diff options
| author | Pratik R. Sampat <psampat@linux.ibm.com> | 2022-02-17 16:23:20 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-03-08 00:05:00 +1100 |
| commit | 3c14b73454cf9f6e2146443fdfbdfb912c0efed3 (patch) | |
| tree | 5c29ed10af89390574941a6a3e7579a0e7682eb5 /Documentation/ABI | |
| parent | cc15ff3275694fedc33cd3d53212a43eec7aa0bc (diff) | |
powerpc/pseries: Interface to represent PAPR firmware attributes
Adds a syscall interface to represent the energy and frequency related
PAPR attributes on the system using the new H_CALL
"H_GET_ENERGY_SCALE_INFO".
H_GET_EM_PARMS H_CALL was previously responsible for exporting this
information in the lparcfg, however the H_GET_EM_PARMS H_CALL
will be deprecated P10 onwards.
The H_GET_ENERGY_SCALE_INFO H_CALL is of the following call format:
hcall(
uint64 H_GET_ENERGY_SCALE_INFO, // Get energy scale info
uint64 flags, // Per the flag request
uint64 firstAttributeId,// The attribute id
uint64 bufferAddress, // Guest physical address of the output buffer
uint64 bufferSize // The size in bytes of the output buffer
);
As specified in PAPR+ v2.11, section 14.14.3.
This H_CALL can query either all the attributes at once with
firstAttributeId = 0, flags = 0 as well as query only one attribute
at a time with firstAttributeId = id, flags = 1.
The output buffer consists of the following
1. number of attributes - 8 bytes
2. array offset to the data location - 8 bytes
3. version info - 1 byte
4. A data array of size num attributes, which contains the following:
a. attribute ID - 8 bytes
b. attribute value in number - 8 bytes
c. attribute name in string - 64 bytes
d. attribute value in string - 64 bytes
The new H_CALL exports information in direct string value format, hence
a new interface has been introduced in
/sys/firmware/papr/energy_scale_info to export this information to
userspace so that the firmware can add new values without the need for
the kernel to be changed.
The H_CALL returns the name, numeric value and string value (if exists)
The format of exposing the sysfs information is as follows:
/sys/firmware/papr/energy_scale_info/
|-- <id>/
|-- desc
|-- value
|-- value_desc (if exists)
|-- <id>/
|-- desc
|-- value
|-- value_desc (if exists)
...
The energy information that is exported is useful for userspace tools
such as powerpc-utils. Currently these tools infer the
"power_mode_data" value in the lparcfg, which in turn is obtained from
the to be deprecated H_GET_EM_PARMS H_CALL.
On future platforms, such userspace utilities will have to look at the
data returned from the new H_CALL being populated in this new sysfs
interface and report this information directly without the need of
interpretation.
Signed-off-by: Pratik R. Sampat <psampat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220217105321.52941-2-psampat@linux.ibm.com
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info b/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info new file mode 100644 index 000000000000..141a6b371469 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info @@ -0,0 +1,29 @@ +What: /sys/firmware/papr/energy_scale_info +Date: February 2022 +Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> +Description: Directory hosting a set of platform attributes like + energy/frequency on Linux running as a PAPR guest. + + Each file in a directory contains a platform + attribute hierarchy pertaining to performance/ + energy-savings mode and processor frequency. + +What: /sys/firmware/papr/energy_scale_info/<id> +Date: February 2022 +Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> +Description: Energy, frequency attributes directory for POWERVM servers + +What: /sys/firmware/papr/energy_scale_info/<id>/desc +Date: February 2022 +Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> +Description: String description of the energy attribute of <id> + +What: /sys/firmware/papr/energy_scale_info/<id>/value +Date: February 2022 +Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> +Description: Numeric value of the energy attribute of <id> + +What: /sys/firmware/papr/energy_scale_info/<id>/value_desc +Date: February 2022 +Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> +Description: String value of the energy attribute of <id> |