Documentation: ACPI: move apei/einj.txt to firmware-guide/acpi and convert to reST

This converts the plain text documentation to reStructuredText format
and adds it to Sphinx TOC tree.

No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 186 insertions, 0 deletions

diff --git a/Documentation/firmware-guide/acpi/apei/einj.rst b/Documentation/firmware-guide/acpi/apei/einj.rst
new file mode 100644
index 000000000000..e588bccf5158
--- /dev/null
+++ b/Documentation/firmware-guide/acpi/apei/einj.rst
@@ -0,0 +1,185 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+APEI Error INJection
+====================
+
+EINJ provides a hardware error injection mechanism. It is very useful
+for debugging and testing APEI and RAS features in general.
+
+You need to check whether your BIOS supports EINJ first. For that, look
+for early boot messages similar to this one::
+
+  ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL           00000001 INTL 00000001)
+
+which shows that the BIOS is exposing an EINJ table - it is the
+mechanism through which the injection is done.
+
+Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
+which is a different representation of the same thing.
+
+It doesn't necessarily mean that EINJ is not supported if those above
+don't exist: before you give up, go into BIOS setup to see if the BIOS
+has an option to enable error injection. Look for something called WHEA
+or similar. Often, you need to enable an ACPI5 support option prior, in
+order to see the APEI,EINJ,... functionality supported and exposed by
+the BIOS menu.
+
+To use EINJ, make sure the following are options enabled in your kernel
+configuration::
+
+  CONFIG_DEBUG_FS
+  CONFIG_ACPI_APEI
+  CONFIG_ACPI_APEI_EINJ
+
+The EINJ user interface is in <debugfs mount point>/apei/einj.
+
+The following files belong to it:
+
+- available_error_type
+
+  This file shows which error types are supported:
+
+  ================  ===================================
+  Error Type Value	Error Description
+  ================  ===================================
+  0x00000001        Processor Correctable
+  0x00000002        Processor Uncorrectable non-fatal
+  0x00000004        Processor Uncorrectable fatal
+  0x00000008        Memory Correctable
+  0x00000010        Memory Uncorrectable non-fatal
+  0x00000020        Memory Uncorrectable fatal
+  0x00000040        PCI Express Correctable
+  0x00000080        PCI Express Uncorrectable fatal
+  0x00000100        PCI Express Uncorrectable non-fatal
+  0x00000200        Platform Correctable
+  0x00000400        Platform Uncorrectable non-fatal
+  0x00000800        Platform Uncorrectable fatal
+  ================  ===================================
+
+  The format of the file contents are as above, except present are only
+  the available error types.
+
+- error_type
+
+  Set the value of the error type being injected. Possible error types
+  are defined in the file available_error_type above.
+
+- error_inject
+
+  Write any integer to this file to trigger the error injection. Make
+  sure you have specified all necessary error parameters, i.e. this
+  write should be the last step when injecting errors.
+
+- flags
+
+  Present for kernel versions 3.13 and above. Used to specify which
+  of param{1..4} are valid and should be used by the firmware during
+  injection. Value is a bitmask as specified in ACPI5.0 spec for the
+  SET_ERROR_TYPE_WITH_ADDRESS data structure:
+
+    Bit 0
+      Processor APIC field valid (see param3 below).
+    Bit 1
+      Memory address and mask valid (param1 and param2).
+    Bit 2
+      PCIe (seg,bus,dev,fn) valid (see param4 below).
+
+  If set to zero, legacy behavior is mimicked where the type of
+  injection specifies just one bit set, and param1 is multiplexed.
+
+- param1
+
+  This file is used to set the first error parameter value. Its effect
+  depends on the error type specified in error_type. For example, if
+  error type is memory related type, the param1 should be a valid
+  physical memory address. [Unless "flag" is set - see above]
+
+- param2
+
+  Same use as param1 above. For example, if error type is of memory
+  related type, then param2 should be a physical memory address mask.
+  Linux requires page or narrower granularity, say, 0xfffffffffffff000.
+
+- param3
+
+  Used when the 0x1 bit is set in "flags" to specify the APIC id
+
+- param4
+  Used when the 0x4 bit is set in "flags" to specify target PCIe device
+
+- notrigger
+
+  The error injection mechanism is a two-step process. First inject the
+  error, then perform some actions to trigger it. Setting "notrigger"
+  to 1 skips the trigger phase, which *may* allow the user to cause the
+  error in some other context by a simple access to the CPU, memory
+  location, or device that is the target of the error injection. Whether
+  this actually works depends on what operations the BIOS actually
+  includes in the trigger phase.
+
+BIOS versions based on the ACPI 4.0 specification have limited options
+in controlling where the errors are injected. Your BIOS may support an
+extension (enabled with the param_extension=1 module parameter, or boot
+command line einj.param_extension=1). This allows the address and mask
+for memory injections to be specified by the param1 and param2 files in
+apei/einj.
+
+BIOS versions based on the ACPI 5.0 specification have more control over
+the target of the injection. For processor-related errors (type 0x1, 0x2
+and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
+param2 for bit 1) so that you have more information added to the error
+signature being injected. The actual data passed is this::
+
+	memory_address = param1;
+	memory_address_range = param2;
+	apicid = param3;
+	pcie_sbdf = param4;
+
+For memory errors (type 0x8, 0x10 and 0x20) the address is set using
+param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
+express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
+function are specified using param1::
+
+         31     24 23    16 15    11 10      8  7        0
+	+-------------------------------------------------+
+	| segment |   bus  | device | function | reserved |
+	+-------------------------------------------------+
+
+Anyway, you get the idea, if there's doubt just take a look at the code
+in drivers/acpi/apei/einj.c.
+
+An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
+In this case a file named vendor will contain identifying information
+from the BIOS that hopefully will allow an application wishing to use
+the vendor-specific extension to tell that they are running on a BIOS
+that supports it. All vendor extensions have the 0x80000000 bit set in
+error_type. A file vendor_flags controls the interpretation of param1
+and param2 (1 = PROCESSOR, 2 = MEMORY, 4 = PCI). See your BIOS vendor
+documentation for details (and expect changes to this API if vendors
+creativity in using this feature expands beyond our expectations).
+
+
+An error injection example::
+
+  # cd /sys/kernel/debug/apei/einj
+  # cat available_error_type		# See which errors can be injected
+  0x00000002	Processor Uncorrectable non-fatal
+  0x00000008	Memory Correctable
+  0x00000010	Memory Uncorrectable non-fatal
+  # echo 0x12345000 > param1		# Set memory address for injection
+  # echo $((-1 << 12)) > param2		# Mask 0xfffffffffffff000 - anywhere in this page
+  # echo 0x8 > error_type			# Choose correctable memory error
+  # echo 1 > error_inject			# Inject now
+
+You should see something like this in dmesg::
+
+  [22715.830801] EDAC sbridge MC3: HANDLING MCE MEMORY ERROR
+  [22715.834759] EDAC sbridge MC3: CPU 0: Machine Check Event: 0 Bank 7: 8c00004000010090
+  [22715.834759] EDAC sbridge MC3: TSC 0
+  [22715.834759] EDAC sbridge MC3: ADDR 12345000 EDAC sbridge MC3: MISC 144780c86
+  [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)
+
+For more information about EINJ, please refer to ACPI specification
+version 4.0, section 17.5 and ACPI 5.0, section 18.6.
diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst
index 869badba6d7a..fca854f017d8 100644
--- a/Documentation/firmware-guide/acpi/index.rst
+++ b/Documentation/firmware-guide/acpi/index.rst
@@ -18,6 +18,7 @@ ACPI Support
    debug
    aml-debugger
    apei/output_format
+   apei/einj
    gpio-properties
    i2c-muxes
    acpi-lid