firewire: reread config ROM when device reset the bus

When a device changes its configuration ROM, it announces this with a
bus reset.  firewire-core has to check which node initiated a bus reset
and whether any unit directories went away or were added on this node.

Tested with an IOI FWB-IDE01AB which has its link-on bit set if bus
power is available but does not respond to ROM read requests if self
power is off.  This implements
  - recognition of the units if self power is switched on after fw-core
    gave up the initial attempt to read the config ROM,
  - shutdown of the units when self power is switched off.

Also tested with a second PC running Linux/ieee1394.  When the eth1394
driver is inserted and removed on that node, fw-core now notices the
addition and removal of the IPv4 unit on the ieee1394 node.

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

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 0d771fda86de..5f131f5129da 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -21,6 +21,7 @@
 
 #include <linux/fs.h>
 #include <linux/cdev.h>
+#include <linux/rwsem.h>
 #include <asm/atomic.h>
 
 enum fw_device_state {
@@ -46,6 +47,11 @@ struct fw_attribute_group {
  * fw_device.node_id is guaranteed to be current too.
  *
  * The same applies to fw_device.card->node_id vs. fw_device.generation.
+ *
+ * fw_device.config_rom and fw_device.config_rom_length may be accessed during
+ * the lifetime of any fw_unit belonging to the fw_device, before device_del()
+ * was called on the last fw_unit.  Alternatively, they may be accessed while
+ * holding fw_device_rwsem.
  */
 struct fw_device {
         atomic_t state;
@@ -53,6 +59,7 @@ struct fw_device {
         int node_id;
         int generation;
         unsigned max_speed;
+        bool cmc;
         struct fw_card *card;
         struct device device;
         struct list_head link;
@@ -92,8 +99,12 @@ int fw_device_enable_phys_dma(struct fw_device *device);
 void fw_device_cdev_update(struct fw_device *device);
 void fw_device_cdev_remove(struct fw_device *device);
 
+extern struct rw_semaphore fw_device_rwsem;
 extern int fw_cdev_major;
 
+/*
+ * fw_unit.directory must not be accessed after device_del(&fw_unit.device).
+ */
 struct fw_unit {
         struct device device;
         u32 *directory;