Documentation: Add tutorial for me_cleaner on Lenovo devices

Add a tutorial how to use ME cleaner, and give some basic steps to
strip the ME. Update the Lenovo Sandy Bridge documentation that no
issues could be observed on X220 and give an example flash layout.

Tested on Lenovo X220 with stripped ME and found no issues:
commit: cbc5b99ac9e5856631109b1e7f20e80799beb1e4

* Displayport
* VGA
* USB
* Bluetooth
* Wifi
* Wifi-kill switch
* libgfxinit
* SATA
* Audio
* SD-card
* Ethernet
* Keyboard
* Fn-Keys
* Display brightness
* ACPI S3 resume
* Battery events
* CPU temperature reporting
* FAN managment
* Stress test stable
  * Youtube videos over Wifi
  * stress -c 2 -m 1 -d 1
  * glxgears

Change-Id: I0b1d04f00b5dbb38cf04333f2b345749b740a375
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39129
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 98 insertions, 3 deletions

diff --git a/Documentation/mainboard/lenovo/Sandy_Bridge_series.md b/Documentation/mainboard/lenovo/Sandy_Bridge_series.md
index 0b833f5cc8..dbbbbeef30 100644
--- a/Documentation/mainboard/lenovo/Sandy_Bridge_series.md
+++ b/Documentation/mainboard/lenovo/Sandy_Bridge_series.md
@@ -33,9 +33,7 @@
   usable by coreboot.
 * ROM chip size should be set to 8MiB.
 
-```eval_rst
-Please also have a look at :doc:`../../flash_tutorial/index`.
-```
+Please also have a look at the [flashing tutorial]
 
 ## Flash layout
 There's one 8MiB flash which contains IFD, GBE, ME and BIOS regions.
@@ -46,3 +44,26 @@ region. The update is then written into the EC once.
 
 [fl]: flashlayout_Sandy_Bridge.svg
 
+## Reducing Intel Managment Engine firmware size
+
+It is possible to reduce the Intel ME firmware size to free additional
+space for the `bios` region. This is usually refered to as *cleaning the ME* or
+*stripping the ME*.
+After reducing the Intel ME firmware size you must modify the original IFD
+and then write a full ROM using an [external programmer].
+Have a look at the [me_cleaner] for more information.
+
+Tests on Lenovo X220 showed no issues with a stripped ME firmware.
+
+**Modified flash layout:**
+
+![][fl2]
+
+[fl2]: flashlayout_Sandy_Bridge_stripped_me.svg
+
+The overall size of the `gbe`, `me,` `ifd` region is less than 128KiB, leaving
+the remaining space for the `bios` partition.
+
+
+[me_cleaner]: ../../northbridge/intel/sandybridge/me_cleaner.md
+[external programmer]: ../../flash_tutorial/index.md
diff --git a/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg b/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg
new file mode 100644
index 0000000000..d8d8213d12
--- /dev/null
+++ b/Documentation/mainboard/lenovo/flashlayout_Sandy_Bridge_stripped_me.svg
@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/PR-SVG-20010719/DTD/svg10.dtd">
+<svg width="9cm" height="8cm" viewBox="268 -156 168 158" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+  <g>
+    <g>
+      <g>
+        <rect style="fill: #ffffff" x="307.888" y="-152.131" width="49.1438" height="30.4667"/>
+        <rect style="fill: none; fill-opacity:0; stroke-width: 2; stroke: #ffffff" x="307.888" y="-152.131" width="49.1438" height="30.4667"/>
+      </g>
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+    <rect style="fill: none; fill-opacity:0; stroke-width: 2; stroke: #000000" x="307.888" y="-152.131" width="49.1438" height="30.4667"/>
+    <text font-size="6.77323" style="fill: #000000;text-anchor:middle;font-family:sans-serif;font-style:normal;font-weight:normal" x="332.46" y="-134.831">
+      <tspan x="332.46" y="-134.831">IFD</tspan>
+    </text>
+  </g>
+  <g>
+    <g>
+      <rect style="fill: #ffffff" x="307.934" y="-56.9106" width="49.1438" height="56.1492"/>
+      <rect style="fill: none; fill-opacity:0; stroke-width: 0.02; stroke: #ffffff" x="307.934" y="-56.9106" width="49.1438" height="56.1492"/>
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+    <tspan x="332.182" y="-24.0245">BIOS</tspan>
+  </text>
+  <g>
+    <g>
+      <g>
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+      <tspan x="332.572" y="-104.29">GBE</tspan>
+    </text>
+  </g>
+  <text font-size="7.15705" style="fill: #000000;text-anchor:start;font-family:sans-serif;font-style:normal;font-weight:normal" x="268.961" y="-148.674">
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+    <tspan x="269.461" y="-56.4289">0x020000</tspan>
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+  <text font-size="6.77323" style="fill: #000000;text-anchor:start;font-family:sans-serif;font-style:normal;font-weight:normal" x="270.008" y="0.198407">
+    <tspan x="270.008" y="0.198407">0x800000</tspan>
+  </text>
+  <path style="fill: none; fill-opacity:0; stroke-width: 1; stroke: #000000" d="M 380.877 -151.013 C 401.876,-151.013 379.377,-73.513 400.627,-72.513"/>
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+    <tspan x="406.127" y="-68.513">Flash #0</tspan>
+  </text>
+  <g>
+    <g>
+      <g>
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+    </text>
+  </g>
+</svg>