bus: brcmstb_gisb: add support for GISBv7 arbiter

This patch set contains changes to enable the GISB arbiter driver on the latest ARM64 architecture Set-Top Box chips from Broadcom.

Since the ARM64 architecture does not support the hooking of low level fault handlers the driver has been adjusted to depend solely on GISB interrupts and notify events to provide diagnostic messaging. The GISB hardware still triggers bus faults for the processor so the default low-level aborts will occur and will be handled based on the architecture specific kernel implementation.

While this tends to obsure the GISB error messaging it is still reasonable so the same approach is applied to the ARM architecture for consistency.

The patches also correct some issues with the existing driver and add the new register map for the GISBv7 hardware first appearing in the BCM7278 device.

Changes since v2 at [2]:
- Removed code associated with enabling the hooking of ARM64 memory faults as well as the code that hooks them for both ARM and ARM64 architectures within the GISB arbiter driver.
- Created separate notifiers for die and panic events to prevent list corruption, and substituted the notifier return name for the previous magic number (Thanks Mark!)

Changes since v1 at [1]:
- Removed code associated with hooking SError handling in favor of a registered notifier (Thanks Mark!)
- Removed an unnecessary explicit cast (Thanks Gregory!)

[1] https://lkml.org/lkml/2017/3/24/413
[2] https://lkml.org/lkml/2017/3/28/1125

Doug Berger (6):
bus: brcmstb_gisb: Use register offsets with writes too
bus: brcmstb_gisb: correct support for 64-bit address output
bus: brcmstb_gisb: add notifier handling
bus: brcmstb_gisb: remove low-level ARM hooks
bus: brcmstb_gisb: enable driver for ARM64 architecture
bus: brcmstb_gisb: update to support new revision

 .../devicetree/bindings/bus/brcm,gisb-arb.txt      |   3 +-
 drivers/bus/Kconfig                                |   2 +-
 drivers/bus/brcmstb_gisb.c                         | 121 ++++++++++++---------
 3 files changed, 75 insertions(+), 51 deletions(-)

2.12.0