[PATCH 1/3][SRU][Unstable][Oracular] Documentation: hid: intel-ish-hid: Add vendor custom firmware loading

[You-Sheng Yang]

From: Zhang Lixu <lixu.zhang at intel.com>

BugLink: https://bugs.launchpad.net/bugs/2071698

Add ISH firmware loading guidelines for vendor custom firmware.

Signed-off-by: Zhang Lixu <lixu.zhang at intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada at linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina at suse.com>
(cherry picked from commit 87de1615194eeb43b14cf5355ede3bd2115e0ff4 linux-next)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 Documentation/hid/intel-ish-hid.rst | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Documentation/hid/intel-ish-hid.rst b/Documentation/hid/intel-ish-hid.rst
index 55cbaa719a794..2adc174fb576c 100644
--- a/Documentation/hid/intel-ish-hid.rst
+++ b/Documentation/hid/intel-ish-hid.rst
@@ -404,6 +404,35 @@ For more detailed information, please refer to the flow descriptions provided be
   | ISHTP Driver  |                                                    | ISH Bootloader  |
   +---------------+                                                    +-----------------+
 
+Vendor Custom Firmware Loading
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The firmware running inside ISH can be provided by Intel or developed by vendors using the Firmware Development Kit (FDK) provided by Intel.
+Intel will upstream the Intel-built firmware to the ``linux-firmware.git`` repository, located under the path ``intel/ish/``. For the Lunar Lake platform, the Intel-built ISH firmware will be named ``ish_lnlm.bin``.
+Vendors who wish to upstream their custom firmware should follow these guidelines for naming their firmware files:
+
+- The firmware filename should use one of the following patterns:
+
+  - ``ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_NAME_CRC32}_${PRODUCT_SKU_CRC32}.bin``
+  - ``ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_SKU_CRC32}.bin``
+  - ``ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_NAME_CRC32}.bin``
+  - ``ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}.bin``
+
+- ``${intel_plat_gen}`` indicates the Intel platform generation (e.g., ``lnlm`` for Lunar Lake) and must not exceed 8 characters in length.
+- ``${SYS_VENDOR_CRC32}`` is the CRC32 checksum of the ``sys_vendor`` value from the DMI field ``DMI_SYS_VENDOR``.
+- ``${PRODUCT_NAME_CRC32}`` is the CRC32 checksum of the ``product_name`` value from the DMI field ``DMI_PRODUCT_NAME``.
+- ``${PRODUCT_SKU_CRC32}`` is the CRC32 checksum of the ``product_sku`` value from the DMI field ``DMI_PRODUCT_SKU``.
+
+During system boot, the ISH Linux driver will attempt to load the firmware in the following order, prioritizing custom firmware with more precise matching patterns:
+
+1. ``intel/ish/ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_NAME_CRC32}_${PRODUCT_SKU_CRC32}.bin``
+2. ``intel/ish/ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_SKU_CRC32}.bin``
+3. ``intel/ish/ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}_${PRODUCT_NAME_CRC32}.bin``
+4. ``intel/ish/ish_${intel_plat_gen}_${SYS_VENDOR_CRC32}.bin``
+5. ``intel/ish/ish_${intel_plat_gen}.bin``
+
+The driver will load the first matching firmware and skip the rest. If no matching firmware is found, it will proceed to the next pattern in the specified order. If all searches fail, the default Intel firmware, listed last in the order above, will be loaded.
+
 ISH Debugging
 -------------
 
-- 
2.45.2