ethtool: Add ability to control transceiver modules' power mode

ethtool: Add ability to control transceiver modules' power mode

Add a pair of new ethtool messages, 'ETHTOOL_MSG_MODULE_SET' and
'ETHTOOL_MSG_MODULE_GET', that can be used to control transceiver
modules parameters and retrieve their status.

The first parameter to control is the power mode of the module. It is
only relevant for paged memory modules, as flat memory modules always
operate in low power mode.

When a paged memory module is in low power mode, its power consumption
is reduced to the minimum, the management interface towards the host is
available and the data path is deactivated.

User space can choose to put modules that are not currently in use in
low power mode and transition them to high power mode before putting the
associated ports administratively up. This is useful for user space that
favors reduced power consumption and lower temperatures over reduced
link up times. In QSFP-DD modules the transition from low power mode to
high power mode can take a few seconds and this transition is only
expected to get longer with future / more complex modules.

User space can control the power mode of the module via the power mode
policy attribute ('ETHTOOL_A_MODULE_POWER_MODE_POLICY'). Possible
values:

* high: Module is always in high power mode.

* auto: Module is transitioned by the host to high power mode when the
  first port using it is put administratively up and to low power mode
  when the last port using it is put administratively down.

The operational power mode of the module is available to user space via
the 'ETHTOOL_A_MODULE_POWER_MODE' attribute. The attribute is not
reported to user space when a module is not plugged-in.

The user API is designed to be generic enough so that it could be used
for modules with different memory maps (e.g., SFF-8636, CMIS).

The only implementation of the device driver API in this series is for a
MAC driver (mlxsw) where the module is controlled by the device's
firmware, but it is designed to be generic enough so that it could also
be used by implementations where the module is controlled by the CPU.

CMIS testing
============

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x03 (ModuleReady)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : Off

The module is not in low power mode, as it is not forced by hardware
(LowPwrAllowRequestHW is off) or by software (LowPwrRequestSW is off).

The power mode can be queried from the kernel. In case
LowPwrAllowRequestHW was on, the kernel would need to take into account
the state of the LowPwrRequestHW signal, which is not visible to user
space.

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy high
 power-mode high

Change the power mode policy to 'auto':

 # ethtool --set-module swp11 power-mode-policy auto

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x01 (ModuleLowPwr)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : On

Put the associated port administratively up which will instruct the host
to transition the module to high power mode:

 # ip link set dev swp11 up

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode high

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x03 (ModuleReady)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : Off

Put the associated port administratively down which will instruct the
host to transition the module to low power mode:

 # ip link set dev swp11 down

Query the power mode again:

 $ ethtool --show-module swp11
 Module parameters for swp11:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp11
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 ...
 Module State                              : 0x01 (ModuleLowPwr)
 LowPwrAllowRequestHW                      : Off
 LowPwrRequestSW                           : On

SFF-8636 testing
================

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) enabled
 Power set                                 : Off
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.7733 mW / -1.12 dBm
 Transmit avg optical power (Channel 2)    : 0.7649 mW / -1.16 dBm
 Transmit avg optical power (Channel 3)    : 0.7790 mW / -1.08 dBm
 Transmit avg optical power (Channel 4)    : 0.7837 mW / -1.06 dBm
 Rcvr signal avg optical power(Channel 1)  : 0.9302 mW / -0.31 dBm
 Rcvr signal avg optical power(Channel 2)  : 0.9079 mW / -0.42 dBm
 Rcvr signal avg optical power(Channel 3)  : 0.8993 mW / -0.46 dBm
 Rcvr signal avg optical power(Channel 4)  : 0.8778 mW / -0.57 dBm

The module is not in low power mode, as it is not forced by hardware
(Power override is on) or by software (Power set is off).

The power mode can be queried from the kernel. In case Power override
was off, the kernel would need to take into account the state of the
LPMode signal, which is not visible to user space.

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy high
 power-mode high

Change the power mode policy to 'auto':

 # ethtool --set-module swp13 power-mode-policy auto

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) not enabled
 Power set                                 : On
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 2)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 3)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 4)    : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 1)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 2)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 3)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 4)  : 0.0000 mW / -inf dBm

Put the associated port administratively up which will instruct the host
to transition the module to high power mode:

 # ip link set dev swp13 up

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode high

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) enabled
 Power set                                 : Off
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.7934 mW / -1.01 dBm
 Transmit avg optical power (Channel 2)    : 0.7859 mW / -1.05 dBm
 Transmit avg optical power (Channel 3)    : 0.7885 mW / -1.03 dBm
 Transmit avg optical power (Channel 4)    : 0.7985 mW / -0.98 dBm
 Rcvr signal avg optical power(Channel 1)  : 0.9325 mW / -0.30 dBm
 Rcvr signal avg optical power(Channel 2)  : 0.9034 mW / -0.44 dBm
 Rcvr signal avg optical power(Channel 3)  : 0.9086 mW / -0.42 dBm
 Rcvr signal avg optical power(Channel 4)  : 0.8885 mW / -0.51 dBm

Put the associated port administratively down which will instruct the
host to transition the module to low power mode:

 # ip link set dev swp13 down

Query the power mode again:

 $ ethtool --show-module swp13
 Module parameters for swp13:
 power-mode-policy auto
 power-mode low

Verify with the data read from the EEPROM:

 # ethtool -m swp13
 Identifier                                : 0x11 (QSFP28)
 ...
 Extended identifier description           : 5.0W max. Power consumption,  High Power Class (> 3.5 W) not enabled
 Power set                                 : On
 Power override                            : On
 ...
 Transmit avg optical power (Channel 1)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 2)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 3)    : 0.0000 mW / -inf dBm
 Transmit avg optical power (Channel 4)    : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 1)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 2)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 3)  : 0.0000 mW / -inf dBm
 Rcvr signal avg optical power(Channel 4)  : 0.0000 mW / -inf dBm

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>