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/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 4fe932e..0c8e662 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -117,6 +117,23 @@
}
EXPORT_SYMBOL(fw_iso_buffer_destroy);
+/* Convert DMA address to offset into virtually contiguous buffer. */
+size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
+{
+ int i;
+ dma_addr_t address;
+ ssize_t offset;
+
+ for (i = 0; i < buffer->page_count; i++) {
+ address = page_private(buffer->pages[i]);
+ offset = (ssize_t)completed - (ssize_t)address;
+ if (offset > 0 && offset <= PAGE_SIZE)
+ return (i << PAGE_SHIFT) + offset;
+ }
+
+ return 0;
+}
+
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)
@@ -133,7 +150,7 @@
ctx->channel = channel;
ctx->speed = speed;
ctx->header_size = header_size;
- ctx->callback = callback;
+ ctx->callback.sc = callback;
ctx->callback_data = callback_data;
return ctx;
@@ -142,9 +159,7 @@
void fw_iso_context_destroy(struct fw_iso_context *ctx)
{
- struct fw_card *card = ctx->card;
-
- card->driver->free_iso_context(ctx);
+ ctx->card->driver->free_iso_context(ctx);
}
EXPORT_SYMBOL(fw_iso_context_destroy);
@@ -155,14 +170,17 @@
}
EXPORT_SYMBOL(fw_iso_context_start);
+int fw_iso_context_set_channels(struct fw_iso_context *ctx, u64 *channels)
+{
+ return ctx->card->driver->set_iso_channels(ctx, channels);
+}
+
int fw_iso_context_queue(struct fw_iso_context *ctx,
struct fw_iso_packet *packet,
struct fw_iso_buffer *buffer,
unsigned long payload)
{
- struct fw_card *card = ctx->card;
-
- return card->driver->queue_iso(ctx, packet, buffer, payload);
+ return ctx->card->driver->queue_iso(ctx, packet, buffer, payload);
}
EXPORT_SYMBOL(fw_iso_context_queue);
