1. 01 Dec, 2006 1 commit
    • Benjamin Herrenschmidt's avatar
      Driver core: add notification of bus events · 116af378
      Benjamin Herrenschmidt authored
      I finally did as you suggested and added the notifier to the struct
      bus_type itself. There are still problems to be expected is something
      attaches to a bus type where the code can hook in different struct
      device sub-classes (which is imho a big bogosity but I won't even try to
      argue that case now) but it will solve nicely a number of issues I've
      had so far.
      
      That also means that clients interested in registering for such
      notifications have to do it before devices are added and after bus types
      are registered. Fortunately, most bus types that matter for the various
      usage scenarios I have in mind are registerd at postcore_initcall time,
      which means I have a really nice spot at arch_initcall time to add my
      notifiers.
      
      There are 4 notifications provided. Device being added (before hooked to
      the bus) and removed (failure of previous case or after being unhooked
      from the bus), along with driver being bound to a device and about to be
      unbound.
      
      The usage I have for these are:
      
       - The 2 first ones are used to maintain a struct device_ext that is
      hooked to struct device.firmware_data. This structure contains for now a
      pointer to the Open Firmware node related to the device (if any), the
      NUMA node ID (for quick access to it) and the DMA operations pointers &
      iommu table instance for DMA to/from this device. For bus types I own
      (like IBM VIO or EBUS), I just maintain that structure directly from the
      bus code when creating the devices. But for bus types managed by generic
      code like PCI or platform (actually, of_platform which is a variation of
      platform linked to Open Firmware device-tree), I need this notifier.
      
       - The other two ones have a completely different usage scenario. I have
      cases where multiple devices and their drivers depend on each other. For
      example, the IBM EMAC network driver needs to attach to a MAL DMA engine
      which is a separate device, and a PHY interface which is also a separate
      device. They are all of_platform_device's (well, about to be with my
      upcoming patches) but there is no say in what precise order the core
      will "probe" them and instanciate the various modules. The solution I
      found for that is to have the drivers for emac to use multithread_probe,
      and wait for a driver to be bound to the target MAL and PHY control
      devices (the device-tree contains reference to the MAL and PHY interface
      nodes, which I can then match to of_platform_devices). Right now, I've
      been polling, but with that notifier, I can more cleanly wait (with a
      timeout of course).
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      116af378
  2. 29 Nov, 2006 22 commits
  3. 28 Nov, 2006 17 commits