Introduce a new function that abstracts finding information about a
region in IPA-local memory, given its memory region ID.  For now it
simply uses the region ID as an index into the IPA memory array.
If the region is not defined, ipa_mem_find() returns a null pointer.

Update all code that accesses the ipa->mem[] array directly to use
ipa_mem_find() instead.  The return value must be checked for null
when optional memory regions are sought.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Stop passing most of the Boolean flags to ipa_table_valid_one(), and
just pass a memory region ID to it instead.  We still need to
indicate whether we're operating on a routing or filter table.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pass a memory region ID rather than the address of a memory region
descriptor to ipa_table_reset_add() to simplify callers.  Similarly,
pass memory region IDs to ipa_table_init_add().

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pass a memory region ID rather than the address of a memory region
descriptor to ipa_filter_reset_table(), to simplify callers.

We can eliminate the check for a zero region size in this function
because ipa_table_reset_add() checks that before adding anything to
the transaction.

Note that here and in subsequent commits there is no need to check
whether a memory region exists, because we will have already
verified that during initialization.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

There are place holder functions in the IPA code that do nothing.
For the most part these are inverse functions, for example, once the
routing or filter tables are set up there is no need to perform any
matching teardown activity at shutdown, or in the case of an error.

These can be safely removed, resulting in some code simplification.
Add comments in these spots making it explicit that there is no
inverse.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Entries in an IPA route or filter table are 64-bit little-endian
addresses, each of which refers to a routing or filtering rule.

The format of these table slots are fixed, but IPA_TABLE_ENTRY_SIZE
is used to define their size.  This symbol doesn't really add value,
and I think it unnecessarily obscures what a table entry *is*.

So get rid of IPA_TABLE_ENTRY_SIZE, and just use sizeof(__le64) in
its place throughout the code.

Update the comments in "ipa_table.c" to provide a little better
explanation of these table slots.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

A recent patch avoided doing 64-bit modulo operations by checking
the alignment of some DMA allocations using only the lower 32 bits
of the address.

David Laight pointed out (after the fix was committed) that DMA
allocations might already satisfy the alignment requirements.  And
he was right.

Remove the alignment checks that occur after DMA allocation requests,
and update comments to explain why the constraint is satisfied.  The
only place IPA_TABLE_ALIGN was used was to check the alignment; it is
therefore no longer needed, so get rid of it.

Add comments where GSI_RING_ELEMENT_SIZE and the tre_count and
event_count channel data fields are defined to make explicit they
are required to be powers of 2.

Revise a comment in gsi_trans_pool_init_dma(), taking into account
that dma_alloc_coherent() guarantees its result is aligned to a page
size (or order thereof).

Don't bother printing an error if a DMA allocation fails.

Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

It is possible for a 32 bit x86 build to use a 64 bit DMA address.

There are two remaining spots where the IPA driver does a modulo
operation to check alignment of a DMA address, and under certain
conditions this can lead to a build error on i386 (at least).

The alignment checks we're doing are for power-of-2 values, and this
means the lower 32 bits of the DMA address can be used.  This ensures
both operands to the modulo operator are 32 bits wide.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>

We currently have a build-time check to ensure that the minimum DMA
allocation alignment satisfies the constraint that IPA filter and
route tables must point to rules that are 128-byte aligned.

But what's really important is that the actual allocated DMA memory
has that alignment, even if the minimum is smaller than that.

Remove the BUILD_BUG_ON() call checking against minimim DMA alignment
and instead verify at rutime that the allocated memory is properly
aligned.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Some build time checks in ipa_table_validate_build() assume that a
DMA address is 64 bits wide.  That is more restrictive than it has
to be.  A route or filter table is 64 bits wide no matter what the
size of a DMA address is on the AP.  The code actually uses a
pointer to __le64 to access table entries, and a fixed constant
IPA_TABLE_ENTRY_SIZE to describe the size of those entries.

Loosen up two checks so they still verify some requirements, but
such that they do not assume the size of a DMA address is 64 bits.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>