ALSA: firewire-lib: split helper function to check incoming CIP header

A parser for CIP header in incoming packet is enough large.

This commit splits it into a helper function to better looks of packet
handler.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index ab9dc7e..e9976a8 100644 (file)
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -549,29 +549,19 @@ static int handle_out_packet_without_header(struct amdtp_stream *s,
        return 0;
 }
 
-static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
-                           const __be32 *ctx_header, __be32 *buffer,
-                           unsigned int index)
+static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
+                           unsigned int payload_length,
+                           unsigned int *data_blocks, unsigned int *syt)
 {
-       unsigned int payload_length;
        u32 cip_header[2];
-       unsigned int sph, fmt, fdf, syt;
-       unsigned int data_block_quadlets, data_block_counter, dbc_interval;
-       unsigned int data_blocks;
-       struct snd_pcm_substream *pcm;
-       unsigned int pcm_frames;
+       unsigned int sph;
+       unsigned int fmt;
+       unsigned int fdf;
+       unsigned int data_block_counter;
        bool lost;
 
-       payload_length = be32_to_cpu(ctx_header[0]) >> ISO_DATA_LENGTH_SHIFT;
-       if (payload_length > s->ctx_data.tx.max_payload_length) {
-               dev_err(&s->unit->device,
-                       "Detect jumbo payload: %04x %04x\n",
-                       payload_length, s->ctx_data.tx.max_payload_length);
-               return -EIO;
-       }
-
-       cip_header[0] = be32_to_cpu(buffer[0]);
-       cip_header[1] = be32_to_cpu(buffer[1]);
+       cip_header[0] = be32_to_cpu(buf[0]);
+       cip_header[1] = be32_to_cpu(buf[1]);
 
        /*
         * This module supports 'Two-quadlet CIP header with SYT field'.
@@ -583,9 +573,7 @@ static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
                dev_info_ratelimited(&s->unit->device,
                                "Invalid CIP header for AMDTP: %08X:%08X\n",
                                cip_header[0], cip_header[1]);
-               data_blocks = 0;
-               pcm_frames = 0;
-               goto end;
+               return -EAGAIN;
        }
 
        /* Check valid protocol or not. */
@@ -595,19 +583,17 @@ static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
                dev_info_ratelimited(&s->unit->device,
                                     "Detect unexpected protocol: %08x %08x\n",
                                     cip_header[0], cip_header[1]);
-               data_blocks = 0;
-               pcm_frames = 0;
-               goto end;
+               return -EAGAIN;
        }
 
        /* Calculate data blocks */
        fdf = (cip_header[1] & CIP_FDF_MASK) >> CIP_FDF_SHIFT;
-       if (payload_length < 12 ||
+       if (payload_length < sizeof(__be32) * 2 ||
            (fmt == CIP_FMT_AM && fdf == AMDTP_FDF_NO_DATA)) {
-               data_blocks = 0;
+               *data_blocks = 0;
        } else {
-               data_block_quadlets =
-                       (cip_header[0] & CIP_DBS_MASK) >> CIP_DBS_SHIFT;
+               unsigned int data_block_quadlets =
+                               (cip_header[0] & CIP_DBS_MASK) >> CIP_DBS_SHIFT;
                /* avoid division by zero */
                if (data_block_quadlets == 0) {
                        dev_err(&s->unit->device,
@@ -618,13 +604,13 @@ static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
                if (s->flags & CIP_WRONG_DBS)
                        data_block_quadlets = s->data_block_quadlets;
 
-               data_blocks = (payload_length / 4 - 2) /
+               *data_blocks = (payload_length / sizeof(__be32) - 2) /
                                                        data_block_quadlets;
        }
 
        /* Check data block counter continuity */
        data_block_counter = cip_header[0] & CIP_DBC_MASK;
-       if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
+       if (*data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
            s->data_block_counter != UINT_MAX)
                data_block_counter = s->data_block_counter;
 
@@ -635,10 +621,12 @@ static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
        } else if (!(s->flags & CIP_DBC_IS_END_EVENT)) {
                lost = data_block_counter != s->data_block_counter;
        } else {
-               if (data_blocks > 0 && s->ctx_data.tx.dbc_interval > 0)
+               unsigned int dbc_interval;
+
+               if (*data_blocks > 0 && s->ctx_data.tx.dbc_interval > 0)
                        dbc_interval = s->ctx_data.tx.dbc_interval;
                else
-                       dbc_interval = data_blocks;
+                       dbc_interval = *data_blocks;
 
                lost = data_block_counter !=
                       ((s->data_block_counter + dbc_interval) & 0xff);
@@ -651,16 +639,48 @@ static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
                return -EIO;
        }
 
-       trace_amdtp_packet(s, cycle, buffer, payload_length, data_blocks, index);
-
-       syt = be32_to_cpu(buffer[1]) & CIP_SYT_MASK;
-       pcm_frames = s->process_data_blocks(s, buffer + 2, data_blocks, &syt);
+       *syt = cip_header[1] & CIP_SYT_MASK;
 
-       if (s->flags & CIP_DBC_IS_END_EVENT)
+       if (s->flags & CIP_DBC_IS_END_EVENT) {
                s->data_block_counter = data_block_counter;
-       else
+       } else {
                s->data_block_counter =
-                               (data_block_counter + data_blocks) & 0xff;
+                               (data_block_counter + *data_blocks) & 0xff;
+       }
+
+       return 0;
+}
+
+static int handle_in_packet(struct amdtp_stream *s, unsigned int cycle,
+                           const __be32 *ctx_header, __be32 *buffer,
+                           unsigned int index)
+{
+       unsigned int payload_length;
+       unsigned int syt;
+       unsigned int data_blocks;
+       struct snd_pcm_substream *pcm;
+       unsigned int pcm_frames;
+       int err;
+
+       payload_length = be32_to_cpu(ctx_header[0]) >> ISO_DATA_LENGTH_SHIFT;
+       if (payload_length > s->ctx_data.tx.max_payload_length) {
+               dev_err(&s->unit->device,
+                       "Detect jumbo payload: %04x %04x\n",
+                       payload_length, s->ctx_data.tx.max_payload_length);
+               return -EIO;
+       }
+
+       err = check_cip_header(s, buffer, payload_length, &data_blocks, &syt);
+       if (err < 0) {
+               if (err != -EAGAIN)
+                       return err;
+               pcm_frames = 0;
+               goto end;
+       }
+
+       trace_amdtp_packet(s, cycle, buffer, payload_length, data_blocks, index);
+
+       pcm_frames = s->process_data_blocks(s, buffer + 2, data_blocks, &syt);
 end:
        if (queue_in_packet(s) < 0)
                return -EIO;