tee: add cancellation support to client interface

Add support of cancellation request to the TEE kernel internal
client interface. Can be used by software TPM drivers, that leverage
TEE under the hood (for instance TPM2.0 mobile profile), for requesting
cancellation of time-consuming operations (RSA key-pair generation etc.).
Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/tee_core.c

@@ -1039,6 +1039,15 @@ int tee_client_invoke_func(struct tee_context *ctx,
 }
 EXPORT_SYMBOL_GPL(tee_client_invoke_func);
 
+int tee_client_cancel_req(struct tee_context *ctx,
+			  struct tee_ioctl_cancel_arg *arg)
+{
+	if (!ctx->teedev->desc->ops->cancel_req)
+		return -EINVAL;
+	return ctx->teedev->desc->ops->cancel_req(ctx, arg->cancel_id,
+						  arg->session);
+}
+
 static int tee_client_device_match(struct device *dev,
 				   struct device_driver *drv)
 {

include/linux/tee_drv.h

@@ -535,6 +535,18 @@ int tee_client_invoke_func(struct tee_context *ctx,
 			   struct tee_ioctl_invoke_arg *arg,
 			   struct tee_param *param);
 
+/**
+ * tee_client_cancel_req() - Request cancellation of the previous open-session
+ * or invoke-command operations in a Trusted Application
+ * @ctx:       TEE Context
+ * @arg:       Cancellation arguments, see description of
+ *             struct tee_ioctl_cancel_arg
+ *
+ * Returns < 0 on error else 0 if the cancellation was successfully requested.
+ */
+int tee_client_cancel_req(struct tee_context *ctx,
+			  struct tee_ioctl_cancel_arg *arg);
+
 static inline bool tee_param_is_memref(struct tee_param *param)
 {
 	switch (param->attr & TEE_IOCTL_PARAM_ATTR_TYPE_MASK) {