firewire: add isochronous multichannel reception
This adds the DMA context programming and userspace ABI for multichannel
reception, i.e. for listening on multiple channel numbers by means of a
single DMA context.
The use case is reception of more streams than there are IR DMA units
offered by the link layer. This is already implemented by the older
ohci1394 + ieee1394 + raw1394 stack. And as discussed recently on
linux1394-devel, this feature is occasionally used in practice.
The big drawbacks of this mode are that buffer layout and interrupt
generation necessarily differ from single-channel reception: Headers
and trailers are not stripped from packets, packets are not aligned with
buffer chunks, interrupts are per buffer chunk, not per packet.
These drawbacks also cause a rather hefty code footprint to support this
rarely used OHCI-1394 feature. (367 lines added, among them 94 lines of
added userspace ABI documentation.)
This implementation enforces that a multichannel reception context may
only listen to channels to which no single-channel context on the same
link layer is presently listening to. OHCI-1394 would allow to overlay
single-channel contexts by the multi-channel context, but this would be
a departure from the present first-come-first-served policy of IR
context creation.
The implementation is heavily based on an earlier one by Jay Fenlason.
Thanks Jay.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index d974aa4..1cd637e 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -372,17 +372,19 @@
* scatter-gather streaming (e.g. assembling video frame automatically).
*/
struct fw_iso_packet {
- u16 payload_length; /* Length of indirect payload. */
- u32 interrupt:1; /* Generate interrupt on this packet */
- u32 skip:1; /* Set to not send packet at all. */
- u32 tag:2;
- u32 sy:4;
- u32 header_length:8; /* Length of immediate header. */
- u32 header[0];
+ u16 payload_length; /* Length of indirect payload */
+ u32 interrupt:1; /* Generate interrupt on this packet */
+ u32 skip:1; /* tx: Set to not send packet at all */
+ /* rx: Sync bit, wait for matching sy */
+ u32 tag:2; /* tx: Tag in packet header */
+ u32 sy:4; /* tx: Sy in packet header */
+ u32 header_length:8; /* Length of immediate header */
+ u32 header[0]; /* tx: Top of 1394 isoch. data_block */
};
-#define FW_ISO_CONTEXT_TRANSMIT 0
-#define FW_ISO_CONTEXT_RECEIVE 1
+#define FW_ISO_CONTEXT_TRANSMIT 0
+#define FW_ISO_CONTEXT_RECEIVE 1
+#define FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL 2
#define FW_ISO_CONTEXT_MATCH_TAG0 1
#define FW_ISO_CONTEXT_MATCH_TAG1 2
@@ -406,24 +408,31 @@
int fw_iso_buffer_init(struct fw_iso_buffer *buffer, struct fw_card *card,
int page_count, enum dma_data_direction direction);
void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer, struct fw_card *card);
+size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed);
struct fw_iso_context;
typedef void (*fw_iso_callback_t)(struct fw_iso_context *context,
u32 cycle, size_t header_length,
void *header, void *data);
+typedef void (*fw_iso_mc_callback_t)(struct fw_iso_context *context,
+ dma_addr_t completed, void *data);
struct fw_iso_context {
struct fw_card *card;
int type;
int channel;
int speed;
size_t header_size;
- fw_iso_callback_t callback;
+ union {
+ fw_iso_callback_t sc;
+ fw_iso_mc_callback_t mc;
+ } callback;
void *callback_data;
};
struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
int type, int channel, int speed, size_t header_size,
fw_iso_callback_t callback, void *callback_data);
+int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels);
int fw_iso_context_queue(struct fw_iso_context *ctx,
struct fw_iso_packet *packet,
struct fw_iso_buffer *buffer,