[PATCH 1/3] Add known list of Ampere ETMv4 errata

[Steve Clevenger]

An Ampere Computing design decision is MMIO reads are considered the
same as an external debug access. If TRCOSLAR.OSLK is left set, a
TRCIDR1 access results in a bus fault followed by a kernel panic. A
TRCIDR1 read should be valid regardless of TRCOSLAR.OSLK provided MMIO
access (now deprecated) is supported.

The Ampere work around is to early clear ETM TRCOSLAR.OSLK prior to
TRCIDR1 access. Do not distinguish between manufacturers.
AC03_DEBUG_06 is described in the AmpereOne Developer Errata document.

An Ampere Computing design decision to not support 64-bit read/write
access in the ETMv4.6 implementation.

The Ampere work around is to split ETMv4.6 64-bit register access
into 2 ea. 32-bit read/write accesses.
AC03_DEBUG_10 is described in the AmpereOne Developer Errata document:

https://solutions.amperecomputing.com/customer-connect/products/AmpereOne-device-documentation

Signed-off-by: Steve Clevenger <scclevenger at os.amperecomputing.com>
---
 Documentation/arm64/silicon-errata.rst | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index ec5f889d7681..a4de304a8bd8 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -205,7 +205,11 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | Qualcomm Tech. | Kryo4xx Gold    | N/A             | ARM64_ERRATUM_1286807       |
 +----------------+-----------------+-----------------+-----------------------------+
-
 +----------------+-----------------+-----------------+-----------------------------+
 | Fujitsu        | A64FX           | E#010001        | FUJITSU_ERRATUM_010001      |
 +----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Ampere         | AmpereOne       | AC03_DEBUG_06   | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Ampere         | AmpereOne       | AC03_DEBUG_10   | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
-- 
2.25.1