On Fri, Jun 25, 2021 at 06:55:43PM +0530, Naveen Krishna Chatradhi wrote: > From: Akshay Gupta <Akshay.Gupta@xxxxxxx> > > - Add documentation for sbrmi module > > Signed-off-by: Akshay Gupta <Akshay.Gupta@xxxxxxx> > Signed-off-by: Naveen Krishna Chatradhi <nchatrad@xxxxxxx> > --- > Documentation/hwmon/index.rst | 1 + > Documentation/hwmon/sbrmi.rst | 79 +++++++++++++++++++++++++++++++++++ > 2 files changed, 80 insertions(+) > create mode 100644 Documentation/hwmon/sbrmi.rst > > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst > index 9ed60fa84cbe..5cd4798fe193 100644 > --- a/Documentation/hwmon/index.rst > +++ b/Documentation/hwmon/index.rst > @@ -158,6 +158,7 @@ Hardware Monitoring Kernel Drivers > q54sj108a2 > raspberrypi-hwmon > sbtsi_temp > + sbrmi > sch5627 > sch5636 > scpi-hwmon > diff --git a/Documentation/hwmon/sbrmi.rst b/Documentation/hwmon/sbrmi.rst > new file mode 100644 > index 000000000000..db50393167bb > --- /dev/null > +++ b/Documentation/hwmon/sbrmi.rst > @@ -0,0 +1,79 @@ > +.. 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@xxxxxxx> > + > +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 > +================ ===== ======================================================== > +power#_input RO Current Power consumed > +power#_cap RW Power limit can be set between 0 and power#_cap_max > +power#_cap_max RO Maximum powerlimit calculated and reported by the SMU FW '#' is always '1', so just say so. > +================ ===== ======================================================== > + > +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
