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>

6 files changed, 560 insertions, 193 deletions

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index cf989e1635e1..ba23646bb108 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -193,6 +193,11 @@ struct iso_interrupt_event {
         struct fw_cdev_event_iso_interrupt interrupt;
 };
 
+struct iso_interrupt_mc_event {
+        struct event event;
+        struct fw_cdev_event_iso_interrupt_mc interrupt;
+};
+
 struct iso_resource_event {
         struct event event;
         struct fw_cdev_event_iso_resource iso_resource;
@@ -415,6 +420,7 @@ union ioctl_arg {
         struct fw_cdev_get_cycle_timer2         get_cycle_timer2;
         struct fw_cdev_send_phy_packet          send_phy_packet;
         struct fw_cdev_receive_phy_packets      receive_phy_packets;
+        struct fw_cdev_set_iso_channels         set_iso_channels;
 };
 
 static int ioctl_get_info(struct client *client, union ioctl_arg *arg)
@@ -932,26 +938,54 @@ static void iso_callback(struct fw_iso_context *context, u32 cycle,
                     sizeof(e->interrupt) + header_length, NULL, 0);
 }
 
+static void iso_mc_callback(struct fw_iso_context *context,
+                            dma_addr_t completed, void *data)
+{
+        struct client *client = data;
+        struct iso_interrupt_mc_event *e;
+
+        e = kmalloc(sizeof(*e), GFP_ATOMIC);
+        if (e == NULL) {
+                fw_notify("Out of memory when allocating event\n");
+                return;
+        }
+        e->interrupt.type      = FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL;
+        e->interrupt.closure   = client->iso_closure;
+        e->interrupt.completed = fw_iso_buffer_lookup(&client->buffer,
+                                                      completed);
+        queue_event(client, &e->event, &e->interrupt,
+                    sizeof(e->interrupt), NULL, 0);
+}
+
 static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
 {
         struct fw_cdev_create_iso_context *a = &arg->create_iso_context;
         struct fw_iso_context *context;
+        fw_iso_callback_t cb;
 
         BUILD_BUG_ON(FW_CDEV_ISO_CONTEXT_TRANSMIT != FW_ISO_CONTEXT_TRANSMIT ||
-                     FW_CDEV_ISO_CONTEXT_RECEIVE  != FW_ISO_CONTEXT_RECEIVE);
-
-        if (a->channel > 63)
-                return -EINVAL;
+                     FW_CDEV_ISO_CONTEXT_RECEIVE  != FW_ISO_CONTEXT_RECEIVE  ||
+                     FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL !=
+                                        FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL);
 
         switch (a->type) {
-        case FW_ISO_CONTEXT_RECEIVE:
-                if (a->header_size < 4 || (a->header_size & 3))
+        case FW_ISO_CONTEXT_TRANSMIT:
+                if (a->speed > SCODE_3200 || a->channel > 63)
                         return -EINVAL;
+
+                cb = iso_callback;
                 break;
 
-        case FW_ISO_CONTEXT_TRANSMIT:
-                if (a->speed > SCODE_3200)
+        case FW_ISO_CONTEXT_RECEIVE:
+                if (a->header_size < 4 || (a->header_size & 3) ||
+                    a->channel > 63)
                         return -EINVAL;
+
+                cb = iso_callback;
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                cb = (fw_iso_callback_t)iso_mc_callback;
                 break;
 
         default:
@@ -959,8 +993,7 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
         }
 
         context = fw_iso_context_create(client->device->card, a->type,
-                                        a->channel, a->speed, a->header_size,
-                                        iso_callback, client);
+                        a->channel, a->speed, a->header_size, cb, client);
         if (IS_ERR(context))
                 return PTR_ERR(context);
 
@@ -980,6 +1013,17 @@ static int ioctl_create_iso_context(struct client *client, union ioctl_arg *arg)
         return 0;
 }
 
+static int ioctl_set_iso_channels(struct client *client, union ioctl_arg *arg)
+{
+        struct fw_cdev_set_iso_channels *a = &arg->set_iso_channels;
+        struct fw_iso_context *ctx = client->iso_context;
+
+        if (ctx == NULL || a->handle != 0)
+                return -EINVAL;
+
+        return fw_iso_context_set_channels(ctx, &a->channels);
+}
+
 /* Macros for decoding the iso packet control header. */
 #define GET_PAYLOAD_LENGTH(v)   ((v) & 0xffff)
 #define GET_INTERRUPT(v)        (((v) >> 16) & 0x01)
@@ -993,7 +1037,7 @@ static int ioctl_queue_iso(struct client *client, union ioctl_arg *arg)
         struct fw_cdev_queue_iso *a = &arg->queue_iso;
         struct fw_cdev_iso_packet __user *p, *end, *next;
         struct fw_iso_context *ctx = client->iso_context;
-        unsigned long payload, buffer_end, transmit_header_bytes;
+        unsigned long payload, buffer_end, transmit_header_bytes = 0;
         u32 control;
         int count;
         struct {
@@ -1013,7 +1057,6 @@ static int ioctl_queue_iso(struct client *client, union ioctl_arg *arg)
          * use the indirect payload, the iso buffer need not be mapped
          * and the a->data pointer is ignored.
          */
-
         payload = (unsigned long)a->data - client->vm_start;
         buffer_end = client->buffer.page_count << PAGE_SHIFT;
         if (a->data == 0 || client->buffer.pages == NULL ||
@@ -1022,8 +1065,10 @@ static int ioctl_queue_iso(struct client *client, union ioctl_arg *arg)
                 buffer_end = 0;
         }
 
-        p = (struct fw_cdev_iso_packet __user *)u64_to_uptr(a->packets);
+        if (ctx->type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL && payload & 3)
+                return -EINVAL;
 
+        p = (struct fw_cdev_iso_packet __user *)u64_to_uptr(a->packets);
         if (!access_ok(VERIFY_READ, p, a->size))
                 return -EFAULT;
 
@@ -1039,19 +1084,24 @@ static int ioctl_queue_iso(struct client *client, union ioctl_arg *arg)
                 u.packet.sy = GET_SY(control);
                 u.packet.header_length = GET_HEADER_LENGTH(control);
 
-                if (ctx->type == FW_ISO_CONTEXT_TRANSMIT) {
-                        if (u.packet.header_length % 4 != 0)
+                switch (ctx->type) {
+                case FW_ISO_CONTEXT_TRANSMIT:
+                        if (u.packet.header_length & 3)
                                 return -EINVAL;
                         transmit_header_bytes = u.packet.header_length;
-                } else {
-                        /*
-                         * We require that header_length is a multiple of
-                         * the fixed header size, ctx->header_size.
-                         */
+                        break;
+
+                case FW_ISO_CONTEXT_RECEIVE:
                         if (u.packet.header_length == 0 ||
                             u.packet.header_length % ctx->header_size != 0)
                                 return -EINVAL;
-                        transmit_header_bytes = 0;
+                        break;
+
+                case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                        if (u.packet.payload_length == 0 ||
+                            u.packet.payload_length & 3)
+                                return -EINVAL;
+                        break;
                 }
 
                 next = (struct fw_cdev_iso_packet __user *)
@@ -1534,6 +1584,7 @@ static int (* const ioctl_handlers[])(struct client *, union ioctl_arg *) = {
         [0x14] = ioctl_get_cycle_timer2,
         [0x15] = ioctl_send_phy_packet,
         [0x16] = ioctl_receive_phy_packets,
+        [0x17] = ioctl_set_iso_channels,
 };
 
 static int dispatch_ioctl(struct client *client,
diff --git a/drivers/firewire/core-iso.c b/drivers/firewire/core-iso.c
index 4fe932e60fb8..0c8e662a5daf 100644
--- a/drivers/firewire/core-iso.c
+++ b/drivers/firewire/core-iso.c
@@ -117,6 +117,23 @@ void fw_iso_buffer_destroy(struct fw_iso_buffer *buffer,
 }
 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 @@ struct fw_iso_context *fw_iso_context_create(struct fw_card *card,
         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 @@ EXPORT_SYMBOL(fw_iso_context_create);
 
 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 @@ int fw_iso_context_start(struct fw_iso_context *ctx,
 }
 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);
 
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 28621e44b111..e6239f971be6 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -90,6 +90,8 @@ struct fw_card_driver {
         int (*start_iso)(struct fw_iso_context *ctx,
                          s32 cycle, u32 sync, u32 tags);
 
+        int (*set_iso_channels)(struct fw_iso_context *ctx, u64 *channels);
+
         int (*queue_iso)(struct fw_iso_context *ctx,
                          struct fw_iso_packet *packet,
                          struct fw_iso_buffer *buffer,
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 2e4b425847a7..4bda1c1b74ba 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -190,11 +190,13 @@ struct fw_ohci {
         struct context at_request_ctx;
         struct context at_response_ctx;
 
-        u32 it_context_mask;
+        u32 it_context_mask;     /* unoccupied IT contexts */
         struct iso_context *it_context_list;
-        u64 ir_context_channels;
-        u32 ir_context_mask;
+        u64 ir_context_channels; /* unoccupied channels */
+        u32 ir_context_mask;     /* unoccupied IR contexts */
         struct iso_context *ir_context_list;
+        u64 mc_channels; /* channels in use by the multichannel IR context */
+        bool mc_allocated;
 
         __be32    *config_rom;
         dma_addr_t config_rom_bus;
@@ -2197,10 +2199,9 @@ static int handle_ir_packet_per_buffer(struct context *context,
         __le32 *ir_header;
         void *p;
 
-        for (pd = d; pd <= last; pd++) {
+        for (pd = d; pd <= last; pd++)
                 if (pd->transfer_status)
                         break;
-        }
         if (pd > last)
                 /* Descriptor(s) not done yet, stop iteration */
                 return 0;
@@ -2210,16 +2211,38 @@ static int handle_ir_packet_per_buffer(struct context *context,
 
         if (le16_to_cpu(last->control) & DESCRIPTOR_IRQ_ALWAYS) {
                 ir_header = (__le32 *) p;
-                ctx->base.callback(&ctx->base,
-                                   le32_to_cpu(ir_header[0]) & 0xffff,
-                                   ctx->header_length, ctx->header,
-                                   ctx->base.callback_data);
+                ctx->base.callback.sc(&ctx->base,
+                                      le32_to_cpu(ir_header[0]) & 0xffff,
+                                      ctx->header_length, ctx->header,
+                                      ctx->base.callback_data);
                 ctx->header_length = 0;
         }
 
         return 1;
 }
 
+/* d == last because each descriptor block is only a single descriptor. */
+static int handle_ir_buffer_fill(struct context *context,
+                                 struct descriptor *d,
+                                 struct descriptor *last)
+{
+        struct iso_context *ctx =
+                container_of(context, struct iso_context, context);
+
+        if (!last->transfer_status)
+                /* Descriptor(s) not done yet, stop iteration */
+                return 0;
+
+        if (le16_to_cpu(last->control) & DESCRIPTOR_IRQ_ALWAYS)
+                ctx->base.callback.mc(&ctx->base,
+                                      le32_to_cpu(last->data_address) +
+                                      le16_to_cpu(last->req_count) -
+                                      le16_to_cpu(last->res_count),
+                                      ctx->base.callback_data);
+
+        return 1;
+}
+
 static int handle_it_packet(struct context *context,
                             struct descriptor *d,
                             struct descriptor *last)
@@ -2245,72 +2268,118 @@ static int handle_it_packet(struct context *context,
                 ctx->header_length += 4;
         }
         if (le16_to_cpu(last->control) & DESCRIPTOR_IRQ_ALWAYS) {
-                ctx->base.callback(&ctx->base, le16_to_cpu(last->res_count),
-                                   ctx->header_length, ctx->header,
-                                   ctx->base.callback_data);
+                ctx->base.callback.sc(&ctx->base, le16_to_cpu(last->res_count),
+                                      ctx->header_length, ctx->header,
+                                      ctx->base.callback_data);
                 ctx->header_length = 0;
         }
         return 1;
 }
 
+static void set_multichannel_mask(struct fw_ohci *ohci, u64 channels)
+{
+        u32 hi = channels >> 32, lo = channels;
+
+        reg_write(ohci, OHCI1394_IRMultiChanMaskHiClear, ~hi);
+        reg_write(ohci, OHCI1394_IRMultiChanMaskLoClear, ~lo);
+        reg_write(ohci, OHCI1394_IRMultiChanMaskHiSet, hi);
+        reg_write(ohci, OHCI1394_IRMultiChanMaskLoSet, lo);
+        mmiowb();
+        ohci->mc_channels = channels;
+}
+
 static struct fw_iso_context *ohci_allocate_iso_context(struct fw_card *card,
                                 int type, int channel, size_t header_size)
 {
         struct fw_ohci *ohci = fw_ohci(card);
-        struct iso_context *ctx, *list;
-        descriptor_callback_t callback;
-        u64 *channels, dont_care = ~0ULL;
-        u32 *mask, regs;
+        struct iso_context *uninitialized_var(ctx);
+        descriptor_callback_t uninitialized_var(callback);
+        u64 *uninitialized_var(channels);
+        u32 *uninitialized_var(mask), uninitialized_var(regs);
         unsigned long flags;
-        int index, ret = -ENOMEM;
+        int index, ret = -EBUSY;
 
-        if (type == FW_ISO_CONTEXT_TRANSMIT) {
-                channels = &dont_care;
-                mask = &ohci->it_context_mask;
-                list = ohci->it_context_list;
+        spin_lock_irqsave(&ohci->lock, flags);
+
+        switch (type) {
+        case FW_ISO_CONTEXT_TRANSMIT:
+                mask     = &ohci->it_context_mask;
                 callback = handle_it_packet;
-        } else {
+                index    = ffs(*mask) - 1;
+                if (index >= 0) {
+                        *mask &= ~(1 << index);
+                        regs = OHCI1394_IsoXmitContextBase(index);
+                        ctx  = &ohci->it_context_list[index];
+                }
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE:
                 channels = &ohci->ir_context_channels;
-                mask = &ohci->ir_context_mask;
-                list = ohci->ir_context_list;
+                mask     = &ohci->ir_context_mask;
                 callback = handle_ir_packet_per_buffer;
-        }
+                index    = *channels & 1ULL << channel ? ffs(*mask) - 1 : -1;
+                if (index >= 0) {
+                        *channels &= ~(1ULL << channel);
+                        *mask     &= ~(1 << index);
+                        regs = OHCI1394_IsoRcvContextBase(index);
+                        ctx  = &ohci->ir_context_list[index];
+                }
+                break;
 
-        spin_lock_irqsave(&ohci->lock, flags);
-        index = *channels & 1ULL << channel ? ffs(*mask) - 1 : -1;
-        if (index >= 0) {
-                *channels &= ~(1ULL << channel);
-                *mask &= ~(1 << index);
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                mask     = &ohci->ir_context_mask;
+                callback = handle_ir_buffer_fill;
+                index    = !ohci->mc_allocated ? ffs(*mask) - 1 : -1;
+                if (index >= 0) {
+                        ohci->mc_allocated = true;
+                        *mask &= ~(1 << index);
+                        regs = OHCI1394_IsoRcvContextBase(index);
+                        ctx  = &ohci->ir_context_list[index];
+                }
+                break;
+
+        default:
+                index = -1;
+                ret = -ENOSYS;
         }
+
         spin_unlock_irqrestore(&ohci->lock, flags);
 
         if (index < 0)
-                return ERR_PTR(-EBUSY);
-
-        if (type == FW_ISO_CONTEXT_TRANSMIT)
-                regs = OHCI1394_IsoXmitContextBase(index);
-        else
-                regs = OHCI1394_IsoRcvContextBase(index);
+                return ERR_PTR(ret);
 
-        ctx = &list[index];
         memset(ctx, 0, sizeof(*ctx));
         ctx->header_length = 0;
         ctx->header = (void *) __get_free_page(GFP_KERNEL);
-        if (ctx->header == NULL)
+        if (ctx->header == NULL) {
+                ret = -ENOMEM;
                 goto out;
-
+        }
         ret = context_init(&ctx->context, ohci, regs, callback);
         if (ret < 0)
                 goto out_with_header;
 
+        if (type == FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL)
+                set_multichannel_mask(ohci, 0);
+
         return &ctx->base;
 
  out_with_header:
         free_page((unsigned long)ctx->header);
  out:
         spin_lock_irqsave(&ohci->lock, flags);
-        *channels |= 1ULL << channel;
+
+        switch (type) {
+        case FW_ISO_CONTEXT_RECEIVE:
+                *channels |= 1ULL << channel;
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                ohci->mc_allocated = false;
+                break;
+        }
         *mask |= 1 << index;
+
         spin_unlock_irqrestore(&ohci->lock, flags);
 
         return ERR_PTR(ret);
@@ -2321,10 +2390,11 @@ static int ohci_start_iso(struct fw_iso_context *base,
 {
         struct iso_context *ctx = container_of(base, struct iso_context, base);
         struct fw_ohci *ohci = ctx->context.ohci;
-        u32 control, match;
+        u32 control = IR_CONTEXT_ISOCH_HEADER, match;
         int index;
 
-        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
+        switch (ctx->base.type) {
+        case FW_ISO_CONTEXT_TRANSMIT:
                 index = ctx - ohci->it_context_list;
                 match = 0;
                 if (cycle >= 0)
@@ -2334,9 +2404,13 @@ static int ohci_start_iso(struct fw_iso_context *base,
                 reg_write(ohci, OHCI1394_IsoXmitIntEventClear, 1 << index);
                 reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, 1 << index);
                 context_run(&ctx->context, match);
-        } else {
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                control |= IR_CONTEXT_BUFFER_FILL|IR_CONTEXT_MULTI_CHANNEL_MODE;
+                /* fall through */
+        case FW_ISO_CONTEXT_RECEIVE:
                 index = ctx - ohci->ir_context_list;
-                control = IR_CONTEXT_ISOCH_HEADER;
                 match = (tags << 28) | (sync << 8) | ctx->base.channel;
                 if (cycle >= 0) {
                         match |= (cycle & 0x07fff) << 12;
@@ -2347,6 +2421,7 @@ static int ohci_start_iso(struct fw_iso_context *base,
                 reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, 1 << index);
                 reg_write(ohci, CONTEXT_MATCH(ctx->context.regs), match);
                 context_run(&ctx->context, control);
+                break;
         }
 
         return 0;
@@ -2358,12 +2433,17 @@ static int ohci_stop_iso(struct fw_iso_context *base)
         struct iso_context *ctx = container_of(base, struct iso_context, base);
         int index;
 
-        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
+        switch (ctx->base.type) {
+        case FW_ISO_CONTEXT_TRANSMIT:
                 index = ctx - ohci->it_context_list;
                 reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, 1 << index);
-        } else {
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE:
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                 index = ctx - ohci->ir_context_list;
                 reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, 1 << index);
+                break;
         }
         flush_writes(ohci);
         context_stop(&ctx->context);
@@ -2384,24 +2464,65 @@ static void ohci_free_iso_context(struct fw_iso_context *base)
 
         spin_lock_irqsave(&ohci->lock, flags);
 
-        if (ctx->base.type == FW_ISO_CONTEXT_TRANSMIT) {
+        switch (base->type) {
+        case FW_ISO_CONTEXT_TRANSMIT:
                 index = ctx - ohci->it_context_list;
                 ohci->it_context_mask |= 1 << index;
-        } else {
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE:
                 index = ctx - ohci->ir_context_list;
                 ohci->ir_context_mask |= 1 << index;
                 ohci->ir_context_channels |= 1ULL << base->channel;
+                break;
+
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                index = ctx - ohci->ir_context_list;
+                ohci->ir_context_mask |= 1 << index;
+                ohci->ir_context_channels |= ohci->mc_channels;
+                ohci->mc_channels = 0;
+                ohci->mc_allocated = false;
+                break;
         }
 
         spin_unlock_irqrestore(&ohci->lock, flags);
 }
 
-static int ohci_queue_iso_transmit(struct fw_iso_context *base,
-                                   struct fw_iso_packet *packet,
-                                   struct fw_iso_buffer *buffer,
-                                   unsigned long payload)
+static int ohci_set_iso_channels(struct fw_iso_context *base, u64 *channels)
+{
+        struct fw_ohci *ohci = fw_ohci(base->card);
+        unsigned long flags;
+        int ret;
+
+        switch (base->type) {
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+
+                spin_lock_irqsave(&ohci->lock, flags);
+
+                /* Don't allow multichannel to grab other contexts' channels. */
+                if (~ohci->ir_context_channels & ~ohci->mc_channels & *channels) {
+                        *channels = ohci->ir_context_channels;
+                        ret = -EBUSY;
+                } else {
+                        set_multichannel_mask(ohci, *channels);
+                        ret = 0;
+                }
+
+                spin_unlock_irqrestore(&ohci->lock, flags);
+
+                break;
+        default:
+                ret = -EINVAL;
+        }
+
+        return ret;
+}
+
+static int queue_iso_transmit(struct iso_context *ctx,
+                              struct fw_iso_packet *packet,
+                              struct fw_iso_buffer *buffer,
+                              unsigned long payload)
 {
-        struct iso_context *ctx = container_of(base, struct iso_context, base);
         struct descriptor *d, *last, *pd;
         struct fw_iso_packet *p;
         __le32 *header;
@@ -2497,14 +2618,12 @@ static int ohci_queue_iso_transmit(struct fw_iso_context *base,
         return 0;
 }
 
-static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
-                                        struct fw_iso_packet *packet,
-                                        struct fw_iso_buffer *buffer,
-                                        unsigned long payload)
+static int queue_iso_packet_per_buffer(struct iso_context *ctx,
+                                       struct fw_iso_packet *packet,
+                                       struct fw_iso_buffer *buffer,
+                                       unsigned long payload)
 {
-        struct iso_context *ctx = container_of(base, struct iso_context, base);
         struct descriptor *d, *pd;
-        struct fw_iso_packet *p = packet;
         dma_addr_t d_bus, page_bus;
         u32 z, header_z, rest;
         int i, j, length;
@@ -2514,14 +2633,14 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
          * The OHCI controller puts the isochronous header and trailer in the
          * buffer, so we need at least 8 bytes.
          */
-        packet_count = p->header_length / ctx->base.header_size;
+        packet_count = packet->header_length / ctx->base.header_size;
         header_size  = max(ctx->base.header_size, (size_t)8);
 
         /* Get header size in number of descriptors. */
         header_z = DIV_ROUND_UP(header_size, sizeof(*d));
         page     = payload >> PAGE_SHIFT;
         offset   = payload & ~PAGE_MASK;
-        payload_per_buffer = p->payload_length / packet_count;
+        payload_per_buffer = packet->payload_length / packet_count;
 
         for (i = 0; i < packet_count; i++) {
                 /* d points to the header descriptor */
@@ -2533,7 +2652,7 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
 
                 d->control      = cpu_to_le16(DESCRIPTOR_STATUS |
                                               DESCRIPTOR_INPUT_MORE);
-                if (p->skip && i == 0)
+                if (packet->skip && i == 0)
                         d->control |= cpu_to_le16(DESCRIPTOR_WAIT);
                 d->req_count    = cpu_to_le16(header_size);
                 d->res_count    = d->req_count;
@@ -2566,7 +2685,7 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
                 pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
                                           DESCRIPTOR_INPUT_LAST |
                                           DESCRIPTOR_BRANCH_ALWAYS);
-                if (p->interrupt && i == packet_count - 1)
+                if (packet->interrupt && i == packet_count - 1)
                         pd->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);
 
                 context_append(&ctx->context, d, z, header_z);
@@ -2575,6 +2694,58 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
         return 0;
 }
 
+static int queue_iso_buffer_fill(struct iso_context *ctx,
+                                 struct fw_iso_packet *packet,
+                                 struct fw_iso_buffer *buffer,
+                                 unsigned long payload)
+{
+        struct descriptor *d;
+        dma_addr_t d_bus, page_bus;
+        int page, offset, rest, z, i, length;
+
+        page   = payload >> PAGE_SHIFT;
+        offset = payload & ~PAGE_MASK;
+        rest   = packet->payload_length;
+
+        /* We need one descriptor for each page in the buffer. */
+        z = DIV_ROUND_UP(offset + rest, PAGE_SIZE);
+
+        if (WARN_ON(offset & 3 || rest & 3 || page + z > buffer->page_count))
+                return -EFAULT;
+
+        for (i = 0; i < z; i++) {
+                d = context_get_descriptors(&ctx->context, 1, &d_bus);
+                if (d == NULL)
+                        return -ENOMEM;
+
+                d->control = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
+                                         DESCRIPTOR_BRANCH_ALWAYS);
+                if (packet->skip && i == 0)
+                        d->control |= cpu_to_le16(DESCRIPTOR_WAIT);
+                if (packet->interrupt && i == z - 1)
+                        d->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);
+
+                if (offset + rest < PAGE_SIZE)
+                        length = rest;
+                else
+                        length = PAGE_SIZE - offset;
+                d->req_count = cpu_to_le16(length);
+                d->res_count = d->req_count;
+                d->transfer_status = 0;
+
+                page_bus = page_private(buffer->pages[page]);
+                d->data_address = cpu_to_le32(page_bus + offset);
+
+                rest -= length;
+                offset = 0;
+                page++;
+
+                context_append(&ctx->context, d, 1, 0);
+        }
+
+        return 0;
+}
+
 static int ohci_queue_iso(struct fw_iso_context *base,
                           struct fw_iso_packet *packet,
                           struct fw_iso_buffer *buffer,
@@ -2582,14 +2753,20 @@ static int ohci_queue_iso(struct fw_iso_context *base,
 {
         struct iso_context *ctx = container_of(base, struct iso_context, base);
         unsigned long flags;
-        int ret;
+        int ret = -ENOSYS;
 
         spin_lock_irqsave(&ctx->context.ohci->lock, flags);
-        if (base->type == FW_ISO_CONTEXT_TRANSMIT)
-                ret = ohci_queue_iso_transmit(base, packet, buffer, payload);
-        else
-                ret = ohci_queue_iso_receive_packet_per_buffer(base, packet,
-                                                        buffer, payload);
+        switch (base->type) {
+        case FW_ISO_CONTEXT_TRANSMIT:
+                ret = queue_iso_transmit(ctx, packet, buffer, payload);
+                break;
+        case FW_ISO_CONTEXT_RECEIVE:
+                ret = queue_iso_packet_per_buffer(ctx, packet, buffer, payload);
+                break;
+        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+                ret = queue_iso_buffer_fill(ctx, packet, buffer, payload);
+                break;
+        }
         spin_unlock_irqrestore(&ctx->context.ohci->lock, flags);
 
         return ret;
@@ -2609,6 +2786,7 @@ static const struct fw_card_driver ohci_driver = {
 
         .allocate_iso_context   = ohci_allocate_iso_context,
         .free_iso_context       = ohci_free_iso_context,
+        .set_iso_channels       = ohci_set_iso_channels,
         .queue_iso              = ohci_queue_iso,
         .start_iso              = ohci_start_iso,
         .stop_iso               = ohci_stop_iso,
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 14831119ff71..bc5c26fc1c64 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -25,17 +25,18 @@
 #include <linux/types.h>
 #include <linux/firewire-constants.h>
 
-#define FW_CDEV_EVENT_BUS_RESET                 0x00
-#define FW_CDEV_EVENT_RESPONSE                  0x01
-#define FW_CDEV_EVENT_REQUEST                   0x02
-#define FW_CDEV_EVENT_ISO_INTERRUPT             0x03
-#define FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED    0x04
-#define FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED  0x05
+#define FW_CDEV_EVENT_BUS_RESET                         0x00
+#define FW_CDEV_EVENT_RESPONSE                          0x01
+#define FW_CDEV_EVENT_REQUEST                           0x02
+#define FW_CDEV_EVENT_ISO_INTERRUPT                     0x03
+#define FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED            0x04
+#define FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED          0x05
 
 /* available since kernel version 2.6.36 */
-#define FW_CDEV_EVENT_REQUEST2                  0x06
-#define FW_CDEV_EVENT_PHY_PACKET_SENT           0x07
-#define FW_CDEV_EVENT_PHY_PACKET_RECEIVED       0x08
+#define FW_CDEV_EVENT_REQUEST2                          0x06
+#define FW_CDEV_EVENT_PHY_PACKET_SENT                   0x07
+#define FW_CDEV_EVENT_PHY_PACKET_RECEIVED               0x08
+#define FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL        0x09
 
 /**
  * struct fw_cdev_event_common - Common part of all fw_cdev_event_ types
@@ -218,35 +219,41 @@ struct fw_cdev_event_request2 {
  * This event is sent when the controller has completed an &fw_cdev_iso_packet
  * with the %FW_CDEV_ISO_INTERRUPT bit set.
  *
- * Isochronous transmit events:
+ * Isochronous transmit events (context type %FW_CDEV_ISO_CONTEXT_TRANSMIT):
  *
- * In version 1 of the ABI, &header_length is 0.  In version 3 and some
- * implementations of version 2 of the ABI, &header_length is a multiple of 4
- * and &header contains timestamps of all packets up until the interrupt packet.
- * The format of the timestamps is as described below for isochronous reception.
+ * In version 3 and some implementations of version 2 of the ABI, &header_length
+ * is a multiple of 4 and &header contains timestamps of all packets up until
+ * the interrupt packet.  The format of the timestamps is as described below for
+ * isochronous reception.  In version 1 of the ABI, &header_length was 0.
  *
- * Isochronous receive events:
+ * Isochronous receive events (context type %FW_CDEV_ISO_CONTEXT_RECEIVE):
  *
  * The headers stripped of all packets up until and including the interrupt
  * packet are returned in the @header field.  The amount of header data per
  * packet is as specified at iso context creation by
  * &fw_cdev_create_iso_context.header_size.
  *
- * In version 1 of this ABI, header data consisted of the 1394 isochronous
- * packet header, followed by quadlets from the packet payload if
- * &fw_cdev_create_iso_context.header_size > 4.
+ * Hence, _interrupt.header_length / _context.header_size is the number of
+ * packets received in this interrupt event.  The client can now iterate
+ * through the mmap()'ed DMA buffer according to this number of packets and
+ * to the buffer sizes as the client specified in &fw_cdev_queue_iso.
  *
- * In version 2 of this ABI, header data consist of the 1394 isochronous
- * packet header, followed by a timestamp quadlet if
- * &fw_cdev_create_iso_context.header_size > 4, followed by quadlets from the
- * packet payload if &fw_cdev_create_iso_context.header_size > 8.
+ * Since version 2 of this ABI, the portion for each packet in _interrupt.header
+ * consists of the 1394 isochronous packet header, followed by a timestamp
+ * quadlet if &fw_cdev_create_iso_context.header_size > 4, followed by quadlets
+ * from the packet payload if &fw_cdev_create_iso_context.header_size > 8.
  *
- * Behaviour of ver. 1 of this ABI is no longer available since ABI ver. 2.
+ * Format of 1394 iso packet header:  16 bits data_length, 2 bits tag, 6 bits
+ * channel, 4 bits tcode, 4 bits sy, in big endian byte order.
+ * data_length is the actual received size of the packet without the four
+ * 1394 iso packet header bytes.
+ *
+ * Format of timestamp:  16 bits invalid, 3 bits cycleSeconds, 13 bits
+ * cycleCount, in big endian byte order.
  *
- * Format of 1394 iso packet header: 16 bits len, 2 bits tag, 6 bits channel,
- * 4 bits tcode, 4 bits sy, in big endian byte order.  Format of timestamp:
- * 16 bits invalid, 3 bits cycleSeconds, 13 bits cycleCount, in big endian byte
- * order.
+ * In version 1 of the ABI, no timestamp quadlet was inserted; instead, payload
+ * data followed directly after the 1394 is header if header_size > 4.
+ * Behaviour of ver. 1 of this ABI is no longer available since ABI ver. 2.
  */
 struct fw_cdev_event_iso_interrupt {
         __u64 closure;
@@ -257,6 +264,43 @@ struct fw_cdev_event_iso_interrupt {
 };
 
 /**
+ * struct fw_cdev_event_iso_interrupt_mc - An iso buffer chunk was completed
+ * @closure:    See &fw_cdev_event_common;
+ *              set by %FW_CDEV_CREATE_ISO_CONTEXT ioctl
+ * @type:       %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL
+ * @completed:  Offset into the receive buffer; data before this offest is valid
+ *
+ * This event is sent in multichannel contexts (context type
+ * %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL) for &fw_cdev_iso_packet buffer
+ * chunks that have the %FW_CDEV_ISO_INTERRUPT bit set.  Whether this happens
+ * when a packet is completed and/or when a buffer chunk is completed depends
+ * on the hardware implementation.
+ *
+ * The buffer is continuously filled with the following data, per packet:
+ *  - the 1394 iso packet header as described at &fw_cdev_event_iso_interrupt,
+ *    but in little endian byte order,
+ *  - packet payload (as many bytes as specified in the data_length field of
+ *    the 1394 iso packet header) in big endian byte order,
+ *  - 0...3 padding bytes as needed to align the following trailer quadlet,
+ *  - trailer quadlet, containing the reception timestamp as described at
+ *    &fw_cdev_event_iso_interrupt, but in little endian byte order.
+ *
+ * Hence the per-packet size is data_length (rounded up to a multiple of 4) + 8.
+ * When processing the data, stop before a packet that would cross the
+ * @completed offset.
+ *
+ * A packet near the end of a buffer chunk will typically spill over into the
+ * next queued buffer chunk.  It is the responsibility of the client to check
+ * for this condition, assemble a broken-up packet from its parts, and not to
+ * re-queue any buffer chunks in which as yet unread packet parts reside.
+ */
+struct fw_cdev_event_iso_interrupt_mc {
+        __u64 closure;
+        __u32 type;
+        __u32 completed;
+};
+
+/**
  * struct fw_cdev_event_iso_resource - Iso resources were allocated or freed
  * @closure:    See &fw_cdev_event_common;
  *              set by %FW_CDEV_IOC_(DE)ALLOCATE_ISO_RESOURCE(_ONCE) ioctl
@@ -311,16 +355,18 @@ struct fw_cdev_event_phy_packet {
 
 /**
  * union fw_cdev_event - Convenience union of fw_cdev_event_ types
- * @common:        Valid for all types
- * @bus_reset:     Valid if @common.type == %FW_CDEV_EVENT_BUS_RESET
- * @response:      Valid if @common.type == %FW_CDEV_EVENT_RESPONSE
- * @request:       Valid if @common.type == %FW_CDEV_EVENT_REQUEST
- * @request2:      Valid if @common.type == %FW_CDEV_EVENT_REQUEST2
- * @iso_interrupt: Valid if @common.type == %FW_CDEV_EVENT_ISO_INTERRUPT
- * @iso_resource:  Valid if @common.type ==
+ * @common:             Valid for all types
+ * @bus_reset:          Valid if @common.type == %FW_CDEV_EVENT_BUS_RESET
+ * @response:           Valid if @common.type == %FW_CDEV_EVENT_RESPONSE
+ * @request:            Valid if @common.type == %FW_CDEV_EVENT_REQUEST
+ * @request2:           Valid if @common.type == %FW_CDEV_EVENT_REQUEST2
+ * @iso_interrupt:      Valid if @common.type == %FW_CDEV_EVENT_ISO_INTERRUPT
+ * @iso_interrupt_mc:   Valid if @common.type ==
+ *                              %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL
+ * @iso_resource:       Valid if @common.type ==
  *                              %FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED or
  *                              %FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED
- * @phy_packet:    Valid if @common.type ==
+ * @phy_packet:         Valid if @common.type ==
  *                              %FW_CDEV_EVENT_PHY_PACKET_SENT or
  *                              %FW_CDEV_EVENT_PHY_PACKET_RECEIVED
  *
@@ -337,10 +383,11 @@ union fw_cdev_event {
         struct fw_cdev_event_bus_reset          bus_reset;
         struct fw_cdev_event_response           response;
         struct fw_cdev_event_request            request;
-        struct fw_cdev_event_request2           request2;     /* added in 2.6.36 */
+        struct fw_cdev_event_request2           request2;               /* added in 2.6.36 */
         struct fw_cdev_event_iso_interrupt      iso_interrupt;
-        struct fw_cdev_event_iso_resource       iso_resource; /* added in 2.6.30 */
-        struct fw_cdev_event_phy_packet         phy_packet;   /* added in 2.6.36 */
+        struct fw_cdev_event_iso_interrupt_mc   iso_interrupt_mc;       /* added in 2.6.36 */
+        struct fw_cdev_event_iso_resource       iso_resource;           /* added in 2.6.30 */
+        struct fw_cdev_event_phy_packet         phy_packet;             /* added in 2.6.36 */
 };
 
 /* available since kernel version 2.6.22 */
@@ -375,6 +422,7 @@ union fw_cdev_event {
 /* available since kernel version 2.6.36 */
 #define FW_CDEV_IOC_SEND_PHY_PACKET    _IOWR('#', 0x15, struct fw_cdev_send_phy_packet)
 #define FW_CDEV_IOC_RECEIVE_PHY_PACKETS _IOW('#', 0x16, struct fw_cdev_receive_phy_packets)
+#define FW_CDEV_IOC_SET_ISO_CHANNELS    _IOW('#', 0x17, struct fw_cdev_set_iso_channels)
 
 /*
  * ABI version history
@@ -391,10 +439,13 @@ union fw_cdev_event {
  *               - shared use and auto-response for FCP registers
  *  3  (2.6.34)  - made &fw_cdev_get_cycle_timer reliable
  *               - added %FW_CDEV_IOC_GET_CYCLE_TIMER2
- *  4  (2.6.36)  - added %FW_CDEV_EVENT_REQUEST2, %FW_CDEV_EVENT_PHY_PACKET_*
+ *  4  (2.6.36)  - added %FW_CDEV_EVENT_REQUEST2, %FW_CDEV_EVENT_PHY_PACKET_*,
+ *                 and &fw_cdev_allocate.region_end
  *               - implemented &fw_cdev_event_bus_reset.bm_node_id
  *               - added %FW_CDEV_IOC_SEND_PHY_PACKET, _RECEIVE_PHY_PACKETS
- *               - added &fw_cdev_allocate.region_end
+ *               - added %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL,
+ *                 %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL, and
+ *                 %FW_CDEV_IOC_SET_ISO_CHANNELS
  */
 #define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */
 
@@ -597,34 +648,43 @@ struct fw_cdev_remove_descriptor {
         __u32 handle;
 };
 
-#define FW_CDEV_ISO_CONTEXT_TRANSMIT    0
-#define FW_CDEV_ISO_CONTEXT_RECEIVE     1
+#define FW_CDEV_ISO_CONTEXT_TRANSMIT                    0
+#define FW_CDEV_ISO_CONTEXT_RECEIVE                     1
+#define FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL        2 /* added in 2.6.36 */
 
 /**
- * struct fw_cdev_create_iso_context - Create a context for isochronous IO
- * @type:       %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE
- * @header_size: Header size to strip for receive contexts
- * @channel:    Channel to bind to
- * @speed:      Speed for transmit contexts
- * @closure:    To be returned in &fw_cdev_event_iso_interrupt
+ * struct fw_cdev_create_iso_context - Create a context for isochronous I/O
+ * @type:       %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE or
+ *              %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL
+ * @header_size: Header size to strip in single-channel reception
+ * @channel:    Channel to bind to in single-channel reception or transmission
+ * @speed:      Transmission speed
+ * @closure:    To be returned in &fw_cdev_event_iso_interrupt or
+ *              &fw_cdev_event_iso_interrupt_multichannel
  * @handle:     Handle to context, written back by kernel
  *
  * Prior to sending or receiving isochronous I/O, a context must be created.
  * The context records information about the transmit or receive configuration
  * and typically maps to an underlying hardware resource.  A context is set up
  * for either sending or receiving.  It is bound to a specific isochronous
- * channel.
+ * @channel.
  *
- * If a context was successfully created, the kernel writes back a handle to the
- * context, which must be passed in for subsequent operations on that context.
+ * In case of multichannel reception, @header_size and @channel are ignored
+ * and the channels are selected by %FW_CDEV_IOC_SET_ISO_CHANNELS.
+ *
+ * For %FW_CDEV_ISO_CONTEXT_RECEIVE contexts, @header_size must be at least 4
+ * and must be a multiple of 4.  It is ignored in other context types.
  *
- * For receive contexts, @header_size must be at least 4 and must be a multiple
- * of 4.
+ * @speed is ignored in receive context types.
  *
- * Note that the effect of a @header_size > 4 depends on
- * &fw_cdev_get_info.version, as documented at &fw_cdev_event_iso_interrupt.
+ * If a context was successfully created, the kernel writes back a handle to the
+ * context, which must be passed in for subsequent operations on that context.
  *
+ * Limitations:
  * No more than one iso context can be created per fd.
+ * The total number of contexts that all userspace and kernelspace drivers can
+ * create on a card at a time is a hardware limit, typically 4 or 8 contexts per
+ * direction, and of them at most one multichannel receive context.
  */
 struct fw_cdev_create_iso_context {
         __u32 type;
@@ -635,6 +695,22 @@ struct fw_cdev_create_iso_context {
         __u32 handle;
 };
 
+/**
+ * struct fw_cdev_set_iso_channels - Select channels in multichannel reception
+ * @channels:   Bitmask of channels to listen to
+ * @handle:     Handle of the mutichannel receive context
+ *
+ * @channels is the bitwise or of 1ULL << n for each channel n to listen to.
+ *
+ * The ioctl fails with errno %EBUSY if there is already another receive context
+ * on a channel in @channels.  In that case, the bitmask of all unoccupied
+ * channels is returned in @channels.
+ */
+struct fw_cdev_set_iso_channels {
+        __u64 channels;
+        __u32 handle;
+};
+
 #define FW_CDEV_ISO_PAYLOAD_LENGTH(v)   (v)
 #define FW_CDEV_ISO_INTERRUPT           (1 << 16)
 #define FW_CDEV_ISO_SKIP                (1 << 17)
@@ -645,42 +721,72 @@ struct fw_cdev_create_iso_context {
 
 /**
  * struct fw_cdev_iso_packet - Isochronous packet
- * @control:    Contains the header length (8 uppermost bits), the sy field
- *              (4 bits), the tag field (2 bits), a sync flag (1 bit),
- *              a skip flag (1 bit), an interrupt flag (1 bit), and the
+ * @control:    Contains the header length (8 uppermost bits),
+ *              the sy field (4 bits), the tag field (2 bits), a sync flag
+ *              or a skip flag (1 bit), an interrupt flag (1 bit), and the
  *              payload length (16 lowermost bits)
- * @header:     Header and payload
+ * @header:     Header and payload in case of a transmit context.
  *
  * &struct fw_cdev_iso_packet is used to describe isochronous packet queues.
- *
  * Use the FW_CDEV_ISO_ macros to fill in @control.
+ * The @header array is empty in case of receive contexts.
+ *
+ * Context type %FW_CDEV_ISO_CONTEXT_TRANSMIT:
+ *
+ * @control.HEADER_LENGTH must be a multiple of 4.  It specifies the numbers of
+ * bytes in @header that will be prepended to the packet's payload.  These bytes
+ * are copied into the kernel and will not be accessed after the ioctl has
+ * returned.
+ *
+ * The @control.SY and TAG fields are copied to the iso packet header.  These
+ * fields are specified by IEEE 1394a and IEC 61883-1.
+ *
+ * The @control.SKIP flag specifies that no packet is to be sent in a frame.
+ * When using this, all other fields except @control.INTERRUPT must be zero.
+ *
+ * When a packet with the @control.INTERRUPT flag set has been completed, an
+ * &fw_cdev_event_iso_interrupt event will be sent.
+ *
+ * Context type %FW_CDEV_ISO_CONTEXT_RECEIVE:
  *
- * For transmit packets, the header length must be a multiple of 4 and specifies
- * the numbers of bytes in @header that will be prepended to the packet's
- * payload; these bytes are copied into the kernel and will not be accessed
- * after the ioctl has returned.  The sy and tag fields are copied to the iso
- * packet header (these fields are specified by IEEE 1394a and IEC 61883-1).
- * The skip flag specifies that no packet is to be sent in a frame; when using
- * this, all other fields except the interrupt flag must be zero.
- *
- * For receive packets, the header length must be a multiple of the context's
- * header size; if the header length is larger than the context's header size,
- * multiple packets are queued for this entry.  The sy and tag fields are
- * ignored.  If the sync flag is set, the context drops all packets until
- * a packet with a matching sy field is received (the sync value to wait for is
- * specified in the &fw_cdev_start_iso structure).  The payload length defines
- * how many payload bytes can be received for one packet (in addition to payload
- * quadlets that have been defined as headers and are stripped and returned in
- * the &fw_cdev_event_iso_interrupt structure).  If more bytes are received, the
- * additional bytes are dropped.  If less bytes are received, the remaining
- * bytes in this part of the payload buffer will not be written to, not even by
- * the next packet, i.e., packets received in consecutive frames will not
- * necessarily be consecutive in memory.  If an entry has queued multiple
- * packets, the payload length is divided equally among them.
- *
- * When a packet with the interrupt flag set has been completed, the
+ * @control.HEADER_LENGTH must be a multiple of the context's header_size.
+ * If the HEADER_LENGTH is larger than the context's header_size, multiple
+ * packets are queued for this entry.
+ *
+ * The @control.SY and TAG fields are ignored.
+ *
+ * If the @control.SYNC flag is set, the context drops all packets until a
+ * packet with a sy field is received which matches &fw_cdev_start_iso.sync.
+ *
+ * @control.PAYLOAD_LENGTH defines how many payload bytes can be received for
+ * one packet (in addition to payload quadlets that have been defined as headers
+ * and are stripped and returned in the &fw_cdev_event_iso_interrupt structure).
+ * If more bytes are received, the additional bytes are dropped.  If less bytes
+ * are received, the remaining bytes in this part of the payload buffer will not
+ * be written to, not even by the next packet.  I.e., packets received in
+ * consecutive frames will not necessarily be consecutive in memory.  If an
+ * entry has queued multiple packets, the PAYLOAD_LENGTH is divided equally
+ * among them.
+ *
+ * When a packet with the @control.INTERRUPT flag set has been completed, an
  * &fw_cdev_event_iso_interrupt event will be sent.  An entry that has queued
  * multiple receive packets is completed when its last packet is completed.
+ *
+ * Context type %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
+ *
+ * Here, &fw_cdev_iso_packet would be more aptly named _iso_buffer_chunk since
+ * it specifies a chunk of the mmap()'ed buffer, while the number and alignment
+ * of packets to be placed into the buffer chunk is not known beforehand.
+ *
+ * @control.PAYLOAD_LENGTH is the size of the buffer chunk and specifies room
+ * for header, payload, padding, and trailer bytes of one or more packets.
+ * It must be a multiple of 4.
+ *
+ * @control.HEADER_LENGTH, TAG and SY are ignored.  SYNC is treated as described
+ * for single-channel reception.
+ *
+ * When a buffer chunk with the @control.INTERRUPT flag set has been filled
+ * entirely, an &fw_cdev_event_iso_interrupt_mc event will be sent.
  */
 struct fw_cdev_iso_packet {
         __u32 control;
@@ -689,9 +795,9 @@ struct fw_cdev_iso_packet {
 
 /**
  * struct fw_cdev_queue_iso - Queue isochronous packets for I/O
- * @packets:    Userspace pointer to packet data
+ * @packets:    Userspace pointer to an array of &fw_cdev_iso_packet
  * @data:       Pointer into mmap()'ed payload buffer
- * @size:       Size of packet data in bytes
+ * @size:       Size of the @packets array, in bytes
  * @handle:     Isochronous context handle
  *
  * Queue a number of isochronous packets for reception or transmission.
@@ -704,6 +810,9 @@ struct fw_cdev_iso_packet {
  * The kernel may or may not queue all packets, but will write back updated
  * values of the @packets, @data and @size fields, so the ioctl can be
  * resubmitted easily.
+ *
+ * In case of a multichannel receive context, @data must be quadlet-aligned
+ * relative to the buffer start.
  */
 struct fw_cdev_queue_iso {
         __u64 packets;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index d974aa4a24c9..1cd637ef62d2 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -372,17 +372,19 @@ void fw_core_remove_descriptor(struct fw_descriptor *desc);
  * 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 @@ struct fw_iso_buffer {
 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,