mirror of
https://github.com/torvalds/linux.git
synced 2024-12-04 01:51:34 +00:00
04165fb73f
- Add documentation for SB-RMI module Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Akshay Gupta <Akshay.Gupta@amd.com> Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com> Link: https://lore.kernel.org/r/20210726133615.9709-2-nchatrad@amd.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
80 lines
3.0 KiB
ReStructuredText
80 lines
3.0 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-or-later
|
|
|
|
Kernel driver sbrmi
|
|
===================
|
|
|
|
Supported hardware:
|
|
|
|
* Sideband Remote Management Interface (SB-RMI) compliant AMD SoC
|
|
device connected to the BMC via the APML.
|
|
|
|
Prefix: 'sbrmi'
|
|
|
|
Addresses scanned: This driver doesn't support address scanning.
|
|
|
|
To instantiate this driver on an AMD CPU with SB-RMI
|
|
support, the i2c bus number would be the bus connected from the board
|
|
management controller (BMC) to the CPU.
|
|
The SMBus address is really 7 bits. Some vendors and the SMBus
|
|
specification show the address as 8 bits, left justified with the R/W
|
|
bit as a write (0) making bit 0. Some vendors use only the 7 bits
|
|
to describe the address.
|
|
As mentioned in AMD's APML specification, The SB-RMI address is
|
|
normally 78h(0111 100W) or 3Ch(011 1100) for socket 0 and 70h(0111 000W)
|
|
or 38h(011 1000) for socket 1, but it could vary based on hardware
|
|
address select pins.
|
|
|
|
Datasheet: The SB-RMI interface and protocol along with the Advanced
|
|
Platform Management Link (APML) Specification is available
|
|
as part of the open source SoC register reference at:
|
|
|
|
https://www.amd.com/en/support/tech-docs?keyword=55898
|
|
|
|
Author: Akshay Gupta <akshay.gupta@amd.com>
|
|
|
|
Description
|
|
-----------
|
|
|
|
The APML provides a way to communicate with the SB Remote Management interface
|
|
(SB-RMI) module from the external SMBus master that can be used to report socket
|
|
power on AMD platforms using mailbox command and resembles a typical 8-pin remote
|
|
power sensor's I2C interface to BMC.
|
|
|
|
This driver implements current power with power cap and power cap max.
|
|
|
|
sysfs-Interface
|
|
---------------
|
|
Power sensors can be queried and set via the standard ``hwmon`` interface
|
|
on ``sysfs``, under the directory ``/sys/class/hwmon/hwmonX`` for some value
|
|
of ``X`` (search for the ``X`` such that ``/sys/class/hwmon/hwmonX/name`` has
|
|
content ``sbrmi``)
|
|
|
|
================ ===== ========================================================
|
|
Name Perm Description
|
|
================ ===== ========================================================
|
|
power1_input RO Current Power consumed
|
|
power1_cap RW Power limit can be set between 0 and power1_cap_max
|
|
power1_cap_max RO Maximum powerlimit calculated and reported by the SMU FW
|
|
================ ===== ========================================================
|
|
|
|
The following example show how the 'Power' attribute from the i2c-addresses
|
|
can be monitored using the userspace utilities like ``sensors`` binary::
|
|
|
|
# sensors
|
|
sbrmi-i2c-1-38
|
|
Adapter: bcm2835 I2C adapter
|
|
power1: 61.00 W (cap = 225.00 W)
|
|
|
|
sbrmi-i2c-1-3c
|
|
Adapter: bcm2835 I2C adapter
|
|
power1: 28.39 W (cap = 224.77 W)
|
|
#
|
|
|
|
Also, Below shows how get and set the values from sysfs entries individually::
|
|
# cat /sys/class/hwmon/hwmon1/power1_cap_max
|
|
225000000
|
|
|
|
# echo 180000000 > /sys/class/hwmon/hwmon1/power1_cap
|
|
# cat /sys/class/hwmon/hwmon1/power1_cap
|
|
180000000
|