firewire: Implement compliant bus management.

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

1 files changed, 108 insertions, 19 deletions

diff --git a/drivers/firewire/fw-card.c b/drivers/firewire/fw-card.c
index 307c8b851382..f94874ce58af 100644
--- a/drivers/firewire/fw-card.c
+++ b/drivers/firewire/fw-card.c
@@ -92,7 +92,7 @@ generate_config_rom (struct fw_card *card, size_t *config_rom_length)
                 bib_generation(card->config_rom_generation++ % 14 + 2) |
                 bib_max_rom(2) |
                 bib_max_receive(card->max_receive) |
-                bib_isc | bib_cmc | bib_imc;
+                bib_bmc | bib_isc | bib_cmc | bib_imc;
         config_rom[3] = card->guid >> 32;
         config_rom[4] = card->guid;
 
@@ -190,48 +190,137 @@ static const char gap_count_table[] = {
         63, 5, 7, 8, 10, 13, 16, 18, 21, 24, 26, 29, 32, 35, 37, 40
 };
 
+struct bm_data {
+        struct fw_transaction t;
+        struct {
+                __be32 arg;
+                __be32 data;
+        } lock;
+        u32 old;
+        int rcode;
+        struct completion done;
+};
+
 static void
-fw_card_irm_work(struct work_struct *work)
+complete_bm_lock(struct fw_card *card, int rcode,
+                 void *payload, size_t length, void *data)
+{
+        struct bm_data *bmd = data;
+
+        if (rcode == RCODE_COMPLETE)
+                bmd->old = be32_to_cpu(*(__be32 *) payload);
+        bmd->rcode = rcode;
+        complete(&bmd->done);
+}
+
+static void
+fw_card_bm_work(struct work_struct *work)
 {
         struct fw_card *card = container_of(work, struct fw_card, work.work);
         struct fw_device *root;
+        struct bm_data bmd;
         unsigned long flags;
-        int root_id, new_irm_id, gap_count, generation, do_reset = 0;
-
-        /* FIXME: This simple bus management unconditionally picks a
-         * cycle master if the current root can't do it.  We need to
-         * not do this if there is a bus manager already.  Also, some
-         * hubs set the contender bit, which is bogus, so we should
-         * probably do a little sanity check on the IRM (like, read
-         * the bandwidth register) if it's not us. */
+        int root_id, new_root_id, irm_id, gap_count, generation, grace;
+        int do_reset = 0;
 
         spin_lock_irqsave(&card->lock, flags);
 
         generation = card->generation;
         root = card->root_node->data;
         root_id = card->root_node->node_id;
+        grace = time_after(jiffies, card->reset_jiffies + DIV_ROUND_UP(HZ, 10));
+
+        if (card->bm_generation + 1 == generation ||
+            (card->bm_generation != generation && grace)) {
+                /* This first step is to figure out who is IRM and
+                 * then try to become bus manager.  If the IRM is not
+                 * well defined (e.g. does not have an active link
+                 * layer or does not responds to our lock request, we
+                 * will have to do a little vigilante bus management.
+                 * In that case, we do a goto into the gap count logic
+                 * so that when we do the reset, we still optimize the
+                 * gap count.  That could well save a reset in the
+                 * next generation. */
+
+                irm_id = card->irm_node->node_id;
+                if (!card->irm_node->link_on) {
+                        new_root_id = card->local_node->node_id;
+                        fw_notify("IRM has link off, making local node (%02x) root.\n",
+                                  new_root_id);
+                        goto pick_me;
+                }
+
+                bmd.lock.arg = cpu_to_be32(0x3f);
+                bmd.lock.data = cpu_to_be32(card->local_node->node_id);
+
+                spin_unlock_irqrestore(&card->lock, flags);
+
+                init_completion(&bmd.done);
+                fw_send_request(card, &bmd.t, TCODE_LOCK_COMPARE_SWAP,
+                                irm_id, generation,
+                                SCODE_100, CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
+                                &bmd.lock, sizeof bmd.lock,
+                                complete_bm_lock, &bmd);
+                wait_for_completion(&bmd.done);
+
+                if (bmd.rcode == RCODE_GENERATION) {
+                        /* Another bus reset happened. Just return,
+                         * the BM work has been rescheduled. */
+                        return;
+                }
+
+                if (bmd.rcode == RCODE_COMPLETE && bmd.old != 0x3f)
+                        /* Somebody else is BM, let them do the work. */
+                        return;
+
+                spin_lock_irqsave(&card->lock, flags);
+                if (bmd.rcode != RCODE_COMPLETE) {
+                        /* The lock request failed, maybe the IRM
+                         * isn't really IRM capable after all. Let's
+                         * do a bus reset and pick the local node as
+                         * root, and thus, IRM. */
+                        new_root_id = card->local_node->node_id;
+                        fw_notify("BM lock failed, making local node (%02x) root.\n",
+                                  new_root_id);
+                        goto pick_me;
+                }
+        } else if (card->bm_generation != generation) {
+                /* OK, we weren't BM in the last generation, and it's
+                 * less than 100ms since last bus reset. Reschedule
+                 * this task 100ms from now. */
+                spin_unlock_irqrestore(&card->lock, flags);
+                schedule_delayed_work(&card->work, DIV_ROUND_UP(HZ, 10));
+                return;
+        }
+
+        /* We're bus manager for this generation, so next step is to
+         * make sure we have an active cycle master and do gap count
+         * optimization. */
+        card->bm_generation = generation;
 
         if (root == NULL) {
                 /* Either link_on is false, or we failed to read the
                  * config rom.  In either case, pick another root. */
-                new_irm_id = card->local_node->node_id;
+                new_root_id = card->local_node->node_id;
         } else if (root->state != FW_DEVICE_RUNNING) {
                 /* If we haven't probed this device yet, bail out now
                  * and let's try again once that's done. */
-                new_irm_id = root_id;
+                spin_unlock_irqrestore(&card->lock, flags);
+                return;
         } else if (root->config_rom[2] & bib_cmc) {
                 /* FIXME: I suppose we should set the cmstr bit in the
                  * STATE_CLEAR register of this node, as described in
                  * 1394-1995, 8.4.2.6.  Also, send out a force root
                  * packet for this node. */
-                new_irm_id = root_id;
+                new_root_id = root_id;
         } else {
                 /* Current root has an active link layer and we
                  * successfully read the config rom, but it's not
                  * cycle master capable. */
-                new_irm_id = card->local_node->node_id;
+                new_root_id = card->local_node->node_id;
         }
 
+ pick_me:
         /* Now figure out what gap count to set. */
         if (card->topology_type == FW_TOPOLOGY_A &&
             card->root_node->max_hops < ARRAY_SIZE(gap_count_table))
@@ -243,16 +332,16 @@ fw_card_irm_work(struct work_struct *work)
          * done less that 5 resets with the same physical topology and we
          * have either a new root or a new gap count setting, let's do it. */
 
-        if (card->irm_retries++ < 5 &&
-            (card->gap_count != gap_count || new_irm_id != root_id))
+        if (card->bm_retries++ < 5 &&
+            (card->gap_count != gap_count || new_root_id != root_id))
                 do_reset = 1;
 
         spin_unlock_irqrestore(&card->lock, flags);
 
         if (do_reset) {
                 fw_notify("phy config: card %d, new root=%x, gap_count=%d\n",
-                          card->index, new_irm_id, gap_count);
-                fw_send_phy_config(card, new_irm_id, generation, gap_count);
+                          card->index, new_root_id, gap_count);
+                fw_send_phy_config(card, new_root_id, generation, gap_count);
                 fw_core_initiate_bus_reset(card, 1);
         }
 }
@@ -294,7 +383,7 @@ fw_card_initialize(struct fw_card *card, const struct fw_card_driver *driver,
 
         card->local_node = NULL;
 
-        INIT_DELAYED_WORK(&card->work, fw_card_irm_work);
+        INIT_DELAYED_WORK(&card->work, fw_card_bm_work);
 
         card->card_device.bus     = &fw_bus_type;
         card->card_device.release = release_card;