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668ce99e4e
Add two additional attributes to the existing power participant driver:
rest_of_platform_power_mw: (RO) Shows the rest of worst case platform
power in mW outside of S0C. This will help in power distribution to SoC
and rest of the system. For example on a test system, this value is 2.5W
with a 15W TDP SoC. Based on the adapter rating (adapter_rating_mw), user
space software can decide on proper power allocation to SoC to improve
short term performance via powercap/RAPL interface.
prochot_confirm: (WO) Confirm EC about a prochot notification.
Also userspace is notified via sysfs_notify(), whenever power source or
rest of the platform power is changed. So user space can use poll()
system call on those attributes.
The ACPI methods used in this patch are as follows:
PROP
This object evaluates to the rest of worst case platform power in mW.
Bits:
23:0 Worst case rest of platform power in mW.
PBOK
PBOK is a method designed to provide a mechanism for OSPM to change power
setting before EC can de-assert a PROCHOT from a device. The EC may
receive several PROCHOTs, so it has a sequence number attached to PSRC
(read via existing attribute "platform_power_source"). Once OSPM takes
action for a PSRC change notification, it can call PBOK method to confirm
with the sequence number.
Bits:
3:0 Power Delivery State Change Sequence number
30 Reserved
31 0 – Not OK to de-assert PROCHOT
1 – OK to de-assert PROCHOT
PSRC (Platform Power Source): Not new in this patch but for
documentation for new bits
This object evaluates to an integer that represents the system power
source as well as the power delivery state change sequence number.
Bits:
3:0 The current power source as an integer for AC, DC, USB, Wireless.
0 = DC, 1 = AC, 2 = USB, 3 = Wireless Charging
7:4 Power Delivery State Change Sequence Number. Default value is 0
Notifications:
0x81: (Power State Change) Used to notify when the power source has
changed.
0x84: (PROP change) Used to notify when the platform rest of power has
changed.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject, minor ABI documentation edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This directory attempts to document the ABI between the Linux kernel and userspace, and the relative stability of these interfaces. Due to the everchanging nature of Linux, and the differing maturity levels, these interfaces should be used by userspace programs in different ways. We have four different levels of ABI stability, as shown by the four different subdirectories in this location. Interfaces may change levels of stability according to the rules described below. The different levels of stability are: stable/ This directory documents the interfaces that the developer has defined to be stable. Userspace programs are free to use these interfaces with no restrictions, and backward compatibility for them will be guaranteed for at least 2 years. Most interfaces (like syscalls) are expected to never change and always be available. testing/ This directory documents interfaces that are felt to be stable, as the main development of this interface has been completed. The interface can be changed to add new features, but the current interface will not break by doing this, unless grave errors or security problems are found in them. Userspace programs can start to rely on these interfaces, but they must be aware of changes that can occur before these interfaces move to be marked stable. Programs that use these interfaces are strongly encouraged to add their name to the description of these interfaces, so that the kernel developers can easily notify them if any changes occur (see the description of the layout of the files below for details on how to do this.) obsolete/ This directory documents interfaces that are still remaining in the kernel, but are marked to be removed at some later point in time. The description of the interface will document the reason why it is obsolete and when it can be expected to be removed. removed/ This directory contains a list of the old interfaces that have been removed from the kernel. Every file in these directories will contain the following information: What: Short description of the interface Date: Date created KernelVersion: Kernel version this feature first showed up in. Contact: Primary contact for this interface (may be a mailing list) Description: Long description of the interface and how to use it. Users: All users of this interface who wish to be notified when it changes. This is very important for interfaces in the "testing" stage, so that kernel developers can work with userspace developers to ensure that things do not break in ways that are unacceptable. It is also important to get feedback for these interfaces to make sure they are working in a proper way and do not need to be changed further. How things move between levels: Interfaces in stable may move to obsolete, as long as the proper notification is given. Interfaces may be removed from obsolete and the kernel as long as the documented amount of time has gone by. Interfaces in the testing state can move to the stable state when the developers feel they are finished. They cannot be removed from the kernel tree without going through the obsolete state first. It's up to the developer to place their interfaces in the category they wish for it to start out in. Notable bits of non-ABI, which should not under any circumstances be considered stable: - Kconfig. Userspace should not rely on the presence or absence of any particular Kconfig symbol, in /proc/config.gz, in the copy of .config commonly installed to /boot, or in any invocation of the kernel build process. - Kernel-internal symbols. Do not rely on the presence, absence, location, or type of any kernel symbol, either in System.map files or the kernel binary itself. See Documentation/process/stable-api-nonsense.rst.