
+#include "tpm-dev.h"
+
+static void user_reader_timeout(struct timer_list *t)
+{
+ struct file_priv *priv = from_timer(priv, t, user_read_timer);
+
+ pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
+ task_tgid_nr(current));
+
+ 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);
+ priv->data_pending = 0;
+ memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
+ mutex_unlock(&priv->buffer_mutex);
+}
+
+void tpm_common_open(struct file *file, struct tpm_chip *chip,
+ struct file_priv *priv)
+{
+ priv->chip = chip;
+ mutex_init(&priv->buffer_mutex);
+ timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
+ INIT_WORK(&priv->work, timeout_work);
+
+ file->private_data = priv;
+}
+
+ssize_t tpm_common_read(struct file *file, char __user *buf,
+ size_t size, loff_t *off)
+{
+ struct file_priv *priv = file->private_data;
+ ssize_t ret_size = 0;
+ int rc;
+
+ del_singleshot_timer_sync(&priv->user_read_timer);
+ flush_work(&priv->work);
+ mutex_lock(&priv->buffer_mutex);
+
+ if (priv->data_pending) {
+ ret_size = min_t(ssize_t, size, priv->data_pending);
+ rc = copy_to_user(buf, priv->data_buffer, ret_size);
+ memset(priv->data_buffer, 0, priv->data_pending);
+ if (rc)
+ ret_size = -EFAULT;
+
+ priv->data_pending = 0;
+ }
+
+ mutex_unlock(&priv->buffer_mutex);
+ return ret_size;
+}
+
+ssize_t tpm_common_write(struct file *file, const char __user *buf,
+ size_t size, loff_t *off, struct tpm_space *space)
+{
+ struct file_priv *priv = file->private_data;
+ size_t in_size = size;
+ ssize_t out_size;
+
+ if (in_size > TPM_BUFSIZE)
+ return -E2BIG;
+
+ mutex_lock(&priv->buffer_mutex);
+
+ /* Cannot perform a write until the read has cleared either via
+ * tpm_read or a user_read_timer timeout. This also prevents split
+ * buffered writes from blocking here.
+ */
+ if (priv->data_pending != 0) {
+ mutex_unlock(&priv->buffer_mutex);
+ return -EBUSY;
+ }
+
+ if (copy_from_user
+ (priv->data_buffer, (void __user *) buf, in_size)) {
+ mutex_unlock(&priv->buffer_mutex);
+ return -EFAULT;
+ }
+
+ if (in_size < 6 ||
+ in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
+ mutex_unlock(&priv->buffer_mutex);
+ return -EINVAL;
+ }
+
+ /* atomic tpm command send and result receive. We only hold the ops
+ * lock during this period so that the tpm can be unregistered even if
+ * the char dev is held open.
+ */
+ if (tpm_try_get_ops(priv->chip)) {
+ mutex_unlock(&priv->buffer_mutex);
+ return -EPIPE;
+ }
+ out_size = tpm_transmit(priv->chip, space, priv->data_buffer,
+ sizeof(priv->data_buffer), 0);
+
+ tpm_put_ops(priv->chip);
+ if (out_size < 0) {
+ mutex_unlock(&priv->buffer_mutex);
+ return out_size;
+ }
+
+ 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 + (120 * HZ));
+
+ return in_size;
+}
+
+/*
+ * Called on file close
+ */
+void tpm_common_release(struct file *file, struct file_priv *priv)
+{
+ del_singleshot_timer_sync(&priv->user_read_timer);
+ flush_work(&priv->work);
+ file->private_data = NULL;
+ priv->data_pending = 0;
+}