--- /dev/null
+/*
+ * ff-stream.c - a part of driver for RME Fireface series
+ *
+ * Copyright (c) 2015-2017 Takashi Sakamoto
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include "ff.h"
+
+#define CALLBACK_TIMEOUT_MS    200
+
+static int get_rate_mode(unsigned int rate, unsigned int *mode)
+{
+       int i;
+
+       for (i = 0; i < CIP_SFC_COUNT; i++) {
+               if (amdtp_rate_table[i] == rate)
+                       break;
+       }
+
+       if (i == CIP_SFC_COUNT)
+               return -EINVAL;
+
+       *mode = ((int)i - 1) / 2;
+
+       return 0;
+}
+
+/*
+ * Fireface 400 manages isochronous channel number in 3 bit field. Therefore,
+ * we can allocate between 0 and 7 channel.
+ */
+static int keep_resources(struct snd_ff *ff, unsigned int rate)
+{
+       int mode;
+       int err;
+
+       err = get_rate_mode(rate, &mode);
+       if (err < 0)
+               return err;
+
+       /* Keep resources for in-stream. */
+       err = amdtp_ff_set_parameters(&ff->tx_stream, rate,
+                                     ff->spec->pcm_capture_channels[mode]);
+       if (err < 0)
+               return err;
+       ff->tx_resources.channels_mask = 0x00000000000000ffuLL;
+       err = fw_iso_resources_allocate(&ff->tx_resources,
+                       amdtp_stream_get_max_payload(&ff->tx_stream),
+                       fw_parent_device(ff->unit)->max_speed);
+       if (err < 0)
+               return err;
+
+       /* Keep resources for out-stream. */
+       err = amdtp_ff_set_parameters(&ff->rx_stream, rate,
+                                     ff->spec->pcm_playback_channels[mode]);
+       if (err < 0)
+               return err;
+       ff->rx_resources.channels_mask = 0x00000000000000ffuLL;
+       err = fw_iso_resources_allocate(&ff->rx_resources,
+                       amdtp_stream_get_max_payload(&ff->rx_stream),
+                       fw_parent_device(ff->unit)->max_speed);
+       if (err < 0)
+               fw_iso_resources_free(&ff->tx_resources);
+
+       return err;
+}
+
+static void release_resources(struct snd_ff *ff)
+{
+       fw_iso_resources_free(&ff->tx_resources);
+       fw_iso_resources_free(&ff->rx_resources);
+}
+
+static inline void finish_session(struct snd_ff *ff)
+{
+       ff->spec->protocol->finish_session(ff);
+       ff->spec->protocol->switch_fetching_mode(ff, false);
+}
+
+static int init_stream(struct snd_ff *ff, enum amdtp_stream_direction dir)
+{
+       int err;
+       struct fw_iso_resources *resources;
+       struct amdtp_stream *stream;
+
+       if (dir == AMDTP_IN_STREAM) {
+               resources = &ff->tx_resources;
+               stream = &ff->tx_stream;
+       } else {
+               resources = &ff->rx_resources;
+               stream = &ff->rx_stream;
+       }
+
+       err = fw_iso_resources_init(resources, ff->unit);
+       if (err < 0)
+               return err;
+
+       err = amdtp_ff_init(stream, ff->unit, dir);
+       if (err < 0)
+               fw_iso_resources_destroy(resources);
+
+       return err;
+}
+
+static void destroy_stream(struct snd_ff *ff, enum amdtp_stream_direction dir)
+{
+       if (dir == AMDTP_IN_STREAM) {
+               amdtp_stream_destroy(&ff->tx_stream);
+               fw_iso_resources_destroy(&ff->tx_resources);
+       } else {
+               amdtp_stream_destroy(&ff->rx_stream);
+               fw_iso_resources_destroy(&ff->rx_resources);
+       }
+}
+
+int snd_ff_stream_init_duplex(struct snd_ff *ff)
+{
+       int err;
+
+       err = init_stream(ff, AMDTP_OUT_STREAM);
+       if (err < 0)
+               goto end;
+
+       err = init_stream(ff, AMDTP_IN_STREAM);
+       if (err < 0)
+               destroy_stream(ff, AMDTP_OUT_STREAM);
+end:
+       return err;
+}
+
+/*
+ * This function should be called before starting streams or after stopping
+ * streams.
+ */
+void snd_ff_stream_destroy_duplex(struct snd_ff *ff)
+{
+       destroy_stream(ff, AMDTP_IN_STREAM);
+       destroy_stream(ff, AMDTP_OUT_STREAM);
+}
+
+int snd_ff_stream_start_duplex(struct snd_ff *ff, unsigned int rate)
+{
+       unsigned int curr_rate;
+       enum snd_ff_clock_src src;
+       int err;
+
+       if (ff->substreams_counter == 0)
+               return 0;
+
+       err = ff->spec->protocol->get_clock(ff, &curr_rate, &src);
+       if (err < 0)
+               return err;
+       if (curr_rate != rate ||
+           amdtp_streaming_error(&ff->tx_stream) ||
+           amdtp_streaming_error(&ff->rx_stream)) {
+               finish_session(ff);
+
+               amdtp_stream_stop(&ff->tx_stream);
+               amdtp_stream_stop(&ff->rx_stream);
+
+               release_resources(ff);
+       }
+
+       /*
+        * Regardless of current source of clock signal, drivers transfer some
+        * packets. Then, the device transfers packets.
+        */
+       if (!amdtp_stream_running(&ff->rx_stream)) {
+               err = keep_resources(ff, rate);
+               if (err < 0)
+                       goto error;
+
+               err = ff->spec->protocol->begin_session(ff, rate);
+               if (err < 0)
+                       goto error;
+
+               err = amdtp_stream_start(&ff->rx_stream,
+                                        ff->rx_resources.channel,
+                                        fw_parent_device(ff->unit)->max_speed);
+               if (err < 0)
+                       goto error;
+
+               if (!amdtp_stream_wait_callback(&ff->rx_stream,
+                                               CALLBACK_TIMEOUT_MS)) {
+                       err = -ETIMEDOUT;
+                       goto error;
+               }
+
+               err = ff->spec->protocol->switch_fetching_mode(ff, true);
+               if (err < 0)
+                       goto error;
+       }
+
+       if (!amdtp_stream_running(&ff->tx_stream)) {
+               err = amdtp_stream_start(&ff->tx_stream,
+                                        ff->tx_resources.channel,
+                                        fw_parent_device(ff->unit)->max_speed);
+               if (err < 0)
+                       goto error;
+
+               if (!amdtp_stream_wait_callback(&ff->tx_stream,
+                                               CALLBACK_TIMEOUT_MS)) {
+                       err = -ETIMEDOUT;
+                       goto error;
+               }
+       }
+
+       return 0;
+error:
+       amdtp_stream_stop(&ff->tx_stream);
+       amdtp_stream_stop(&ff->rx_stream);
+
+       finish_session(ff);
+       release_resources(ff);
+
+       return err;
+}
+
+void snd_ff_stream_stop_duplex(struct snd_ff *ff)
+{
+       if (ff->substreams_counter > 0)
+               return;
+
+       amdtp_stream_stop(&ff->tx_stream);
+       amdtp_stream_stop(&ff->rx_stream);
+       finish_session(ff);
+       release_resources(ff);
+}
+
+void snd_ff_stream_update_duplex(struct snd_ff *ff)
+{
+       /* The device discontinue to transfer packets.  */
+       amdtp_stream_pcm_abort(&ff->tx_stream);
+       amdtp_stream_stop(&ff->tx_stream);
+
+       amdtp_stream_pcm_abort(&ff->rx_stream);
+       amdtp_stream_stop(&ff->rx_stream);
+
+       fw_iso_resources_update(&ff->tx_resources);
+       fw_iso_resources_update(&ff->rx_resources);
+}