firewire: core: integrate software-forced bus resets with bus management

Bus resets which are triggered
  - by the kernel drivers after updates of the local nodes' config ROM,
  - by userspace software via ioctl
shall be deferred until after >=2 seconds after the last bus reset.

If multiple modifications of the local nodes' config ROM happen in a row,
only a single bus reset should happen after them.

When the local node's link goes from inactive to active or vice versa,
and at the two occasions of bus resets mentioned above --- and if the
current gap count differs from 63 --- the bus reset should be preceded
by a PHY configuration packet that reaffirms the gap count.  Otherwise a
bus manager would have to reset the bus again right after that.

This is necessary to promote bus stability, e.g. leave grace periods for
allocations and reallocations of isochronous channels and bandwidth,
SBP-2 reconnections etc.; see IEEE 1394 clause 8.2.1.

This change implements all of the above by moving bus reset initiation
into a delayed work (except for bus resets which are triggered by the
bus manager workqueue job and are performed there immediately).  It
comes with a necessary addition to the card driver methods that allows
to get the current gap count from PHY registers.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 3000dd74acf..ff6c9092200 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -51,6 +51,7 @@ struct fw_card_driver {
 	int (*enable)(struct fw_card *card,
 		      const __be32 *config_rom, size_t length);
 
+	int (*read_phy_reg)(struct fw_card *card, int address);
 	int (*update_phy_reg)(struct fw_card *card, int address,
 			      int clear_bits, int set_bits);
 
@@ -102,8 +103,8 @@ void fw_card_initialize(struct fw_card *card,
 int fw_card_add(struct fw_card *card,
 		u32 max_receive, u32 link_speed, u64 guid);
 void fw_core_remove_card(struct fw_card *card);
-int fw_core_initiate_bus_reset(struct fw_card *card, int short_reset);
 int fw_compute_block_crc(__be32 *block);
+void fw_schedule_bus_reset(struct fw_card *card, bool delayed, bool short_reset);
 void fw_schedule_bm_work(struct fw_card *card, unsigned long delay);
 
 static inline struct fw_card *fw_card_get(struct fw_card *card)
@@ -225,6 +226,9 @@ void fw_core_handle_response(struct fw_card *card, struct fw_packet *packet);
 int fw_get_response_length(struct fw_request *request);
 void fw_fill_response(struct fw_packet *response, u32 *request_header,
 		      int rcode, void *payload, size_t length);
+
+#define FW_PHY_CONFIG_NO_NODE_ID	-1
+#define FW_PHY_CONFIG_CURRENT_GAP_COUNT	-1
 void fw_send_phy_config(struct fw_card *card,
 			int node_id, int generation, int gap_count);