soc/intel/common/basecode: Implement CSE update flow

The following changes are done in this patch:
 1. Get the CSE partition info containing version of CSE RW using
    GET_BOOT_PARTITION_INFO HECI command
 2. Get the me_rw.version from the currently selected RW slot.
 3. If the versions from the above 2 locations don't match start the update
    - If CSE's current boot partition is not RO, then
        * Set the CSE's next boot partition to RO using SET_BOOT_PARTITION
          HECI command.
        * Send global reset command to reset the system.
    - Enable HMRFPO (Host ME Region Flash Protection Override) operation
      mode using HMRFPO_ENABLE HECI command
    - Erase and Copy the CBFS CSE RW to CSE RW partition
    - Set the CSE's next boot partition to RW using
      SET_BOOT_PARTITION HECI command
    - Trigger global reset
    - The system should boot with the updated CSE RW partition.

TEST=Verified basic update flows on hatch and helios.
BUG=b:111330995

Change-Id: I12f6bba3324069d65edabaccd234006b0840e700
Signed-off-by: Rizwan Qureshi <rizwan.qureshi@intel.com>
Signed-off-by: Sridhar Siricilla <sridhar.siricilla@intel.com>
Signed-off-by: V Sowmya <v.sowmya@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35403
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

3 files changed, 372 insertions, 0 deletions

diff --git a/Documentation/soc/intel/cse_fw_update/Layout_after.svg b/Documentation/soc/intel/cse_fw_update/Layout_after.svg
new file mode 100644
index 0000000000..95720db6b5
--- /dev/null
+++ b/Documentation/soc/intel/cse_fw_update/Layout_after.svg
@@ -0,0 +1,150 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by Microsoft Visio, SVG Export Layout_after.svg Page-1 -->
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ev="http://www.w3.org/2001/xml-events"
+		width="2.39231in" height="2.05998in" viewBox="0 0 172.246 148.318" xml:space="preserve" color-interpolation-filters="sRGB"
+		class="st12">
+	<style type="text/css">
+	<![CDATA[
+		.st1 {fill:#ffffff;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st2 {fill:#000000;font-family:Calibri;font-size:0.333344em}
+		.st3 {fill:#ffc000;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st4 {fill:#000000;font-family:Calibri;font-size:0.499992em}
+		.st5 {fill:#a5a5a5;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st6 {fill:#a5a5a5;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:1}
+		.st7 {fill:none;stroke:none;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.75}
+		.st8 {stroke:#4bacc6;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.75}
+		.st9 {font-size:1em}
+		.st10 {marker-end:url(#mrkr4-59);stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.75}
+		.st11 {fill:#000000;fill-opacity:1;stroke:#000000;stroke-opacity:1;stroke-width:0.22935779816514}
+		.st12 {fill:none;fill-rule:evenodd;font-size:12px;overflow:visible;stroke-linecap:square;stroke-miterlimit:3}
+	]]>
+	</style>
+
+	<defs id="Markers">
+		<g id="lend4">
+			<path d="M 2 1 L 0 0 L 2 -1 L 2 1 " style="stroke:none"/>
+		</g>
+		<marker id="mrkr4-59" class="st11" refX="-8.72" orient="auto" markerUnits="strokeWidth" overflow="visible">
+			<use xlink:href="#lend4" transform="scale(-4.36,-4.36) "/>
+		</marker>
+	</defs>
+	<g>
+		<title>Page-1</title>
+		<g id="shape116-1" transform="translate(38.7567,-139.932)">
+			<title>Rectangle.116</title>
+			<desc>DESC</desc>
+			<rect x="0" y="143.783" width="79.3701" height="4.53543" class="st1"/>
+			<text x="35.49" y="147.25" class="st2">DESC</text>		</g>
+		<g id="shape117-4" transform="translate(38.7567,-130.935)">
+			<title>Rectangle.117</title>
+			<desc>CSE - RO</desc>
+			<rect x="0" y="139.605" width="79.3701" height="8.71293" class="st3"/>
+			<text x="29.35" y="145.76" class="st4">CSE - RO</text>		</g>
+		<g id="shape118-7" transform="translate(38.5344,-4.54823)">
+			<title>Rectangle.118</title>
+			<rect x="0" y="29.8973" width="79.5923" height="118.421" class="st1"/>
+		</g>
+		<g id="shape119-9" transform="translate(41.225,-5.80807)">
+			<title>Rectangle.119</title>
+			<desc>COREBOOT_RO</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st5"/>
+			<text x="18.32" y="135.95" class="st4">COREBOOT_RO</text>		</g>
+		<g id="shape120-12" transform="translate(41.225,-34.1545)">
+			<title>Rectangle.120</title>
+			<desc>RW_MISC</desc>
+			<rect x="0" y="143.907" width="74.3581" height="4.41113" class="st5"/>
+			<text x="29.12" y="147.31" class="st2">RW_MISC</text>		</g>
+		<g id="shape121-15" transform="translate(41.225,-38.7215)">
+			<title>Rectangle.121</title>
+			<desc>FW_MAIN_B</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st6"/>
+			<text x="21.52" y="129.37" class="st4">FW_MAIN_B</text>		</g>
+		<g id="shape122-18" transform="translate(41.225,-67.0679)">
+			<title>Rectangle.122</title>
+			<desc>FW_MAIN_A</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st6"/>
+			<text x="21.41" y="129.37" class="st4">FW_MAIN_A</text>		</g>
+		<g id="shape123-21" transform="translate(3.88308,-0.375)">
+			<title>Sheet.123</title>
+			<desc>0x1FFFFFF</desc>
+			<rect x="0" y="137.688" width="41.4007" height="10.6299" class="st7"/>
+			<text x="8.09" y="144.8" class="st4">0x1FFFFFF</text>		</g>
+		<g id="shape124-24" transform="translate(21.7488,-138.564)">
+			<title>Sheet.124</title>
+			<desc>0x0</desc>
+			<rect x="0" y="138.939" width="21.2598" height="9.37934" class="st7"/>
+			<text x="6.29" y="145.43" class="st4">0x0</text>		</g>
+		<g id="shape125-27" transform="translate(41.2627,-96.0443)">
+			<title>Rectangle.125</title>
+			<desc>RW_LEGACY</desc>
+			<rect x="0" y="122.448" width="74.3581" height="25.8706" class="st5"/>
+			<text x="27.04" y="136.58" class="st2">RW_LEGACY</text>		</g>
+		<g id="shape126-30" transform="translate(119.253,-6.75295)">
+			<title>Right Brace.126</title>
+			<path d="M-0 148.32 A9.42279 2.96575 -180 0 0 5.11 146.6 L5.11 135.46 L10.21 135.46 L5.11 135.46 L5.11 124.32 A9.42279
+						 2.96575 -180 0 0 0 122.6" class="st8"/>
+		</g>
+		<g id="shape127-33" transform="translate(120.961,-10.2963)">
+			<title>Sheet.127</title>
+			<desc>HW WP</desc>
+			<rect x="0" y="137.688" width="31.1811" height="10.6299" class="st7"/>
+			<text x="6.16" y="144.8" class="st4">HW WP</text>		</g>
+		<g id="shape128-36" transform="translate(119.43,-123.061)">
+			<title>Right Brace.128</title>
+			<path d="M-0 148.32 a10.4615 0.900102 -180 0 0 5.66929 -0.520272 L5.67 144.42 L11.34 144.42 L5.67 144.42 L5.67 141.03
+						 a10.4615 0.900102 -180 0 0 -5.66929 -0.520272" class="st8"/>
+		</g>
+		<g id="shape129-39" transform="translate(126.517,-119.597)">
+			<title>Sheet.129</title>
+			<desc>SPI Controller WP via descriptor</desc>
+			<rect x="0" y="138.043" width="45.3543" height="10.2756" class="st7"/>
+			<text x="5.53" y="141.98" class="st2">SPI Controller WP via <tspan x="14.37" dy="1.2em" class="st9">descriptor</tspan></text>		</g>
+		<g id="group130-43" transform="translate(42.8947,-77.0772)">
+			<title>Sheet.130</title>
+			<g id="shape131-44">
+				<title>Rectangle.423</title>
+				<desc>CSE-RW</desc>
+				<rect x="0" y="141.232" width="70.8661" height="7.08661" class="st3"/>
+				<text x="25.77" y="146.58" class="st4">CSE-RW</text>			</g>
+		</g>
+		<g id="group132-47" transform="translate(42.8947,-48.7307)">
+			<title>Sheet.132</title>
+			<g id="shape133-48">
+				<title>Rectangle.423</title>
+				<desc>CSE-RW</desc>
+				<rect x="0" y="141.232" width="70.8661" height="7.08661" class="st3"/>
+				<text x="25.77" y="146.58" class="st4">CSE-RW</text>			</g>
+		</g>
+		<g id="shape134-51" transform="translate(38.6427,-123.114)">
+			<title>Rectangle.134</title>
+			<desc>CSE-RW</desc>
+			<rect x="0" y="140.497" width="79.3701" height="7.82103" class="st3"/>
+			<text x="30.03" y="146.21" class="st4">CSE-RW</text>		</g>
+		<g id="shape135-54" transform="translate(41.225,-52.8947)">
+			<title>Universal connector.473</title>
+			<path d="M0 148.32 L-8.38 148.32 A8.37776 8.37776 0 0 1 -16.76 139.94 L-16.76 111.25 L-16.76 81.27 A7.08661 7.08661 0
+						 0 1 -9.67 74.19 L-9.12 74.19" class="st10"/>
+		</g>
+		<g id="shape136-60" transform="translate(41.225,-81.2411)">
+			<title>Universal connector.136</title>
+			<path d="M0 148.32 L-8.38 148.32 A8.37776 8.37776 0 0 1 -16.76 139.94 L-16.76 125.43 L-16.76 109.62 A7.08661 7.08661
+						 0 0 1 -9.67 102.53 L-9.12 102.53" class="st10"/>
+		</g>
+		<g id="shape138-65" transform="translate(-124.557,86.8317) rotate(-90)">
+			<title>Sheet.138</title>
+			<desc>CSE RW copied during an update</desc>
+			<rect x="0" y="124.932" width="58.1102" height="23.3858" class="st7"/>
+			<text x="10.77" y="134.83" class="st4">CSE RW copied <tspan x="8.15" dy="1.2em" class="st9">during an update</tspan></text>		</g>
+		<g id="shape139-69" transform="translate(119.43,-133.052)">
+			<title>Right Brace.139</title>
+			<path d="M0 148.32 a10.4615 0.736641 -180 0 0 5.66929 -0.425789 L5.67 145.12 L11.34 145.12 L5.67 145.12 L5.67 142.36
+						 a10.4615 0.736641 -180 0 0 -5.66929 -0.425789" class="st8"/>
+		</g>
+		<g id="shape140-72" transform="translate(127.934,-133.061)">
+			<title>Sheet.140</title>
+			<desc>GRP0 Protected</desc>
+			<rect x="0" y="140.523" width="35.4331" height="7.79528" class="st7"/>
+			<text x="4.86" y="145.62" class="st2">GRP0 Protected</text>		</g>
+	</g>
+</svg>
diff --git a/Documentation/soc/intel/cse_fw_update/Layout_before.svg b/Documentation/soc/intel/cse_fw_update/Layout_before.svg
new file mode 100644
index 0000000000..d03754880e
--- /dev/null
+++ b/Documentation/soc/intel/cse_fw_update/Layout_before.svg
@@ -0,0 +1,95 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by Microsoft Visio, SVG Export Layout_before.svg Page-1 -->
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ev="http://www.w3.org/2001/xml-events"
+		width="2.3058in" height="2.05998in" viewBox="0 0 166.017 148.318" xml:space="preserve" color-interpolation-filters="sRGB"
+		class="st11">
+	<style type="text/css">
+	<![CDATA[
+		.st1 {fill:#ffffff;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st2 {fill:#000000;font-family:Calibri;font-size:0.333344em}
+		.st3 {fill:#ffc000;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st4 {fill:#000000;font-family:Calibri;font-size:0.499992em}
+		.st5 {fill:#a5a5a5;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.24}
+		.st6 {fill:#a5a5a5;stroke:#000000;stroke-linecap:round;stroke-linejoin:round;stroke-width:1}
+		.st7 {fill:none;stroke:none;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.75}
+		.st8 {stroke:#4bacc6;stroke-linecap:round;stroke-linejoin:round;stroke-width:0.75}
+		.st9 {fill:#000000;font-family:Calibri;font-size:0.416656em}
+		.st10 {font-size:1em}
+		.st11 {fill:none;fill-rule:evenodd;font-size:12px;overflow:visible;stroke-linecap:square;stroke-miterlimit:3}
+	]]>
+	</style>
+
+	<g>
+		<title>Page-1</title>
+		<g id="shape87-1" transform="translate(35.2486,-139.932)">
+			<title>Rectangle.178</title>
+			<desc>DESC</desc>
+			<rect x="0" y="143.783" width="79.3701" height="4.53543" class="st1"/>
+			<text x="35.49" y="147.25" class="st2">DESC</text>		</g>
+		<g id="shape88-4" transform="translate(35.2486,-122.945)">
+			<title>Rectangle.179</title>
+			<desc>CSME/PMC</desc>
+			<rect x="0" y="131.615" width="79.3701" height="16.7031" class="st3"/>
+			<text x="25.8" y="141.02" class="st4">CSME/PMC</text>		</g>
+		<g id="shape89-7" transform="translate(35.0263,-4.54823)">
+			<title>Rectangle.180</title>
+			<rect x="0" y="29.8973" width="79.5923" height="118.421" class="st1"/>
+		</g>
+		<g id="shape90-9" transform="translate(37.7169,-5.80807)">
+			<title>Rectangle.181</title>
+			<desc>COREBOOT_RO</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st5"/>
+			<text x="18.32" y="135.95" class="st4">COREBOOT_RO</text>		</g>
+		<g id="shape91-12" transform="translate(37.7169,-34.1545)">
+			<title>Rectangle.182</title>
+			<desc>RW_MISC</desc>
+			<rect x="0" y="143.907" width="74.3581" height="4.41113" class="st5"/>
+			<text x="29.12" y="147.31" class="st2">RW_MISC</text>		</g>
+		<g id="shape92-15" transform="translate(37.7169,-38.7215)">
+			<title>Rectangle.183</title>
+			<desc>FW_MAIN_B</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st6"/>
+			<text x="21.52" y="129.37" class="st4">FW_MAIN_B</text>		</g>
+		<g id="shape93-18" transform="translate(37.7169,-67.0679)">
+			<title>Rectangle.184</title>
+			<desc>FW_MAIN_A</desc>
+			<rect x="0" y="119.972" width="74.3581" height="28.3465" class="st6"/>
+			<text x="21.41" y="129.37" class="st4">FW_MAIN_A</text>		</g>
+		<g id="shape94-21" transform="translate(0.375,-0.375)">
+			<title>Sheet.94</title>
+			<desc>0x1FFFFFF</desc>
+			<rect x="0" y="137.688" width="41.4007" height="10.6299" class="st7"/>
+			<text x="8.09" y="144.8" class="st4">0x1FFFFFF</text>		</g>
+		<g id="shape95-24" transform="translate(18.2407,-138.564)">
+			<title>Sheet.95</title>
+			<desc>0x0</desc>
+			<rect x="0" y="138.939" width="21.2598" height="9.37934" class="st7"/>
+			<text x="6.29" y="145.43" class="st4">0x0</text>		</g>
+		<g id="shape106-27" transform="translate(37.7546,-96.0443)">
+			<title>Rectangle.106</title>
+			<desc>RW_LEGACY</desc>
+			<rect x="0" y="122.448" width="74.3581" height="25.8706" class="st5"/>
+			<text x="27.04" y="136.58" class="st2">RW_LEGACY</text>		</g>
+		<g id="shape113-30" transform="translate(115.744,-6.75295)">
+			<title>Right Brace.398</title>
+			<path d="M-0 148.32 A9.42279 2.96575 -180 0 0 5.11 146.6 L5.11 135.46 L10.21 135.46 L5.11 135.46 L5.11 124.32 A9.42279
+						 2.96575 -180 0 0 0 122.6" class="st8"/>
+		</g>
+		<g id="shape96-33" transform="translate(117.453,-10.2963)">
+			<title>Sheet.96</title>
+			<desc>HW WP</desc>
+			<rect x="0" y="137.688" width="31.1811" height="10.6299" class="st7"/>
+			<text x="6.16" y="144.8" class="st4">HW WP</text>		</g>
+		<g id="shape115-36" transform="translate(116.508,-123.131)">
+			<title>Right Brace.115</title>
+			<path d="M0 148.32 A10.4615 2.27029 -180 0 0 5.67 147.01 L5.67 138.48 L11.34 138.48 L5.67 138.48 L5.67 129.95 A10.4615
+						 2.27029 -180 0 0 0 128.63" class="st8"/>
+		</g>
+		<g id="shape97-39" transform="translate(120.288,-122.265)">
+			<title>Sheet.97</title>
+			<desc>SPI Controller WP via descriptor</desc>
+			<rect x="0" y="124.932" width="45.3543" height="23.3858" class="st7"/>
+			<text x="4.71" y="135.13" class="st9">SPI Controller WP <tspan x="8.83" dy="1.2em" class="st10">via descriptor</tspan></text>		</g>
+	</g>
+</svg>
diff --git a/Documentation/soc/intel/cse_fw_update/cse_fw_update.md b/Documentation/soc/intel/cse_fw_update/cse_fw_update.md
new file mode 100644
index 0000000000..98fe310113
--- /dev/null
+++ b/Documentation/soc/intel/cse_fw_update/cse_fw_update.md
@@ -0,0 +1,127 @@
+CSE FW update mechanism for devices in field
+
+## Introduction
+
+CSE Firmware and PMC Firmware are critical components of Intel SoCs.
+CSE and PMC cooperate by providing platform services during boot and other
+power transition flows.
+
+## Problem Statement
+
+Currently, on Chromium OS Systems, CSE region is not updatable. So, new CSE FW
+versions that are released by Intel to address important functional and security
+bugs post-product launch will not be available to the end-user. Hence, the proposed
+solution allows in-field CSE FW update to propagate those bug fixes
+to end user platforms.
+
+## Design Proposal
+
+### CSE FW design Proposal:
+
+Key Elements:
+
+- CSE FW layout is composed of two bootable partitions (RO Recovery Partition
+  and RW Normal Partition).
+
+- Boot partition selection: An API-based mechanism is used to decide from which partition
+  CSE will boot.
+
+- The HECI APIs below will be supported in this CSE FW:
+
+    - HMRFPO_ENABLE: This command requests the CSE enter a mode in which writes to
+    the CSE region from the CSE are disabled. It also grants temporary write access
+    to the RW partition from the host (RO is still protected by GPR0).
+
+    - GET_PARTITION_INFO: The command retrieves information for each boot partition from CSE
+    like version, start/end offsets of a partition within CSE region, and boot
+    partition status. Also, it provides below information:
+	    - The current boot partition which was used during this boot,
+	    - The boot partition that will be used on the next CSE reset
+	    - The number of boot partitions available in the CSE region
+
+    - SET_BOOT_PARTITION_INFO: This command allows the firmware to request the
+    CSE to boot from either its RO or RW partition at its next reset.
+
+    - DATA_CLEAR: This command requests the CSE to reset its data partition back
+    to manufacturing defaults
+
+FW Layout, RW/RO Partitions:
+
+The CSE RO partition is the first in the CSE boot order, hence it will be used
+out of G3. RO partition contains minimum CSE code capable to boot platform and
+execute FW update of RW partition. In addition to CSE code, the RO partition also
+contains PMC FW patch and other CSE-loadable platform FW components.
+
+RW partition contains fully operational CSE FW, PMC FW, other CSE loadable
+platform FW components.
+
+Boot partition selection:
+
+CSE FW shall support 2 APIs to get boot partition info, and set boot partition
+info to notify CSE to select the partition on the next boot.
+
+### HOST FW Design proposal:
+
+Key Elements:
+
+- Build time artifacts:
+
+    CSE RW Version update binary - The FW shall pack CSE RW update blob and
+    corresponding version binary which contains version of the CSE RW blob.
+
+- FW Update:
+
+    coreboot will implement the logic to compare the CSE's FW version with CBFS
+    CSE RW binary's version in the firmware slot (FW_MAIN_A/FW_MAIN_B) and update
+    the CSE RW region if there is a version mismatch. If there is no version
+    mismatch, firmware skips CSE FW update.
+
+- Handling of CSE FW Downgrade:
+
+  coreboot will send DATA_CLEAR HECI command when there is a CSE FW downgrade.
+  This must be done to avoid data mismatch due to CSE FW downgrade. Further,
+  CSE will restore the data back to manufacturing defaults after data reset.
+
+
+## Implementation Details
+
+
+To enable CSE FW update flow the following changes are required in coreboot:
+
+* Descriptor change may be required to accommodate CSE binary. The CSE binary is tied with
+a platform. So CSE size may vary from one platform to another.
+* FMAP changes may be required to accommodate CSE binary and CSE RW blob in the RW CBFS region.
+Please check platform specific CSE kit for CSE binary information.
+* CSE Lite SKU binary and CSE RW blob
+* Makefile change to pack CSE RW binaries in the CBFS
+* Implementation of update flow:
+ - Get CSE boot partition info using GET_BOOT_PARTITION_INFO HECI command.
+ - Get the cbfs_me_rw.version from the currently selected RW slot.
+ - If the version from the above 2 locations don't match, then start CSE FW update.
+	 - If CSE is not booting from RO, then
+		- Set the CSE's next boot partition to RO using SET_BOOT_PARTITION_INFO
+        HECI command.
+		- Send GLOBAL_RESET HECI command to reset the system.
+	 - If RW update is a CSE FW downgrade, then coreboot has to send
+        DATA_CLEAR command to clear run time data of CSE.
+	 - Enable HMRFPO Mode (Host ME Region Flash Protection Override) by
+        sending HMRFPO_ENABLE HECI command to CSE.
+	 - Erase and Copy the CBFS CSE RW to CSE RW partition
+     - Set CSE's next boot partition to RW.
+	 - Trigger Global Reset which resets both CSE and Host.
+	Then system should boot with the updated CSE.
+
+* The resulting flash layout is shown below:
+
+![Flash Layout](./Layout_before.svg) ![FlashLayout](./Layout_after.svg)
+
+
+ - Typical boot flow
+
+   - Vboot selects the RW FW (FW_MAIN_A or FW_MAIN_B) to boot.
+   - coreboot skips CSE FW update flow if boot mode is recovery.
+   - If CSE RW blob is not locatable in the CBFS, then RW Firmware skips update flow
+     and sends SET_BOOT_PARTITION_INFO command to switch CSE to boot from RW
+     and issues Global Reset if CSE is already not booting from RW partition.
+   - The RW firmware will compare the CSE RW version with CSE RW blob in the slot.
+   - If there is a mismatch, then firmware will carry out update flow as explained before.