diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index f6595aba4f0f..fa567f1158c2 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -43,6 +43,7 @@ config TCG_NSC
 
 config TCG_ATMEL
 	tristate "Atmel TPM Interface"
+	depends on PPC64 || HAS_IOPORT
 	---help---
 	  If you have a TPM security chip from Atmel say Yes and it 
 	  will be accessible from within Linux.  To compile this driver 
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index caf8012ef47c..9ca5c021d0b6 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -383,6 +383,9 @@ static ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
 	u32 count, ordinal;
 	unsigned long stop;
 
+	if (bufsiz > TPM_BUFSIZE)
+		bufsiz = TPM_BUFSIZE;
+
 	count = be32_to_cpu(*((__be32 *) (buf + 2)));
 	ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
 	if (count == 0)
@@ -1102,6 +1105,7 @@ ssize_t tpm_read(struct file *file, char __user *buf,
 {
 	struct tpm_chip *chip = file->private_data;
 	ssize_t ret_size;
+	int rc;
 
 	del_singleshot_timer_sync(&chip->user_read_timer);
 	flush_work_sync(&chip->work);
@@ -1112,8 +1116,11 @@ ssize_t tpm_read(struct file *file, char __user *buf,
 			ret_size = size;
 
 		mutex_lock(&chip->buffer_mutex);
-		if (copy_to_user(buf, chip->data_buffer, ret_size))
+		rc = copy_to_user(buf, chip->data_buffer, ret_size);
+		memset(chip->data_buffer, 0, ret_size);
+		if (rc)
 			ret_size = -EFAULT;
+
 		mutex_unlock(&chip->buffer_mutex);
 	}
 
diff --git a/drivers/char/tpm/tpm_nsc.c b/drivers/char/tpm/tpm_nsc.c
index 82facc9104c7..4d2464871ada 100644
--- a/drivers/char/tpm/tpm_nsc.c
+++ b/drivers/char/tpm/tpm_nsc.c
@@ -396,8 +396,6 @@ static void __exit cleanup_nsc(void)
 	if (pdev) {
 		tpm_nsc_remove(&pdev->dev);
 		platform_device_unregister(pdev);
-		kfree(pdev);
-		pdev = NULL;
 	}
 
 	platform_driver_unregister(&nsc_drv);