[PATCH v11 4/4] EINJ, Documentation: Update EINJ kernel doc

[Ben Cheatham <Benjamin.Cheatham@amd.com>]

Update EINJ kernel document to include how to inject CXL protocol error
types, build the kernel to include CXL error types, and give an example
injection.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
 .../firmware-guide/acpi/apei/einj.rst         | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/firmware-guide/acpi/apei/einj.rst b/Documentation/firmware-guide/acpi/apei/einj.rst
index d6b61d22f525..f179adf7b61c 100644
--- a/Documentation/firmware-guide/acpi/apei/einj.rst
+++ b/Documentation/firmware-guide/acpi/apei/einj.rst
@@ -181,6 +181,25 @@ You should see something like this in dmesg::
   [22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
   [22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 -  area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)
 
+CXL error types are supported from ACPI 6.5 onwards. These error types
+are not available in the legacy interface at /sys/kernel/debug/apei/einj,
+and are instead at /sys/kernel/debug/cxl/. There is a file under debug/cxl
+called "einj_type" that is analogous to available_error_type under debug/cxl.
+There is also a "einj_inject" file in each $dport_dev directory under debug/cxl
+that will inject a given error into the dport represented by $dport_dev.
+For example, to inject a CXL.mem protocol correctable error into
+$dport_dev=pci0000:0c::
+
+    # cd /sys/kernel/debug/cxl/
+    # cat einj_type                 # See which error can be injected
+	0x00008000  CXL.mem Protocol Correctable
+	0x00010000  CXL.mem Protocol Uncorrectable non-fatal
+	0x00020000  CXL.mem Protocol Uncorrectable fatal
+    # cd 0000:e0:01.1               # Navigate to dport to inject into
+    # echo 0x8000 > einj_inject     # Inject error
+
+To use CXL error types, ``CONFIG_CXL_EINJ`` will need to be enabled.
+
 Special notes for injection into SGX enclaves:
 
 There may be a separate BIOS setup option to enable SGX injection.
-- 
2.34.1