Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
40e639041d
On new SoCs (SDM845 onwards) the Operating State Manager (OSM) is being programmed in the bootloader and write-protected by the hypervisor, leaving to the OS read-only access to some of its registers (in order to read the Lookup Tables and also some status registers) and write access to the p-state register, for for the OS to request a specific performance state to trigger a DVFS switch on the CPU through the OSM hardware. On old SoCs though (MSM8998, SDM630/660 and variants), the bootloader will *not* initialize the OSM (and the CPRh, as it is a requirement for it) before booting the OS, making any request to trigger a performance state change ineffective, as the hardware doesn't have any Lookup Table, nor is storing any parameter to trigger a DVFS switch. In this case, basically all of the OSM registers are *not* write protected for the OS, even though some are - but write access is granted through SCM calls. This commit introduces support for OSM programming, which has to be done on these old SoCs that were distributed (almost?) always with a bootloader that does not do any CPRh nor OSM init before booting the kernel. In order to program the OSM on these SoCs, it is necessary to fullfill a "special" requirement: the Core Power Reduction Hardened (CPRh) hardware block must be initialized, as the OSM is "talking" to it in order to perform the Voltage part of DVFS; here, we are calling initialization of this through Linux generic power domains, specifically by requesting a genpd attach from the qcom-cpufreq-hw driver, which will give back voltages associated to each CPU frequency that has been declared in the OPPs, scaled and interpolated with the previous one, and will also give us parameters for the Array Power Mux (APM) and mem-acc, in order for this driver to be then able to generate the Lookup Tables that will be finally programmed to the OSM hardware. After writing the parameters to the OSM and enabling it, all the programming work will never happen anymore until a OS reboot, so all of the allocations and "the rest" will be disposed-of: this is done mainly to leave the code that was referred only to the new SoCs intact, as to also emphasize on the fact that the OSM HW is, in the end, the exact same; apart some register offsets that are slightly different, the entire logic is the same. This also adds the parameters to support CPU scaling on SDM630 and MSM8998. Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org> [Fixup for 5.15 by Jami] |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.