[PATCH v5] bus: uniphier-system-bus: add UniPhier System Bus driver
olof at lixom.net
Tue Dec 22 11:22:52 PST 2015
On Wed, Dec 09, 2015 at 03:52:59PM +0900, Masahiro Yamada wrote:
> The UniPhier System Bus is an external bus that connects on-board
> devices to the UniPhier SoC. Each bank (chip select) is dynamically
> mapped to the CPU-viewed address base via the bus controller. The
> bus controller must be configured before any access to the bus.
> This driver parses the "ranges" property of the System Bus node and
> initialized the bus controller. After the bus becomes ready, devices
> below it are populated.
> Each bank can be mapped anywhere in the supported address space;
> there is nothing preventing us from assigning bank 0 on 0x42000000,
> 0x43000000, or anywhere as long as such region is not used by others.
> So, the "ranges" is just one possible software configuration, which
> does not seem to fit in device tree because device tree is a hardware
> description language. However, of_translate_address() requires
> "ranges" in every bus node between CPUs and device mapped on the CPU
> address space. In other words, "ranges" properties must be statically
> defined in device tree. After some discussion, I decided the dynamic
> address reassignment by the driver is too bothersome. Instead, the
> device tree should provide a reasonable translation setup that the OS
> can rely on.
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
> Acked-by: Rob Herring <robh at kernel.org>
> Acked-by: Arnd Bergmann <arnd at arndb.de>
Thanks, applied to next/drivers.
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