When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>

Implement specialized function to clenup caches (and therefore
sync instruction and data caches) which can be used for cleanup before linux
launch or to sync caches during U-Boot self-relocation.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Use CONFIG_ARC_DBG_IOC_ENABLE Kconfig option instead of
ioc_enable global variable.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

There is a problem with current implementation if we start U-Boot
from ROM, as we use global variables before ther initialization,
so these variables get overwritten when we copy .data section
from ROM.

Instead we move these global variables into our "global data"
structure so that we may really start from ROM.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

We're starting to use more and more BCRs and having their
definitions in-lined in sources becomes a bit annoying
so we move it all to a separate header.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

We don't implement separate flush_dcache_all() intentionally as
entire data cache invalidation is dangerous operation even if we flush
data cache right before invalidation.

There is the real example:
We may get stuck in the following code if we store any context (like
BLINK register) on stack in invalidate_dcache_all() function.

BLINK register is the register where return address is automatically saved
when we do function call with instructions like 'bl'.

void flush_dcache_all() {
	__dc_entire_op(OP_FLUSH);
	// Other code //
}

void invalidate_dcache_all() {
	__dc_entire_op(OP_INV);
	// Other code //
}

void foo(void) {
	flush_dcache_all();
	invalidate_dcache_all();
}

Now let's see what really happens during that code execution:

foo()
  |->> call flush_dcache_all
  	[return address is saved to BLINK register]
  	[push BLINK] (save to stack)              ![point 1]
  	|->> call __dc_entire_op(OP_FLUSH)
  		[return address is saved to BLINK register]
  		[flush L1 D$]
  		return [jump to BLINK]
  	<<------
  	[other flush_dcache_all code]
  	[pop BLINK] (get from stack)
  	return [jump to BLINK]
  <<------
  |->> call invalidate_dcache_all
  	[return address is saved to BLINK register]
  	[push BLINK] (save to stack)               ![point 2]
  	|->> call __dc_entire_op(OP_FLUSH)
  		[return address is saved to BLINK register]
  		[invalidate L1 D$]                 ![point 3]
  		// Oops!!!
  		// We lose return address from invalidate_dcache_all function:
  		// we save it to stack and invalidate L1 D$ after that!
  		return [jump to BLINK]
  	<<------
  	[other invalidate_dcache_all code]
  	[pop BLINK] (get from stack)
  	// we don't have this data in L1 dcache as we invalidated it in [point 3]
  	// so we get it from next memory level (for example DDR memory)
  	// but in the memory we have value which we save in [point 1], which
  	// is return address from flush_dcache_all function (instead of
  	// address from current invalidate_dcache_all function which we
  	// saved in [point 2] !)
  	return [jump to BLINK]
  <<------
  // As BLINK points to invalidate_dcache_all, we call it again and
  // loop forever.

Fortunately we may do flush and invalidation of D$ with a single one
instruction which automatically mitigates a situation described above.

And because invalidate_dcache_all() isn't used in common U-Boot code we
implement "flush and invalidate dcache all" instead.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Introduce is_isa_arcv2() and is_isa_arcompact() functions.

These functions only check configuration options and return
compile-time constant so they can be used instead of #ifdef's to
to write cleaner code.

Now we can write:
-------------->8---------------
if (is_isa_arcv2())
	ioc_configure();
-------------->8---------------
instead of:
-------------->8---------------
ifdef CONFIG_ISA_ARCV2
	ioc_configure();
endif
-------------->8---------------

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

We improve on 2 things:
 1. Only ARC HS family has "dmb" instructions so do compile-time
    check for automatically defined macro __ARCHS__.
    Previous check for ARCv2 ISA was not good enough because ARC EM
    family is v2 ISA as well but still "dmb" instaruction is not
    supported in EM family.

 2. Still if there's no dedicated instruction for memory barrier
    let's at least insert compile-time barrier to make sure
    compiler deosn't reorder critical memory operations.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

U-Boot is a bit special piese of software because it is being
only executed once on power-on as compared to operating system
for example. That's why we don't care much about performance
optimizations instead we're more concerned about size. And up-to-date
compilers might produce much smaller code compared to
performance-optimized routines copy-pasted from the Linux kernel.

Here's an example:
------------------------------->8--------------------------
--- size_asm_strings.txt
+++ size_c_strings.txt
@@ -1,2 +1,2 @@
    text	   data	    bss	    dec	    hex	filename
- 121260	   3784	   3308	 128352	  1f560	u-boot
+ 120448	   3784	   3308	 127540	  1f234	u-boot
------------------------------->8--------------------------

See we were able to shave off ~800 bytes of .text section.

Also usage of string routines implemented in C gives us an ability
to support more HW flavors for free: generated instructions will match
our target as long as correct compiler option is used.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Previous SLC management implementation is broken. Seems like it was
never sufficiently tested probably because most of the time IOC was used
instead (i.e. no manual cache operations were done).

Now if we disable IOC in U-boot we'll get a lot of errors while using
DMA-enabled peripherals.

This time we fix it by substitution of broken per-line SLC operations
region operations as it is done in the Linux kernel (we took it from
v4.14 which is the latest stable as of today).

Among other things this implementation might be a bit faster because
instead of iteration over each and every cache line we're taking care
about entire region in one go.

Main changes:
 * Replaced __slc_line_op (per line operations) by __slc_rgn_op
   (region operations).

 * Reworked __slc_entire_op to get rid of __after_slc_op and
   __before_slc_op functions.
   Note flush fix (flush only instead of flush-n-inv when OP_FLUSH is
   used, see [1] for more details) is already incorporated here.

 * Added SLC invalidation to invalidate_icache_all().

 * Added (start >= end) check to invalidate_dcache_range() and
   flush_dcache_range() as some buggy drivers pass region start == end.

 * Added read-out of MMU BCR so we may know if PAE40 exists in HW and then
   act on a particular AUX regs accordingly.

[1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-January/003357.html

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>