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On Apple platforms, firmware selection uses the following elements:
Property Example Source
============== ======= ========================
* Chip name 4378 Device ID
* Chip revision B1 OTP
* Platform shikoku DT (ARM64) or ACPI (x86)
* Module type RASP OTP
* Module vendor m OTP
* Module version 6.11 OTP
* Antenna SKU X3 DT (ARM64) or ACPI (x86)
In macOS, these firmwares are stored using filenames in this format
under /usr/share/firmware/wifi:
C-4378__s-B1/P-shikoku-X3_M-RASP_V-m__m-6.11.txt
To prepare firmwares for Linux, we rename these to a scheme following
the existing brcmfmac convention:
brcmfmac<chip><lower(rev)>-pcie.apple,<platform>-<mod_type>-\
<mod_vendor>-<mod_version>-<antenna_sku>.txt
The NVRAM uses all the components, while the firmware and CLM blob only
use the chip/revision/platform/antenna_sku:
brcmfmac<chip><lower(rev)>-pcie.apple,<platform>-<antenna_sku>.bin
e.g.
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-m-6.11-X3.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-X3.bin
In addition, since there are over 1000 files in total, many of which are
symlinks or outright duplicates, we deduplicate and prune the firmware
tree to reduce firmware filenames to fewer dimensions. For example, the
shikoku platform (MacBook Air M1 2020) simplifies to just 4 files:
brcm/brcmfmac4378b1-pcie.apple,shikoku.clm_blob
brcm/brcmfmac4378b1-pcie.apple,shikoku.bin
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-m.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-u.txt
This reduces the total file count to around 170, of which 75 are
symlinks and 95 are regular files: 7 firmware blobs, 27 CLM blobs, and
61 NVRAM config files. We also slightly process NVRAM files to correct
some formatting issues.
To handle this, the driver must try the following path formats when
looking for firmware files:
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-m-6.11-X3.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-m-6.11.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP-m.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-RASP.txt
brcm/brcmfmac4378b1-pcie.apple,shikoku-X3.txt *
brcm/brcmfmac4378b1-pcie.apple,shikoku.txt
* Not relevant for NVRAM, only for firmware/CLM.
The chip revision nominally comes from OTP on Apple platforms, but it
can be mapped to the PCI revision number, so we ignore the OTP revision
and continue to use the existing PCI revision mechanism to identify chip
revisions, as the driver already does for other chips. Unfortunately,
the mapping is not consistent between different chip types, so this has
to be determined experimentally.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/E1oZDns-0077aY-Qn@rmk-PC.armlinux.org.uk
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.