Currently, CONFIG_BCM2835 is defined for all BCM283x builds and _BCM2836
is defined when building for that SoC. That means there isn't a single
define that means "exactly BCM2835". This will complicate future patches
where BCM2835-vs-anything-else needs to be determined simply.
Modify the code to define one or the other of CONFIG_BCM2835/BCM2836 so
future patches are simpler.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
The BCM283[56] contain both a L1 and L2 cache between the GPU (a/k/a
VideoCore CPU?) and DRAM. DMA-capable peripherals can also optionally
access DRAM via this same L2 cache (although they always bypass the L1
cache). Peripherals select whether to use or bypass the cache via the
top two bits of the bus address.
An IOMMU exists between the ARM CPU and the rest of the system. This
controls whether the ARM CPU's accesses use or bypass the L1 and/or L2
cache. This IOMMU is configured/controlled exclusively by the VideoCore
CPU.
In order for DRAM accesses made by the ARM core to be coherent with
accesses made by other DMA peripherals, we must program a bus address
into those peripherals that causes the peripheral's accesses to use the
same set of caches that the ARM core's accesses will use.
On the RPi1, the VideoCore firmware sets up the IOMMU to enable use of
the L2 cache. This corresponds to addresses based at 0x40000000.
On the RPi2, the VideoCore firmware sets up the IOMMU to disable use of
the L2 cache. This corresponds to addresses based at 0xc0000000.
This patch implements U-Boot's phys_to_bus/bus_to_phys APIs according
to those rules.
For full details of this setup, please see Dom Cobley's description at:
http://lists.denx.de/pipermail/u-boot/2015-March/208201.htmlhttp://permalink.gmane.org/gmane.comp.boot-loaders.u-boot/215038https://www.mail-archive.com/u-boot@lists.denx.de/msg166568.html
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
