firewire: Move async transmit to use the general context code.

The old async transmit context handling was starting and stopping
DMA for every packet transmission.  This could cause silently failing
packet transmission, if the DMA was reprogrammed too close to being
stopped.

The general context code keeps DMA running at all times and fixes this
problem.  It's also a nice cleanup.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

2 files changed, 149 insertions, 214 deletions

diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c
index 37467923e98b..9e8a8f909303 100644
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -112,25 +112,6 @@ struct context {
         struct tasklet_struct tasklet;
 };
 
-struct at_context {
-        struct fw_ohci *ohci;
-        dma_addr_t descriptor_bus;
-        dma_addr_t buffer_bus;
-        struct fw_packet *current_packet;
-
-        struct list_head list;
-
-        struct {
-                struct descriptor more;
-                __le32 header[4];
-                struct descriptor last;
-        } d;
-
-        u32 regs;
-
-        struct tasklet_struct tasklet;
-};
-
 #define it_header_sy(v)          ((v) <<  0)
 #define it_header_tcode(v)       ((v) <<  4)
 #define it_header_channel(v)     ((v) <<  8)
@@ -173,8 +154,8 @@ struct fw_ohci {
 
         struct ar_context ar_request_ctx;
         struct ar_context ar_response_ctx;
-        struct at_context at_request_ctx;
-        struct at_context at_response_ctx;
+        struct context at_request_ctx;
+        struct context at_response_ctx;
 
         u32 it_context_mask;
         struct iso_context *it_context_list;
@@ -210,6 +191,8 @@ static inline struct fw_ohci *fw_ohci(struct fw_card *card)
 #define SELF_ID_BUF_SIZE                0x800
 #define OHCI_TCODE_PHY_PACKET           0x0e
 #define OHCI_VERSION_1_1                0x010010
+#define ISO_BUFFER_SIZE                 (64 * 1024)
+#define AT_BUFFER_SIZE                  4096
 
 static char ohci_driver_name[] = KBUILD_MODNAME;
 
@@ -587,210 +570,166 @@ static void context_stop(struct context *ctx)
         }
 }
 
-static void
-do_packet_callbacks(struct fw_ohci *ohci, struct list_head *list)
-{
-        struct fw_packet *p, *next;
-
-        list_for_each_entry_safe(p, next, list, link)
-                p->callback(p, &ohci->card, p->ack);
-}
-
-static void
-complete_transmission(struct fw_packet *packet,
-                      int ack, struct list_head *list)
-{
-        list_move_tail(&packet->link, list);
-        packet->ack = ack;
-}
+struct driver_data {
+        struct fw_packet *packet;
+};
 
-/* This function prepares the first packet in the context queue for
- * transmission.  Must always be called with the ochi->lock held to
- * ensure proper generation handling and locking around packet queue
- * manipulation. */
-static void
-at_context_setup_packet(struct at_context *ctx, struct list_head *list)
+/* This function apppends a packet to the DMA queue for transmission.
+ * Must always be called with the ochi->lock held to ensure proper
+ * generation handling and locking around packet queue manipulation. */
+static int
+at_context_queue_packet(struct context *ctx, struct fw_packet *packet)
 {
-        struct fw_packet *packet;
         struct fw_ohci *ohci = ctx->ohci;
+        dma_addr_t d_bus, payload_bus;
+        struct driver_data *driver_data;
+        struct descriptor *d, *last;
+        __le32 *header;
         int z, tcode;
+        u32 reg;
 
-        packet = fw_packet(ctx->list.next);
-
-        memset(&ctx->d, 0, sizeof ctx->d);
-        if (packet->payload_length > 0) {
-                packet->payload_bus = dma_map_single(ohci->card.device,
-                                                     packet->payload,
-                                                     packet->payload_length,
-                                                     DMA_TO_DEVICE);
-                if (dma_mapping_error(packet->payload_bus)) {
-                        complete_transmission(packet, RCODE_SEND_ERROR, list);
-                        return;
-                }
-
-                ctx->d.more.control      =
-                        cpu_to_le16(descriptor_output_more |
-                                    descriptor_key_immediate);
-                ctx->d.more.req_count    = cpu_to_le16(packet->header_length);
-                ctx->d.more.res_count    = cpu_to_le16(packet->timestamp);
-                ctx->d.last.control      =
-                        cpu_to_le16(descriptor_output_last |
-                                    descriptor_irq_always |
-                                    descriptor_branch_always);
-                ctx->d.last.req_count    = cpu_to_le16(packet->payload_length);
-                ctx->d.last.data_address = cpu_to_le32(packet->payload_bus);
-                z = 3;
-        } else {
-                ctx->d.more.control   =
-                        cpu_to_le16(descriptor_output_last |
-                                    descriptor_key_immediate |
-                                    descriptor_irq_always |
-                                    descriptor_branch_always);
-                ctx->d.more.req_count = cpu_to_le16(packet->header_length);
-                ctx->d.more.res_count = cpu_to_le16(packet->timestamp);
-                z = 2;
+        d = context_get_descriptors(ctx, 4, &d_bus);
+        if (d == NULL) {
+                packet->ack = RCODE_SEND_ERROR;
+                return -1;
         }
 
+        d[0].control   = cpu_to_le16(descriptor_key_immediate);
+        d[0].res_count = cpu_to_le16(packet->timestamp);
+
         /* The DMA format for asyncronous link packets is different
          * from the IEEE1394 layout, so shift the fields around
          * accordingly.  If header_length is 8, it's a PHY packet, to
          * which we need to prepend an extra quadlet. */
+
+        header = (__le32 *) &d[1];
         if (packet->header_length > 8) {
-                ctx->d.header[0] = cpu_to_le32((packet->header[0] & 0xffff) |
-                                               (packet->speed << 16));
-                ctx->d.header[1] = cpu_to_le32((packet->header[1] & 0xffff) |
-                                               (packet->header[0] & 0xffff0000));
-                ctx->d.header[2] = cpu_to_le32(packet->header[2]);
+                header[0] = cpu_to_le32((packet->header[0] & 0xffff) |
+                                        (packet->speed << 16));
+                header[1] = cpu_to_le32((packet->header[1] & 0xffff) |
+                                        (packet->header[0] & 0xffff0000));
+                header[2] = cpu_to_le32(packet->header[2]);
 
                 tcode = (packet->header[0] >> 4) & 0x0f;
                 if (TCODE_IS_BLOCK_PACKET(tcode))
-                        ctx->d.header[3] = cpu_to_le32(packet->header[3]);
+                        header[3] = cpu_to_le32(packet->header[3]);
                 else
-                        ctx->d.header[3] = packet->header[3];
+                        header[3] = (__force __le32) packet->header[3];
+
+                d[0].req_count = cpu_to_le16(packet->header_length);
         } else {
-                ctx->d.header[0] =
-                        cpu_to_le32((OHCI1394_phy_tcode << 4) |
-                                    (packet->speed << 16));
-                ctx->d.header[1] = cpu_to_le32(packet->header[0]);
-                ctx->d.header[2] = cpu_to_le32(packet->header[1]);
-                ctx->d.more.req_count = cpu_to_le16(12);
+                header[0] = cpu_to_le32((OHCI1394_phy_tcode << 4) |
+                                        (packet->speed << 16));
+                header[1] = cpu_to_le32(packet->header[0]);
+                header[2] = cpu_to_le32(packet->header[1]);
+                d[0].req_count = cpu_to_le16(12);
         }
 
-        /* FIXME: Document how the locking works. */
-        if (ohci->generation == packet->generation) {
-                reg_write(ctx->ohci, command_ptr(ctx->regs),
-                          ctx->descriptor_bus | z);
-                reg_write(ctx->ohci, control_set(ctx->regs),
-                          CONTEXT_RUN | CONTEXT_WAKE);
-                ctx->current_packet = packet;
+        driver_data = (struct driver_data *) &d[3];
+        driver_data->packet = packet;
+        
+        if (packet->payload_length > 0) {
+                payload_bus =
+                        dma_map_single(ohci->card.device, packet->payload,
+                                       packet->payload_length, DMA_TO_DEVICE);
+                if (dma_mapping_error(payload_bus)) {
+                        packet->ack = RCODE_SEND_ERROR;
+                        return -1;
+                }
+
+                d[2].req_count    = cpu_to_le16(packet->payload_length);
+                d[2].data_address = cpu_to_le32(payload_bus);
+                last = &d[2];
+                z = 3;
         } else {
-                /* We dont return error codes from this function; all
-                 * transmission errors are reported through the
-                 * callback. */
-                complete_transmission(packet, RCODE_GENERATION, list);
+                last = &d[0];
+                z = 2;
         }
-}
 
-static void at_context_stop(struct at_context *ctx)
-{
-        u32 reg;
+        last->control |= cpu_to_le16(descriptor_output_last |
+                                     descriptor_irq_always |
+                                     descriptor_branch_always);
 
-        reg_write(ctx->ohci, control_clear(ctx->regs), CONTEXT_RUN);
+        /* FIXME: Document how the locking works. */
+        if (ohci->generation != packet->generation) {
+                packet->ack = RCODE_GENERATION;
+                return -1;
+        }
+
+        context_append(ctx, d, z, 4 - z);
 
+        /* If the context isn't already running, start it up. */
         reg = reg_read(ctx->ohci, control_set(ctx->regs));
-        if (reg & CONTEXT_ACTIVE)
-                fw_notify("Tried to stop context, but it is still active "
-                          "(0x%08x).\n", reg);
+        if ((reg & CONTEXT_ACTIVE) == 0)
+                context_run(ctx, 0);
+
+        return 0;
 }
 
-static void at_context_tasklet(unsigned long data)
+static int handle_at_packet(struct context *context,
+                            struct descriptor *d,
+                            struct descriptor *last)
 {
-        struct at_context *ctx = (struct at_context *)data;
-        struct fw_ohci *ohci = ctx->ohci;
+        struct driver_data *driver_data;
         struct fw_packet *packet;
-        LIST_HEAD(list);
-        unsigned long flags;
+        struct fw_ohci *ohci = context->ohci;
+        dma_addr_t payload_bus;
         int evt;
 
-        spin_lock_irqsave(&ohci->lock, flags);
-
-        packet = fw_packet(ctx->list.next);
-
-        at_context_stop(ctx);
+        if (last->transfer_status == 0)
+                /* This descriptor isn't done yet, stop iteration. */
+                return 0;
 
-        /* If the head of the list isn't the packet that just got
-         * transmitted, the packet got cancelled before we finished
-         * transmitting it. */
-        if (ctx->current_packet != packet)
-                goto skip_to_next;
+        driver_data = (struct driver_data *) &d[3];
+        packet = driver_data->packet;
+        if (packet == NULL)
+                /* This packet was cancelled, just continue. */
+                return 1;
 
-        if (packet->payload_length > 0) {
-                dma_unmap_single(ohci->card.device, packet->payload_bus,
+        payload_bus = le32_to_cpu(last->data_address);
+        if (payload_bus != 0)
+                dma_unmap_single(ohci->card.device, payload_bus,
                                  packet->payload_length, DMA_TO_DEVICE);
-                evt = le16_to_cpu(ctx->d.last.transfer_status) & 0x1f;
-                packet->timestamp = le16_to_cpu(ctx->d.last.res_count);
-        }
-        else {
-                evt = le16_to_cpu(ctx->d.more.transfer_status) & 0x1f;
-                packet->timestamp = le16_to_cpu(ctx->d.more.res_count);
-        }
-
-        if (evt < 16) {
-                switch (evt) {
-                case OHCI1394_evt_timeout:
-                        /* Async response transmit timed out. */
-                        complete_transmission(packet, RCODE_CANCELLED, &list);
-                        break;
-
-                case OHCI1394_evt_flushed:
-                        /* The packet was flushed should give same
-                         * error as when we try to use a stale
-                         * generation count. */
-                        complete_transmission(packet,
-                                              RCODE_GENERATION, &list);
-                        break;
-
-                case OHCI1394_evt_missing_ack:
-                        /* Using a valid (current) generation count,
-                         * but the node is not on the bus or not
-                         * sending acks. */
-                        complete_transmission(packet, RCODE_NO_ACK, &list);
-                        break;
-
-                default:
-                        complete_transmission(packet, RCODE_SEND_ERROR, &list);
-                        break;
-                }
-        } else
-                complete_transmission(packet, evt - 16, &list);
 
- skip_to_next:
-        /* If more packets are queued, set up the next one. */
-        if (!list_empty(&ctx->list))
-                at_context_setup_packet(ctx, &list);
+        evt = le16_to_cpu(last->transfer_status) & 0x1f;
+        packet->timestamp = le16_to_cpu(last->res_count);
 
-        spin_unlock_irqrestore(&ohci->lock, flags);
+        switch (evt) {
+        case OHCI1394_evt_timeout:
+                /* Async response transmit timed out. */
+                packet->ack = RCODE_CANCELLED;
+                break;
 
-        do_packet_callbacks(ohci, &list);
-}
+        case OHCI1394_evt_flushed:
+                /* The packet was flushed should give same error as
+                 * when we try to use a stale generation count. */
+                packet->ack = RCODE_GENERATION;
+                break;
 
-static int
-at_context_init(struct at_context *ctx, struct fw_ohci *ohci, u32 regs)
-{
-        INIT_LIST_HEAD(&ctx->list);
+        case OHCI1394_evt_missing_ack:
+                /* Using a valid (current) generation count, but the
+                 * node is not on the bus or not sending acks. */
+                packet->ack = RCODE_NO_ACK;
+                break;
 
-        ctx->descriptor_bus =
-                dma_map_single(ohci->card.device, &ctx->d,
-                               sizeof ctx->d, DMA_TO_DEVICE);
-        if (dma_mapping_error(ctx->descriptor_bus))
-                return -ENOMEM;
+        case ACK_COMPLETE + 0x10:
+        case ACK_PENDING + 0x10:
+        case ACK_BUSY_X + 0x10:
+        case ACK_BUSY_A + 0x10:
+        case ACK_BUSY_B + 0x10:
+        case ACK_DATA_ERROR + 0x10:
+        case ACK_TYPE_ERROR + 0x10:
+                packet->ack = evt - 0x10;
+                break;
 
-        ctx->regs = regs;
-        ctx->ohci = ohci;
+        default:
+                packet->ack = RCODE_SEND_ERROR;
+                break;
+        }
 
-        tasklet_init(&ctx->tasklet, at_context_tasklet, (unsigned long)ctx);
+        packet->callback(packet, &ohci->card, packet->ack);
 
-        return 0;
+        return 1;
 }
 
 #define header_get_destination(q)       (((q) >> 16) & 0xffff)
@@ -869,7 +808,7 @@ handle_local_lock(struct fw_ohci *ohci, struct fw_packet *packet, u32 csr)
 }
 
 static void
-handle_local_request(struct at_context *ctx, struct fw_packet *packet)
+handle_local_request(struct context *ctx, struct fw_packet *packet)
 {
         u64 offset;
         u32 csr;
@@ -903,10 +842,10 @@ handle_local_request(struct at_context *ctx, struct fw_packet *packet)
 }
 
 static void
-at_context_transmit(struct at_context *ctx, struct fw_packet *packet)
+at_context_transmit(struct context *ctx, struct fw_packet *packet)
 {
-        LIST_HEAD(list);
         unsigned long flags;
+        int retval;
 
         spin_lock_irqsave(&ctx->ohci->lock, flags);
 
@@ -917,13 +856,12 @@ at_context_transmit(struct at_context *ctx, struct fw_packet *packet)
                 return;
         }
 
-        list_add_tail(&packet->link, &ctx->list);
-        if (ctx->list.next == &packet->link)
-                at_context_setup_packet(ctx, &list);
-
+        retval = at_context_queue_packet(ctx, packet);
         spin_unlock_irqrestore(&ctx->ohci->lock, flags);
 
-        do_packet_callbacks(ctx->ohci, &list);
+        if (retval < 0)
+                packet->callback(packet, &ctx->ohci->card, packet->ack);
+        
 }
 
 static void bus_reset_tasklet(unsigned long data)
@@ -977,8 +915,8 @@ static void bus_reset_tasklet(unsigned long data)
         spin_lock_irqsave(&ohci->lock, flags);
 
         ohci->generation = generation;
-        at_context_stop(&ohci->at_request_ctx);
-        at_context_stop(&ohci->at_response_ctx);
+        context_stop(&ohci->at_request_ctx);
+        context_stop(&ohci->at_response_ctx);
         reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
 
         /* This next bit is unrelated to the AT context stuff but we
@@ -1216,24 +1154,24 @@ static void ohci_send_response(struct fw_card *card, struct fw_packet *packet)
 static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
 {
         struct fw_ohci *ohci = fw_ohci(card);
-        LIST_HEAD(list);
-        unsigned long flags;
-
-        spin_lock_irqsave(&ohci->lock, flags);
+        struct context *ctx = &ohci->at_request_ctx;
+        struct driver_data *driver_data = packet->driver_data;
+        int retval = -ENOENT;
 
-        if (packet->ack == 0) {
-                fw_notify("cancelling packet %p (header[0]=%08x)\n",
-                          packet, packet->header[0]);
+        tasklet_disable(&ctx->tasklet);
 
-                complete_transmission(packet, RCODE_CANCELLED, &list);
-        }
+        if (packet->ack != 0)
+                goto out;
 
-        spin_unlock_irqrestore(&ohci->lock, flags);
+        driver_data->packet = NULL;
+        packet->ack = RCODE_CANCELLED;
+        packet->callback(packet, &ohci->card, packet->ack);
+        retval = 0;
 
-        do_packet_callbacks(ohci, &list);
+ out:
+        tasklet_enable(&ctx->tasklet);
 
-        /* Return success if we actually cancelled something. */
-        return list_empty(&list) ? -ENOENT : 0;
+        return retval;
 }
 
 static int
@@ -1314,8 +1252,6 @@ static int handle_ir_dualbuffer_packet(struct context *context,
         return 1;
 }
 
-#define ISO_BUFFER_SIZE (64 * 1024)
-
 static int handle_it_packet(struct context *context,
                             struct descriptor *d,
                             struct descriptor *last)
@@ -1872,11 +1808,11 @@ pci_probe(struct pci_dev *dev, const struct pci_device_id *ent)
         ar_context_init(&ohci->ar_response_ctx, ohci,
                         OHCI1394_AsRspRcvContextControlSet);
 
-        at_context_init(&ohci->at_request_ctx, ohci,
-                        OHCI1394_AsReqTrContextControlSet);
+        context_init(&ohci->at_request_ctx, ohci, AT_BUFFER_SIZE,
+                     OHCI1394_AsReqTrContextControlSet, handle_at_packet);
 
-        at_context_init(&ohci->at_response_ctx, ohci,
-                        OHCI1394_AsRspTrContextControlSet);
+        context_init(&ohci->at_response_ctx, ohci, AT_BUFFER_SIZE,
+                     OHCI1394_AsRspTrContextControlSet, handle_at_packet);
 
         reg_write(ohci, OHCI1394_ATRetries,
                   OHCI1394_MAX_AT_REQ_RETRIES |
diff --git a/drivers/firewire/fw-transaction.h b/drivers/firewire/fw-transaction.h
index b0d057533fb0..e7301b83f91e 100644
--- a/drivers/firewire/fw-transaction.h
+++ b/drivers/firewire/fw-transaction.h
@@ -203,8 +203,6 @@ struct fw_packet {
         size_t payload_length;
         u32 timestamp;
 
-        dma_addr_t payload_bus;
-
         /* This callback is called when the packet transmission has
          * completed; for successful transmission, the status code is
          * the ack received from the destination, otherwise it's a
@@ -215,6 +213,7 @@ struct fw_packet {
         fw_packet_callback_t callback;
         int ack;
         struct list_head link;
+        void *driver_data;
 };
 
 struct fw_transaction {