ARC: [Review] Multi-platform image #6: cpu-to-dma-addr optional

All the current platforms can work with 0x8000_0000 based dma_addr_t
since the Bus Bridges typically ignore the top bit (the only excpetion
was Angel4 PCI-AHB bridge which we no longer care for).
That way we don't need plat-specific cpu-addr to bus-addr conversion.

Hooks still provided - just in case a platform has an obscure device
which say needs 0 based bus address.

That way <asm/dma_mapping.h> no longer needs to unconditinally include
<plat/dma_addr.h>

Also verfied that on Angel4 board, other peripherals (IDE-disk / EMAC)
work fine with 0x8000_0000 based dma addresses.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
ARC: [Review] Multi-platform image #7: SMP common code to use callbacks

This again is for switch from singleton platform SMP API to
multi-platform paradigm

Platform code is not yet setup to populate the callbacks, that happens
in next commit

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
ARC: [Review] Multi-platform image #8: platform registers SMP callbacks

Platforms export their SMP callbacks by populating arc_smp_ops.
The population itself needs to be done pretty early, from init_early
callback.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
ARC: [plat-arcfpga] defconfig for fully loaded ARC Linux

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Provide a default serial.h for uart drivers needing BASE_BAUD

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Add self to MAINTAINERS

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Don't fiddle with non-existent caches

!CONFIG_ARC_HAS_(I|D)CACHE makes Linux disable caches (assuming they
exist in hardware) - mostly for debugging issues with new peripherals.
However, independent of CONFIG_ARC_HAS_(I|D)CACHE, Linux also needs to
handle, non-existant caches, using the information in Cache BCRs (Build
Configuration Reg)

Reported-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: 64bit RTSC timestamp hardware issue

The 64bit RTSC is not reliable, causing spurious "jumps" in higher word,
making Linux timekeeping go bonkers. So as of now just use the lower
32bit timestamp.

A cleaner approach would have been removing RTSC support altogether as the
32bit RTSC is equivalent to old TIMER1 based solution, but some customers
can use the 32bit RTSC in SMP syn fashion (vs. TIMER1 which being incore
can't be done easily).

A fallout of this is sched_clock()'s hardware assisted version needs to
go away since it can't use 32bit wrapping counter - instead we use the
generic "weak" jiffies based version.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: [3.9] Fallout of hlist iterator update

Commit 0bbacca "hlist: drop the node parameter from iterators" changed
the iterator across the board - but ARC port being out-of-tree missed
it.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>